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Chapter 1

MULTIPLE CHOICE QUESTIONS Topic: Atomic Orbitals

1. In quantum mechanics a node (nodal surface or plane) is: A) a place where Ψ is negative. B) a place where Ψ is positive. C) a place where Ψ = 0. D) a place where Ψ2 is large. E) a place where Ψ2 is negative.

Ans: C Topic: Atomic Orbitals, Molecular Orbitals

2. When the 1s orbitals of two hydrogen atoms combine to form a hydrogen molecule, how many molecular orbitals are formed?

A) 1 B) 2 C) 3 D) 4 E) 5

Ans: B Topic: Atomic Orbitals

3. Which principle(s) or rule must be used to determine the correct electronic configuration for carbon in its ground state?

A) Aufbau Principle B) Hund's Rule C) Pauli Exclusion Principle D) (A) and (B) only E) All three

Ans: E

Chapter 1

Topic: Atomic Orbitals, Bonding

4. What point on the potential energy diagram below represents the most stable state for the hydrogen molecule?

A) I B) II C) III D) IV E) V

Ans: C Topic: Atomic Orbitals, Molecular Orbitals

5. According to molecular orbital theory, which molecule could not exist? A) H2 B) He2 C) Li2 D) F2 E) N2

Ans: B Topic: Atomic Orbitals, Molecular Orbitals

6. When the ls orbitals of two hydrogen atoms combine to form a hydrogen molecule, which molecular orbitals are formed?

A) One bonding molecular orbital only B) Two bonding molecular orbitals C) One bonding molecular orbital and one antibonding molecular orbital D) Two antibonding molecular orbitals E) Three bonding molecular orbitals

Ans: C

Chapter 1

Topic: Atomic Orbitals, Hybridization

7. The following electron configuration represents _______.

1s 2sp32sp32sp32sp3

A) the ground state of boron. B) the sp3 hybridized state of carbon. C) the sp3 hybridized state of nitrogen. D) the ground state of carbon. E) an excited state of carbon.

Ans: C Topic: Atomic Orbitals, Molecular Orbitals

8. According to molecular orbital theory, in the case of a carbon-carbon double bond, the carbon-carbon bonding electrons of higher energy occupy this molecular orbital.

A) σ bonding MO B) π bonding MO C) σ* antibonding MO D) π* antibonding MO E) π* bonding MO

Ans: B Topic: Atomic Orbitals, Hybridization

9. Identify the atomic orbitals in the C-C sigma bond in ethyne. A) (2sp2, 2sp2) B) (2sp3, 2sp3) C) (2sp, 2sp) D) (2p, 2p) E) (2sp, 1s)

Ans: C

Chapter 1

Topic: Lewis Structures, Formal Charges

10. Listed below are electron dot formulas for several simple molecules and ions. All valence electrons are shown; however, electrical charges have been omitted deliberately.

H H H H

I II III IV V

H : Be : H H : B : H H : N : H H : N : H H : O : H. .. .. .. .

. . . . . . . .

Which of the structures actually bear(s) a positive charge?

A) I B) II C) III D) III & V E) IV & V

Ans: E Topic: Lewis Structures, Formal Charges

11. What is the formal charge on oxygen in the following structure? OH3C CH3

CH3

. .

A) +2 B) +1 C) 0 D) -1 E) -2

Ans: B

Chapter 1

Topic: Lewis Structures, Formal Charges

12. In which structure(s) below does the oxygen have a formal charge of +1?

OC HHOHOH H

OH3C CH3

CH3

II III IVI

. .. .. .. .:. .

A) I only B) II only C) I and III D) I and IV E) I, III, and IV

Ans: E Topic: Lewis Structures, Formal Charges

13. Which structure(s) contain(s) an oxygen that bears a formal charge of +1?

OH3C CH3

CH3

OH3C H

HIII

OCO

. .. .. .::. .

. .

. . ::

A) I and II B) III and IV C) V D) II E) I and V

Ans: B

Chapter 1

Topic: Lewis Structures, Formal Charges

14. Which of the following molecules or ions has a nitrogen with a formal charge of -1? (Charges on ions have been omitted.)

A) N H

. .:

B) NH H

. .

C) NH CH3

. .

D) NH3C CH3

. .

E) CH3C N:

Ans: A Topic: Lewis Structures, Formal Charges

15. In which structure(s) below does nitrogen have a formal charge of +1?

NH3C CH3

CH3

NH3C CH2

NH3C H NH2H3C

IVIIIIII V

OHH

. .. . . .. .

. . . .. .

A) I B) II and IV C) III and V D) I and V E) V

Ans: A

Chapter 1

Topic: Lewis Structures, Formal Charges

16. Which of the following is an ion with a single negative charge? A) OH3C

. .:. .

B) ONO. .

::. .. .

. .

ONO

. .

: ::

. .

D) All of these E) None of these

Ans: D Topic: Lewis Structures, Formal Charges

17. Which of these is a correct electron-dot representation of the nitrite ion, NO2-?

IIIIII

: O : N : : O : O : : N : O : : O : : N : : O

: O : N : O : : O : : N : O

. .

. .. . . .

. .. .. . . .

. . . .. .

. .. .

. .. . . .

. .. . . . . . . .. .. .

A) I B) II C) III D) IV E) V

Ans: A

Chapter 1

Topic: Lewis Structures, Formal Charges

18. Which is NOT a correct Lewis structure? A) NH F

. .. . :

CH F

:....

C) OH O

. .

. . H. .. .

OBO

. .

:. .. .H

H E) None of these

Ans: A Topic: Lewis Structures, Formal Charges

19. Listed below are electron dot formulas for several simple molecules and ions. All valence electrons are shown; however, electrical charges have been omitted deliberately.

H H H H

I IV VII III

H : Be : H H : B : H H : N : H H : N : H H : O : H. .. .. .. .

. . . . . . . .

Which of the structures is negatively charged?

A) I B) II C) III D) IV E) V

Ans: B

Chapter 1

Topic: Lewis Structures, Formal Charges

20. Which compound contains a nitrogen atom with a formal positive charge?

HN N

I II III

A) I B) II C) III D) More than one of the above E) None of the above

Ans: D Topic: Lewis Structures

21. Considering Lewis structures, which of these compounds possesses a single unpaired electron?

A) N2 B) N2O C) NO D) N2O4 E) O2

Ans: C Topic: Lewis Structures

22. Y

.. is a generalized structural representation which can be used for all of the following, except:

A) OF2 B) NH2

– C) H2S D) BeBr2 E) There is no exception

Ans: D

Chapter 1

Topic: Lewis Structures, Formal Charges

23. In which of these cases does the central atom have a zero formal charge? A) HFH B)

OH3C CH3

BF F

F D)

NH3C CH3

H E)

CH3C CH3

CH3

CH3 Ans: E

Topic: Lewis Structures, Formal Charges

24. The formal charge on sulfur in sulfuric acid is:

SO O

H H

A) 0 B) -1 C) +1 D) -2 E) +2

Ans: A Topic: Lewis Structures, Formal Charges

25. ExpAns:ion of the valence shell to accommodate more than eight electrons is possible with:

A) Fluorine B) Nitrogen C) Carbon D) Sulfur E) Beryllium

Ans: D

Chapter 1

Topic: Lewis Structures, Molecular Geometry

26. Based on VSEPR theory, which of the following would have a trigonal planar shape? A) CH3)3N B) HCN C) NH4

+ D) CH3

− E) CH3

+ Ans: E

Topic: Lewis Structures, Molecular Geometry

27. VSEPR theory predicts an identical shape for all of the following, except: A) NH3 B) H3O+ C) BH3 D) CH3

- E) All have the same geometry

Ans: C Topic: Lewis Structures, Molecular Geometry

28. What shape does the methyl cation, CH3+, have?

A) Octahedral B) Tetrahedral C) Trigonal planar D) Linear E) Trigonal pyramidal

Ans: C

Chapter 1

Topic: Lewis Structures, Molecular Geometry

29. Which of the structures below would be trigonal planar (a planar triangle)? (Electrical charges have been deliberately omitted.)

I II III

HB : F. .. . :

: ....: ....

H : O : H H : C : F : N :. .. .:

. .

: ....: ....

......

A) I B) II C) III D) IV E) I and IV

Ans: A Topic: Lewis Structures, Molecular Geometry

30. Which of the following would have a trigonal planar (or triangular) structure?

I II III IV V: CH3 : CH3 : NH3 : OH3BH3

A) I, II, and IV B) II and IV C) IV D) II, IV, and V E) All of these

Ans: B Topic: Molecular Geometry

31. What bond angle is associated with a tetrahedral molecule? A) 120° B) 109.5° C) 180° D) 90° E) 45°

Ans: B

Chapter 1

Topic: Molecular Geometry

32. What would be the spatial arrangement of the atoms of the methyl anion, :CH3-?

A) Octahedral B) Tetrahedral C) Trigonal planar D) Linear E) Trigonal pyramidal

Ans: E Topic: Lewis Structures, Molecular Geometry

33. Which of these structures would be a perfectly regular tetrahedron? A) CH3Br B) CH2Br2 C) CHBr3 D) CBr4 E) More than one of these

Ans: D Topic: Lewis Structures, Molecular Geometry

34. Which molecule would be linear? (In each case you should write a Lewis structure before deciding.)

A) SO2 B) HCN C) H2O2 D) H2S E) OF2

Ans: B Topic: Lewis Structures, Molecular Geometry

35. The bond angles in PH3 would be expected to be approximately: A) 60° B) 90° C) 105° D) 109° E) 120°

Ans: C

Chapter 1

Topic: Periodic Properties, Electronegativity

36. Select the most electronegative element. A) H B) O C) N D) B E) C

Ans: N Topic: Atomic Orbitals, Hybridization

37. Select the hybridized atomic orbital.

I II III IV V

A) I B) II C) III D) IV E) V

Ans: C Topic: Atomic Orbitals, Hybridization

38. How many 2p atomic orbitals from boron must be mixed with a 2s atomic orbital to yield the bonding hybrid atomic orbitals in BF3?

A) 1 B) 2 C) 3 D) 4 E) 5

Ans: B

Chapter 1

Topic: Atomic Orbitals, Hybridization

39. In which molecule is the central atom sp3 hybridized? A) CH4 B) NH3 C) H2O D) All of these E) None of these

Ans: D Topic: Atomic Orbitals, Hybridization

40. In which of the following would you expect the central atom to be sp3 hybridized (or approximately sp3 hybridized)?

A) BH4-

B) NH4+

C) CCl4 D) CH3:- E) All of these

Ans: D Topic: Atomic orbitals, hybridization

41. Which compound has the shortest carbon-carbon bond(s)? A) CH3CH3 B) CH2=CH2 C) HC≡CH D) CH3CH2CH3 E) All carbon-carbon bonds are the same length.

Ans: C Topic: Atomic Orbitals, Hybridization

42. Which of the following contains an sp2-hybridized carbon? A) CH4 B) CH3:− C) CH3CH3 D) CH3

+ E) HC≡CH

Ans: D

Chapter 1

Topic: Atomic Orbitals, Hybridization

43. Which is the shortest of the carbon-carbon single bonds indicated by arrows in the following compounds?

H3C CH3 B)

H3C C CH C)

H3C CH

CH2

HC C C CH E) H2C

HC C CH Ans: D

Topic: Atomic Orbitals, Hybridization

44. How many sigma (1s-2sp3) bonds are there in ethane? A) 7 B) 6 C) 5 D) 3 E) 1

Ans: B Topic: Atomic Orbitals, Bonding

45. Which of these substances contains both covalent and ionic bonds? A) NH4Cl B) H2O2 C) CH4 D) HCN E) H2S

Ans: A

Chapter 1

Topic: Atomic Orbitals, Periodic Trends, Electronegativity

46. The greatest degree of ionic character is anticipated for the bond between: A) H and C B) H and Cl C) C and Cl D) H and Br E) Br and Cl

Ans: B Topic: Atomic Orbitals, Hybridization

47. Which molecule contains an sp-hybridized carbon? A) HCN B) CH2=CH2 C) CH3Cl D) H

C O

H E) CH3CH3

Ans: A Topic: Atomic Orbitals, Lewis structures, Resonance

48. Which of the structures below is not expected to contribute to the CO2 resonance hybrid?

A) O C O

B) O C O C) O C O D) O C O E)

O C O Ans: D

Chapter 1

Topic: Atomic orbitals, Lewis structures, resonance

49. Which of the following could not be a resonance structure of CH3NO2? A)

: ....

: ....: ..

: ....: ....

: ....

.. E) Both C and D

Ans: D Topic: Atomic Orbitals, Lewis Structures, Resonance

50. Which of the following pairs are NOT resonance structures? A)

H3C O N O: : :

: : H3C O N O

: : :

:and :

:....O C O O C Oand

: ..

:..

H3C O N O

: : :

: : H3C NO

O: ........

and

D) Each of these pairs represents resonance structures. E) None of these pairs represents resonance structures.

Ans: C

Chapter 1

Topic: Atomic Orbitals, Lewis Structures, Resonance

51. How many resonance structures can be written for the NO3- ion in which the nitrogen

atom bears a formal charge of +1? A) 1 B) 2 C) 3 D) 4 E) 5

Ans: C Topic: Empirical and Molecular Formulas

52. What is the empirical formula for cyclohexane? (Its molecular formula is C6H12.) A) CH B) CH2 C) C2H4 D) C6H6 E) C2H2

Ans: B Topic: Empirical and Molecular Formulas

53. A compound has the empirical formula, CCl. Its molecular weight is 285 +/- 5. What is the molecular formula for the compound?

A) C2Cl2 B) C3Cl3 C) C4Cl4 D) C5Cl5 E) C6Cl6

Ans: E Topic: Empirical and Molecular Formulas

54. A compound consists only of carbon, hydrogen and oxygen. Elemental analysis gave: C, 70.5%, H, 13.8%. The molecular weight of the compound was found to be 103 +/- 3. What is the molecular formula for the compound?

A) C6H12O B) C5H12O2 C) C3H2O4 D) C3H6O3 E) C6H14O

Ans: E

Chapter 1

Topic: Isomerism

55. Which of the following is a set of constitutional isomers?

Br Br

IVIIIIII

A) I and II B) II and III C) I, II, and III D) II, III, and IV E) I, III, and IV

Ans: E Topic: General

56. Credit for the first synthesis of an organic compound from an inorganic precursor is usually given to:

A) Berzelius B) Arrhenius C) Kekule D) Wohler E) Lewis

Ans: D Topic: Isomerism

57. CH3CH2OCH2CH3 and CH3CH2CH2CH2OH are examples of what are now termed: A) Structural isomers B) Resonance structures C) Functional isomers D) Empirical isomers E) Constitutional isomers

Ans: E

Chapter 1

Topic: Hybridization

58. What is the approximate hybridization state of the oxygen molecule in ethanol, C2H5OH?

A) sp B) sp2 C) sp3 D) p3 E) d2sp3

Ans: C Topic: Hybridization

59. What is the approximate hybridization state of the oxygen molecule in trimethylamine, (CH3)3N?

A) sp B) sp2 C) sp3 D) p3 E) d2sp3

Ans: C Topic: Lewis structures, Hybridization

60. Which molecule has a non-linear structure (i.e., for which molecule are the nuclei not in a straight line)?

A) O=C=O B) H–O–H C) H–Cl D) H–C≡N E) H–C≡C–H

Ans: B

Chapter 1

Topic: Isomerism

61. Which of the following structures represent compounds that are constitutional isomers of each other?

IIIIII IV

A) I and II B) I and III C) I, II, and III D) I, II, III, and IV E) II and III

Ans: C Topic: Isomerism

62. Which compound is not an isomer of the others?

IIIIII IV

OHOH

A) I B) II C) III D) IV E) All of the above are isomers of each other.

Ans: A

Chapter 1

Topic: Isomerism

63. Consider the following:

CH3CH2CH=CHCH2CH3 CH3CH2CH2CH2CH=CH2I II

CH3CH=CHCH2CH2CH3 CH2=CHCH2CH2CH2CH3III IV

Which two structures represent the same compound?

A) I and II B) II and III C) I and III D) II and IV E) None of these

Ans: D Topic: Isomerism

64. Consider the following: CH3CH2CH2CH=CHCH2CH2CH3 CH3CH2CH2CH2CH2CH2CH=CH2

I II

CH3CH2CH=CHCH2CH2CH2CH3 CH2=CHCH2CH2CH2CH2CH2CH3 III IV

Which structures can exist as cis-trAns: isomers?

A) I and II B) I and III C) I and IV D) II and III E) I alone

Ans: B

Chapter 1

Topic: Isomerism

65. Which of the following represent a pair of constitutional isomers? A)

and B) CH3CH=CH2 and CH2=CHCH3 C)

and

E) More than one of these Ans: E

Topic: Isomerism

66. Which of the following represent pairs of constitutional isomers? A) OH

O O

andB)

CH3

and

Br CH3

CH2

CH3

and

D) More than one of these pairs E) All of these pairs

Ans: D Topic: Isomerism

67. Cis-trAns: isomerism is possible only in the case of: A) CH2=CBr2 B) CH2=CHBr C) BrCH=CHBr D) Br2C=CHBr E) Br2C=CBr2

Ans: C

Chapter 1

Topic: Atomic orbitals, molecular orbitals

68. When the 1s orbitals of two hydrogen atoms combine to form a hydrogen molecule, how are the electrons distributed in the resulting molecular orbitals?

A) 2 electrons in the bonding molecular orbital B) 1 electron in the bonding molecular orbital, 1 electron in the non-bonding molecular

orbital C) 1 electron in the bonding molecular orbital, 1 electron in the antibonding molecular

orbital D) 2 electrons in the non-bonding molecular orbital E) 2 electrons in the antibonding molecular orbital

Ans: A Topic: Atomic Orbitals, Electron Configuration, Hybridization

69. The following electron configuration represents:

1s 2sp32sp32sp32sp3

A) The ground state of nitrogen B) The ground state of oxygen C) The sp3 hybridized state of carbon D) The excited state of oxygen E) None of the above correctly identifies the given electron configuration

Ans: E Topic: Atomic Orbitals, Hybridization, Bonding

70. Identify the atomic orbitals involved in the C-2---C-3 sigma bond (indicated by an arrow) in the following molecule:

7A) sp2, sp2 B) sp2, sp C) sp2, sp3 D) sp3, sp2 E) sp, sp2

Ans: E

Chapter 1

Topic: Lewis Structures

71. In which of the following does the central atom have 2 pairs of non-bonding electrons? A) O3 B) CO2 C) CO3

2− D) NH4

+ E) H2S

Ans: E Topic: Molecular Geometry

72. Based on the VSEPR theory, which of the following would have a tetrahedral arrangement of electrons around the central atom?

A) BH3 B) NO2

− C) SiH4 D) CO3

2− E) SO3

Ans: C Topic: Molecular Geometry

73. What would be the spatial arrangement of the atoms of the ozone molecule (O3)? A) Linear B) Angular C) Trigonal planar D) Trigonal pyramidal E) Tetrahedral

Ans: B Topic: Periodic Trends, Electronegativity

74. Select the least electronegative element A) P B) N C) Mg D) Si E) K

Ans: E

Chapter 1

Topic: Atomic Orbitals, Hybridization

75. In which molecule(s) can the molecular geometry be attributed to an sp2 hybridized central atom?

A) PBr3 B) CH4 C) CHCl3 D) HNO2 E) None of the above has an sp2 hybridized central atom

Ans: D Topic: Bonding, Atomic Orbitals, Hybridization

76. Which molecule has the shortest carbon-carbon single bond?

I II III

IV V A) I B) II C) III D) IV E) V

Ans: E Topic: Atomic Orbitals, Hybridization 77. How many s-sp2 bonds are there in the following substance?

A) 2 B) 3 C) 4 D) 5 E) 12

Ans: B

Chapter 1

Topic: Atomic Orbitals, Hybridization

78. How many s-sp3 bonds are there in the following substance?

A) 3 B) 8 C) 12 D) 13 E) 16

Ans: D Topic: Resonance

79. Which of the following species exhibits resonance stabilization? A) H2SO4 B) O3 C) CO2 D) CCl4 E) None of the above species exhibit resonance

Ans: B SHORT ANS:WER QUESTIONS Topic: General

80. Organic compounds were originally defined as compounds obtained from __________. Ans: living sources/organisms

Topic: General

81. The modern definition of organic chemistry is _________________. Ans: the study of carbon compounds

Topic: General

82. Different compounds with the same molecular formula are referred to as __________. Ans: isomers

Chapter 1

Topic: General

83. Constitutional isomers differ in the _________________. Ans: connectivity of their atoms

Topic: General

84. The bond that results when two atoms share a pair of electrons is called a _________________.

Ans: covalent bond Topic: Atomic orbitals

85. Define an orbital. Ans: a region of space where the probability of finding an electron is high

Topic: Atomic orbitals

86.

An orbital is defined as a region of space where the probability of _________________ is high.

Ans: finding an electron Topic: Atomic orbitals

87. There are three fundamental rules that we use in writing electronic configurations for atoms and molecules. The configuration shown below (for oxygen) violates one of these rules. Which one?

1s 2p2p2p2sAns: Pauli exclusion principle

Topic: Molecular orbitals

88.

When atomic orbitals of opposite phase overlap a(n) _________________ molecular orbital is formed.

Ans: antibonding Topic: Molecular orbitals

89. When atomic orbitals of the same phase overlap a(n) _________________ molecular orbital is formed.

Ans: bonding

Chapter 1

Topic: Lewis Structures

90. Draw the Lewis structure of the nitrite ion, NO2

− , clearly indicating resonance contributors as well as non-bonding pairs of electrons and formal charges, as relevant.

Ans:

. .

Topic: Isomers, Bond-Line Formulas

91. Draw all the isomers of C4H9Br, using bond-line formulas. Ans:

BrBr

Topic: Isomers, Bond-Line Formulas

92. Draw all the isomers of C4H10O, using bond-line formulas. Ans:

Topic: Isomers, Bond-Line Formulas

93. Draw all isomers of C4H8, using bond-line formulas. Ans:

Chapter 1

Topic: Lewis Structures

94.

Draw the Lewis structure of acetic acid, CH3CO2H, clearly indicating all non-bonding pairs of electrons.

Ans:

H. .

.. ..

. .

Chapter 2

MULTIPLE CHOICE QUESTIONS Topic: Intermolecular forces

1. Which compound would you expect to have the lowest boiling point? A) NH2

B) NH2

NH2 Ans::

Topic: Molecular geometry, dipole moment

2. Which molecule would you expect to have no dipole moment (i.e., μ = 0 D)? A) CHF3 B)

C) :NF3 D)

E) CH2F2

Ans: B

Chapter 2

Topic: Intermolecular forces

3. Which of these compounds would have the highest boiling point? A) CH3OCH2CH2CH2OCH3 B) CH3CH2OCH2CH2OCH3 C) CH3CH2OCH2OCH2CH3 D) CH3OCH2CHOCH3

CH3 E) HOCH2CH2CH2CH2CH2OH

Ans: E Topic: Intermolecular forces

4. Which of these would you expect to have the lowest boiling point? A) CH3CH2CH2OH B) CH3CHCH3

OH C) CH3OCH2CH3 D) CH3CH2CH2CH2OH E) CH3CH2OCH2CH3

Ans: C Topic: Intermolecular forces

5. Which compound would have the highest boiling point? A) CH3CH2CH2CH2CH2CH3 B) CH3CH2OCH2CH2CH3 C) CH3CH2CH2CH2CH2OH D) CH3CH2OCH(CH3)2 E) CH3OCH2CH2CH2CH3

Ans: C Topic: Intermolecular forces

6. Which of the following is not found in the following substance? CH3CH2CH2CH2CH2OH

A) Ion-ion B) van der Waals C) Dipole-dipole D) Resonance E) Hydrogen bonding

Ans: D

Chapter 2

Topic: Intermolecular forces

7. Which compound would you expect to have the lowest boiling point? A)

NH2

B) H

O C)

NH2

O E)

O NH

Ans: C Topic: Intermolecular forces

8. Which compound would you expect to have the highest boiling point? A) CH3OCH2CH2OCH3 B) CH3OCH2OCH2CH3 C) HOCH2CH2CH2CH2OH D) CH3OCH2CH2CH2OH E) (CH3O)2CHCH3

Ans: C Topic: Molecular geometry, dipole moment

9. Which of the following would have no net dipole moment (μ = 0 D)?

A) CBr4 B) cis-1,2-Dibromoethene C) trAns:-1,2-Dibromoethene D) 1,1-Dibromoethene E) More than one of these

Ans: E

Chapter 2

Topic: Molecular geometry, dipole moment

10. Which molecule has dipole moment greater than zero? A)

D) More than one of these E) None of these

Ans: D Topic: Intermolecular forces

11. The strongest of attractive forces is which type? A) van der Waals B) Ion-dipole C) Dipole-dipole D) Cation-anion E) Hydrogen bonds

Ans: D Topic: Intermolecular forces

12. Of the following compounds, the one with the highest boiling point is: A) CH3CH3 B) CH3CH2Cl C) CH3C=O

H D) CH3CH2OH E) CH3CH2OCH2CH3

Ans: D

Chapter 2

Topic: Intermolecular forces

13. This alkane is predicted to have the highest melting point of those shown: A) CH3CH2CH2CH3 B) CH3CHCH3

CH3 C) CH3CH2CH2CH2CH3 D) CH3CHCH2CH3

CH3 E)

CH3CCH3

CH3

CH3 Ans: E

Topic: Intermolecular forces

14. The solid alkane CH3(CH2)18CH3 is expected to exhibit the greatest solubility in which of the following solvents?

A) CCl4 B) CH3OH C) H2O D) CH3NH2 E) HOCH2CH2OH

Ans: A

Chapter 2

Topic: Intermolecular forces

15. Which compound would have the lowest boiling point?

OOH

I II III

IV V

A) I B) II C) III D) IV E) V

Ans: A Topic: Molecular geometry, Polarity

16. Which molecule(s) has dipole moment equal to zero? A) Cl

B) ClCl

C) Cl

D) Cl

E) None of these have dipole moment equal to zero Ans: C

Chapter 2

Topic: Molecular geometry, polarity

17. Which molecule has a zero dipole moment? A) SO2 B) CO2 C) CO D) CHCl3 E) None of these

Ans: B Topic: Molecular geometry, polarity

18. Which molecule has a zero dipole moment? A) CH3Cl B) CH2Cl2 C) CHCl3 D) CCl4 E) None of these

Ans: D Topic: Molecular geometry, polarity

19. Which molecule would have a dipole moment greater than zero? A) BeCl2 B) BCl3 C) CO2 D) H2O E) CCl4

Ans: D Topic: Molecular geometry, polarity

20. For a molecule to possess a dipole moment, the following condition is necessary but not sufficient.

A) Three or more atoms in the molecule B) Presence of one or more polar bonds C) A non-linear structure D) Presence of oxygen or fluorine E) Absence of a carbon-carbon double or triple bond

Ans: B

Chapter 2

Topic: Molecular geometry, polarity

21. A non-zero dipole moment is exhibited by: A) SO2 B) CO2 C) CCl4 D) BF3 E) Cl

Cl Ans: A

Topic: Intermolecular forces

22. Which of these is the weakest of the intermolecular attractive forces? A) Ion-ion B) van der Waals C) Dipole-dipole D) Covalent bonding E) Hydrogen bonding

Ans: B Topic: Functional groups

23. Which compound listed below is a secondary alcohol? A) CH3CHCH2CH3

OH B) CH3CHCH2OH

CH3 C)

CH3COH

CH3

CH3 D) CH3CH2CH2CH2OH E) CH3CH2CH2OCH3

Ans: A

Chapter 2

Topic: Functional groups

24. Which compound is a secondary amine? A) CH3CH2CH2NH2 B) CH3CHCH3

NH2 C)

CH3

CH3CH2NH

D) NH3C CH3

CH3 E) CH3CH2CHNH2

CH3 Ans: C

Topic: Functional groups

25. Which compound is an aldehyde?

I II III

IV V

O O

A) I B) II C) III D) IV E) V

Ans: D

Chapter 2

Topic: Functional groups

26. Which compound is a ketone? A)

OHO

CH3CCH2CH3

HCOCH3

CHH3C

OHH3C

Ans: B

Topic: Functional groups

27. Which compound is an ester?

I II III

IV V

A) I B) II C) III D) IV E) V

Ans: C

Chapter 2

Topic: Functional groups

28. The compound shown below is a synthetic estrogen. It is marketed as an oral contraceptive under the name Enovid.

In addition to an alkane (actually cycloalkane) skeleton, the Enovid molecule also contains the following functional groups:

A) Ether, alcohol, alkyne. B) Aldehyde, alkene, alkyne, alcohol. C) Alcohol, carboxylic acid, alkene, alkyne. D) Ketone, alkene, alcohol, alkyne. E) Amine, alkene, ether, alkyne.

Ans: D Topic: Functional Groups

29. Which is a 3° alkyl halide?

I II III

IV V

BrF

Br I

A) I B) II C) III D) IV E) V

Ans: B

Chapter 2

Topic: Functional groups

30. Which is a 3° amine?

H2N

I II III

IV V

NH2NH

NNH2O

A) I B) II C) III D) IV E) V

Ans: D Topic: Functional groups

31. Which functional group is not contained in prostaglandin E1?

HOOHH H

Prostaglandin E1

A) Ketone B) 2° alcohol C) 3° alcohol D) Carboxylic acid E) Alkene

Ans: C

Chapter 2

Topic: Functional groups

32. The compound below is an adrenocortical hormone called cortisone. Which functional group is not present in cortisone?

OHO

OOH

A) 1° alcohol B) 2° alcohol C) 3° alcohol D) Ketone E) Alkene

Ans: B Topic: Functional groups

33. The compound shown below is a substance called Capsaicin, found in varying concentrations in several varieties of hot peppers, and responsible for their respective degrees of “heat”. Which functional groups are present in the molecule of capsaicin?

CapsaicinA) Alkene, ketone, amine, alcohol, ester B) Alkene, ketone, alcohol, ether C) Alkene, amine, phenol, ether D) Ether, phenol, alkene, amide E) Ester, phenol, alkene, amide

Ans: D

Chapter 2

Topic: Functional groups

34. Drawn below is Atropine, found in Atropa belladonna, sometimes used in dilating pupils during an eye-exam. Which of the following functional groups is NOT in atropine?

O OH

Atropine

A) Amine B) Ester C) Alcohol D) Benzene Ring E) Ketone

Ans: E Topic: Functional groups

35. The compound shown below is the male sex hormone, testosterone.

OHO

In addition to a cycloalkane skeleton, testosterone also contains the following functional groups:

A) Alkene, ester, tertiary alcohol. B) Alkene, ether, secondary alcohol. C) Alkene, ketone, secondary alcohol. D) Alkyne, ketone, secondary alcohol. E) Alkene, ketone, tertiary alcohol.

Ans: C

Chapter 2

Topic: Functional groups

36. Which is a carboxylic acid?

I II III

IV V

O O

A) I B) II C) III D) IV E) V

Ans: E Topic: Functional groups

37. Which compound is a tertiary alcohol?

H3CH2C HO

CH3

I II III

IV V

A) I B) II C) III D) IV E) V

Ans: E

Chapter 2

Topic: Functional groups

38. Which compound is a primary amine with the formula C5H13N?

H2N

I II III

IV V

NH2

A) I B) II C) III D) IV E) V

Ans: C Topic: Functional groups

39. Which compound can be classified as an ester as well as a ketone?

O O

I II III

IV VOH

A) I B) II C) III D) IV E) V

Ans: D

Chapter 2

Topic: Functional groups

40. The C–O–C bond angle in diethyl ether is predicted to be approximately: A) 90º B) 105º C) 110º D) 120º E) 180º

Ans: C Topic: Functional groups

41. Which compound(s) contain(s) tertiary carbon atom(s)?

BrOH

I II III

IV VA) I, II, III B) I C) II, III D) I, IV E) V

Ans: D Topic: Isomers

42. The number of unique open-chain structures corresponding to the molecular formula C3H5Cl is:

A) 2 B) 3 C) 4 D) 5 E) 6

Ans: C

Chapter 2

Topic: General, Bonding

43. The C4-C5 carbon-carbon bond in the following molecule results from the overlap of which orbitals ( in the order C4-C5) ?

A) sp–sp2 B) sp–sp3 C) sp2–sp2 D) sp2–sp3 E) sp3–sp2

Ans: E Topic: Functional groups

44. An example of a tertiary amine is:

NH2 H2N

NH2

I II III

IV V

A) I B) II C) III D) IV E) V

Ans: E

Chapter 2

Topic: Functional groups

45. Which functional groups are present in the following compound?

A) Alkene, 1º alcohol, ketone B) Alkene, 2º alcohol, aldehyde C) Alkene, 2º alcohol, ketone D) Alkyne, 1º alcohol, aldehyde E) Alkyne, 2º alcohol, ketone

Ans: B Topic: Functional groups, Isomerism

46. How many constitutional isomers are possible with the formula C4H10O? A) 3 B) 4 C) 5 D) 6 E) 7

Ans: E Topic: Functional groups

47. A tertiary carbon atom is present in which of these compounds?

ClCl

I II III

IV VA) I B) II, IV C) III, V D) IV E) All of these

Ans: C

Chapter 2

Topic: Functional groups

48. Which of these compounds is a secondary alkyl chloride? A) CH3CH2CH2CH2CH2Cl B)

CH3CCH2CH3

CH3

Cl C) CH3CHCH2CH2CH3

Cl D) CH3CH2CHCl

CH2CH3 E) Two of these

Ans: E Topic: Functional groups, Isomerism

49. How many 2º alkyl bromides, neglecting stereoisomers, exist with the formula C6H13Br?A) 4 B) 5 C) 6 D) 7 E) 8

Ans: C

Chapter 2

Topic: Functional Groups

50. Many organic compounds contain more than one functional group. Which of the following is both an aldehyde and an ether?

O O

OCH3

I II III

IV VA) I, B) II, IV C) V D) I, V E) III

Ans: A Topic: IR Spectroscopy

51. An oxygen-containing compound shows strong IR absorption at 1630-1780 cm-1 and 3200-3550 cm-1. What type of compound is it likely to be?

A) An alcohol B) A carboxylic acid C) An ether D) A ketone E) An aldehyde

Ans: B Topic: IR Spectroscopy

52. The absorption band for the O-H stretch in the IR spectrum of an alcohol is sharp and narrow in the case of:

A) a Nujol mull of the alcohol. B) a concentrated solution of the alcohol. C) a gas phase spectrum of the alcohol. D) the spectrum of the neat liquid E) none of these

Ans: C

Chapter 2

Topic: IR Spectroscopy

53. A split peak for the IR absorption due to bond stretching is observed for the carbonyl group in which of these compounds?

A) CH3CH2CH2COH

ca B)

CH3CH2CClO

CH3CH2CNH2

CH3CH2COCH2CH3

CH3CH2COCCH2CH3

O O

Ans: E

Topic: IR Spectroscopy

54. The IR stretching frequency occurs at the lowest frequency for which of these bonds? A) C–H B) C–O C) C–Br D) C–N E) C–F

Ans: C Topic: IR Spectroscopy

55. The IR stretching frequency can be expected to occur at the lowest frequency for which of these bonds?

A) C–H B) O–H C) N–H D) S–H E) Difficult to predict

Ans: D

Chapter 2

Topic: IR Spectroscopy

56. The IR stretching frequency can be predicted to occur at the highest frequency for which of these bonds?

A) C–H B) C–F C) C–Cl D) C–Br E) C–I

Ans: A Topic: IR Spectroscopy

57. An anticipated IR absorption band may not be observed because: A) it occurs outside the range of the instrument used. B) no change occurs in the dipole moment during the vibration. C) the absorption band is eclipsed by another. D) the intensity is so weak that it cannot be differentiated from instrument noise. E) All of these

Ans: E Topic: IR Spectroscopy 58. IR evidence for the presence of the C=C would be most difficult to detect in the case of

which of these alkenes? A) B) C)

Ans: D

Chapter 2

Topic: IR Spectroscopy

59. The IR absorption due to the stretching of which of these carbon-hydrogen bonds occurs at the highest frequency?

I II III

IV V

HH H

H H

A) I B) II C) III D) IV E) V

Ans: E Topic: IR Spectroscopy

60. The IR spectrum of which type of compound will not show evidence of hydrogen bonding?

A) Aldehyde B) Alcohol C) Carboxylic acid D) Phenol E) Primary amine

Ans: A Topic: IR Spectroscopy

61. The IR spectrum of which type of compound generally exhibits evidence of hydrogen bonding?

A) Aldehyde B) Carboxylic acid C) Alkene D) Ester E) Ketone

Ans: B

Chapter 2

Topic: Intermolecular forces

62. The following substance is expected to have low solubility in which of the following solvent(s)?

O Na

OA) CCl4 B) C2H5OH C) CHCl3 D) CH2OHCH2CH2CH2CH2CH2OH E) The given substance is likely to be quite soluble in all of the solvents described

Ans: A Topic: IR Spectroscopy

63. The IR stretching frequency occurs at the lowest frequency for which of these bonds? A) B–H B) O-H C) N-H D) S-H E) Difficult to predict

Ans: D Topic: IR Spectroscopy

64. An oxygen-containing compound which shows sharp IR absorption at 2200 cm-1 and 3300 cm-1 is likely to be what type of compound?

A) An ester B) An alkene C) An alkyne D) An ether E) An aldehyde

Ans: B

Chapter 2

Topic: IR Spectroscopy

65. The IR spectrum of which of the following substances is likely to show a small, but sharp peak at 2200 cm-1?

I II III

IV VA) I B) II C) III D) IV E) V

Ans: E SHORT ANSWER QUESTIONS Topic: Functional Groups

66. Hydrocarbons containing carbon-carbon double bonds are referred to as ___________.

Ans: alkenes Topic: Functional Groups, IR Spectroscopy

67. An IR spectrum has significant peaks at 2200 and 3300 cm-1. What functional group is present in the molecule? Ans: A terminal alkyne

Topic: Functional Groups

68. A group in which a carbon atom has a double bond to an oxygen atom is called a __________. Ans: carbonyl

Chapter 2

Topic: Functional Groups, IR Spectroscopy

69. An IR spectrum has significant peaks at 3080 and 1650 cm-1. What functional group is present in the molecule?

Ans: an alkene Topic: Functional Groups, IR Spectroscopy

70. Examine the following IR spectrum, for substance P (C8H22O). Which oxygen containing functional group is present in P?

Ans: aldehyde

Topic: Functional Groups, IR Spectroscopy

Chapter 2

71. Examine the following IR spectrum, for substance P (C5H12O). Which oxygen containing functional group is present in P? Ans: alcohol

Topic: General

72. The six p-electrons in benzene are _____________ about the ring, which explains why all of the C-C bonds are the same length. Ans: delocalized

Topic: General

73. A polar covalent bond is one in which electrons are _____________. Ans: not shared equally

Topic: Functional Groups

74. Organic compounds are classified into chemical families on the basis of similarities in chemical properties; these similarities are primarily due to the presence of characteristic arrangements of atoms known as ________________. Ans: functional groups

Topic: Functional Groups

75. Unsaturated hydrocarbons may be distinguished from saturated hydrocarbons by the presence of one or more _____________. Ans: Pi bonds

Topic: Bonding, Solubility

76. Sodium chloride, which is quite soluble in water, is not very soluble in hexane. Why? Ans: Sodium chloride, which is an ionic substance, is soluble in a polar solvent such as

water, but not in a non-polar solvent such as hexane. Topic: Isomers, Functional Groups

77. Draw all tertiary amine isomers of C6H15N. Ans:

N N N

Chapter 2

Topic: Isomers, Functional Groups

78. Draw all isomers of C6H14. Ans:

Topic: Isomers, Functional Groups

79. Draw a structural formula for C8H18 , in which there are two quaternary carbons. Ans:

Topic: Isomers, Functional Groups

80. Draw all isomers of C5H10O that are ketones. Ans: O O O

Topic: Isomers, Functional Groups

81. Draw all isomers of C3H8O and classify each according to functional group Ans:

C3H8O OHOH

Oprimary alcohol secondary alcohol ether

Topic: Isomers, Functional Groups

82. Draw all isomers of C6H12O that are aldehydes. Ans:

O O OO

O OO

Topic: Isomers, Functional Groups

83. Draw all isomers of C6H12O that are aldehydes and contain at least one tertiary carbon Ans:

O OOO

Chapter 2

Topic: IR Spectroscopy

84. The IR absorption frequencies of the C-H bond in alkanes, alkenes and alkynes are measurably different. Briefly explain why. Ans: IR absorption frequency depends on bond strength; the bond strength of C-H

bonds in alkanes, alkenes and alkynes is different because different atomic orbitals (hybridized) of carbon are involved in the bond: the C-H bond in alkanes is described as (sp3-s), that in alkenes is (sp2-s) and in alkynes, it is (sp-s). The relative % s v. % p character of the hybrid orbitals of carbon would indicate different bond lengths /bond strengths for alkanes, alkenes and alkynes, with the bond length / bond strength being the longest/weakest respectively. This results in different IR absorption frequencies.

Topic: Molecular Geometry, Dipole Moment

85. Carbon dioxide is non- polar, despite the fact that oxygen is much more electronegative than carbon. Briefly explain why, using relevant diagrams as appropriate to illustrate your Ans:wer. Ans: The overall dipole moment of a polyatomic molecule depends on two factors: the

polarity of various bonds and molecular geometry, since dipole forces have both magnitude and direction. In some molecules containing bonds of identical polarity, the molecular geometry may result in a net cancellation of the overall dipole forces. This is what happens in carbon dioxide: although there are two polar C-O bonds, because of the linear geometry of the molecule, the net dipole is zero. OCO

. .::. .

Topic: Intermolecular Forces

86. Ethanol, C2H5OH, and propane, C3H8, have approximately the same molar mass, yet, ethanol has a much higher boiling point. Briefly explain why. Ans: Strong hydrogen bonding between molecules of ethanol leads to elevation in

boiling point. No hydrogen bonding is possible between molecules of propane, resulting in a lower boiling point compared with ethanol.

Topic: Intermolecular Forces

87. Ethanol, C2H5OH, and dimethyl ether, CH3OCH3, have the same molar mass, yet, ethanol has a much higher boiling point. Briefly explain why. Ans: Strong hydrogen bonding between molecules of ethanol leads to elevation in

boiling point. No hydrogen bonding is possible between molecules of dimethyl ether, resulting in a lower boiling point compared with ethanol.

Chapter 2

Topic: IR Spectroscopy

88. IR absorption signals of alcohols are typically broad. However, IR spectra of gaseous samples show sharp peaks. Briefly explain why. Ans: Broad signals of alcohols are due to hydrogen bonding associated with the O-H

group. In gaseous samples, no hydrogen bonding is possible, and the signal becomes sharp.

Chapter 3

MULTIPLE CHOICE QUESTIONS Topic: Acid-Base Definitions

1. According to the Lewis definition, a base is a(n): A) Proton donor. B) Electron pair donor. C) Hydroxide ion donor.

D) Hydrogen ion donor. E) Electron pair acceptor. Ans: B Topic: Acid-Base Definitions

2. Which of the following is not both a Bronsted-Lowry acid and a Bronsted-Lowry base? A) HSO4

− B) H2PO4

− C) HCO3

− D) OH− E) SH−

Ans: D Topic: Acid-Base Definitions

3. Which of the following is not a conjugate acid - conjugate base pair (in that order)? A) H3PO4, H2PO4

− B) HBF4, BF4

− C) CH3CH2OH, CH3CH2O− D) H3O+, H2O E) HPO4

−, H2PO4−

Ans: E Topic: Acid-Base Definitions

4. The conjugate base of sulfuric acid is: A) H3SO4

+ B) SO3 C) HSO4

− D) H2SO3 E) HSO3

− Ans: C

Chapter 3

Topic: Acid-Base Definitions

5. Consider the equilibrium PO4

3− + H2O ⇄ ΗPΟ42− + ΟΗ−

Which are the Bronsted-Lowry bases? A) PO4

3− and HPO42−

B) PO43− and OH−

C) PO43− and H2O

D) H2O and OH−

E) H2O and HPO42−

Ans: B Topic: Acid-Base Definitions

6. Which of these is not a true statement? A) All Lewis bases are also Bronsted-Lowry bases. B) All Lewis acids contain hydrogen. C) All Bronsted-Lowry acids contain hydrogen. D) All Lewis acids are electron deficient. E) According to the Bronsted-Lowry theory, water is both an acid and a base.

Ans: B Topic: Acid-Base Definitions

7. For the equilibrium CH3NH3

+ + H2O ⇄ CH3NH3+ + H3O+

the two substances which both are acids are: A) H2O and H3O+ B) CH3NH3

+ and H2O C) CH3NH3

+ and CH3NH2 D) CH3NH3

+ and H3O+ E) CH3NH2 and H2O Ans: D

Chapter 3

Topic: Acid-Base Definitions

8. Which of the following is not a Lewis base? A) NH3

B) H− C) BF3 D) H2O E) H3C−

Ans: C Topic: Acid-Base Definitions

9. Which of the following is not a Bronsted-Lowry acid? A) H2O

B) (CH3)3N C) NH4

+ D) CH3CO2H E) HC≡CH

Ans: E Topic: Acid-Base Definitions

10. The reaction between which combination of substances below cannot be classified as a Bronsted-Lowry acid-base reaction? A) CH3Li + C2H5OH B) H2SO4 + CH3CO2Na C) BF3 + NH3 D) H3O+ + CH3NH- E) two of the above Ans: C

Topic: Acid-Base Definitions

11. Which of these is not a Lewis acid? A) AlCl3 B) H3O+ C) FeCl3 D) SO3 E) C4H10

Ans: E

Chapter 3

Topic: Acid-Base Definitions

12. This species is a carbon-based Lewis acid: A) CH4 B) HCCl3 C) CH3

+ D) :CH3

− E) ·CH3

Ans: C Topic: Acid-Base Definitions

13. What is the conjugate base of ethanol? A) CH3CH2O− B) CH3CH2

− C) CH3CH2OH2

+ D) CH3CH3 E) CH3OCH3

Ans: A Topic: Acid-Base Strength

14. Which of the acids below would have the strongest conjugate base? A) CH3CH2OH pKa = 18 B) CH3CO2H pKa = 4.75 C) ClCH2CO2H pKa = 2.81 D) Cl2CHCO2H pKa = 1.29 E) Cl3CCO2H pKa = 0.66 Ans: A

Topic: Acid-Base Definitions

15. Which of the following is a Lewis acid? A) H3O+

B) BF3 C) NF3 D) OH− E) N≡N

Ans: B

Chapter 3

Topic: Acid-Base Reactions

16. Adding sodium hydride to ethanol would produce: A) CH3CH2OCH2CH3 + H2 D) CH3CH2Na + NaOH B) CH3CH2OCH2CH3 + NaOH E) CH3CH3 + NaOH C) CH3CH2ONa + H2

D)CH3CH2Na + NaOH E) CH3CH3 + NaOH Ans: C Topic: Acid-Base Reactions

17. Adding sodium amide (NaNH2) to 1-butyne (CH3CH2C≡CH) would produce: A) CH3CH2C≡CNa + NH3 B) CH3CH2C≡C-C≡CH2CH3 + NaH + NH3 C) CH3CH2C≡CNH2 + NaH D) NaCH2CH2C≡CH + NH3 E) CH3CH(Na)C≡CH + NH3 Ans: A

Topic: Acid-Base Reactions

18. Which acid-base reaction would not take place as written? A) CH3Li + CH3CH2OH ⎯⎯⎯⎯→ CH4 + CH3CH2OLi B) HC≡CH + NaOH ⎯⎯⎯⎯→ HC≡CNa + H2O C) HC≡CNa + H2O ⎯⎯⎯⎯→ HC≡CH + NaOH D) CH3OH + NaH ⎯⎯⎯⎯→ CH3ONa + H2 E) CH3CO2H + CH3ONa ⎯⎯⎯⎯→ CH3CO2Na + CH3OH

Ans: E Topic: Acid-Base Reactions 19. Which acid-base reaction would not take place as written?

A) CH3Li + CH3CH2CH2CH2NH2 ⎯⎯⎯⎯→ CH4 + CH3CH2CH2CH2NHLi B) CH3C≡CH + NaOCH3 ⎯⎯⎯⎯→ HC≡CNa + CH3OH C) HC≡CNa + H2O ⎯⎯⎯⎯→ HC≡CH + NaOH D) CH3OH + NaNH2 ⎯⎯⎯⎯→ CH3ONa + NH3 E) CH3CO2H + CH3ONa ⎯⎯⎯⎯→ CH3CO2Na + CH3OH Ans: B

Chapter 3

Topic: Acid-Base Reactions

20. Which acid-base reaction would not take place as written? A) CH3Li + CH3CH2OH ⎯⎯⎯⎯→ CH4 + CH3CH2OLi B) H2C=CH2 + NaOH ⎯⎯⎯⎯→ H2C=CHNa + H2O C) CH3C≡CNa + H2O ⎯⎯⎯⎯→ CH3C≡CH + NaOH D) (CH3)2CHOH + NaH ⎯⎯⎯⎯→ (CH3)2CHONa + H2 E) CH3CO2H + CH3ONa ⎯⎯⎯⎯→ CH3CO2Na + CH3OH Ans: B

Topic: Acid-Base Reactions

21. The amide ion, NH2−, is a base which can be used only in which of the solvents shown

below: A) CH3OH B) CH3CH2OH C) H2O D) D2O E) Liquid NH3

Ans: E Topic: Acid-Base Reactions

22. Acetic acid dissociates most completely in: A) CCl4

B) Cl2C=CCl2 C) H2O D) (CH3CH2)2O E) the gas phase.

Ans: C Topic: Acid-base definitions, Acid-Base Reactions

23. Which pair of species are both bases in the following reaction? HCN and H2O ⇄ H3O+ and CN− A) H2O and CN− B) H3O+ and H2O C) HCN and H3O+

D) HCN and CN−

E) H3O+ and CN− Ans: A

Chapter 3

Topic: Acid-Base Reactions

24. What compounds are produced when sodium nitrate is added to a mixture of water and ethanol? A) HNO3 + NaOH B) HNO3 + CH3CH2ONa C) NaOH + CH3CH2ONa D) CH3CH2OCH2CH3 + NaOH E) No reaction occurs. Ans: E

Topic: Acid-Base Reactions

25. Which reaction of these potential acids and bases does not occur to any appreciable degree due to an unfavorable equilibrium? A) NaOH (aq) + CH3CH2CH2CO2H B) CH3CH2ONa in ethanol + ethene C) CH3Li in hexane + ethyne

D) NaNH2 in liq. NH3 + ethanol E) NaC2H3O2 (aq) + HI Ans: B Topic: Acid-Base Reactions

26. Which reaction of these potential acids and bases does not occur to any appreciable degree due to an unfavorable equilibrium? A) NaNH2 + CH3CH2CH2CH2CH2CH3 B) CH3CH2CO2Na + HI C) CH3Li in hexane + ethyne D) NaH + methanol E) Two of the above will not occur

Ans: A Topic: Acid-Base Reactions

27. Which reaction of these potential acids and bases does not occur to any appreciable degree due to an unfavorable equilibrium? A) NaNH2 + CH3CH2CH2CH2CH2OH B) CH3CH2CO2H + NaCl C) NaHCO3 + CH3CH2CO2H D) NaH + CH3CH2CH2CH2CH2NH2 E) all of the above will occur due to a favorable equilibrium Ans: E

Chapter 3

Topic: Acid-Base Reactions

28. Which combination of reagents is the least effective in generating sodium ethoxide, CH3CH2ONa? A) CH3CH2OH + NaH B) CH3CH2OH + NaNH2 C) CH3CH2OH + NaOH D) CH3CH2OH + CH3Li E) CH3CH2OH + HC≡CNa Ans: C

Topic: Acid-Base Reactions

29. Which combination of reagents is effective in generating sodium ethoxide, CH3CH2ONa?

A) CH3CH2OH + KH B) CH3CH2OH + NaNH2 C) CH3CH2OH + Na D) Two of the above E) All of the above Ans: E Topic: Acid-Base Reactions

30. Which combination of reagents is effective in generating sodium propynide, CH3C≡CNa?

A) CH3C≡CH + KH B) CH3C≡CH + (CH3)2CHONa C) CH3C≡CH + C2H5Li D) Two of the above E) All of the above Ans: B Topic: Acid-Base Reactions, base strength

31. In the reaction, Na+NH2− + CH3OH ⎯⎯⎯⎯→ CH3O−Na+ + NH3, the stronger

base is: A) NaNH2 B) CH3OH C) CH3ONa

D) NH3 E) This is not an acid-base reaction. Ans: A

Chapter 3

Topic: Acid-Base Reactions, isotope labeling

32. Which sequence is the best one to use to prepare CH3C≡CD? A) CH3C CH NaH D2O

B) CH3C CH NaOH D2O

CH3C CHCH3ONa D2O

D) CH3C CH DOH

E) None of these will be successful. Ans: A Topic: Acid-Base Reactions

33. Adding sodium hydride, NaH, to water produces: A) H2 and NaOH(aq) B) H-(aq) + Na+(aq) C) H3O+(aq) + Na+(aq)

D) H3O−(aq) + Na+(aq) E) Na2O + H2

Ans: A Topic: Acid-Base Reactions

34. Adding methyllithium , CH3Li, to ethanol produces: A) CH3CH2Li + CH3OH B) CH3CH2OLi + CH4 C) CH3CH2OCH3 + LiH D) All of the above E) No reaction takes place

Ans: A Topic: Acid-Base Reactions, isotope labeling

35. Which reaction will yield CH3CH2-D? A) CH3CH3 + D2O B) CH3CH2Li + D2O C) CH3CH2OLi + D2O

D) CH3CH2OH + D2O E) More than one of these Ans: B

Chapter 3

Topic: Acid-Base Reactions, isotope labeling

36. A product of the reaction, CH3CH2Li + D2O ⎯⎯⎯⎯→ is A) CH3CH2OD B) CH3CH2CH2CH3 C) CH2=CH2

D) CH3CH2D E) CH3CH2OCH2CH3

Ans: D Topic: Relative acid strength

37. The compounds ethane, ethene, and ethyne exhibit this order of increasing acidity: A) Ethyne < ethene < ethane B) Ethene < ethyne < ethane C) Ethane < ethyne < ethene

D) Ethane < ethene < ethyne E) Ethene < ethane < ethyne Ans: D Topic: Relative acid/base strength

38. Which is an incorrect statement? A) RSH compounds are stronger acids than ROH compounds. B) PH3 is a weaker base than NH3. C) NH2

− is a stronger base than OH−. D) OH− is a stronger base than OR−. E) H− is a stronger base than OR−.

Ans: D Topic: Relative acid/base strength

39. The correct sequence of the ions shown, in order of increasing basicity, is: A) CH3CH2:− < CH2=CH:− < HC≡C:− B) CH3CH2:− < HC≡C:− < CH2=CH:− C) HC≡C:− < CH3CH2:− < CH2=CH:−

D) CH2=CH:− < HC≡C:− < CH3CH2:−

E) HC≡C:− < CH2=CH:− < CH3CH2:− Ans: E

Chapter 3

Topic: Solvent effects

40. Which is a protic solvent? A) CCl4 B) HCCl3 C) CH3OH D) CH3(CH2)4CH3 E) CH3CH2OCH2CH3 Ans: C

Topic: Solvent effects

41. Which might be used as protic solvent? A)

H2N C)

O E) O

Ans: B

Topic: Solvent effects

42. Which of the following classes of substances cannot be used as protic solvents? A) esters B) aldehydes C) ketones D) carboxylic acids E) two of the above Ans: D

Chapter 3

Topic: Acid constants

43. If a 0.01 M solution of a weak acid has a pH of 4.0, the pKa of the acid is: A) 10.0

B) 8.0 C) 6.0 D) 4.0 E) 2.0 Ans: C

Topic: General

44. Which one of the following is a true statement? A) The stronger the acid, the larger is its pKa. B) The conjugate base of a strong acid is a strong base. C) Acid-base reactions always favor the formation of the stronger acid and the stronger

base. D) Strong acids can have negative pKa values. E) Hydrogen need not be present in the molecular formula of a Bronsted-Lowry acid.

Ans: D Topic: Relative acid/base strengths

45. The basic species are arranged in decreasing order of basicity in the sequence: A) F− > OCH3

− > NH2− > CH3CH2

− B) OCH3

− > CH3CH2− > NH2

− > F− C) CH3CH2

− > NH2− > OCH3

− > F− D) NH2

− > CH3CH2− > F− > OCH3

− E) NH2

− > OCH3− > CH3CH2

− > F− Ans: C Topic: pKa calculations

46. A particular acid has Ka = 2.0 x 10-5 (in aqueous solution). The evaluation of which of these expressions gives the value for pKa? A) 10-14/2.0 x 10-5 B) 10-14(2.0 x 10-5) C) 5 – log 2.0 D) -5 + log 2.0 E) 2.0 x 10-5/10-14

Ans: C

Chapter 3

Topic: Solvent effects

47. As a consequence of the "leveling effect," the strongest acid which can exist in appreciable concentration in aqueous solution is:

A) H3O+ B) H2SO4 C) HClO4 D) HCl E) HNO3 Ans: A

Topic: Relative acid/base strengths

48. Based on the position of the central atom in the periodic chart, we predict that the strongest acid of the following is:

A) H2O B) H2S C) H2Se D) H2Te Ans: D

Topic: Acid dissociation, thermodynamic calculations

49. An acid, HA, has the following thermodynamic values for its dissociation in water at 27º C: ΔH = -8.0 kJ mol-1; ΔS = -70 kJ K-1mol-1. The ΔG for the process is: A) +29 kJ mol-1 B) +13 kJ mol-1 C) -6.1 kJ mol-1

D) -13 kJ mol-1 E) -29 kJ mol-1 Ans: B Topic: Relative acid/base strengths, solvent effects

50. Which of these bases is the strongest one which can be used (and retains its basic character) in aqueous solution?

A) OCH3−

B) F− C) OH− D) C2H3O2

− E) HSO4

−

Ans: C

Chapter 3

Topic: Acidity constant- thermodynamic principles

51. The acidity constant, Ka, differs from the equilibrium constant, Keq, for the dissociation of the same acid in water at the same temperature and concentration in what way? A) Ka can be determined experimentally with less accuracy than Keq. B) The two terms are identical numerically. C) Ka is used for strong acids only; Keq for weak acids. D) Ka is the reciprocal of Keq. E) Keq = Ka/[H2O].

Ans: E Topic: Acids/bases-general principles

52. Which of the following is an untrue statement? A) The % dissociation of a weak acid increases with increasing dilution of the acid

solution. B) The stronger an acid, the weaker its conjugate base. C) The larger the value of Ka for an acid, the smaller the value of its pKa. D) Comparison of the acidity of strong acids in solution requires the use of a solvent

less basic than water. E) The stronger the acid, the more positive the value of ΔGº for the dissociation.

Ans: E Topic: Acid-base reactions

53. When proton transfer reactions reach equilibrium, there have been formed: A) the weaker acid and the weaker base. B) the weaker acid and the stronger base. C) the stronger acid and the weaker base. D) the stronger acid and the stronger base. E) All proton transfers go to completion; they are not equilibrium processes.

Ans: A Topic: Relative acid-base strengths

54. For the simple hydrides, MHn, pKa values decrease in the order: A) CH4 > NH3 > H2O > H2S > HBr B) HBr > H2S > H2O > NH3 > CH4 C) HBr > H2O > NH3 > H2S > CH4

D) NH3 > H2S > CH4 > H2O > HBr E) H2S > H2O > HBr > NH3 > CH4

Ans: A

Chapter 3

Topic: Relative acid-base strengths, solvent effects

55. The compound aniline, C6H5NH2, has weakly basic properties in aqueous solution. In this other solvent, aniline would behave as a strong base. A) CH3OH B) CH3CH2OH C) CF3CO2H

D) Liquid NH3 E) CH3(CH2)4CH3 Ans: C Topic: Relative acid-base strengths

56. Which of the following organic compounds is the strongest acid? A) C6H12 pKa = 52 B) CH3CH3 pKa = 50 C) CH3CH2OH pKa = 18

D) CH3CO2H pKa = 5 E) CF3CO2H pKa = 0 Ans: E Topic: Relative acid-base strengths

57. Which is the strongest acid? A) CH3CH2OH B) CH3CO2H C) HC≡CH D) CH2=CH2 E) CH3CH3 Ans: B

Topic: Relative acid-base strengths

58. Which is the strongest acid? A) CH2ClCH2CH2CH2CH2CO2H B) CH3CHBrCH2CH2CH2CO2H C) CH3CH2CH2CBr2CH2CO2H D) CH3CH2CH2CHFCH2CO2H E) CH3CH2CH2CF2CH2CO2H

Ans: E

Chapter 3

Topic: Relative acid-base strengths

59. Which is the strongest acid? A) CH3CH2CH2CH2CHFCO2H B) CH3CHBrCH2CH2CH2CO2H C) CH3CH2CH2CHClCH2CO2H D) CH3CH2CH2CHFCH2CO2H E) CH3CH2CH2CHICH2CO2H

Ans: A Topic: Relative acid-base strengths

60. Which is the weakest acid? A) CH3CH2CH2CH2CHFCO2H B) CH3CHCH2CH2CH2CH2OH C) CH3CH2CH2CH2CH2SO3H D) CH3CH2CH2CH2CH=CH2 E) CH3CH2CH2CH2NH2

Ans: A Topic: Relative acid-base strengths

61. Which of the following substances has a hydrogen atom with pKa ≈25? A) CH3CH2CH2CH2CO2H B) CH3CHCH2C≡CCH3 C) CH3CH2CH2C≡CH D) CH3CH2CH2CH2CH=CH2 E) CH3CH2CH2CH2NH2

Ans: C

Chapter 3

Topic: Relative acid-base strengths

62. Hydrogen atom(s) from which position(s) is (are) most likely to be abstracted when the following substance is treated with NaH?

910

A) 1 B) 1, 5, 6 C) 1, 2 D) 3, 4, 7, 8, 9, 10 E) Hydrogens from all of the positions are equally likely to be abstracted by NaH.

Ans: A Topic: Relative acid-base strengths

63. Which of the following correctly lists the compounds in order of decreasing acidity? A) H2O > HC≡CH > NH3 > CH3CH3 B) HC≡CH > H2O > NH3 > CH3CH3 C) CH3CH3 > HC≡CH > NH3 > H2O

D) CH3CH3 > HC≡CH > H2O > NH3 E) H2O > NH3 > HC≡CH > CH3CH3

Ans: A Topic: Relative acid-base strengths

64. Select the strongest base. A) OH− B) RC≡C− C) NH2

− D) CH2=CH− E) CH3CH2

−

Ans: E

Chapter 3

Topic: Relative acid-base strengths

65. A group of acids arranged in order of decreasing acidity is: HNO3 > CH3COOH > C6H5OH > H2O > HC≡CH What is the arrangement of the conjugate bases of these compounds in decreasing order of basicity? A) NO3

− > CH3COO− > C6H5O− > OH− > HC≡C− B) CH3COO− > C6H5O− > NO3

− > OH− > HC≡C− C) C6H5O− > NO3

− > HC≡C− > OH− > CH3COO− D) HC≡C− > OH− > C6H5O− > CH3COO− > NO3

− E) No prediction of relative base strength is possible.

Ans: D Topic: Relative acid-base strengths

66. What prediction can be made of the relative strengths of the conjugate bases of: H2S, HCl, SiH4, PH3? A) PH2

− > SiH3− > HS− > Cl−

B) SiH3− > PH2

− > HS− > Cl− C) Cl− > HS− > PH2

− > SiH3−

D) HS− > Cl− > SiH3− > PH2

− E) Cl− > PH2

− > SiH3− > HS−

Ans: B Topic: Acids/bases- general

67. Which of these species is not amphoteric? A) HC≡C−

B) HS− C) NH3 D) CH3

− E) HPO4

−

Αns: D

Chapter 3

Topic: Acids/bases- general

68. Which of these phosphorus-based acids is dibasic? A)

OHHO

OHO P

OH E)

PHO

Ans: B Topic: Acids/bases- general

69. Why cannot one determine the relative acid strengths of HClO4 and HNO3 using aqueous solutions of these acids? A) The acids are insufficiently soluble for the measurements. B) A more basic solvent than H2O must be used. C) H2O is too basic a solvent for the distinction to be made. D) These oxidizing acids cause redox reactions to occur. E) Actually, the acid strengths can be determined using aqueous solutions.

Ans: C Topic: Acids/bases- general

70. Which of these is not a diprotic acid? A) H2S B) H2SO4 C) H2O D) (COOH)2 E) H2PO4

- Ans: C

Chapter 3

Topic: Acids/bases- thermodynamic principles

71. Which set contains non-equivalent members? A) Enthalpy and heat content B) Endothermic reaction and +ΔH C) Exothermic reaction and -ΔH

D) Kinetic energy and energy of motion E) High energy and high stability Ans: E SHORT-ANSWER QUESTIONS: Topic: General Reactivity

72. Addition reactions are characteristic of compounds with ______________. Ans: multiple bonds Topic: Reaction Types

73. The four basic types of reactions are: ________________. Ans: substitution, addition, elimination, rearrangement Topic: Reaction Mechanisms

74. The process of bond-breaking where each fragment takes away one of the electrons from the bond is called ____________.

Ans: homolysis Topic: Reaction Mechanisms

75. Heterolytic bond-breaking produces __________. Ans: charged fragments/ions Topic: Acids and Bases

76. According to Bronsted-Lowry theory, an acid is a substance that can ____________. Ans: donate a proton Topic: Acids and Bases

77. According to Lewis theory, a base is a substance that can _________. Ans: donate a lone pair of electrons

Chapter 3

Topic: Acids and Bases

78. The molecule or ion that is formed when an acid loses its proton is called the ______________.

Ans: conjugate base Topic: Nucleophiles and Electrophiles

79. Reagents that seek to react with a proton or some other electron-deficient center are called ____________.

Ans: nucleophiles Topic: Acids and Bases

80. A substance that can donate a lone pair of electrons is a ____________ according to ____________ theory.

Ans: base; Lewis Topic: Curved Arrow Notation

81. When drawing mechanisms, chemists generally use curved arrows. The curved arrow begins with ______________ and points toward ______________.

Ans: a lone pair or covalent bond; a site of electron deficiency Topic: Acids and Bases

82. Why do water-insoluble carboxylic acids dissolve in aqueous sodium hydroxide? Ans: Because they are converted to water-soluble salts. Topic: Relative Acidity

83. Bond polarization that takes place through space and through the bonds of the molecule is called the _____________.

Ans: inductive effect Topic: Energy

84. What are the two fundamental types of energy? Ans: potential energy and kinetic energy Topic: Types of Solvents

85. Define a protic solvent. Ans: one that has a hydrogen atom attached to a strongly electronegative element such as oxygen

Chapter 3

Topic: Relative acid strength

86. Briefly, but clearly, explain why the –OH hydrogen in acetic acid (CH3CO2H) is more acidic than in ethanol (C2H5OH).

Ans: The greater acidity of the –OH hydrogen in acetic acid is due primarily to two factors: resonance and inductive effects. In acetic acid, the presence of the neighboring carbonyl group has an electron-withdrawing inductive effect on the –OH hydrogen, increasing its acidity relative to ethanol, in which there is no carbonyl group. Also, comparison of the respective conjugate bases shows that, unlike the ethoxide ion, the acetate ion is stabilized by resonance. This too, is reflected in the greater acid strength of the corresponding acid species.

O(- H+)

(- H+)

Inductive effect: electron withdrawing resonance stabilized anion

Chapter 3

Topic: Relative acid strength, isotope labeling

87. Isotope labeling is an important tool in the study of reaction mechanisms. How will you selectively deuterate the specified hydrogen atom, indicated by an arrow, in the following compound? Use equations to clarify your answer and briefly explain your rationale.

Ans: The specified hydrogen is attached to an sp-hybridized carbon and is thus more acidic than all the other hydrogens in the molecule. By using an appropriate strong base, such as NaH or NaNH2, the acetylenic hydrogen is selectively removed; adding D2O then replaces the lost hydrogen atom with a deuterium atom.

Hi) NaH or NaNH2

ii) D2O

Topic: Acid-base reactions

88. Write an equation to show the reaction between ethanol, C2H5OH and methyllithium, CH3Li. Draw all non-bonding electrons and show electron flow with curved arrows.

Ans: O

HCH3 Li+ O Li+ CH4+

....

: +....:

Topic: Acid-base reactions, solvent selection

89. You are planning to carry out a reaction between propyne, CH3C≡CH and sodium amide, NaNH2. You also need to choose an appropriate solvent for carrying out the reaction. Would ethanol be suitable for this purpose? Explain your rationale clearly.

Ans: No, ethanol would be unsuitable for carrying out the reaction between propyne and methyllithium. The pKa of ethanol is ~16, and sodium amide is strong enough a base to readily abstract a proton from the solvent ( pKa of NH3 is ~38); in doing so, it becomes deactivated and is no longer available to react with propyne (pKa ~25). Typically, the selected solvent should be chemically inert toward all substances used in the reaction, so that it does not interfere with the desired reaction.

Chapter 3

Topic: Acid-base reactions, solvent selection

90. You are planning to purify an impure sample of benzoic acid, known to be contaminated with naphthalene. Propose a strategy for purifying this sample, making use of acid-base principles, using equations to further clarify your answer.

Ans: Benzoic acid reacts with aqueous NaOH to form a water soluble salt, while naphthalene, which is not soluble in water to any appreciable extent, does not react with NaOH. So, upon shaking the impure sample with NaOH (aq), the naphthalene remains as a solid, while the benzoic acid dissolves in the aqueous medium as sodium benzoate. After filtration, HCl is added to the filtrate to regenerate benzoic acid, which precipitates as almost pure crystals. Cooling maximizes the yield of the purified product, after which pure crystals can be obtained by filtration.

Alternatively, before beginning the reaction with aqueous NaOH, the impure sample is first dissolved in diethyl ether (benzoic acid and naphthalene are both soluble in ether) and placed in a separatory funnel. After shaking thoroughly with aqueous NaOH, the aqueous layer (which now contains sodium benzoate) is collected. The rest of the procedure is as described earlier.

ONaOH

ONa

OHCl OH

No reaction

water soluble

water insoluble

water insoluble water insolublePURE

Chapter 4

MULTIPLE CHOICE QUESTIONS Topic: Nomenclature

The IUPAC name for is: A) 6-Ethyl-3,4-dimethylheptane B) 2-Ethyl-4,5-dimethylheptane C) 3,4,6-Trimethyloctane D) 3,5,6-Trimethyloctane E) 2-(1-Methylpropyl)-4-methylhexane

Ans: C Topic: Nomenclature

An IUPAC name for is: A) 5-Methyl-4-(1-methylpropyl)hexane B) 2-Methyl-3-(1-methylpropyl)hexane C) 2-Methyl-3-(2-methylpropyl)hexane D) 3-Methyl-4-(1-methylethyl)heptane E) 5-Methyl-4-(1-methylethyl)heptane

Ans: D Topic: Nomenclature

3. A correct IUPAC name for the following compound is:

A) 2,5-Dimethyl-3-propylheptane B) 3,6-Dimethyl-5-propylheptane C) 6-Methyl-4-(1-methylethyl)octane D) 2-Methyl-3-(2-methylbutyl)hexane E) 3-Methyl-5-(1-methylethyl)octane

Ans: E

Chapter 4

Topic: Nomenclature

4. A correct IUPAC name for the following compound is:

OH Cl A) 4-propyl-5-chloro-3-heptanol B) 4-propyl-3-chloro-5-heptanol C) 4-(1-chloropropyl)-3-heptanol D) 5-chloro-4-propyl-3-heptanol E) 3-hydroxy-4-propyl-5-chloroheptane Ans: D

Topic: Nomenclature

5. Which of the following pairs of compounds represent pairs of constitutional isomers? A) 2-Methylbutane and pentane B) 2-Chlorohexane and 3-chlorohexane C) sec-Butyl bromide and tert-butyl bromide D) Propyl chloride and isopropyl chloride E) All of the above

Ans: E

Chapter 4

Topic: Nomenclature

6. Which of the following is bicyclo[3.2.2]nonane?

I II III

IV VA) I B) II C) III D) IV E) V

Ans: C Topic: Nomenclature

7. Select the systematic name for HCl

H Cl A) cis-1,3-Dichlorocyclopentane B) trans-1,4-Dichlorocyclopentane C) cis-1,2-Dichlorocyclopentane D) trans-1,3-Dichlorocyclopentane E) 1,1-Dichlorocyclopentane

Ans: D

Chapter 4

Topic: Nomenclature

8. Which compound is a bicycloheptane?

I II III

IV VA) I B) II C) III D) IV E) V

Ans: D Topic: Nomenclature

9. Which isomer of C5H10 would you expect to have the smallest heat of combustion? A) Cyclopentane B) Methylcyclobutane C) 1,1-Dimethylcyclopropane D) cis-1,2-Dimethylcyclopropane E) trans-1,2-Dimethylcyclopropane

Ans: A Topic: Nomenclature

10. Which is the correct name for the compound shown below?

A) Bicyclo[2.2.0]hexane B) Bicyclo[2.2.0]butane C) Bicyclo[2.2.2]hexane D) Bicyclo[2.2.1]hexane E) Disquarane

Ans: A

Chapter 4

Topic: Nomenclature

11. What is the name of this compound?

A) Bicyclo[2.2.2]octane B) Bicyclo[3.2.1]octane C) Bicyclo[4.1.1]octane D) Bicyclo[4.2.0]octane E) Bicyclo[3.3.0]octane

Ans: D Topic: Nomenclature

12. What is the common name for this compound?

A) Isobutyl bromide B) tert-Butyl bromide C) Butyl bromide D) sec-Butyl bromide E) Bromo-sec-butane

Ans: A Topic: Nomenclature

13. A correct IUPAC name for the following compound is: Br

A) 3,6,7-trimethyl-4-bromo-1-octene B) 4-bromo-3-methyl-6-isopropyl-1-heptene C) 4-bromo-3,6,7-trimethyl-1-octene D) 4-bromo-6-isopropyl-3-methyl-1-heptene E) 4-bromo-6-isopropyl-3,6-dimethyl-1-hexene Ans: C

Chapter 4

Topic: Nomenclature

14. A correct name for the following compound is:

A) 2-Methylbicyclo[4.3.0]nonane B) 1-Methylbicyclo[4.3.1]nonane C) 7-Methylbicyclo[4.3.0]nonane D) 2-Methylbicyclo[4.3.1]nonane E) 1-Methylbicyclo[4.3.0]nonane

Ans: A Topic: Nomenclature Use the following to answer questions 15-17:

I II III

IV V

15. Which of the above is bicyclo[3.3.1]nonane? A) I B) II C) III D) IV E) V

Ans: D Topic: Nomenclature

16. Which of the above is bicyclo[5.2.0]nonane? A) I B) II C) III D) IV E) V

Ans: E

Chapter 4

Topic: Nomenclature

17. Which of the above is bicyclo[4.3.0]nonane? A) I B) II C) III D) IV E) V

Ans: A Topic: Nomenclature Use the following to answer questions 18-19:

I II III Topic: Nomenclature

18. trans-1,2-Dibromocyclohexane is represented by structure(s): A) I B) II C) III D) II and III E) I and II

Ans: D Topic: Nomenclature

19. cis-1,2-Dibromocyclohexane is represented by structure(s): A) I B) II C) III D) II and III E) I and II

Ans: A

Chapter 4

Topic: Nomenclature

20. cis-1,3-Dibromocyclohexane is represented by structure(s):

H H

BrH

I II IIIA) I B) II C) III D) II and III E) I and II

Ans: A Topic: Nomenclature

21.

An IUPAC name for the group

CH3CHCH2−CH2CH3 is:

A) Isopentyl B) Isoamyl C) sec-Butylmethyl D) 2-Methylbutyl E) 2-Ethylpropyl

Ans: D Topic: Nomenclature

22. The neopentyl group has the alternative name: A) 1,1-Dimethylpropyl B) 1,2-Dimethylpropyl C) 2,2-Dimethylpropyl D) 1-Methylbutyl E) 2-Methylbutyl

Ans: C

Chapter 4

Topic: Nomenclature

23.

The correct IUPAC name for Cl

is: A) 2-Bromo-4-chloro-4-isopropylpentane B) 4-Bromo-2-chloro-2-isopropylpentane C) 5-Bromo-3-chloro-2,3-dimethylhexane D) 2-Bromo-4-chloro-4,5-dimethylhexane E) 2-(2-Bromopropyl)-2-chloro-3-methylbutane

Ans: C Topic: Nomenclature

24. Which of the following is a correct name which corresponds to the common name tert-pentyl alcohol?

A) 2,2-Dimethyl-1-propanol B) 2-Ethyl-2-propanol C) 2-Methyl-2-butanol D) 3-Methyl-1-butanol E) Methyl tert-butanol

Ans: C Topic: Nomenclature

25. The correct IUPAC name for the following compound is:

A) 1-Hydroxy-3-sec-butylcyclopentane B) 3-sec-Butyl-1-cyclopentanol C) 1-sec-Butyl-3-cyclopentanol D) 4-sec-Butyl-1-cyclopentanol E) 3-Isobutyl-1-cyclopentanol

Ans: B

Chapter 4

Topic: Nomenclature

26. What is a correct name for the following compound?

A) 3-Isobutyl-2-methylheptane B) 3-sec-Butyl-2-methyloctane C) 5-Isobutyl-6-methylheptane D) 2-Ethyl-3-isopropyloctane E) 4-Isopropyl-3-methylnonane

Ans: E Topic: Nomenclature

27. What is the correct name of the following compound?

A) 1-Chlorobicyclo[4.1.1]octane B) 2-Chlorobicyclo[4.1.0]octane C) 2-Chlorobicyclo[4.1.1]octane D) 2-Chlorobicyclo[4.1.1]heptane E) 5-Chlorobicyclo[4.1.1]octane

Ans: C Topic: Nomenclature

28. What is the correct IUPAC name for the following compound?

HO A) 3-Hydroxymethylheptane B) 3-Hydroxymethylhexane C) 3-Methyloxyheptane D) 2-Ethyl-1-hexanol E) 2-Ethyl-1-heptanol

Ans: D

Chapter 4

Topic: Nomenclature

29. Which of the following structures represents bicyclo[3.2.1]octane?

I II III

IV VA) I B) II C) III D) IV E) V

Ans: E Topic: Nomenclature

30. Which of these is the common name for the 1,1-dimethylpropyl group? A) tert-Butyl B) tert-Pentyl C) Isopentyl D) Neopentyl E) sec-Pentyl

Ans: B Topic: Nomenclature

31. Neglecting stereochemistry, which of these common group names is ambiguous, i.e., does not refer to one specific group?

A) Butyl B) sec-Butyl C) tert-Pentyl D) Neopentyl E) sec-Pentyl

Ans: E

Chapter 4

Topic: Nomenclature

32. What is the correct IUPAC name for the following compound? OH

A) 5-Ethyl-3-methylhexanol B) 5-Ethyl-3-methyl-1-hexanol C) 2-Ethyl-4-methyl-6-hexanol D) 3,5-Dimethyl-7-heptanol E) 3,5-Dimethyl-1-heptanol

Ans: E Topic: Nomenclature

33. Isopentyl is the common name for which alkyl group? A) CH3CH2CH2CH

CH3 B) CH3CH2CHCH2

CH3 C) CH3CHCH2CH2

CH3 D) CH3CH2CH

CH2CH3 E)

CH3CCH2

CH3

CH3 Ans: C

Chapter 4

Topic: Nomenclature

34.

An IUPAC name for is: A) 3-Isobutyl-2,4-dimethylhexane B) 3-sec-Butyl-2,5-dimethylhexane C) 4-sec-Butyl-2,5-dimethylhexane D) 4-Isopropyl-2,5-dimethylheptane E) 4-Isopropyl-3,6-dimethylheptane

Ans: D Topic: Nomenclature

35. An IUPAC name for the following compound is:

A) 4-Isobutyl-3,4-dimethylheptane B) 4-sec-Butyl-2,4-dimethylheptane C) 2,4,5-Trimethyl-4-propylheptane D) 3,4,6-Trimethyl-4-propylheptane E) 4-Isobutyl-4,5-dimethylheptane

Ans: C Topic: Nomenclature

36. What is the correct IUPAC name for the following compound?

HO A) 3-Hydroxymethyl-2-heptene B) 2-(1-methylethyl)-4-hexen-1-ol C) 5-(1-methylethyl)-2-hexen-6-ol D) 5-isopropyl-2,6-hexenol E) 2-(1-methylethyl)-4-hepten-1-ol

Ans: B

Chapter 4

100

Topic: Nomenclature

37. What is the correct IUPAC name for the following compound? OH

F A) 5-Ethyl-3-fluorohexanol B) 5-Ethyl-3-fluoro-1-hexanol C) 2-Ethyl-4-fluoro-6-hexanol D) 3-fluoro-5-methyl-7-heptanol E) 3-fluoro-5-methyl-1-heptanol

Ans: E Topic: Nomenclature

38. A correct name for the following compound is:

Cl A) 3-chloro-8-methylbicyclo[4.3.0]nonane B) 8-Methyl-3-chlorobicyclo[4.3.1]nonane C) 3-Methyl-7-chlorobicyclo[4.3.0]nonane D) 3-Methyl-7-chlorobicyclo[4.3.1]decane E) 3-chloro-8-methyl[4.3.0]bicyclononane

Ans: A Topic: Nomenclature

39. A correct name for the following compound is:

A) 4-bromo-3,8-dimethylbicyclo[5.2.2]nonane B) 3,8-dimethyl-4-bromo-bicyclo[5.2.0]nonane C) 4-bromo-3,8-dimethylbicyclo[5.2.1]decane D) 7-bromo-2,6-dimethylbicyclo[5.2.0]nonane E) 4-bromo-3,8-dimethylbicyclo[5.2.0]nonane

Ans: E

Chapter 4

101

Topic: Conformational Analysis

40. The least stable conformation of butane is:

HH3C

CH3

CH3H

HH3C

CH3H

CH3

I II III

IV V

A) I B) II C) III D) IV E) V

Ans: B Topic: Conformational Analysis 41. The preferred conformation of cis-3-tert-butyl-1-methylcyclohexane is the one in which:

A) the tert-butyl group is axial and the methyl group is equatorial. B) the methyl group is axial and the tert-butyl group is equatorial. C) both groups are axial. D) both groups are equatorial. E) the molecule exists in a boat conformation.

Ans: D

Chapter 4

102

Topic: Conformational Analysis

42. What structure represents the most stable conformation of cis-1,3-dimethylcyclohexane?

H3C

CH3

H3C

CH3

H3C

CH3

HCH3

HI II III

CH3

H3C

VIV

A) I B) II C) III D) IV E) V

Ans: B Topic: Ring Strain

43. Which cycloalkane has the largest heat of combustion per CH2 group?

I II III

VIVA) I B) II C) III D) IV E) V

Ans: A

Chapter 4

103

Topic: Ring Strain

44. Which cycloalkane has the lowest heat of combustion per CH2 group?

I II III

VIV

A) I B) II C) III D) IV E) V

Ans: D Topic: Ring Strain 45. Which isomer would have the largest heat of combustion?

A) Propylcyclopropane B) Ethylcyclobutane C) Methylcyclopentane D) Cyclohexane E) Since they are all isomers, all would have the same heat of combustion.

Ans: A Topic: Ring Strain

46. Which is the most stable conformation of cyclohexane? A) Chair B) Twist C) Boat D) One-half chair E) Staggered

Ans: A

Chapter 4

104

Topic: Ring Strain

47. Which cycloalkane has the greatest ring strain? A) Cyclopropane B) Cyclobutane C) Cyclopentane D) Cyclohexane E) Cycloheptane

Ans: A Topic: Conformational Analysis

48. The most stable conformation of butane is:

HH3C

CH3

CH3H

HH3C

CH3H

CH3

I II III

IV V

A) I B) II C) III D) IV E) V

Ans: C

Chapter 4

105

Topic: Conformational Analysis

49. The most stable conformation of 1,2-dibromoethane is:

BrH

HBr

BrH

HBr

BrH

I II III

IV VA) I B) II C) III D) IV E) V

Ans: C

Chapter 4

106

Topic: Conformational Analysis

50. The most stable conformation of 2,3-dibromobutane, viewed through the C-2—C-3 bond :

BrH3C

HBr

CH3

HBr

HH3C

CH3

BrH

BrH3C

CH3Br

HH3C

I II III

IV V

A) I B) II C) III D) IV E) V

Ans: C

Chapter 4

107

Topic: Conformational Analysis

51. The most stable conformation of 3-bromo-2-methylpentane, viewed through the C-3—C-4 bond (i.e., C-3 in the front, C-4 in the back):

BrH

CH(CH3)2

CH3H

III

CH(CH3)2H

CH3H

HBr

CH(CH3)2

CH3

CH(CH3)2Br

CH3H

CH3

CH2CH3

HBr

VA) I B) II C) III D) IV E) V

Ans: A

Chapter 4

108

Topic: Conformational Analysis

52. The most stable conformation of 3-bromo-2-methylpentane, viewed through the C-2—C-3 bond (i.e., C-2 in the front, C-3 in the back):

CH2CH3H3C

CH3H

CH3

CH3Br

CH3H

CH3

CH2CH3

HBr

BrH

CH(CH3)2

CH3H

III

CH2CH3Br

CH3

CH3H

A) I B) II C) III D) IV E) V

Ans: E

Chapter 4

109

Topic: Conformational Analysis

53. The most stable conformation of 2,3-dimethylpentane, viewed through the C-2—C-3 bond (i.e., C-2 in the front, C-3 in the back):

HH3C

CH3

CH2CH3H

CH3H

CH3

CH2CH3H

CH3H

CH3

CH(CH3)2

HH3C

CH3H

CH(CH3)2

CH3

III

CH3H

CH3

HH3CH2C

A) I B) II C) III D) IV E) V

Ans: D Topic: Ring Strain 54. Which cycloalkane has the least ring strain?

A) Cyclopropane B) Cyclobutane C) Cyclopentane D) Cyclohexane E) Cycloheptane

Ans: D Topic: Conformational Analysis

55. The most stable conformation of cis-1-tert-butyl-2-methylcyclohexane is the one in which:

Ans: B

Chapter 4

110

Topic: Conformational Analysis

56. The most stable conformation of trans-1-tert-butyl-2-methylcyclohexane is the one in which:

Ans: D Topic: Conformational Analysis

57. The most stable conformation of trans-1-tert-butyl-3-methylcyclohexane is the one in which:

Ans: B Topic: Conformational Analysis

58. In the most stable conformation of cis-1,4-dimethylcyclohexane, the methyl groups are: A) one axial, one equatorial. B) both axial. C) both equatorial. D) alternating between being both axial and both equatorial. E) None of the above

Ans: A

Chapter 4

111

Topic: Conformational Analysis

59. The most stable conformation for 1,2-ethanediol (ethylene glycol) is shown below. It is the most stable conformation because:

OHH

A) this corresponds to an anti conformation. B) in general, gauche conformations possess the minimum energy. C) it is stabilized by intramolecular hydrogen bonding. D) it is a staggered conformation. E) it has the highest energy of all the possibilities.

Ans: C Topic: Conformational Analysis

60. The graph below is a plot of the relative energies of the various conformations of:

0o 60o 120o 180o 240o 300o 360o

Rel

ativ

e en

ergy

Angle of rotationA) Ethane B) Propane C) Chloroethane D) 1-Chloropropane (C1-C2 rotation) E) Butane (C1-C2 rotation)

Ans: D

Chapter 4

112

Topic: Conformational Analysis

61. The graph below is a plot of the relative energies of the various conformations of:

0o 60o 120o 180o 240o 300o 360o

Rel

ativ

e en

ergy

Angle of rotationA) 2-chloropropane B) 1,3-dichloropropane C) 2-methylpropane D) Butane (C1-C2 rotation) E) Butane (C2-C3 rotation)

Ans: E Topic: Conformational Analysis

62. Consider the graph below, which is a plot of the relative energies of the various conformations of hexane, viewed through the C2-C3 bond. The conformations corresponding to the 60o and 300o are:

0o 60o 120o 180o 240o 300o 360o

Rel

ativ

e en

ergy

Angle of rotationA) Eclipsed B) Staggered, and gauche C) Staggered and anti D) More stable than the conformation at 180o E) None of the above

Ans: B

Chapter 4

113

Topic: Conformational Analysis

63. Consider the graph below, which is a plot of the relative energies of the various conformations of 2,3-dimethylbutane, viewed through the C2-C3 bond. The conformations corresponding to the 120o and 240o are:

0o 60o 120o 180o 240o 300o 360o

Rel

ativ

e en

ergy

Angle of rotationA) Eclipsed, more stable than the conformation at 0o B) Eclipsed, more stable than the conformation at 180o C) Staggered, more stable than the conformation at 0o D) Staggered, less stable than the conformation at 180o E) Two of the above are true

Ans: A Topic: Conformational Analysis 64. Which conformation of trans-1-isopropyl-3-methylcyclohexane would be present in

greatest amount at equilibrium? A) The conformation with the methyl group equatorial and the isopropyl group axial B) The conformation with the methyl group axial and the isopropyl group equatorial C) The conformation with both groups axial D) The conformation with both groups equatorial E) The twist boat conformation.

Ans: B

Chapter 4

114

Topic: Conformational Analysis

65. Which conformation represents the most stable conformation of trans-1-bromo-4-methylcyclohexane?

CH3

CH3Br

BrH3C

BrCH3

I II III

IV V

A) I B) II C) III D) IV E) V

Ans: A Topic: Cis-Trans Isomers

66. Which of the following can be described as cis isomers?

CH3

CH2CH3

CH3

BrHO

CH3HO

BrF

I II III

IV V

A) I B) II, V C) III, IV D) I, III and IV E) None of the above are cis isomers.

Ans: B

Chapter 4

115

Topic: Cis-Trans Isomers

67. Which of the following can be described as trans isomers?

CH3

CH2CH3

CH3

BrHO

CH3HO

BrF

I II III

IV V

A) I B) II, V C) III, IV D) I, III and IV E) None of the above are trans isomers.

Ans: C Topic: Conformational Analysis

68. Which of the following will have the same energy after undergoing ring flip?

CH2CH3

CH3

OHHO

CH3HO

BrF

I II III

IV V

A) I B) II C) III D) IV E) V.

Ans: E

Chapter 4

116

Topic: Conformational Analysis

69. The least stable conformation of cyclohexane is the: A) boat. B) twist boat. C) chair. D) half-chair. E) twist chair.

Ans: D Topic: Conformational Analysis

70. Express, quantitatively, the difference in stability of the two structures shown below.

H3C

CH3CH3H3C

I II

A) I is more stable than II by 7.5 kJ mol-1. B) I is more stable than II by 15 kJ mol-1. C) II is more stable than I by 7.5 kJ mol-1. D) II is more stable than I by 15 kJ mol-1. E) The two are equal in stability.

Ans: A Topic: Conformational Analysis

71. The twist boat conformation is the preferred conformation for this compound. A) cis-1,4-Di-tert-butylcyclohexane B) trans-1,4-Di-tert-butylcyclohexane C) cis-1,3-Di-tert-butylcyclohexane D) trans-1,2-Di-tert-butylcyclohexane E) None of these

Ans: A

Chapter 4

117

Topic: Ring Strain

72. Which of these C10H18 isomers is predicted to be the most stable?

I II III

IV V

A) I B) II C) III D) IV E) V

Ans: E Topic: Alkane Synthesis

73. Select the reagents necessary to convert cyclopentene into cyclopentane. A) H2 and Ni B) H2O C) Heat D) Zn, H3O+ E) Light

Ans: A Topic: Alkane Synthesis

74. Select the reagents necessary to convert 3-bromohexane into hexane. A) Zn, H3O+ B) CuI C) H2O D) H3O+ E) OH-

Ans: A

Chapter 4

118

Topic: General

75. How many constitutional isomers are possible for the formula C6H14? A) 2 B) 3 C) 4 D) 5 E) 6

Ans: D Topic: General

76. How many compounds with the formula C7H16 (heptanes) contain a single 3° carbon atom?

A) 2 B) 3 C) 4 D) 5 E) 6

Ans: C Topic: Alkane Synthesis, Nomenclature

77. Catalytic hydrogenation of which of the following will yield 2-methylpentane? A) 2-methyl-1-pentene

2 B) 2-methyl-2-pentene

C) 4-methyl-2-pentene

D) 4-methyl-1-pentene

E) All of the above Ans: E

Topic: Alkane Synthesis, Nomenclature

78. The synthesis of an alkyne precursor to 2,2-dimethylheptane is accomplished most effectively by the reaction between these two reagents:

A) CH3CH2CH2C≡CNa and (CH3)3CBr B) CH3CH2C≡CNa and (CH3)3CCH2Br C) (CH3)3CC≡CNa and CH3CH2CH2Br D) (CH3)3CCH2CH2C≡CH and CH3CH2I E) HC≡CNa and (CH3)3CCH2CH2Br

Ans: C

Chapter 4

119

Topic: Alkane Synthesis, Nomenclature

79. The reaction of the Na salt of 3-methyl-1-pentyne with 1-bromo-3-methylbutane produces which of these?

A) 3,8-dimethyl-4-nonyne B) 2,7-dimethyl-4-nonyne C) 3,8-dimethyl-5-nonyne D) 3,7-dimethyl-4-nonyne E) 3,7-dimethyl-5-nonyne

Ans: A Topic: General

80. What is the simplest alkane, i.e., the one with the smallest molecular weight, which possesses primary, secondary and tertiary carbon atoms?

A) 2-Methylpropane B) 2-Methylbutane C) 2-Methylpentane D) 3-Methylpentane E) 2,2-Dimethylbutane

Ans: B Topic: General

81. How many alkanes of formula C7H16 possess a quaternary carbon atom? A) 1 B) 2 C) 3 D) 4 E) 5

Ans: C SHORT ANSWER QUESTIONS Topic: General

82. To determine the parent name for an alkane, we begin by finding the ___________________________. Ans: longest continuous chain of carbons

Chapter 4

120

Topic: Nomenclature

83. When more than one substituent is present on the parent chain, how do we organize the names of the substituents in the name of the compound? ___________________________. Ans: alphabetical order

Topic: General

84. A compound containing two fused or bridged rings is referred to as a ___________________________. Ans: bicycloalkane

Topic: General

85. A compound containing a triple bond between the first two carbons in the chain is called a ___________________________. Ans: terminal alkyne

Topic: General

86. When non-bonded atoms/groups are closely positioned, the repulsive interactions between their electron clouds are referred to as ___________________________. Ans: steric hindrance

Topic: General

87. _____________________ have the same molecular formula and connectivity but different arrangements of atoms in three-dimensional space. Ans: Stereoisomers

Topic: Nomenclature

88. Alkanes in which some or all of the carbon atoms are arranged in a ring are called ___________________________. Ans: cycloalkanes

Topic: Nomenclature

89. What is the fundamental principle of the IUPAC system of nomenclature for organic compounds? Ans: Each different compound should have an unambiguous name.

Chapter 4

121

Topic: Nomenclature

90. What are the four possible parts of a IUPAC name? Ans: locant, prefix, parent name, suffix

Topic: General

91. In a bicyclic compound, the carbon atoms common to both rings are called ___________________________. Ans: bridgeheads

Topic: Nomenclature 92. Give the IUPAC name corresponding to the following structure.

OH Ans: 5-bromo-6-cyclopentyl-2-hexanol

Topic: Nomenclature 93. Give the IUPAC name corresponding to the following structure:

BrHO

Ans: 3-(2-bromobutyl)cyclopentanol

Topic: Nomenclature 94. Give the IUPAC name corresponding to the following structure:

F Ans: trans-1-bromo-2-fluorocyclohexane

Topic: Nomenclature 95. Give the IUPAC name corresponding to the following structure:

Ans: 3-ethyl-6,7-dimethyl-2-octanol

Chapter 4

122

Topic: Nomenclature, Conformations 96. Draw the bond-line structural formula corresponding to the most stable conformation of

the following substance: trans-1-bromo-3-(1-methylpropyl)cyclohexane Ans: Br

Topic: Nomenclature 97. Draw the bond-line structural formula corresponding to the name: 2,5,9-trimethyl-2-

decen-7-yne Ans:

Topic: Alkane Conformations 98. Draw the Newman projection formula for the gauche conformation of the C2-C3 bond

in pentane. Ans:

CH3

CH2CH3H

Topic: Alkane Conformations 99. Draw the Newman projection formula for the most stable conformation of the C2-C3

bond in 3-methylpentane. Ans:

CH3

CH2CH3

CH3H

Topic: Alkane Synthesis 100. Complete the following reaction sequence, giving structural details of A, B and C.

NaH

AC2H5Br

BH2,Ni

Ans: NaH C2H5Br

ANa+

H2,Ni

Chapter 5

123

MULTIPLE CHOICE QUESTIONS Topic: Identifications and Comparisons

1. Which of the following is the enantiomer of the following substance? H

CH3BrH

CH3HBr

CH3

H HBr

CH3

H BrH

I II III A) I B) II C) III D) It does not have a non-superposable enantiomer. E) Both II and III Ans: D

Topic: Identifications and Comparisons

2. Which of the following molecules is achiral?

CC CH3C

CH3

FClH

CO2H

OHH

HHO2C

CO2H

OHH

HHOBr

CH2CH3

CH3

I II III

IV V A) I B) II C) III D) IV E) V Ans: B

Chapter 5

124

Topic: Identifications and Comparisons

3. Hexane and 3-methylpentane are examples of: A) enantiomers. B) stereoisomers. C) diastereomers. D) constitutional isomers. E) None of these Ans: D

Topic: Identifications and Comparisons

4. I and II are:

H3C Cl

CH2CH3

H H

CH2Cl

I II A) constitutional isomers. B) enantiomers. C) non-superposable mirror images. D) diastereomers. E) not isomeric. Ans: A

Chapter 5

125

Topic: Identifications and Comparisons

5. Pairs of enantiomers are:

CH2CH2CH3

H3C Cl

CH3

CH2CH2CH3

Cl CH3

CH3

I II

H3C Cl

CH2CH2CH3

H H

CH2Cl

IV V

CH2CH2CH3

H3C Cl

III

A) I, II and III, IV B) I, II C) III, IV D) IV, V E) None of the structures Ans: C

Topic: Identifications and Comparisons

6. Chiral molecules are represented by:

C2H5

ClH3C

CH3

IC2H5

CH3Cl

CH3

IIC2H5

ClH3C

III

ClH3C

C2H5

IVC2H5

CH2Cl

VA) I, II, III, IV and V B) I, II, III and IV C) I and II D) III and IV E) IV alone Ans: D

Chapter 5

126

Topic: Identifications and Comparisons

7. The molecules shown are: H

CH3

OHH

BrH

CH3

OHH

HBr

A) constitutional isomers. B) enantiomers. C) diastereomers. D) identical. E) None of these Ans: B

Topic: Identifications and Comparisons

8. The

The molecules shown are: Cl

CH2CH3

HH3CH2C

ClH

CH2CH3

CH2CH3Cl

HCland are

A) enantiomers. B) diastereomers. C) constitutional isomers. D) two conformations of the same molecule. E) not isomeric. Ans: B

Topic: Identifications and Comparisons

9. The molecules shown are: CH3

CH3

F A) constitutional isomers. B) enantiomers. C) diastereomers. D) identical. E) None of these Ans: B

Chapter 5

127

Topic: Identifications and Comparisons

10. The molecules below are: H

F A) constitutional isomers. B) enantiomers. C) diastereomers. D) identical. E) stereoisomers. Ans: A

Topic: Identifications and Comparisons

11. The molecules shown are: CH3

CH3

HCl

ClH

CH3

CH3Cl

HCl

A) enantiomers. B) diastereomers. C) constitutional isomers. D) two different conformations of the same molecule. E) not isomeric. Ans: A

Topic: Identifications and Comparisons

12. The molecules shown are: CH3

CH3

A) constitutional isomers. B) enantiomers. C) diastereomers. D) identical. E) None of these Ans: B

Chapter 5

128

Topic: Identifications and Comparisons

13. The molecules shown are:

A) constitutional isomers. B) enantiomers. C) diastereomers. D) identical. E) None of these Ans: E

Topic: Identifications and Comparisons

14. The molecules below are: H

CH3

A) structural isomers. B) enantiomers. C) diastereomers. D) identical. E) None of these Ans: C

Topic: Identifications and Comparisons

15. Cis-trans isomers are: A) diastereomers. B) enantiomers. C) stereoisomers. D) constitutional isomers. E) More than one of these Ans: E

Chapter 5

129

Topic: Identifications and Comparisons

16. The molecules below are:

FCl

CH3

FBr

II A) constitutional isomers. B) enantiomers. C) diastereomers. D) identical. E) None of these Ans: D

Topic: Identifications and Comparisons

17. The molecules below are: CH3

CH3H2N

FH3C

CH3

NH2

A) constitutional isomers. B) enantiomers. C) diastereomers. D) identical. E) None of these Ans: C

Topic: Identifications and Comparisons

18. The molecules shown are: CH3

A) constitutional isomers. B) enantiomers. C) diastereomers. D) identical. E) None of these Ans: A

Chapter 5

130

Topic: Identifications and Comparisons

19. The molecules below are:

ClF

CH3

A) constitutional isomers. B) enantiomers. C) diastereomers. D) identical. E) None of these Ans: D

Topic: Identifications and Comparisons

20. The molecules below are: H

ClH

CH3

Cl A) constitutional isomers. B) enantiomers. C) diastereomers. D) identical. E) None of these Ans: B

Chapter 5

131

Topic: Identifications and Comparisons

21. Which molecule is achiral? H

BrCl

HBr

ClH

Br Cl

BrCl

I II III A) I B) II C) III D) More than one of these E) None of these Ans: A

Topic: Identifications and Comparisons

22. Which molecule is achiral? H

BrH

BrCl

H Cl

ClBr

I II III A) I B) II C) III D) More than one of the above E) None of the above Ans: C

Chapter 5

132

Topic: Identifications and Comparisons

23. The molecules below are: H

FHH H

I II

HHF

HHH F

A) constitutional isomers. B) enantiomers. C) diastereomers. D) identical. E) None of these Ans: A

Topic: Identifications and Comparisons

24. The structures

CH3

H CH3

CH3

H CH3

represent: A) a single compound. B) enantiomers. C) meso forms. D) diastereomers. E) conformational isomers. Ans: A

Chapter 5

133

Topic: Identifications and Comparisons

25. Which pair of structures represents the same compound? CH3

OHHOHH

H OHCH3

I II

CH3OHHHHO

H OHCH3

CH3OHHHHO

HO HCH3

III IV

CH3HHOHHO

H OHCH3

CH3OHHOHH

HO HCH3

A) I and II B) II and III C) III and IV D) III and V E) IV and V Ans: D

Topic: Identifications and Comparisons

26. Which structure(s) represent(s) diastereomer(s) of I?

CH3OHHHHO

HO HCH3

I II

CH3OHHHHO

H OHCH3

CH3OHHOHH

H OHCH3

III IV

CH3HHOHHO

H OHCH3

CH3OHHOHH

HO HCH3

A) II B) II and III C) II and IV D) III and V E) IV and V Ans: B

Chapter 5

134

Topic: Identifications and Comparisons

27. The two compounds shown below are: Br

FHCl

ClBrH

A) enantiomers. B) diastereomers. C) constitutional isomers. D) identical. E) different but not isomeric. Ans: A

Topic: Identifications and Comparisons

28. The two compounds shown below are:

HBr

H Br

HBr

Hand

are: A) identical. B) enantiomers. C) diastereomers. D) conformational isomers. E) meso forms. Ans: B

Topic: Identifications and Comparisons

29. (2R,4S) –2,4–Dichloropentane and (2S,4R)-2,4-dichloropentane are: A) enantiomers B) diastereomers C) identical D) conformational isomers E) constitutional isomers Ans: C

Chapter 5

135

Topic: Meso compounds

30. Which of the following is a meso compound? H

HOH3C

CH3

CH2OH

OHH

CH2OH

CH3

OHH

H H2C

H3CHO

CH3

I II

III IV V A) I B) II C) III D) IV E) V Ans: A

Topic: Meso compounds

31. Which of the following is(are) meso compound(s)? H

CH3

CH3Cl

ClH

CH3

H H

ClH

CH3

I II III A) I B) II C) III D) Both II and III E) Both I and III Ans: E

Chapter 5

136

Topic: Meso compounds

32. Which of the following molecules is achiral? A) (2R,3R)-2,3-Dichloropentane B) (2R,3S)-2,3-Dichloropentane C) (2S,4S)-2,4-Dichloropentane D) (2S,4R)-2,4-Dichloropentane E) Two of these Ans: D

Topic: Meso compounds

33. Which of the following is(are) meso? Br

I II III IVA) I B) II C) III D) IV E) Two of the above Ans: E

Topic: Meso compounds

34. Which molecule has a plane of symmetry? F

HClHH

CH3

I II IIIA) I B) II C) III D) More than one of these E) None of these Ans: D

Chapter 5

137

Topic: Meso compounds

35. Which molecule has a plane of symmetry?

CH3HO

H CH3 CH2CH3

CH3HOH

I II III A) I B) II C) III D) More than one of these E) None of these Ans: D

Topic: Meso compounds

36. Which compound does NOT possess a plane of symmetry?

CH3

III

CH3

H3CIV V

A) I, II and V B) I, III and IV C) II, III and IV D) III and IV E) V Ans: D

Chapter 5

138

Topic: Meso compounds

37. Which molecule is a meso compound? CH3

CH3

BrH

H3C

CH3H

OH H3C

CH3

I II III A) I B) II C) III D) More than one of the above E) None of the above Ans: D

Topic: Meso compounds

38. Which molecule is a meso compound? H

III

CH3

V A) I and II B) IV and V C) II and III D) I, II and III E) None of the above Ans: E

Chapter 5

139

Topic: Meso compounds

39. Which of the following substances is achiral ? H

CH3

I II III

CH3

A) I B) II C) III D) IV E) More than one of these Ans: E

Topic: Meso compounds

40. Which statement is not true for a meso compound? A) The specific rotation is 0º. B) There are one or more planes of symmetry. C) A single molecule is identical to its mirror image. D) More than one stereogenic center must be present. E) The stereochemical labels, (R) and (S), must be identical for each stereogenic

center. Ans: E

Topic: Meso compounds

41. Which is a meso compound? A) (2R,3R)-2,3-Dibromobutane B) (2R,3S)-2,3-Dibromopentane C) (2R,4R)-2,4-Dibromopentane D) (2R,4S)-2,4-Dibromopentane E) (2R,4S)-2,4-Dibromohexane Ans: D

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Topic: Specific names

42. (R)-2-Chlorobutane is represented by: CH3

CH2CH3

ClH3C

CH3

CH2CH3

CH3Cl

CH2CH3

ClH3C

III

CH2CH3

HClH3C

CH2Cl

CH2CH3

V A) I B) II C) III D) IV E) V Ans: C

Topic: Specific names

43. Which of the following represent (R)-2-butanol? H

CH2CH3

OHH3C

CH3

CH2CH3

OHH

CH2CH3

CH3HO

III

CH3

CH2CH3

HHO

CH2CH3

CH3

OHH

V A) III and V B) I, III, IV and V C) I, IV and V D) I and III E) I, II, IV and V Ans: C

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Topic: Specific names

44. Which structure represents (S)-1-chloro-1-fluoroethane? F

CH3

HCl

CH3

ClH

CH3

FClH

III A) I B) II C) III D) More than one of the above E) None of the above Ans: D

Topic: Specific names

45. Which structure represents (R)-1-chloro-1-fluoroethane? F

CH3

HCl

CH3

ClH

CH3

FClH

III A) I B) II C) III D) More than one of the above E) None of the above Ans: B

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142

Topic: Specific names

46. Which structure represents (S)-2-bromobutane? CH3

CH2CH3

BrH

CH3

CH2CH3

HBr

CH2CH3

BrH3C

III A) I B) II C) III D) More than one of the above E) None of the above Ans: A

Topic: Specific names

47.

CH2CH3

ClH

CH3HCl H

CH3 is properly named: A) (3R,4S,5R)- 3,5-Dichloro-4-methylhexane B) (2S,3S,4S)- 2,4-Dichloro-3-methylhexane C) (2S,3R,4R)- 2,4-Dichloro-3-methylhexane D) (2S,3R,4S)-2,4-Dichloro-3-methylhexane E) (2S,3S,4R)- 2,4-Dichloro-3-methylhexane Ans: D

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143

Topic: Specific names

48. The Cahn-Ingold-Prelog stereochemical designations used for the following substance are:

ClH

Cl A) 2R,4S B) 2S,4R C) 2R,4R D) 2S,4S E) The “R,S” terminology doesn't apply in this case. Ans: C

Topic: Specific names

49. Which of these is not a correct Fischer projection formula of the (S) form of 3-bromo-1,1-dichloro-2-propanol ?

CHCl2

CH2BrOHH

CH2Br

CHCl2

HHO

OHCH2BrCl2HC

III

CH2BrCHCl2H

HCHCl2BrH2C

V A) I B) II C) III D) IV E) V Ans: D

Topic: Optical activity

50. What is the percent composition of a mixture of (S)-(+)-2-butanol,[α]D25 = +13.52º,

and (R)-(-)-2-butanol,[α]D25 = -13.52º, with a specific rotation [α]

D25 = +6.76º?

A) 75%(R) 25%(S) B) 25%(R) 75%(S) C) 50%(R) 50%(S) D) 67%(R) 33%(S) E) 33%(R) 67%(S) Ans: B

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144

Topic: Optical activity

51. Which one of the following can exist in optically active forms? A) cis-1,3-Dichlorocyclohexane B) trans-1,3-Dichlorocyclohexane C) cis-1,4-Dichlorocyclohexane D) trans-1,4-Dichlorocyclohexane E) cis-1,2-Dichlorocyclohexane Ans: B

Topic: Optical activity

52. The compounds whose molecules are shown below would have: CH3

CH2CH3

CH3

II A) the same melting point. B) different melting points. C) equal but opposite optical rotations. D) More than one of the above E) None of the above Ans: D

Topic: Optical activity

53. The compounds whose molecules are shown below would have: CH3

CH3H

FH3C

CH3

A) the same melting point. B) different melting points. C) equal but opposite optical rotations. D) More than one of the above E) None of the above Ans: B

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Topic: Optical activity

54. The compounds whose molecules are shown below would have:

OHOH

A) the same melting point. B) different melting points. C) equal but opposite optical rotations. D) More than one of these E) None of these Ans: B

Topic: Optical activity

55. The compounds whose structures are shown below would have:

CH3

A) the same melting point. B) different melting points. C) equal but opposite optical rotations. D) More than one of these E) None of these Ans: D

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146

Topic: Optical activity

56. A solution of which of these allenes will rotate plane-polarized light?

C C C

H H

C C C

Cl H

C C C

Cl Cl

C C C

Cl Cl

C C C

Cl Cl

I II III

IV V A) I B) II C) III D) IV E) V Ans: C

Topic: Optical activity

57. How many optically active compounds are represented by the following generalized formula?

BrHC CHBr

A) 0 B) 1 C) 2 D) 3 E) 4 Ans: C

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147

Topic: Optical activity

58. Which of these is a comparatively insignificant factor affecting the magnitude of specific optical rotation? A) Concentration of the substance of interest B) Purity of the sample C) Temperature of the measurement D) Length of the sample tube E) All of the above are equally significant. Ans: C

Topic: Optical activity

59. What can be said with certainty if a compound has [α]D25 = -9.25º ?

A) The compound has the (S) configuration. B) The compound has the (R) configuration. C) The compound is not a meso form. D) The compound possesses only one stereogenic center. E) The compound has an optical purity of less than 100%. Ans: C

Topic: Optical activity

60. An alkane which can exhibit optical activity is: A) Neopentane B) Isopentane C) 3–Methylpentane D) 3–Methylhexane E) 2,3–Dimethylbutane Ans: D

Topic: Optical activity

61. In the absence of specific data, it can only be said that (R)–2–bromopentane is: A) dextrorotatory (+). B) levorotatory (–). C) optically inactive. D) achiral. E) analogous in absolute configuration to (R)–2–chloropentane. Ans: E

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Topic: Optical activity

62. If a solution of a compound (30.0 g/100 mL of solution) has a measured rotation of +15º in a 2 dm tube, the specific rotation is: A) +50º B) +25º C) +15º D) +7.5º E) +4.0º Ans: B

Topic: Optical activity

63. Which compound would show optical activity? A) cis 1,4- Dimethylcyclohexane B) trans 1,4- Dimethylcyclohexane C) cis 1,4- Dimethylcycloheptane D) trans 1,4- Dimethylcycloheptane E) More than one of these Ans: D

Topic: Optical activity

64. Of the compounds which correspond to the general name "dichlorocyclobutane", how many are optically active? A) 0 B) 1 C) 2 D) 3 E) 4 Ans: C

Topic: General definitions

65. Which of the following is true about any (R)-enantiomer? A) It is dextrorotatory. B) It is levorotatory. C) It is an equal mixture of + and -. D) It is the mirror image of the (S)-enantiomer. E) (R) indicates a racemic mixture. Ans: D

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149

Topic: General definitions

66. Which of the following is true of any (S)-enantiomer? A) It rotates plane-polarized light to the right. B) It rotates plane-polarized light to the left. C) It is a racemic form. D) It is the mirror image of the corresponding (R)-enantiomer. E) It has the highest priority group on the left. Ans: D

Topic: General definitions

67. Enantiomers are: A) molecules that have a mirror image. B) molecules that have at least one stereogenic center. C) non-superposable molecules. D) non-superposable constitutional isomers. E) non-superposable molecules that are mirror images of each other. Ans: E

Topic: General definitions

68. Which of the following is NOT true of enantiomers? They have the same: A) boiling point. B) melting point. C) specific rotation. D) density. E) chemical reactivity toward achiral reagents. Ans: C

Topic: General definitions

69. Which statement is true of 1,3-dimethylcyclobutane? A) Only one form of the compound is possible. B) Two diastereomeric forms are possible. C) Two sets of enantiomers are possible. D) Two enantiomeric forms and one meso compound are possible. E) None of the previous statements is true. Ans: B

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150

Topic: Reaction stereochemistry

70. In which of the following reactions is the absolute configuration of the product likely to be the same as that of the reactant? A)

OHBr PBr3

BrBr

(R)B)

OHBr

OBr

(R)HA

C) OH

Br H2OOH

OH(R)

D) All of the above E) Answers A) and B) only Ans: E

Topic: Reaction Stereochemistry

71. Which of the following reactions must occur with retention of configuration? A)

KMnO4

(R)

OH Cl

(R)POCl3

C) OH

NH3OH

NH2

(S)

D) OH

OCH3 PCl5Cl

OCH3(R)

E) (S) OH

Cl P, Cl2OH

Cl Cl

Ans: D

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151

Topic: Reaction stereochemistry

72. Which reaction must take place with retention of configuration at the stereogenic center? A)

BrHCl

BrOH Cl

F F

B) OHF

PCl3ClF

OHF

OFO

O O

OD) More than one of the above E) None of the above Ans: D

Topic: Reaction stereochemistry

73.

The reaction of O with H2/Ni forms: A) 2-methylheptane. B) (R)-2-methyl-5-heptanol C) (S)-6-methyl-3-heptanol D) (R,S)-6-methyl-3-heptanol E) Achiral 6,6-dimethyl-3-hexanol Ans: D

Topic: General stereochemistry

74. CH3CHBrCH2CHClCH3 is the generalized representation of what number of stereoisomers? A) 3 B) 4 C) 5 D) 6 E) 7 Ans: Bs

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152

Topic: General stereochemistry

75. For the generalized structure BrCH2CHClCH2CHClCH2Br there exists what number of stereoisomers? A) 2 B) 3 C) 4 D) 6 E) 8 Ans: B

Topic: General stereochemistry

76. How many discrete dimethylcyclopropanes are there? A) 2 B) 3 C) 4 D) 5 E) 6 Ans: C

Topic: General stereochemistry

77. What is the molecular formula for the alkane of smallest molecular weight which possesses a stereogenic center? A) C4H10 B) C5H12 C) C6H14 D) C7H16 E) C8H18 Ans: D

Topic: General stereochemistry

78. How many chiral stereoisomers can be drawn for CH3CHFCHFCH(CH3)2? A) 1 B) 2 C) 3 D) 4 E) 8 Ans: D

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153

Topic: General stereochemistry

79. How many different compounds are there which correspond to the general name "3-(1-methylbutyl)cyclobutanol”? A) 2 B) 4 C) 6 D) 8 E) None of the above Ans: B

Topic: General stereochemistry

80. How many stereogenic centers are there in Lovastatin ( Mevacor® : a cholesterol-lowering drug) ?

(Lovastatin) A) 4 B) 5 C) 6 D) 7 E) 8 Ans: E

Topic: General stereochemistry

81. What is the total number of compounds, stereoisomers included, designated by the general name "dichlorocyclopentane"? A) 4 B) 5 C) 7 D) 8 E) 9 Ans: C

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154

Use the following to answer questions 82-85: Consider the following compounds:

CH2OH

CH3

OHH

CH3H

CH3 HO

CH3HO

CH3

I II III

HH3C

CH3

IV Topic: General stereochemistry

82. Which of the compounds above (I-IV) represent enantiomers? A) I and II B) II and III C) III and IV D) II and IV E) III and IV Ans: B

Topic: General stereochemistry

83. Which compound above (I-IV) is a meso compound? A) I B) II C) III D) IV E) None of these Ans: D

Topic: General stereochemistry

84. Which compound above (I-IV) is (2R,3R)-2,3-butanediol? A) I B) II C) III D) IV E) None of these Ans: C

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155

Topic: General stereochemistry

85. Which compounds above (I-IV) form a set of stereoisomers? A) I, II and III B) II, III and IV C) II and III D) I, III and IV E) I, II, III and IV Ans: B

SHORT ANSWER QUESTIONS Topic: General stereochemistry

86. To be superposable, when one object is placed on top of another, _________________. Ans: all parts of each object must coincide

Topic: General stereochemistry

87. An achiral molecule is one that is __________________ upon its mirror image. Ans: superposable

Topic: General stereochemistry

88. Enantiomers are stereoisomers whose molecules are ____________________. Ans: nonsuperposable mirror images

Topic: General stereochemistry

89. A chiral molecule is defined as one that is _____________________ on its mirror image. Ans: nonsuperposable

Topic: General stereochemistry

90. A meso compound has __________ chiral center(s), and is __________ upon its mirror image. Ans: two or more, superposable

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156

Topic: General stereochemistry

91. The molecule of aspartame ( Nutrasweet® ), depicted below, has ___________ ( how many? ) stereogenic centers.

H2N

HNOHO

Aspartame Ans: two

Topic: General stereochemistry

92. All molecules with a plane of symmetry are _________. Ans: achiral

Topic: General stereochemistry

93. When using the Cahn-Ingold-Prelog rules for prioritizing groups on a stereogenic carbon, priority is first assigned on the basis of ____________________. Ans: atomic number

Topic: General stereochemistry

94. Enantiomers have ______________ physical properties. Ans: identical

Topic: General stereochemistry

95. The device that is used for measuring the effect of optically active compounds on plane-polarized light is called a ________________. Ans: polarimeter

Topic: General stereochemistry

96. True or false: A sample consisting of the pure R enantiomer of a compound will always rotate plane-polarized light in a clockwise direction. A) True B) False Ans: B

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157

Topic: General stereochemistry

97. An equimolar mixture of two enantiomers is called a ________________. Ans: racemic mixture

Topic: General stereochemistry

98. A molecule that contains stereogenic carbons but is nonetheless achiral is referred to as a ______________. Ans: meso compound

Topic: General stereochemistry

99. When discussing the stereochemical relationship of cis/trans isomers of cyclic compounds, we refer to them as __________________. Ans: diastereomers

Topic: Nomenclature

100. Draw a dash-wedge structure for (3R)-3-methyl-5-hexen-3-ol Ans: OH

Topic: Nomenclature

101. Draw a dash-wedge structure for (1R)-1-bromo-1,3,3-trimethylcyclohexane Ans:

Topic: Nomenclature

102. Draw a dash-wedge structure for (1R,3R)-1,3-dibromo-1,3-dimethylcyclohexane Ans:

Chapter 5

158

Topic: Nomenclature

103. Draw a dash-wedge structure for (1S,3R)-1-ethyl-1,3-dimethylcyclopentane Ans: CH3

H CH3

C2H5

Topic: Nomenclature

104. What is the complete IUPAC name of the following substance? (Remember to give stereochemical details, as relevant.)

H3C CH3

C2H5

Ans: (1S)-1-ethyl-1,3,3-trimethylcyclopentane

Topic: Nomenclature

105. What is the complete IUPAC name of the following substance? (Remember to give stereochemical details, as relevant.)

H3C OH

Ans: (1R,3S)-1-methylcyclopentane-1,3-diol

Chapter 5

159

Topic: Fischer projections

106. Draw Fischer projection formulas for all stereoisomers of 2,4-dibromohexane, giving stereochemical details for each structure. Ans:

2,4-dibromohexane

CH3

HBr

CH3

BrH

HBr

CH3

HBr

BrH

CH3

2R,4S

CH3

BrH

CH3

2S,4R 2S,4S 2R,4R

Topic: Stereoisomers

107. Draw dash-wedge structures for all stereoisomers of 1-bromo-3-isopropylcyclohexane, giving stereochemical details for each structure. Ans:

H Br

Br H

H Br

Br H

1-bromo-3-isopropylcyclohexane

1S, 3R 1R, 3S 1S, 3S 1R, 3R

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160

Topic: Fischer projections

108. Draw Fischer projection formulas for all stereoisomers of 2,4-dimethyl-3-hexanol, giving stereochemical details for each structure. Ans:

CH3

HH3C

OHH

HH3C

CH3

HH3C

OHH

CH3H

CH3

HH3C

HHO

HH3C

CH3

HH3C

HHO

CH3H

CH3

3S,4S 3R,4R 3S,4R 3R,4S

2,4-dimethyl-3-hexanol Topic: Fischer projections

109. Draw a Fischer projection formula of (3R)-6-Bromo-1-hexen-3-ol. Ans:

H2C

OHH

CH2Br

(3R)-6-Bromo-1-hexen-3-ol.

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161

MULTIPLE CHOICE QUESTIONS Topic: Reaction kinetics

1. Consider the SN2 reaction of butyl bromide with OH- ion. CH3CH2CH2CH2Br + OH- ⎯⎯⎯⎯→ CH3CH2CH2CH2OH + Br-

Assuming no other changes, what effect on the rate would result from simultaneously doubling the concentrations of both butyl bromide and OH- ion?

A) No effect. B) It would double the rate. C) It would triple the rate. D) It would increase the rate four times. E) It would increase the rate six times.

Ans: D Topic: Reaction kinetics

2. Consider the SN2 reaction of 2-iodopentane with CH3CO2− ion.

ONa

O OONaI

Assuming no other changes, what effect on the rate would result from simultaneously doubling the concentrations of both 2-iodopentane and CH3CO2− ion?

A) No effect. B) It would double the rate. C) It would triple the rate. D) It would increase the rate four times. E) It would increase the rate six times.

Ans: D

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162

Topic: Reaction kinetics

3. Consider the SN2 reaction of 1-chloro-5-methylhexane with CN− ion.

Cl NaCN CN NaCl

Assuming no other changes, what effect on the rate would result from simultaneously doubling the concentrations of both 1-chloro-5-methylhexane and CN− ion?

A) No effect. B) It would double the rate. C) It would triple the rate. D) It would increase the rate four times. E) It would increase the rate six times.

Ans: D Topic: Reaction kinetics

4. Select the rate law for the following reaction, e.g., CH3CH2CH2CHBrCH3 + OH− ⎯⎯⎯→ CH3CH2CH2CHOHCH3 + X− ( RBr )

A) Rate = k [RBr] B) Rate = k [RBr] [OH−] C) Rate = k [RBr]2 [OH−] D) Rate = k [RBr] [OH−]2 E) Rate = k [RBr]2 [OH−]2

Ans: B Topic: Activation Energy

5. Increasing the temperature of a chemical reaction usually increases greatly the rate of the reaction. The most important reason for this is that increasing the temperature:

A) Increases the collision frequency. B) Decreases the probability factor. C) Increases the fraction of collisions with energy greater than Eact. D) Decreases the energy of activation. E) Makes the reaction more exothermic

Ans: C

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Topic: Activation Energy

6. Increasing the temperature of a chemical reaction usually increases greatly the rate of the reaction. The primary reason for this is that increasing the temperature:

A) Decreases the energy of activation. B) Increases the total number of collisions between reactants C) Decreases the rate of the reverse reaction. D) Favors endothermic processes. E) None of the above properly explains the observed increase in reaction rates with

increase in temperature. Ans: E

Topic: Reaction Kinetics

7. The rate equation for a nucleophilic substitution reaction of a tertiary alkyl bromide (R-Br) with I− ion would be:

A) Rate = k [RBr] B) Rate = k [I−] C) Rate = k [RBr][I−] D) Rate = k [RBr]2[I−] E) Rate = k [RBr][I−]2

Ans: A Topic: Reaction Kinetics

8. The rate equation for a nucleophilic substitution reaction of a secondary alkyl chloride (R-Cl) with I− ion would be:

A) Rate = k [RCl] B) Rate = k [I−] C) Rate = k [RCl][I−] D) Rate = k [RCl]2[I−] E) Rate = k [RCl][I−]2

Ans: C

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164

Topic: Reaction Kinetics

9. Consider the reaction of 2-chloro-2-methylpentane with sodium iodide.

NaII

NaCl

Assuming no other changes, how would it affect the rate if one simultaneously doubled the concentration of 2-chloro-2-methylpentane and sodium iodide?

A) No effect B) It would double the rate. C) It would triple the rate. D) It would quadruple the rate. E) It would increase the rate five times.

Ans: B Topic: Predicting mechanisms, products

10. What would you expect to be the chief organic product(s) when tert-butyl bromide reacts with sodium acetylide, i.e.,

BrHC C: Na

HC CH

II III

A) I B) II C) III D) IV E) None of these

Ans: D

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165

Topic: Predicting mechanisms, products

11. What would you expect to be the chief organic product(s) when 2-bromo-2-methylpentane reacts with sodium propynide, i.e.,

BrC: Na

HC CH

III

A) I B) II C) III D) IV E) V

Ans: D Topic: Predicting products

12. What product(s) would you expect to obtain from the following SN2 reaction?

CH3

CH3ONa

CH3OH

OCH3

CH3 H

OCH3H

CH3

I II

CH3O

III

A) I B) II C) An equimolar mixture of I and II. D) III E) None of these

Ans: B

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166

Topic: Predicting mechanisms, products

13. What major product(s) are likely to be obtained from the following reaction?

CH3CH2ONa

CH3CH2OH, 65oC

H H

I II

III

A) I, by predominantly SN2 B) II, by predominantly SN2 C) An equimolar mixture of I and II, by predominantly SN1. D) III, by substitution of the alkyl group, rather than substitution of the chloro group E) Actually, none of these products are likely to be obtained as major products, because

elimination will probably predominate, leading to the formation of an alkene. Ans: E

Topic: Predicting mechanisms, products

14. Treating (CH3)3C-Cl with a mixture of H2O and CH3OH at room temperature would yield:

A) CH2=C(CH3)2 B) (CH3)3COH C) (CH3)3COCH3 D) All of these E) None of these

Ans: D

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167

Topic: Predicting mechanisms, products

15. Treating 1-bromo-1-methylcyclohexane with CH3OH at room temperature would yield: A)

OCH3

D) All of these E) None of these

Ans: D Topic: Predicting products

16. The major product of the following reaction would be: C H 2 C l

H O C H 3

C H 3

O H −

C H 2 O H

H 3 C O H

C H 3

C H 2 C l

H O H

C H 3

I I I IV

C H 2 C l

H O H

C H 3

I I

C H 2 O H

H O C H 3

C H 3

S N 2?

A) I B) II C) III D) IV E) An equimolar mixture of I and II.

Ans: B

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168

Topic: Predicting mechanisms, products

17. Which would be formed in the following reaction? CH3

BrH3C

CH3OH

OCH3

CH3H3C

CH3

CH2

IVIII

CH3

OCH3H3C

55oC?

A) I B) II C) III D) IV E) All of the above

Ans: E

Chapter 6

169

Topic: Predicting mechanisms, products

18. Which would be formed in the following reaction? CH3

H3COH

CH3

H3C

III

CH3

H3C

50oC?

A) I B) II C) III D) IV E) All of the above

Ans: E

Chapter 6

170

Topic: Predicting mechanisms, products

19. Which would be the major product of the following reaction?

ClH

CH3

OC(CH3)3

CH3

OC(CH3)3

CH3

I II

H3C

III

H3C

(CH3)3COH 55oC

?(CH3)3CO−

A) I B) II C) III D) IV E) None of the above

Ans: C

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171

Topic: Predicting mechanisms, products

20. When 1,4-diiodo-2,2-dimethylbutane (0.10 mol) is treated with 0.10 mol of NaCN in dimethyl sulfoxide at 30°C, the product formed is:

A) NCI

B) ICN

C) both A) and B).

D) NCCN

E) I

Ans: B

Topic: Predicting mechanisms, products

21. The major product(s) of the following reaction is(are):

CH3

I II

CH3

III IV

CH3

OCH2CH3

NaI, CH3CH2OH

25oC

A) I B) II C) III D) IV E) Equal amounts of I and II

Ans: A

Chapter 6

172

Topic: Predicting products

22. What would be the major product of the following reaction?

CH2Cl

H CH3

OH−

CH2OH

H3C H

CH2Cl

HO CH3

III

CH2Cl

H OH

CH2OH

H CH3

SN2

A) I B) II C) III D) IV E) An equimolar mixture of I and II

Ans: B

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173

Topic: Predicting mechanisms, products

23. What would be the major product(s) of the following reaction?

CH3H3C

H Br

CH3H3C

H OCH3

OCH3H3C

H CH3

I II

H3C CH3 H3C

III IV

CH3O− / CH3OH

55oC

A) I B) II C) III and IV D) I and II E) All of the above

Ans: C

Chapter 6

174

Topic: Predicting mechanisms, products

24. What would be the major product of the following reaction?

HH3C

H Br

HH3C

H CN

CNH3C

H Br

I II

III IV

CNH3C

H H

HH3C

NC Br

CΝ −

25oC

A) I B) II C) III D) IV E) Equal amounts of I and III

Ans: C Topic: Predicting mechanisms, products

25. What would be the major product obtained when trans-1-bromo-3-methylcyclopentane is allowed to react with NaSH at 25oC?

HH3C

H SH

SHH3C

H H

SHH3C

H Br

HH3C

HS Br

I II III IV

A) I B) II C) III D) IV E) Equal amounts of I and II

Ans: B

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175

Topic: Synthesis, reagent selection

26. You want to synthesize 3-methyl-2-pentene from 2-chloro-3-methylpentane. Which reagent would you use?

A) HCl, heat B) NH3(aq), 25oC C) CH3CO2Na, CH3CO2H, heat D) CH3CH2ONa, CH3CH2OH, heat E) CH3CH2OH, heat

Ans: D Topic: Predicting mechanisms, products

27. When tert-pentyl chloride undergoes solvolysis in aqueous ethanol at room temperature, there is/are formed:

OH B)

OC2H5 C)

E) All of these

Ans: E Topic: Predicting mechanisms, products

28. Reaction of sodium ethoxide with 1-bromopentane at 30°C yields primarily: A) CH3CH2CH2CH=CH2 B) CH3CH2CH=CHCH3 C) CH3CH2CH2CH2CH3 D) CH3CH2CH2CH2CH2OH E) CH3CH2CH2CH2CH2OCH2CH3

Ans: E

Chapter 6

176

Topic: Predicting mechanisms, products

29. Heating an alcoholic solution of sodium hydroxide and 1-bromopentane at 60°C yields primarily:

A) B) C) D) OH E) O

Ans: D Topic: Predicting mechanisms, products

30. If 0.10 mol of HSCH2CH2OH reacts at 25°C, sequentially, with 0.20 mol of NaH, 0.10 mol of CH3CH2Br and H2O, which is the major product?

A) HSCH2CH2OCH2CH3 B) CH3CH2SCH2CH2OH C) CH3CH2SCH2CH2OCH2CH3 D) CH2=CH2 E) CH3CH3

Ans: B Topic: Predicting mechanisms, products

31. When 0.10 mol of ICH2CH2CH2CH2Cl reacts with 0.10 mol of NaOCH3 in CH3OH at 40°C, the major product is:

A) CH3OCH2CH2CH2CH2Cl B) CH3OCH2CH2CH2CH2I C) CH3OCH2CH2CH2CH2OCH3 D) CH2=CHCH2CH2Cl E) CH2=CHCH2CH2I

Ans: A Topic: Generalities

32. SN2 reactions of the type, Nu- + RL ⎯⎯⎯⎯→ Nu-R + L-, are favored: A) when tertiary substrates are used. B) by using a high concentration of the nucleophile. C) by using a solvent of high polarity. D) by the use of weak nucleophiles. E) by none of the above.

Ans: B

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Topic: Generalities

33. Which of the following statements is (are) true of SN1 reactions of alkyl halides in general?

A) The rate of an SN1 reaction depends on the concentration of the alkyl halide. B) The rate of an SN1 reaction depends on the concentration of the nucleophile. C) SN1 reactions of alkyl halides are favored by polar solvents. D) Answers A) and C) only are true. E) Answers A), B) and C) are true.

Ans: D Topic: Generalities

34. Which of the following statements is (are) true of SN1 reactions of alkyl halides in general?

A) The rate of an SN1 reaction depends on the concentration of the alkyl halide. B) The rate of an SN1 reaction depends on the concentration of the nucleophile. C) SN1 reactions of alkyl halides occur faster in polar aprotic solvents (compared to protic

solvents) D) Answers A) and C) only are true. E) Answers A), B) and C) are true.

Ans: A Topic: Generalities

35. SN1 reactions of the type, Nu- + RL ⎯⎯⎯⎯→ Nu–R + L-, are favored: A) when tertiary substrates are used. B) by using a high concentration of the nucleophile. C) when L- is a strong base. D) by use of a non-polar solvent. E) by none of the above.

Ans: A Topic: Generalities

36. Which of the following statements is (are) true of an SN2 reaction of (R)-2-bromobutane with hydroxide ion?

A) Doubling the hydroxide ion concentration would double the rate of the reaction. (Assume that all other experimental conditions are unchanged.)

B) The major product would be (S)-2-butanol. C) Doubling the concentration of (R)-2-bromobutane would double the rate of the reaction.

(Assume that all other experimental conditions are unchanged.) D) All of the above E) Two of the above

Ans: D

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178

Topic: Generalities

37. SN1 reactions of the following type, Nu:- + R-X ⎯⎯⎯⎯→ R-Nu + :X-

are favored: A) by the use of tertiary substrates (as opposed to primary or secondary substrates). B) by increasing the concentration of the nucleophile. C) by increasing the polarity of the solvent. D) by use of a weak nucleophile. E) by more than one of the above.

Ans: E Topic: Generalities

38. SN1 reactions of the following type, Nu:- + R-X ⎯⎯⎯⎯→ R-Nu + :X-

Ans: A Topic: Generalities

39. A true statement about the transition state(s) of an SN2 reaction is: A) the two transition states are of unequal energy. B) the transition states precede and follow an unstable reaction intermediate. C) the single transition state represents the point of maximum free energy of the reaction. D) existence of this transition state implies an exothermic reaction. E) the transition state will always have a net charge of -1.

Ans: C

Chapter 6

179

Topic: Generalities

40. Elimination reactions are favored over nucleophilic substitution reactions: A) at high temperatures. B) when tert-butoxide ion is used. C) when 3° alkyl halides are used as substrates. D) when nucleophiles are used which are strong bases and the substrate is a 2° alkyl halide.E) in all of these cases.

Ans: E Topic: Carbocations

41. The hybridization state of the charged carbon in a carbocation is A) sp4 B) sp3 C) sp2 D) sp E) s

Ans: C Topic: Carbocations

42. The p orbital of a methyl cation, CH3+, contains how many electrons?

A) 1 B) 2 C) 3 D) 4 E) 0

Ans: E Topic: Carbocations

43. The p orbital of the charged carbon in the isopropyl cation, (CH3)2CH+, contains how many electrons?

A) 1 B) 2 C) 3 D) 4 E) 0

Ans: E

Chapter 6

180

Topic: Generalities, solvent effects

44. Considering the relative solvation of reactants and the transition states of SN reactions of these reactants, predict which general type of reaction would be most favored by the use of a polar solvent.

A) Y: + RX ⎯⎯⎯⎯→ RY+ + X:- B) Y:- + RX ⎯⎯⎯⎯→ RY + X:- C) Y: + RX+ ⎯⎯⎯⎯→ RY+ + X: D) Y:- + RX+ ⎯⎯⎯⎯→ RY + X: E) RX+ ⎯⎯⎯⎯→ R+ + X:

Ans: A Topic: Generalities, solvent effects

45. Which is not a polar aprotic solvent? A)

H3CC

CH3

B) H3C C N C)

H3CS

CH3

CH3 E)

H3CCH

CH3

Ans: E

Topic: Generalities, solvent effects

46. Which is a polar aprotic solvent? A) 2-methylhexane B) CH3CN C) NH3(l) D) CH3CH2CH2OCH2CH2CH3 E) 2-methyl-2-propanol

Ans: E

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181

Topic: Generalities, nucleophiles 47. Identify the nucleophile in the following reaction.

2 H2O + RX ROH + H3O+ + X−

A) X- B) H3O+ C) ROH D) H2O E) RX

Ans: D Topic: Generalities, nucleophiles 48. Identify the nucleophile in the following reaction.

2 R’OH + RX ROR’ + [ROH2]+ + X−

A) X− B) [ROH2]+ C) ROR’ D) R’OH E) RX

Ans: D Topic: Transition State theory

49. An increase in the kinetic energy of reacting molecules results in: A) a decrease in reaction rate. B) an increase in the probability factor. C) a decrease in the probability factor. D) an increase in the reaction rate. E) no changes.

Ans: D

Chapter 6

182

Topic: Generalities, leaving group

50. Identify the leaving group in the following reaction. S−Na+

Na+ + I −

A) C6H5S- B) Na+ C) CH3CH2I D) C6H5SCH2CH3 E) I-

Ans: E Topic: Generalities, solvent effects

51. Which is the weakest nucleophile in polar aprotic solvents? A) I- B) Br- C) Cl- D) F- E) All of the above are equally strong nucleophiles, regardless of the type of solvent used

Ans: A Topic: Generalities, solvent effects

52. Which is the weakest nucleophile in polar protic solvents? A) I- B) Br- C) Cl- D) F- E) All of the above are equally strong nucleophiles, regardless of the type of solvent used

Ans: D Topic: Generalities, leaving group

53. Which of the following is the poorest leaving group? A) H− B) CH3O− C) H2O D) OH− E) NH2

− Ans: E

Chapter 6

183

Topic: Generalities, nucleophiles 54. Which of the following is not a nucleophile?

A) H2O B) CH3O- C) NH3 D) NH4

+ E) All are nucleophiles.

Ans: D Topic: Generalities, solvent effects

55. Which ion is the strongest nucleophile in aqueous solution? A) F- B) Cl- C) Br- D) I- E) All of these are equally strong.

Ans: D Topic: Leaving groups

56. Which of the following is not a good leaving group? A) C2H5O− B) Cl− C) I− D) CH3CO2

− E) All of these are good leaving groups

Ans: A Topic: Leaving groups

57. Identify the leaving group in the following reaction:

CH3OH + CH3OH2 CH3OCH3 + H2OH

A) CH3OH B) CH3OH2

+ C) CH3OCH3 D) H2O E) None of these

Ans: D

Chapter 6

184

Topic: Nucleophiles

58. Which is the strongest nucleophile? A) OH- B) CH3CH2O- C)

D) CH3CH2OH E) H2O

Ans: B Topic: Nucleophile, solvent effects

59. Which is the most reactive nucleophile in DMF (structure shown below) ?

CH3

A) F- B) Cl- C) Br- D) I- E) They are all equally reactive.

Ans: A Topic: Nucleophile, solvent effects

60. Which of these species, acting in a protic solvent, exhibits greater nucleophilic activity than expected on the basis of its basicity?

A) OH- B) CH3O- C) SH- D) Cl- E) H2O

Ans: C

Chapter 6

185

Topic: Nucleophilicity

61. The relative nucleophilicities of species do not necessarily parallel the relative basicities of the same species because:

A) not all nucleophiles are bases, and vice versa. B) experimental measurements of sufficient accuracy are not available to make the

comparisons. C) nucleophilicity is a thermodynamic matter; basicity is a matter of kinetics. D) basicity is a thermodynamic matter; nucleophilicity is a matter of kinetics. E) Actually, the relative values do parallel one another.

Ans: D Topic: Nucleophiles

62. Ambident nucleophiles are ones which can react with a substrate at either of two nucleophilic sites. Which of the following is not an ambident nucleophile?

:CN: :OH

:O:N::OH

I II

VIV

N:O:H

:OCH2CH2S:

III

....

.. ......

.. ....

......

A) I B) II C) III D) IV E) V

Ans: B Topic: Nucleophile, solvent effects

63. Which ion is the strongest nucleophile in an aprotic solvent such as dimethylsulfoxide? A) I- B) Br- C) Cl- D) F- E) These are all equal.

Ans: D

Chapter 6

186

Topic: Leaving group

64. Which of the following is a feasible substitution reaction? A) CH3CH2Cl + NaBr ⎯⎯⎯⎯→ CH3CH2I + NaCl B) CH3CH3 + NaCN ⎯⎯⎯⎯→ CH3CH2CN + NaH C) CH3CH2Cl + NaOH ⎯⎯⎯⎯→ CH2=CH2 + H2O + NaCl D) More than one of the above E) None of the above

Ans: A Topic: Predicting mechanism, products

65. Heating tert-butyl chloride with 1.0 M NaOH in a mixture of water and methanol would yield mainly:

A) (CH3)3COH through an SN1 reaction. B) (CH3)3COCH3 through an SN1 reaction. C) (CH3)3COH through an SN2 reaction. D) (CH3)3COCH3 through an SN2 reaction. E) CH2=C(CH3)2 through an E2 reaction.

Ans: E

Chapter 6

187

Topic: Free energy diagrams

66. Select the potential energy diagram that represents an exothermic (exergonic) reaction.

A) I B) II C) III D) IV E) V

Ans: E

Chapter 6

188

Topic: Free energy diagrams

67. Select the potential energy diagram that represents a single-step endothermic (endergonic) reaction.

A) I B) II C) III D) IV E) V

Ans: A

Chapter 6

189

Topic: Free energy diagrams

68. Select the potential energy diagram that represents a two-step endothermic (endergonic) reaction.

A) I B) II C) III D) IV E) V

Ans: B Topic: Hammond-Leffler postulate

69. The Hammond-Leffler postulate when applied to nucleophilic substitutions and elimination reactions states that:

A) a negatively-charged nucleophile is stronger than its conjugate acid. B) polar aprotic solvents strongly accelerate the rate of SN2 processes. C) bimolecular nucleophilic substitutions are 2nd order kinetically. D) the transition state for an endergonic reaction step (one accompanied by an increase in

free energy) resembles the product of that step. E) elimination reactions will always compete with nucleophilic substitution reactions.

Ans: D

Chapter 6

190

Topic: Transition state theory

70. Which will be true for any actual or potential nucleophilic substitution reaction? A) ΔH° is positive. B) ΔH° is negative. C) ΔG‡ is positive. D) ΔG° is positive. E) ΔG° is negative.

Ans: C Topic: Entropy changes

71. For the typical SN2 reaction Y- + RX ⎯⎯⎯⎯→ RY + X-

it can be predicted that ΔS‡ will be: A) positive. B) zero. C) negative. D) either positive or negative. E) unpredictable as to algebraic sign.

Ans: C Topic: Free energy changes

72. The reaction, CH3Cl + OH− CH3OH + Cl−

H2O has the following thermodynamic values at 27ºC: ΔH = -75.3 kJ mol-1; ΔS = 54.4 J K-1 mol-1. What is the value of ΔG for this reaction?

A) -73.8 kJ mol-1 B) -76.8 kJ mol-1 C) -59.0 kJ mol-1 D) +91.6 kJ mol-1 E) -91.6 kJ mol-1

Ans: E

Chapter 6

191

Topic: Activation energy

73. An increase in the temperature at which reaction is carried out increases: A) the collision frequency. B) the fraction of molecules with proper orientation. C) the fraction of molecules with energy greater than Eact. D) More than one of the above E) None of the above

Ans: D Topic: Free energy diagrams

74. The difference in the bond energies of reactants and the transition state of a reaction is designated by the notation:

A) ΔH° B) ΔH‡ C) ΔG° D) ΔG‡ E) ΔS‡

Ans: B Topic: Hammond-Leffler postulate

75. Which is a true statement concerning the transition state of the rate-determining step of an SN1 reaction?

A) Structurally, it closely resembles the carbocation intermediate. B) Both covalent bond-breaking and bond-making are occurring. C) Formation of the transition state is an exothermic reaction. D) Necessarily, the transition state has zero charge overall. E) More than one of the above

Ans: A Topic: Stereochemistry of SN/E reactions

76. Which of the following reactions proceeds with inversion of configuration at the carbon bearing the leaving group?

A) SN2 B) SN1 C) E2 D) E1 E) All of these

Ans: A

Chapter 6

192

Topic: Predicting mechanism, stereochemistry of SN reactions

77. Consider the substitution reaction that takes place when (R)-3-bromo-3-methylhexane is treated with methanol. Which of the following would be true?

A) The reaction would take place only with inversion of configuration at the stereogenic center.

B) The reaction would take place only with retention of configuration at the stereogenic center.

C) The reaction would take place with racemization. D) No reaction would take place. E) The alkyl halide does not possess a stereogenic center.

Ans: C Topic: Predicting mechanism, stereochemistry of SN reactions

78. Consider the substitution reaction that takes place when (R)-3-bromo-3-methylhexane is treated with sodium methoxide. Which of the following would be true?

A) An SN2 reaction would take place with inversion of configuration at the stereogenic center.

B) An SN1 reaction would take place with retention of configuration at the stereogenic center.

C) An SN1 reaction would take place with racemization of configuration at the stereogenic center.

D) An SN1 reaction would take place, accompanied by an E1 reaction, affording a complex mixture of products.

E) An E2 reaction would take place, during which the stereogenic center is lost. Ans: E

Topic: Predicting mechanism, stereochemistry of SN reactions

79. Consider the substitution reaction that takes place when (R)-3-iodo-3-methylheptane is treated with sodium acetate (CH3CO2Na). Which of the following would be true?

A) An SN2 reaction would take place with inversion of configuration at the stereogenic center.

B) An SN1 reaction would take place with retention of configuration at the stereogenic center.

C) An SN1 reaction would take place with racemization of configuration at the stereogenic center.

D) An SN1 reaction would take place, accompanied by an E1 reaction, affording a complex mixture of products.

E) An E2 reaction would take place, during which the stereogenic center is lost. Ans: D

Chapter 6

193

Topic: Predicting products

80. Which alkyl halide, when treated with sodium ethoxide in ethanol, would afford a product mixture consisting of more than one elimination product?

A) 1-bromo-3,3-dimethylpentane B) 1-bromo-2,3-dimethylpentane C) 2-bromo-3,4-dimethylpentane D) 2-bromo-3,3-dimethylpentane E) None of the above would yield more than one elimination product

Ans: C Topic: Leaving groups, nucleophiles

81. Which SN2 reaction will occur most rapidly in a mixture of water and ethanol? A) I- + CH3CH2–Br ⎯⎯⎯⎯→ CH3CH2–I + Br- B) I- + CH3CH2–Cl ⎯⎯⎯⎯→ CH3CH2–I + Cl- C) I- + CH3CH2–F ⎯⎯⎯⎯→ CH3CH2–I + F- D) Br- + CH3CH2–Cl ⎯⎯⎯⎯→ CH3CH2–Br + Cl- E) Br- + CH3CH2–F ⎯⎯⎯⎯→ CH3CH2–Br + F-

Ans: A Topic: Predicting mechanism, kinetics

82. Which SN2 reaction will occur most rapidly in aqueous acetone solution? Assume concentrations and temperature are the same in each instance.

A) HO- + CH3-Cl ⎯⎯⎯⎯→ CH3OH + Cl- B) HO- + CH3CH2-Cl ⎯⎯⎯⎯→ CH3CH2OH + Cl- C) HO- + (CH3)2CH-Cl ⎯⎯⎯⎯→ (CH3)2CHOH + Cl- D) HO- + (CH3)3C-Cl ⎯⎯⎯⎯→ (CH3)3COH + Cl- E) HO- + (CH3)3CCH2-Cl ⎯⎯⎯⎯→ (CH3)3CCH2OH + Cl-

Ans: A Topic: Kinetics

83. Which alkyl halide would you expect to undergo an SN2 reaction most slowly? A) 1-bromohexane B) 1-bromo-2-methylpentane C) 1-bromo-3-methylpentane D) 1-bromo-4-methylpentane E) 1-bromo-2,2-dimethylbutane

Ans: E

Chapter 6

194

Topic: Kinetics, nucleophilicity

84. Which SN2 reaction would take place most rapidly? A)

OH− + CH3Cl CH3OH + Cl−25oCH2O

H3C O−

OH2O25oC H3CO CH3

+ CH3Cl + Cl−

C) H2O + CH3Cl CH3OH2

+ + Cl−25oCH2O

D) CH3OH

25oC H3CO

CH3

CH3OH + CH3Cl + Cl−

E) SH− + CH3Cl CH3SH + Cl−

25oCH2O

Ans: E Topic: Leaving groups

85. Which nucleophilic substitution reaction would be unlikely to occur? A) HO− + CH3CH2–I ⎯⎯⎯⎯→ CH3CH2–OH + I− B) I− + CH3CH2–H ⎯⎯⎯⎯→ CH3CH2–I + H− C) CH3S− + CH3–Br ⎯⎯⎯⎯→ CH3S–CH3 + Br− D) All of the above would be unlikely to occur E) None of the above would be unlikely to occur

Ans: B Topic: Predicting products

86. Which nucleophilic substitution reaction would be likely to occur (although probably not in excellent yield, due to competing elimination) ?

A) HO− + CH3CH2CH2CHICH3 ⎯⎯⎯⎯→ CH3 CH2CH2CHOHCH3 + I− B) Cl− + CH3CH2CH2CH2–OH ⎯⎯⎯⎯→ CH3CH2CH2CH2–Cl + OH− C) CH3S− + CH3CH2CH2–OCH3 ⎯⎯⎯⎯→ CH3S–CH2CH2CH3 + OCH3

− D) All of the above are likely to occur E) None of the above are likely to occur

Ans: B

Chapter 6

195

Topic: Leaving groups

87. Which alkyl halide would you expect to react most slowly when heated in aqueous solution?

A) (CH3)3C-F B) (CH3)3C-Cl C) (CH3)3C-Br D) (CH3)3C-I E) They would all react at the same rate.

Ans: A Topic: Nucleophilicity, leaving groups

88. Which SN2 reaction would you expect to take place most rapidly? Assume that the concentrations of the reactants and the temperature are the same in each instance:

A) CH3S− + CH3I CH3SCH3 + I −

H3CS

CH3

CH3SH + CH3I + I −

C) CH3O− + CH3I CH3OCH3 + I −

H3CO

CH3

CH3OH + CH3I + I −

E) CH3S− + CH3Cl CH3SCH3 + Cl −

Ans: A Topic: Leaving groups

89. Which nucleophilic substitution reaction is not likely to occur? A) I− + CH3CH2–Cl ⎯⎯⎯⎯→ CH3CH2–I + Cl− B) I− + CH3CH2–Br ⎯⎯⎯⎯→ CH3CH2–I + Br− C) I− + CH3CH2–OH ⎯⎯⎯⎯→ CH3CH2–I + OH− D) CH3O− + CH3CH2–Br ⎯⎯⎯⎯→ CH3CH2–OCH3 + Br− E) OH− + CH3CH2–Cl ⎯⎯⎯⎯→ CH3CH2–OH + Cl−

Ans: C

Chapter 6

196

Topic: Leaving groups

90. Which of the following would be most reactive in an SN2 reaction? A) Br

Br C)

Br D) Br

Br Ans: D

Topic: Steric hindrance

91. Which alkyl chloride, though primary, is essentially unreactive in SN2 reactions? A) Cl

D) Cl

Ans: E

Chapter 6

197

Topic: Kinetics

92. Which alkyl halide would be most reactive in an SN1 reaction?

Br Br

BrBr

IV V

IIIIII

A) I B) II C) III D) IV E) V

Ans: D Topic: Predicting mechanisms

93. Which of these compounds would give the largest E2/SN2 product ratio on reaction with sodium ethoxide in ethanol at 55°C?

A) Cl

Cl E)

Ans: D

Chapter 6

198

Topic: Multistep synthesis, acid-base reactions, SN2

94. What final product is likely to be obtained through the following series of reactions?

NaNH2 A Br

NH3(l)B

Ans:

Topic: Multistep synthesis, acid-base reactions, SN2, hydrogenation

95. What final product is likely to be obtained through the following series of reactions?

NaNH2 ACl

NH3(l)

excess H2B C

Ni Ans:

Topic: Multistep synthesis, acid-base reactions, SN2

96. What final product is likely to be obtained through the following series of reactions?

OH NaH

diethyletherA

ClB

Ans: O

SHORT ANSWER QUESTIONS Topic: Bond length, bond strength, leaving groups

97. As we go down Group 7A of the periodic table, the size of the halogen atom increases; accordingly, the carbon-halogen bond length gets _______________ and the bond strength gets _______________. Ans: longer; weaker

Chapter 6

199

Topic: Transition state theory

98. In the SN2 reaction, the unstable arrangement of atoms in which both the nucleophile and the leaving group are partially bonded to the same carbon atom is called the ______________________. Ans: transition state

Topic: Solvolysis

99. A reaction in which the nucleophile is a molecule of the solvent is referred to as a ______________ reaction. Ans: solvolysis

Topic: Carbocation stability

100. The substitution mechanism whose rate depends primarily on the relative stability of the intermediate carbocation is the _________. Ans: SN1

Topic: Steric hindrance

101. The substitution mechanism whose rate depends primarily on the degree of steric hindrance around the leaving group is the _________. Ans: SN2

Topic: Carbocation stability

102. The stabilizing effect of alkyl substituents on carbocations can be explained through _____________________. Ans: hyperconjugation

Topic: Activation energy, kinetics

103. Increasing the concentration of either of the reactants of an SN2 reaction increases the rate of the reaction. The primary reason for this is that increasing the concentration increases ________________________. Ans: the frequency of collisions between reactant species, thereby statistically

increasing the chance encounters between species having the requisite Eactivation Topic: Activation energy, transition state theory

104. In order for colliding species to react, they must _____________ and ____________. Ans: have energy equal/greater than the activation energy, approach with the proper

orientation.

Chapter 6

200

Topic: Free energy diagrams

105. Draw the potential energy diagram that represents an exothermic reaction between a tertiary alkyl halide and methanol. Briefly explain your rationale. Ans: The reaction is likely to occur via an SN1 mechanism. The first step is the rate-

determining step, leading to the formation of a tertiary carbocation. The second step is a fast step, where the methanol oxygen acts as a nucleophile, attaching to the positively charged carbon, forming a protonated ether; the last step is a fast loss of a proton to form the (uncharged) ether product.

Energy

time Topic: Predicting reaction mechanisms

106. Give a detailed reaction mechanism for the reaction expected to occur when 2-bromo-2-methylpentane is heated with sodium methoxide. Draw clear structural formulas of all relevant species and use curved arrows to represent electron flow. Also indicate which step is likely to be rate-determining. Ans: The reaction is likely to occur via an E2 mechanism. The first step is the rate-

determining step, leading to the formation of a tertiary carbocation, followed by base promoted elimination to afford 2 different alkene products.

Br H

:OCH3

....

..: :

slow

fast[ - Br: ]....

Chapter 6

201

Topic: SN1 kinetics

107. Typically, increasing the concentration of the nucleophile of an SN1 reaction has no impact on the rate of the reaction. The reason for this is that ________________________. Ans: An SN1 reaction is a multi-step process; the overall reaction rate is determined by

the rate of formation of the carbocation intermediate. Since the nucleophile is not involved in the rate-determining step, changes in its concentration typically have no impact on the rate of reaction.

Topic: Nucleophilicity, solvent effects

108. The relative nucleophilicity of the halide ions in polar aprotic solvents is observed to be markedly different from that in protic solvents. Explain briefly. Ans: The smaller, more highly electronegative fluoride ion is more effectively solvated

in a protic solvent and is therefore a weaker nucleophile compared to the larger, less electronegative and more polarizable iodide ion. The situation is reversed in aprotic solvents, where the nucleophile is essentially unsolvated; thus, the nucleophilicity parallels the basicity of the halide ions, so that the fluoride ion is the strongest nucleophile of the halide ions

Topic: Acid-base reactions, intramolecular SN2

109. When 5-bromo-1-pentanol is treated with sodium hydride in diethyl ether, the product is analyzed to be C5H10O. Propose a likely structure for this product, suggesting a reasonable mechanistic pathway for its formation. Ans: The alcohol is likely to be first deprotonated by the strong base, generating an

alkoxide ion, which can then undergo intramolecular SN2 reaction to afford the observed product, a cyclic ether.

Cl OHNaH

Cl O Na+

−H2

O NaCl....

.. :

Chapter 7

202

MULTIPLE CHOICE QUESTIONS Topic: Nomenclature

1. A correct IUPAC name for the following compound is:

A) 3,3,5-trimethyl-2-hexene B) 3-isobutyl-3-isopropyl-2-propene C) 3-isobutyl-4-methyl-2-pentene D) 3-(1-methylethyl)-5-methyl-2-hexene E) None of the above

Ans: D Topic: Nomenclature

2. The correct IUPAC name for the following compound is: Br

A) 2-Bromo-4-methylenehexane B) 2-(2-Bromopropyl)-1-butene C) 4-Bromo-2-ethyl-1-pentene D) 2-Bromo-4-ethyl-1-pentene E) 2-Bromo-4-ethyl-4-pentene

Ans: C Topic: Nomenclature

3. Give the IUPAC name for

A) 3-Methyl-4-hexyne B) 4-Methyl-2-hexyne C) 2-Ethyl-3-pentyne D) 4-Ethyl-2-pentyne E) 3-Methyl-2-hexyne

Ans: B

Chapter 7

203

Topic: Nomenclature

4. The correct IUPAC name for the following compound is:

A) 4,5-Dimethyl-3-propyl-2-hexene B) 4,5-Dimethyl-3-propyl-1-hexene C) 3-(2,3-Dimethylpropyl)-1-hexene D) 2,3-Dimethyl-4-isopropyl-5-hexene E) 2,3-Dimethyl-4-propyl-5-hexene

Ans: B Topic: Nomenclature

5. Select the structure of 4–ethyl-2,3-dimethyl-2-heptene. A)

Ans: B

Chapter 7

204

Topic: Nomenclature

6. Select the structure for cis-3-methyl-6-vinylcyclohexene.

I II III

IV V

A) I B) II C) III D) IV E) V

Ans: B Topic: Nomenclature

7. The correct IUPAC name for the following compound is:

A) (E)-2-Bromo-3-chloro-5-methyl-2-hexene B) (E)-2-Bromo-3-chloro-5-methyl-3-hexene C) (Z)-2-Bromo-3-chloro-5-methyl-3-hexene D) (Z)-2-Bromo-3-chloro-5-methyl-2-hexene E) (E)-2-Methyl-5-bromo-4-chloro-4-hexene

Ans: A

Chapter 7

205

Topic: Nomenclature

8. The IUPAC name for diisobutylacetylene is A) 2,7-Dimethyl-4-octene B) 2,7-Dimethyl-4-octyne C) 3,6-Dimethyl-4-octyne D) 2,5-Diethyl-3-hexyne E) 2,2,5,5-Tetramethyl-3-hexyne

Ans: B Topic: Carbocation Stability, Rearrangement

9. Which of the following carbocations would NOT be likely to undergo rearrangement? A) CH3CHCHCH3

CH3 B)

CH3CHCCH3

CH3

CH3CCH2CH3

CH3

CH3CHCH2

CH3

CH3CCHCH2CH3

CH3

Ans: C

Chapter 7

206

Topic: Carbocation stability

10. Which alcohol would initially produce the most stable carbocation when treated with concentrated H2SO4?

A) OH

OH C)

OH D)

E) HO

Ans: A

Topic: Carbocation Stability, Rearrangement

11. Which statement(s) is (are) true of acid-catalyzed alcohol dehydrations? A) Protonation of the alcohol is a fast step. B) Formation of a carbocation from the protonated alcohol is a slow step. C) Rearrangements of less stable carbocations to more stable carbocations are common. D) Loss of a proton by the carbocation is a fast step. E) All of the above

Ans: E Topic: Carbocation Stability, Rearrangement

12. Carbocations are frequent intermediates in acidic reactions of alkenes, alcohols, etc. What do carbocations usually do? They may:

A) rearrange to a more stable carbocation. B) lose a proton to form an alkene. C) combine with a nucleophile. D) react with an alkene to form a larger carbocation. E) do all of the above.

Ans: E

Chapter 7

207

Topic: Carbocation Stability, Rearrangement

13. Neopentyl alcohol, (CH3)3CCH2OH, cannot be dehydrated to an alkene without rearrangement. What is the chief product of dehydration?

I II III

IV V

A) I B) II C) III D) IV E) V

Ans: B Topic: Carbocation Stability, Rearrangement

14. Rearrangements are likely to occur in which of the following reaction types? A) SN1 reactions B) SN2 reactions C) E1 reactions D) E2 reactions E) Both SN1 and E1 reactions

Ans: E

Chapter 7

208

Topic: Alkene Synthesis, Reaction Mechanisms

15. Which compound listed below would you expect to be the major product when 2-bromo-2-methylbutane is refluxed with KOH/ethanol?

A) OH

O C)

Ans: D

Topic: Alkene Synthesis, Reaction Mechanisms

16. Which product(s) would be produced by acid-catalyzed dehydration of 2-methyl-2-pentanol?

B) and

C) and

E) O

Ans: B

Chapter 7

209

Topic: Alkene Synthesis, Reaction Mechanisms

17. Which product (or products) would be formed in appreciable amount(s) when trans-1-bromo-2-methylcyclohexane undergoes dehydrohalogenation upon treatment with sodium ethoxide in ethanol?

I II III IV

A) I B) II C) III D) IV E) More than one of these

Ans: B Topic: Alkene Reactions, Reaction Mechanisms

18. Which would be the major product of the following reaction?

CH3

I II

IV V

CH3

III

CH3

D2, Ni?

A) I B) II C) III D) IV E) V

Ans: A

Chapter 7

210

Topic: Alkene Synthesis, Reaction Mechanisms

19. What is the major product of the reaction,

(CH3)3COK

(CH3)3COHheat

A) (CH3)2C=C(CH3)2 B) (CH3)3C–CH=CH2 C) (CH3)2C=CHCH3 D) (CH3)2C=CHCH2CH3 E) None of these

Ans: B Topic: Alkene Synthesis, Reaction Mechanisms

20. Which compound would be the major product? Br (CH3)3COK

(CH3)3COHheat

A) O

D) OH

Ans: E

Chapter 7

211

Topic: Alkene Synthesis, Reaction Mechanisms, Carbocation Rearrangements

21. What will be the major product of the following reaction?

85% H3PO4

heat?

D) O

Ans: A

Chapter 7

212

Topic: Alkene Synthesis, Reaction Mechanisms, Carbocation Rearrangements

22. Which alkene would you expect to be the major product of the following dehydration?

H2SO4

IV V

III

heat?

I II

A) I B) II C) III D) IV E) V

Ans: C

Chapter 7

213

Topic: Alkyne Synthesis, Catalytic hydrogenation

23. The structure of the product, C, of the following sequence of reactions would be:

ACH3CH2Br

BH2 C

NH3(l) Ni2B [P-2]

NaNH2

D) Br

Ans: A

Topic: Dissolving Metal Reduction; trans-hydrogenation

24. The structure of the product obtained from 2-butyne and Li/C2H5NH2 is: A)

Ans: A

Chapter 7

214

Topic: Catalytic hydrogenation

25. Which alkene would yield 3-methylpentane when subjected to catalytic hydrogenation? A) B)

C) D)

Ans: B

Topic: Alkyne Synthesis

26. Which reaction would yield 2-butyne? A) CH3C≡C:− Na+ + CH3Br ⎯⎯⎯⎯→ B) CH3CH2Br + HC≡C:− Na+ ⎯⎯⎯⎯→ C) CH3:− Na+ + HC≡CCH3 ⎯⎯⎯⎯→ D) More than one of these E) None of these

Ans: A Topic: Alkyne Synthesis

27. Which of the following methods could be used to synthesize 4,4-dimethyl-2-hexyne? A)

CCH3

C2H5CH3

C C: Na H3C I

B) H3C C C: Na C

CH3

C2H5CH3

BrBr

NaNH2 ( excess)

NH3 (l)

D) More than one of these E) None of these

Ans: D

Chapter 7

215

Topic: Alkene Synthesis

28. Your task is to convert 2-bromobutane to 1-butene in highest yield. Which reagents would you use?

A) KOH/H2O B) KOH/CH3OH C) CH3ONa/CH3OH D) CH3CH2ONa/CH3CH2OH E) (CH3)3COK/(CH3)3COH

Ans: E Topic: Alkene Synthesis, Nomenclature

29. Which of the following reactions would yield 3,3-dimethyl-1-butene in a reasonable percentage yield (i.e., greater than 50%)?

OHheat

H2SO4

Brheat

(CH3)3COK, (CH3)3COH

BrBr

i) 3 NaNH2, mineral oil, heat

ii) H3O+

D) All of these E) Answers B) and C) only

Ans: B

Chapter 7

216

Topic: Alkene Synthesis, Reaction Mechanisms

30. Which compound(s) would be produced by the following reaction?

CH3

H3CCH3CH2OH

CH3

OCH2CH3

H3C

OCH2CH3

CH3

H3C

I II III

CH3

55oC?

A) I B) II C) III D) More than one of the above E) All of the above

Ans: E Topic: Alkene Synthesis, Nomenclature, Reaction Mechanisms

31. Dehydrohalogenation of tert-pentyl bromide will produce 2-methyl-1-butene as the chief product when:

A) CH3COONa is employed as the base. B) KOH/C2H5OH is employed as the base. C) CH3CH2ONa/CH3CH2OH is employed as the base. D) (CH3)3COK/(CH3)3COH is employed as the base. E) any base is used, as long as the temperature is sufficiently high.

Ans: D Topic: Alkene Synthesis, Nomenclature, Reaction Mechanisms

32. Which is not a satisfactory procedure for the synthesis of 3-methyl-1-butene? A) (CH3)2CHCΗΟΗCH3 + conc. H2SO4 B) (CH3)2CHC≡CH + Li/liq.NH3 C) (CH3)2CHCH2CH2Br + CH3ONa/CH3OH D) (CH3)2CHCHBrCH3 + (CH3)3COK/(CH3)3COH E) (CH3)2CHC≡CH + H2/Ni2B (P-2)

Ans: A

Chapter 7

217

Topic: Alkene Synthesis, Nomenclature, Reaction Mechanisms

33. Which of these is the most satisfactory method for the preparation of cis-2-pentene? A) CH3CHBrCH2CH2CH3 + (CH3)3COK/(CH3)3COH B) CH3C≡CCH2CH3 + H2,Pt C) CH3C≡CCH2CH3 + H2, Ni2B (P-2) D) CH3C≡CCH2CH3 + Li/liq. NH3 E) CH3CH2CHBrCH2CH3 + CH3CH2ONa/CH3CH2OH

Ans: C Topic: Alkyne Reduction, Nomenclature, Reaction Mechanisms 34. Which of the following reductions of an alkyne is NOT correct?

A) 2-Pentyne + 2H2/Pt pentane B) 2-Pentyne + H2/Ni2B Z-2-Pentene C) 2-Pentyne + Li/NH3(l) Z-2-Pentene D) All of the above are correct. E) None of the above is correct.

Ans: C Topic: Alkene Synthesis, Nomenclature, Reaction Mechanisms

35. Which of the following reactions would yield 2-pentyne? A) I

(1 mol)

NaNH2

B) NaNH2 Br(1 mol)

C) Br

ZnCH3CO2H

HAheat

E) Br

NaOC2H5C2H5OH

Ans: B

Chapter 7

218

Topic: Alkyne Synthesis, Nomenclature, Reaction Mechanisms

36. Which reaction would not be a method for preparing 5-methyl-1-hexyne? A)

Br1) NaNH2 (2 mol), liq NH3

2) NH4+

B) HC CNa Cl+

Li HC CH+D)

BrBr

1) NaNH2 (3 mol), liq NH3

2) NH4+

Br1) NaNH2 (3 mol), liq NH3

2) NH4+

Ans: C Topic: Index of Hydrogen Deficiency

37. Compute the index of hydrogen deficiency for the molecule C10H8. A) 3 B) 4 C) 5 D) 6 E) 7

Ans: E

Chapter 7

219

Topic: Index of Hydrogen Deficiency

38. Which compound has an index of hydrogen deficiency equal to three?

I II III

IV V

A) I, III B) IV, V C) V D) II E) II, V

Ans: E Topic: Index of Hydrogen Deficiency, Nomenclature

39. What is the index of hydrogen deficiency of bicyclo[2.2.2]octane? A) 1 B) 2 C) 3 D) 4 E) 5

Ans: B Topic: Index of Hydrogen Deficiency, Catalytic Hydrogenation

40. Which is a possible structure for a compound with an index of hydrogen deficiency equal to 3 and which absorbs one molar equivalent of hydrogen when treated with hydrogen and a platinum catalyst?

I II III IV VA) I B) II C) III D) IV E) V

Ans: C

Chapter 7

220

Topic: Index of Hydrogen Deficiency, Catalytic Hydrogenation

41. Upon catalytic hydrogenation, a compound C6H6 absorbs four moles of hydrogen. Select a structure for C6H6.

I II III IV V

A) I, II B) III C) II, III D) IV, V E) I, IV, V

Ans: D Topic: Index of Hydrogen Deficiency, Catalytic Hydrogenation

42. A compound, C6H10, which reacts with 2 mol of hydrogen over a platinum catalyst and which shows an IR absorption band at approximately 3300 cm-1 could be:

I II III

IV V

A) I B) II C) III D) IV E) V

Ans: C

Chapter 7

221

Topic: Index of Hydrogen Deficiency, Catalytic Hydrogenation

43. On hydrogenation, a compound C9H12 absorbs 2 mol of hydrogen. Which of the following is a possible structure for the compound?

IIII II

IV V A) I B) II C) III D) IV E) V

Ans: D Topic: Index of Hydrogen Deficiency, Catalytic Hydrogenation

44. A compound with the formula C10H14 reacts with excess hydrogen and a catalyst to yield a compound with the formula C10H18. The compound could have:

A) one ring and three double bonds. B) two rings and two double bonds. C) two rings and a triple bond. D) no rings and two double bonds. E) More than one of the above

Ans: E Topic: Index of Hydrogen Deficiency, Catalytic Hydrogenation

45.

Given:

H2, Pt

25oCX (C8H14) Y (C8H16)

One can conclude that X has:

A) no rings and no double bonds. B) no rings and one double bond. C) one ring and one double bond. D) two rings and no double bonds. E) one triple bond.

Ans: C

Chapter 7

222

Topic: Index of Hydrogen Deficiency, Catalytic Hydrogenation

46. What is the structure of a compound with formula C6H10 which has IR absorption at approximately 3300 cm-1 and which can be catalytically reduced with hydrogen to 2-methylpentane?

B) C)

Ans: D

Topic: Index of Hydrogen Deficiency, Catalytic Hydrogenation

47. A compound X with the formula C7H10 undergoes catalytic hydrogenation to produce a compound Y with the formula C7H14. What might be true of X?

A) X might have one triple bond and one ring. B) X might have two double bonds and one ring. C) X might have one double bond and two rings. D) X might have one double bond and one triple bond. E) More than one of the above

Ans: E Topic: Alkene Stability, Heats of Hydrogenation and Combustion

48. Which reaction would you expect to liberate the least heat? A)

+ 9O2 6CO2 + 6H2OB) + 9O2 6CO2 + 6H2O

C) + 9O2 6CO2 + 6H2O

D) + 9O2 6CO2 + 6H2OE) + 9O2 6CO2 + 6H2O

Ans: C

Chapter 7

223

Topic: Alkene Stability, Heats of Hydrogenation and Combustion

49. One mol of each of the following alkenes is subjected to complete combustion. Which would you expect to liberate the LEAST heat?

A) 1-Pentene B) 2-Pentene C) 2-Methyl-1-butene D) 2-Methyl-2-butene E) 3-Methyl-1-butene

Ans: D Topic: Alkene Stability, Heats of Hydrogenation and Combustion

50. Which molecule would have the lowest heat of hydrogenation?

I II III IV V A) I B) II C) III D) IV E) V

Ans: A Topic: Alkene Stability, Heats of Hydrogenation and Combustion, Nomenclature

51. One mole of each of the following alkenes is subjected to complete combustion. Which would you expect to liberate the most heat?

A) 1-Pentene B) cis-2-Pentene C) 2-Methyl-1-butene D) 2-Methyl-2-butene E) trans-2-Pentene

Ans: A

Chapter 7

224

Topic: Alkene Stability, Heats of Hydrogenation and Combustion

52. Which reaction would you expect to liberate the most heat? A)

+ 9O2 6CO2 + 6H2OB) + 9O2 6CO2 + 6H2O

C) + 9O2 6CO2 + 6H2O

D) + 9O2 6CO2 + 6H2OE) + 9O2 6CO2 + 6H2O

Ans: C Topic: Alkene Stability, Heats of Hydrogenation and Combustion

53. Heats of hydrogenation data would be useful in comparing the relative stabilities of which of the following substances?

I II III IV V A) I, II, III B) III, IV C) I, II, V D) Heats of hydrogenation data would not be a useful way to compare relative stabilities of

any of the substances E) All of the above substances could effectively be compared using heats of hydrogenation

data Ans: C

Topic: Alkene Stability, Heats of Hydrogenation and Combustion

54. Which alkene would liberate the most heat per mole when subjected to complete combustion?

A) B) C)

D) E)

Ans: A

Chapter 7

225

Topic: Alkene Stability, Heats of Hydrogenation and Combustion

55. Which alkene would liberate the most heat per mole when subjected to catalytic hydrogenation?

A) B) C)

D) E)

Ans: A Topic: Alkene Stability, Heats of Hydrogenation and Combustion

56. One mole of each of the following alkenes is subjected to complete combustion. Which would liberate the least heat?

I II III IV VA) I B) II C) III D) IV E) V

Ans: D Topic: Alkene Stability, Heats of Hydrogenation and Combustion

57. Which alkene is most stable?

I II III IV V

A) I B) II C) III D) IV E) V

Ans: A

Chapter 7

226

Topic: Alkene Stability, Heats of Hydrogenation and Combustion

58. Concerning the relative stabilities of alkenes, which is an untrue statement? A) Unless hydrogenation of the alkenes gives the same alkane, heats of hydrogenation

cannot be used to measure their relative stabilities. B) In general, the greater the number of alkyl groups attached to the carbon atoms of the

double bond, the greater the stability of the alkene. C) The greater the quantity of heat liberated on combustion or hydrogenation of an alkene,

the greater its energy content. D) trans-Cycloalkenes are always more stable than the cis-isomers. E) Heats of combustion can be used to measure the relative stabilities of isomeric alkenes,

even though their hydrogenation products are not identical. Ans: D

Topic: Relative Acidity of Alkenes, Alkynes; Acid-Base Chemistry

59. Which of the following correctly lists the compounds in order of decreasing acidity? A) H2O > HC≡CH > NH3 > CH3CH3 B) HC≡CH > H2O > NH3 > CH3CH3 C) CH3CH3 > HC≡CH > NH3 > H2O D) CH3CH3 > HC≡CH > H2O > NH3 E) H2O > NH3 > HC≡CH > CH3CH3

Ans: A Topic: Relative Acidity of Alkenes, Alkynes; Acid-Base Chemistry

60. Select the strongest base. A) OH− B) RC≡C− C) NH2

− D) CH2=CH− E) CH3CH2

− Ans: E

Topic: Relative Acidity of Alkenes, Alkynes; Acid-Base Chemistry

61. Which ion is the weakest base? A) CH3CH2: − B) CH2=CH: − C) HC≡C: − D) NH2

−....

E) OH −..

Ans: E

Chapter 7

227

Topic: Relative Acidity of Alkenes, Alkynes; Acid-Base Chemistry

62. In the following hydrocarbon, which hydrogen would have the smallest value for pKa? CH3CH2CH=CHCH2CH2C≡CH

A) CH3CH2CH=CHCH2CH2C CH

B) CH3CH2CH=CHCH2CH2C CH

C) CH3CH2CH=CHCH2CH2C CH

D) CH3CH2CH=CHCH2CH2C CH

E) CH3CH2CH=CHCH2CH2C CH

Ans: E Topic: Relative Acidity of Alkenes, Alkynes; Bond Lengths

63. Which of the following statements is true when ethane, ethene and acetylene are compared with one another?

A) Acetylene is the weakest acid and has the longest C-H bond length. B) Acetylene is the strongest acid and has the shortest C-H bond length. C) Ethane is the strongest acid and has the longest C-H bond length. D) Ethene is the strongest acid and has the shortest C-H bond length. E) Ethene is the weakest acid and has the longest C-H bond length.

Ans: B

Chapter 7

228

Topic: Alkene Synthesis; Alcohol Dehydration

64. Which one of the following alcohols would dehydrate most rapidly when treated with sulfuric acid?

OH OH OH

OHOH

I II III

IV VA) I B) II C) III D) IV E) V

Ans: B Topic: Alkene Synthesis; Alcohol Dehydration

65. Which mechanistic step in the acid-catalyzed dehydration of 3,3-dimethyl-2-butanol is the rate determining step?

OH+ H3O+

OH2+

+ H2O

Step 1:

OH2+

+ H2O

Step 2:

C) Step 3:

D) Step 4a:

+ H3O++ H2O

E) Step 4b:

+ H3O++ H2O

Ans: B

Chapter 7

229

Topic: Alkene Synthesis; Alcohol Dehydration

66. Which alcohol would be most easily dehydrated? A)

CH3CH2CCH2CH3

CH3

OH B)

CH3CH2CHCHCH3

CH3

OH C)

CH3CH2CHCH2CH2OH

CH3

HOCH2CHCH2CH2CH3

CH3

CH3CH2CHCH2CH3

CH2OH

Ans: A

Topic: Alkene Synthesis; Alcohol Dehydration

67. Which alcohol would be most easily dehydrated?

VIVOH

II IIIIOHOH OH

A) I B) II C) III D) IV E) V

Ans: B

Chapter 7

230

Topic: Alkene Structure; Stereochemistry

68. What is the simplest alkene, i.e., the one with the smallest molecular weight, which can exhibit optical activity?

A) 3-methyl-1-pentene B) 3-methyl-2-pentene C) 4-methyl-1-pentene D) 3-methyl-1-butene E) 4-methyl-2-hexene

Ans: A Topic: Alkene Structure; Stereochemistry

69. Determine the total number of stereoisomers which correspond to this general structure:

CH3CHCHCH=CHCH3

CH3 A) 4 B) 6 C) 8 D) 10 E) 12

Ans: C Topic: Alkene Structure; Stereochemistry

70. Which can exist as cis-trans isomers? A) 1-Pentene B) 3-Hexene C) Cyclopentene D) 2-Methyl-2-butene E) 3-Ethyl-2-pentene

Ans: B Topic: Alkene Structure; Stereochemistry

71. For which of the following is cis-trans isomerism impossible? A) 2-Hexene B) 3-Methyl-2-pentene C) 3-Hexene D) 2-Methyl-2-butene E) 2-Pentene

Ans: D

Chapter 7

231

Topic: Alkene Structure; Stereochemistry

72. Which of the following compounds can exhibit cis-trans isomerism? A) 1-Pentene B) 2-Pentene C) 2-Methyl-2-pentene D) 3-Methyl-1-pentene E) 1-Hexene

Ans: B Topic: Alkene Structure; Stereochemistry

73. Which of the following compounds can exhibit cis-trans isomerism? I. 1-Pentene II. 2-Pentene III. 2-Methyl-2-pentene IV. 1,2-Dibromoethene V. 1,1-Dichloroethene

A) II, III, IV B) I, III, V C) II, IV D) II, III E) None of these

Ans: C Topic: Alkene Structure; Stereochemistry

74. What is the total number of pentene isomers, including stereoisomers? A) 2 B) 3 C) 4 D) 5 E) 6

Ans: E

Chapter 7

232

Topic: Nomenclature; Stereochemistry

75. Cis-trans alkenes are often distinguished from each other by examining the spatial orientation of identical groups relative to the double bond. While this often also corresponds to (Z) and (E) descriptions, sometimes it does not. For which of the following alkenes does cis- not equal (Z) or trans not equal (E)?

Br Br

OOH

I II III IV V

A) I B) II C) III D) IV E) V

Ans: C Topic: Nomenclature; Stereochemistry

76. The most specific term used to designate the relationship of cis-3-hexene to trans-3-hexene is:

A) stereoisomers. B) enantiomers. C) diastereomers. D) constitutional isomers. E) conformational isomers.

Ans: C Topic: Nomenclature; Stereochemistry 77. How many stereoisomers can be predicted for 4–ethyl-2,3-dimethyl-2-heptene?

A) 1 B) 2 C) 3 D) 4 E) None of the above

Ans: B

Chapter 7

233

Topic: General Information, Bonding

78. How many sigma bonds are there in CH2=CH–C≡CH? A) 6 B) 7 C) 8 D) 9 E) 10

Ans: B Topic: General Information, Bonding

79. What characteristic(s) of alkynes would make it difficult to prepare cyclohexyne? A) The requirement for linearity at the triple bond center B) The large electron density between carbons of a triple bond C) The short carbon-carbon triple bond length D) The need that the carbon-carbon triple bond be internal in the chain E) All of these

Ans: A Topic: General Information, Nomenclature

80. The ambiguous name "methylcyclohexene" does not differentiate among this number of compounds (ignoring stereoisomers):

A) 2 B) 3 C) 4 D) 5 E) 6

Ans: B Topic: Alkene Synthesis

81. Zaitsev's rule states that: A) In electrophilic addition of an unsymmetrical reagent to an unsymmetrical alkene, the

more positive portion of the reagent will become attached to the carbon of the double bond bearing the greater number of hydrogen atoms.

B) An equatorial substituent in cyclohexane results in a more stable conformation than if that substituent were axial.

C) E2 reactions occur only if the β-hydrogen and leaving group can assume an anti-periplanar arrangement.

D) When a reaction forms an alkene, and several possibilities exist, the more (or most) stable isomer is the one which predominates.

E) The order of reactivity of alcohols in dehydration reactions is 3º > 2º > 1º. Ans: D

Chapter 7

234

Topic: Alkene Synthesis

82. Regarding the use of potassium tert-butoxide as a base in E2 reactions, it is incorrect to state that:

A) this base is more effective than ethoxide ion, because it (KO-t-Bu) is the more basic of the two.

B) it tends to give the anti-Zaitsev, i.e., Hofmann, product. C) it is more reactive in dimethyl sulfoxide than it is in tert-butyl alcohol. D) it favors E2 reactions over competing SN2 reactions. E) it will form, predominantly, the more stable alkene.

Ans: E Topic: General Information

83. When an elimination reaction gives the most stable alkene as the major product, we say that the elimination follows ________________'s rule. Ans: Zaitsev

Topic: General Information

84. When an elimination reaction gives the less substituted alkene as the major product, we say that the elimination follows ________________'s rule. Ans: Hofmann

Topic: General Information

85. In a dehydration reaction, the leaving group is _______________. Ans: a molecule of water

Topic: General Information

86. In hydrogenation reactions, both hydrogen atoms add to the pi system from the same face of the molecule. This is an example of a(n) _________ addition. Ans: syn

Topic: General Information

87. Syn hydrogenation of an alkyne will produce a _________ alkene. Ans: Cis / Z

Topic: General Information

88. Dehydration of alcohols requires a __________________ catalyst. Ans: strong acid

Chapter 7

235

Topic: General Information

89. Carbocations have three options available for further reaction. These options include reaction with a nucleophile, loss of a beta proton to give an alkene, and ________________. Ans: rearrangement

Topic: General Information

90. Alkynes can be produced from either __________________ or _________________ dihalides. Ans: vicinal/geminal

Topic: General Information

91. Conversion of alkynes to E-alkenes (trans-alkenes) can be accomplished via a __________________ reaction. Ans: dissolving metal reduction

Topic: Nomenclature, Bonding

92. The number of (s-sp2) bonds in a molecule of 2,3-dimethyl-2,4-heptadiene is _____. Ans: two

Topic: Alkene Hydrogenation

93. How will you prepare cis-1,2-dimethylcyclohexane from 1,2-dimethylcyclohexene? Ans: Catalytic hydrogenation with H2, Ni (or Pt/Pd)

H2, Ni

Topic: Alkyne Reduction

94. How will you prepare trans-2-heptene from 2-heptyne? Ans: Dissolving metal reduction with metallic Na in NH3(l).

Na, NH3 (l)

Chapter 7

236

SHORT EXPLANATION / STRUCTURE DRAWING QUESTIONS Topic: Nomenclature, Stereochemistry

95. Draw the structures of all stereoisomers of 2-chloro-4-methyl-3-hexene, clearly showing all stereochemical details, using appropriate 3-D representations (dash-wedge, etc.) as relevant. Ans: 2-chloro-4-methyl-3-hexene

Cl H H Cl Cl H H Cl

(2R, 3E) (2S, 3E) (2R, 3Z) (2S, 3Z) Topic: Alkene Nomenclature, Relative Stability

96. The ambiguous name dimethylcyclopentene does not clearly distinguish between several structures. a) Draw the structures of all constitutional isomers corresponding to this name. b) Indicate which of these is likely to be the most stable, i.e, have the smallest heat of combustion, justifying your rationale briefly. c) Which of these structures represents an achiral molecule? Ans: a)

I II III IV V VI

dimethylcyclopentene

b) Structure I is likely to be the most stable, because it is a tetra-substituted alkene: II, IV and V are tri-substituted; III and VI are di-substituted. c) Structure I is achiral

Chapter 7

237

Topic: Alkyne Synthesis, Acid-Base reactions

97. Complete the following reaction sequence, providing a brief rationale for your answer.

Oi) PCl5ii) 3 NaNH2,

mineral oil, heat

iii) H3O+

Ans: O Cl Cl

(-2HCl)I II

NaH3O+

III

3 NaNH2, mineral oil, heat

:PCl5

Reaction with PCl5 would afford a geminal dihalide I, which would undergo E2 elimination when heated, losing 2 moles of HCl to afford the alkyne III. However, since III is a terminal alkyne, it has a hydrogen atom that is labile in presence of NaNH2; hence, an extra mole equivalent of the base is required to ensure complete reaction and convert all of the initially formed III into the sodium alkynide intermediate, II; this, upon acidification, affords the final alkyne product III.

Topic: Alkyne Synthesis, Alkyne Hydrogenation

98. Complete the following reaction, giving structural details of all intermediates as well as the final product.

?1) NaNH2, NH3 (l)2) CH3CH2CH2Br3) H2, Lindlar catalyst

Ans: NaNH2NH3 (l)

H2Lindlar catalyst

: Na

CH3CH2CH2Br

Chapter 7

238

Topic: Carbocation Stability, Rearrangement

99. What “new”, more stable, carbocation(s) may be formed when the following carbocation undergoes spontaneous rearrangement?

Ans:

Topic: Nomenclature, Multistep Synthesis 100. Propose a two-step synthetic strategy for the synthesis of 2-methylhexane from 5-

methyl-2-hexanol. Ans: OH

H3O+

heat+

H2Ni

Step 1: Acid-catalyzed dehydration of 5-methyl-2-hexanol to yield an isomeric mixture of 5-methyl-1-hexene and 5-methyl-2-hexene Step 2: Catalytic hydrogenation of the double bond with H2, Ni to yield the desired 2-methylhexane

Topic: Nomenclature, Multistep Synthesis

101. Propose a reasonable synthetic strategy for the synthesis of trans-6-methyl-3-heptene from 4-methyl-1-pentyne. Ans: NaNH2

NH3 (l):Na+

Li, NH3(l)

CH3CH2Br

Step 1: Add NaNH2/NH3(l) to selectively deprotonate the alkyne hydrogen. Step 2: Add ethyl iodide to give 6-methyl-3-pentyne by an SN2 process. Step 3: Add Na(s)/NH3(l) to give the desired trans-alkene by dissolving metal reduction.

Chapter 7

239

Topic: Carbocation Rearrangement, Alkene Synthesis, Dehydration Mechanism

102. Provide a mechanistic explanation for the formation of the observed products in the following reaction.

H3O+

heat Ans:

OH2+

OH O

[-H2O]

OH2+ O

rearrangement

Chapter 7

240

Topic: Nomenclature, Index of Hydrogen Deficiency, IR Spectroscopy, Catalytic Hydrogenation

103. The IR spectrum of an unknown substance Q, C9H16, is found to have distinct peaks at 3310 cm-1 and 2140 cm-1. Treatment of Q with excess H2 in presence of Raney Ni affords nearly quantitative yields of 2,3-dimethylheptane. Propose a reasonable structure for Q, based on the above information, briefly explaining your rationale. Also give its IUPAC name. Ans:

IR: 2140, 3310 cm-1

excess H2 Ni

2,3-dimethylheptane

Substance Q: 5,6-dimethyl-1-heptyne

The Index of Hydrogen deficiency of Q is 2 (compared with C9H20). The IR data suggests that Q is a terminal alkyne; thus, there must be no rings in its structure. The catalytic hydrogenation data provides further details of the carbon skeleton. Due to the specific substitution pattern in this carbon skeleton, there is only one possible position for a terminal triple bond. Thus, the structure given above is consistent with all of the given information. IUPAC Name: 5,6-dimethyl-1-heptyne

Chapter 8

241

MULTIPLE CHOICE QUESTIONS Topic: Structure Elucidation

1. An alkene adds hydrogen in the presence of a catalyst to give 3,4-dimethylhexane. Ozonolysis of the alkene followed by treatment with zinc and acetic acid gives a single organic product. The structure of the alkene is:

CH3CH=C-CHCH2CH3

CH3

(cis or trans)

CH3CH2C=CCH3

CH3

CH2CH3

(cis or trans)

C) CH2=CCH2CHCH2CH3

CH3

CH3 D)

CH3CH2CCHCH2CH3

CH2

CH3 E)

CH3CH2CHCHCH=CH2

CH3

Ans: B

Chapter 8

242

Topic: Structure Elucidation

2. Ozonolysis of compound Z yields the products shown below. What is the structure of Z?

OI II III

IV V

O O O

Z 2HCH + CH3CCH2CH1) O32) Zn, HOAc

A) I B) II C) III D) IV E) V

Ans: B

Chapter 8

243

Topic: Structure Elucidation

3. Compound C has the molecular formula C7H12. On catalytic hydrogenation, 1 mol of C absorbs 1 mol of hydrogen and yields a compound with the molecular formula C7H14. On ozonolysis and subsequent treatment with zinc and acetic acid, C yields only:

The structure of C is:

I II III

IV VA) I B) II C) III D) IV E) V

Ans: E Topic: Structure Elucidation

4. Compound X has the molecular formula C6H10. X decolorizes bromine in carbon tetrachloride. X also shows IR absorption at about 3300 cm-1. When treated with excess hydrogen and a nickel catalyst, X yields 2-methylpentane. The most likely structure for X is:

Ans: D

Chapter 8

244

Topic: Structure Elucidation

5. An unknown compound, A, has the molecular formula C7H12. On oxidation with hot aqueous potassium permanganate, A yields CH3CH2COOH and (CH3)2CHCOOH. Which of the following structures best represents A?

Ans: C

Chapter 8

245

Topic: Structure Elucidation

6. Determine a possible structure for an alkene, X, formula C9H14, on the basis of the following information: X adds one mole of hydrogen on catalytic hydrogenation. On treatment with hot basic KMnO4 followed by acidification, X yields the following dicarboxylic acid.

OHO

A possible structure for X might be:

I II III

IV V

A) I B) II C) III D) IV E) V

Ans: C Topic: Structure Elucidation

7. An optically active compound, Y, with the molecular formula C7H12 gives a positive test with cold dilute KMnO4 and shows IR absorption at about 3300 cm-1. On catalytic hydrogenation, Y yields Z(C7H16) and Z is also optically active. Which is a possible structure for Y?

A) CH3CH2CH2CH2CH2C≡CH B) (CH3)2CHCH2CH2C≡CH C) CH3CH2CH(CH3)CH2C≡CH D) CH3CH2CH(CH3)C≡CCH3 E) CH2=CHCH(CH3)CH2CH=CH2

Ans: C

Chapter 8

246

Topic: Structure Elucidation

8. One mole of an optically active compound, X, with the molecular formula C6H8 reacts with three moles of hydrogen in the presence of a catalyst to yield an optically inactive product that cannot be resolved. X also exhibits IR absorption at approximately 3300 cm-1. Which is a possible structure for X?

A) (E)-4-hexen-1-yne B) (Z)-4-hexen-1-yne C) (E)-2-hexen-4-yne D) 2-methyl-1-penten-3-yne E) 3-methyl-1-penten-4-yne

Ans: E Topic: Structure Elucidation

9. An alkene with the molecular formula C10H18 is treated with ozone and then with zinc and acetic acid. The product isolated from these reactions is:

What is the structure of the alkene?

II III

IV V

A) I B) II C) III D) IV E) V

Ans: C

Chapter 8

247

Topic: Structure Elucidation

10. An optically active compound, A, with the molecular formula C7H12 reacts with cold dilute KMnO4 and gives IR absorption at about 3300 cm-1. On catalytic hydrogenation, A is converted to B (C7H16) and B is also optically active. Which is a possible structure for A?

II III

IV V

A) I B) II C) III D) IV E) V

Ans: E Topic: Structure Elucidation

11. Which substance would undergo the following reaction?

i. O3ii. Zn, HOAc?

O + H O

A) 4-Hexen-1-yne r

B) 3-methyl-1-hexene C) (E)-2-hexene D) (Z)-2-hexene E) 4-methyl-1-hexene

Ans: E

Chapter 8

248

Topic: Structure Elucidation

12. Which alkene would yield only CH3CH2COOH on oxidation with hot alkaline potassium permanganate (followed by acid work-up)?

A) (E)-2-hexene B) (Z)-2-hexene C) 2-methyl-2-pentene D) (E)-3-hexene E) (E)-4-methyl-2-pentene

Ans: D Topic: Structure Elucidation

13. An unknown compound, B, has the molecular formula C7H12. On catalytic hydrogenation 1 mol of B absorbs 2 mol of hydrogen and yields 2-methylhexane. B has significant IR absorption band at about 3300 and 2200 cm-1. Which compound best represents B?

A) 3-methyl-1-hexyne B) 5-methyl-2-hexyne C) 5-methyl-1,3-hexadiene D) 5-methyl-1-hexyne E) 2-methyl-1,5-hexadiene

Ans: D Topic: Structure Elucidation

14. What compound would yield an equimolar mixture of CH3CH2CH2CHO and CH3CHO upon treatment with O3, followed by Zn/HOAc?

A) 1-Hexene B) cis-2-Hexene C) trans-2-Hexene D) More than one of these E) None of these

Ans: D Topic: Structure Elucidation

15. An alkene with the molecular formula C8H16 undergoes ozonolysis to yield a mixture of (CH3)2C=O and (CH3)3CCHO. The alkene is:

A) 2,2-Dimethyl-2-hexene B) 2,3-Dimethyl-2-hexene C) 2,4-Dimethyl-2-hexene D) 2,4,4-Trimethyl-2-pentene E) More than one of the above is a possible answer.

Ans: D

Chapter 8

249

Topic: Structure Elucidation

16. Which of the following would decolorize bromine in carbon tetrachloride and yield a ketone upon reaction with sulfuric acid in the presence of catalytic amounts of HgSO4?

A) CH3CH=CHCH3 B) CH3CH=CH2 C) CH3CH2C≡CH D) CH3CH2CH2CH3 E) All of these would give positive results in each test.

Ans: C Topic: Structure Elucidation

17. Which of these compounds will react with cold concd. H2SO4, as well as Br2 in CCl4 ?

A) CH3CH2CH=CHCH3 B) CH3CH2CH2CH=CH2 C) CH3CH2C≡CCH3 D) (CH3)2CHC≡CH E) All of these

Ans: E Topic: Structure Elucidation

18. Which of the following reagents might serve as the basis for a simple chemical test that would distinguish between pure 1-pentene and pure pentane?

A) Bromine in carbon tetrachloride B) Dilute aqueous potassium permanganate C) Concentrated sulfuric acid D) All of the above E) Answers A) and B) only

Ans: D Topic: Structure Elucidation

19. Which reagent or test could be used to distinguish between 3-pentyne and 1-pentyne? A) Br2/CCl4 B) IR examination C) Concd. H2SO4 D) KMnO4,OH- E) None of these

Ans: B

Chapter 8

250

Topic: Structure Elucidation

20. Which reagent or test could be used to distinguish between 2-methyl-2-pentene and 2-methylpentane?

A) Br2/CCl4 B) KMnO4, OH− C) Concd. H2SO4 D) Two of the above E) All of the above

Ans: E Topic: Structure Elucidation

21. Which of the following could be used to distinguish between 1-octyne and 3-octyne? A) Treatment with 2 mol of HX B) Addition of water C) Reaction with KMnO4 D) Decolorization of bromine in CCl4 E) IR examination

Ans: E Topic: Structure Elucidation

22. A reagent or test that could be used to distinguish between 1-pentene and 1-pentyne would be:

A) Bromine in carbon tetrachloride B) Dilute aqueous potassium permanganate C) CrO3 in H2SO4 D) H2SO4 E) IR examination

Ans: E Topic: Structure Elucidation

23. Which of the following could be used as the basis for a simple test that would distinguish between 1-pentyne and pentane?

A) IR examination B) Br2/CCl4 C) KMnO4/H2O D) Two of these E) All of these

Ans: E

Chapter 8

251

Topic: Reaction Products

24. Treating 1-methylcyclohexene with H3O+ would yield primarily which of these?

II III

IV V

HO HOHO

HOOH

A) I and V B) II C) III and V D) IV E) I, III and V

Ans: D Topic: Reaction Products

25. What would be the major product of the following reaction? HCl

III

ClCl

A) I B) II C) III D) IV E) V

Ans: B

Chapter 8

252

Topic: Reaction Products

26. Treating 1-methylcyclohexene with HCl would yield primarily which of these?

H3C

ClH3C

H3C

H3CCl

III

A) I B) II C) III D) IV E) V

Ans: C Topic: Reaction Products

27. Which product would you expect from the following reaction?

H3O+

III

H2O

A) I B) II C) III D) IV E) V

Ans: D

Chapter 8

253

Topic: Reaction Products

28. The reaction of Br2/CCl4 to cyclohexene would produce the compound(s) represented by structure(s):

I II III

HBr

BrBr

A) I alone B) II alone C) II and III D) III alone E) I , II and II

Ans: C Topic: Reaction Products

29. What product would you expect from addition of deuterium chloride to 2-cyclohexyl-4-methyl-2-pentene?

I II

III

D H

DCl

A) I B) II C) III D) IV E) V

Ans: B

Chapter 8

254

Topic: Reaction Products

30. What is the chief product of the reaction of IBr with 2-methyl-2-pentene? A) 2-bromo-3-iodo-2-methylpentane B) 3-bromo-2-iodo-2-methylpentane C) 1-bromo-2-iodo-2-methylpentane D) 2-bromo-1-iodo-2-methylpentane E) All of the above

Ans: A Topic: Reaction Products

31. What is the chief product of the acid-catalyzed hydration of 2,5-dimethyl-2-hexene? A) 2,5-dimethyl-1-hexanol B) 2,5-dimethyl-2-hexanol C) 2,5-dimethyl-3-hexanol D) 2,5-dimethyl-2,3-hexanediol E) 2,5-dimethyl-3,4-hexanediol

Ans: B Topic: Reaction Products

32. What product would result from the following reaction?

I II

OCO2H

K MnO4

OH OHVOH OH

III

OH OH

KMnO4, H2Ocold, dilute ?

A) I B) II C) III D) IV E) V

Ans: C

Chapter 8

255

Topic: Reaction Products

33. Acid-catalyzed hydration of 2-methyl-1-butene would yield which of the following? A) (CH3)2C(OH)CH2CH3 B) CH2OHCH(CH3)CH2CH3 C) (CH3)2CHCHOHCH3 D) (CH3)2CHCH2CH2OH E) CH3CH2CH(CH3)CH2OH

Ans: A Topic: Reaction Products

34. Which of these is not formed when cyclopentene reacts with an aqueous solution of bromine?

I II III IV V

Br OH

Br Br

A) I B) II C) III D) IV E) V

Ans: E Topic: Reaction Products

35. What would be the major product of the following reaction?

I II III IVOH

Br Br

OH Br

Br2, H2O?

A) I B) II C) III D) IV E) V

Ans: A

Chapter 8

256

Topic: Reaction Products

36. Addition of hydrogen chloride to the following molecule would produce:

I II III

IV V

?HCl

A) I and II B) II and III C) I and IV D) V E) All of the above are equally likely to be formed

Ans: A

Chapter 8

257

Topic: Reaction Products

37. In addition to the expected major product, which compound may be reasonably anticipated as a by-product in the hydroxylation of R-2-methylcyclohexene with cold alkaline permanganate?

I II

III

i. KMnO4, H2O

cold, dilute

ii. H3O+?

H3C H

H3C HOH

H3C H

H CH3

O O

H CH3 OH

A) I B) II C) III D) IV E) V

Ans: E

Chapter 8

258

Topic: Reaction Products

38. Select the structure of the major product formed in the following reaction.

I II

ClCl

III

?2 HCl

A) I B) II C) III D) IV E) V

Ans: D Topic: Reaction Products

39. Which of these compounds is not formed when gaseous ethene is bubbled into an aqueous solution of bromine, sodium chloride and sodium nitrate?

A) BrCH2CH2Br B) BrCH2CH2Cl C) BrCH2CH2OH D) ClCH2CH2OH E) BrCH2CH2ONO2

Ans: D

Chapter 8

259

Topic: Reaction Products

40. Select the structure of the major product formed in the following reaction.

2 Cl2

I II

ClCl

III

Cl Cl

A) I B) II C) III D) IV E) V

Ans: C

Chapter 8

260

Topic: Reaction Products

41. Addition of excess HBr to 2-methyl-3-heptyne would produce: 2-methyl-3,3-dichloroheptane 2-methyl-2,3-dichloroheptane I II 2-methyl-4,4-dichloroheptane 2-methyl-3,4-dichloroheptane III IV 2-methyl-3-chloroheptene V

A) I and II B) I and III C) II and IV D) V E) All of the above

Ans: B Topic: Reaction Products

42. What would be the major product of the following reaction? Br2, CCl4

CH3

BrBr

C3H7

CH3

BrBr

C3H7

CH3

BrH

C3H7

HBr

III

C3H7

BrH

CH3

HBr

A) Equal amounts of I and II B) Equal amounts of II and III C) Equal amounts of III and IV D) I and II as major products, III and IV as minor products E) All of the above in equal amounts

Ans: A

Chapter 8

261

Topic: Reaction Products

43. What would be the major product of the following reaction? Br2, CCl4

I II III

C2H5

BrBr

C3H7

H3CH

C2H5

BrH

C3H7

H3CBr

C2H5

BrBr

C3H7

CH3

C3H7

BrCH3

C2H5

HBr

A) Equal amounts of I and II B) Equal amounts of II and III C) Equal amounts of III and IV D) I and II as major products, III and IV as minor products E) All of the above in equal amounts

Ans: A Topic: Reaction Products

44. Hydroxylation of cis-2-pentene with cold alkaline KMnO4 yields

I II III

CH3

OHOH

C2H5

CH3

OHH

C2H5

HHO

CH3

HOHO

C2H5

OHH

CH3

HHO

IVA) Equal amounts of I and II B) Equal amounts of II and III C) Equal amounts of III and IV D) I and II as major products, III and IV as minor products E) All of the above in equal amounts

Ans: B

Chapter 8

262

Topic: Reaction Products

45. The reaction of BrCl (bromine monochloride) with 1-methylcyclopentene will produce as the predominant product:

I II III

BrCH3 CH3

BrCl

ClBrCH3

CH3

BrCl

CH2Cl

+enantiomer

A) I B) II C) III D) IV E) V

Ans: D Topic: Reaction Products

46. Reaction of trans-2-hexene with a solution of Br2 in CCl4 produces:

I II III

BrH

HHBr Br

HBr

BrH

HBr

BrH

VA) I and II B) II and V C) III and IV D) IV and V E) V

Ans: C

Chapter 8

263

Topic: Reaction Products

47. When either cis- or trans-2-butene is treated with hydrogen chloride in ethanol, the product mixture that results includes:

A) CH3CH2CH2CH2Cl B) CH3CH2CH2CH2OCH2CH3 C) CH3CH2CH(CH3)OCH2CH3 D) (CH3)3CCl E) (CH3)2CHCH2OCH2CH3

Ans: C Topic: Reaction Products

48. What is the major product of the following reaction? H2SO4, H2O HgSO4

I II

III

A) I B) II C) III D) IV E) V

Ans: D Topic: Reaction Products

49. Addition of 2 mol of HCl to 1-butyne would yield: A) CH3CH2CH2CHCl2 B) CH3CH2CCl2CH3 C) CH3CH2CHClCH2Cl D) CH3CH2CH=CHCl E) CH3CHClCHClCH3

Ans: B

Chapter 8

264

Topic: Reaction Products

50. Consider the addition of HCl to 3-methyl-1-butene. The major product of the reaction would be:

A) 1-Chloro-2-methylbutane B) 1-Chloro-3-methylbutane C) 2-Chloro-2-methylbutane D) 2-Chloro-3-methylbutane E) 1-Chloropentane

Ans: C Topic: Reaction Products

51. What is the final product of the following synthesis?

C4H8

OHCH3

CH3

HHO

HCH3

CH3

OHH

HCH3

CH3

I II III

Final Product

HHO

OHCH3

CH3

H2Ni2B (P-2)

i. OsO4ii. NaHSO4

2-Butyne

A) I B) II C) III D) IV E) An equimolar mixture of III and IV

Ans: B Topic: Synthetic Strategy

52. A synthetic strategy for converting trans-2-butene into pure cis-2-butene would consist of which of the following?

A) Reaction with H2, Ni2B (P-2) B) Reaction with i) Br2, CCl4; ii) 2 NaNH2, NH3(l); iii) Na, NH3 (l) C) Reaction with H3O+, heat D) Reaction with i) Br2, CCl4; ii) 2 NaNH2, NH3(l); iii) H2, Ni2B (P-2) E) None of these will successfully effect the desired transformation

Ans: D

Chapter 8

265

Topic: Synthetic Strategy

53. Which reagent(s) given below could be used to synthesize cis-1,2-cycloheptanediol from cycloheptene?

A) KMnO4, OH−, 5oC B) KMnO4, H3O+, 75oC C) H2SO4, heat D) All of these E) None of these

Ans: A Topic: Synthetic Strategy

54. Which reaction sequence would convert cis-2-butene to trans-2-butene? A) Br2/CCl4; then 2 NaNH2; then H2/Ni2B(P-2) B) Br2/CCl4; then 2 NaNH2; then Li/liq. NH3 C) H3O+, heat; then cold dilute KMnO4 D) HBr; then NaNH2; then H2, Pt E) None of these

Ans: B Topic: Synthetic Strategy

55. The conversion of ethylene to vinyl bromide can be accomplished by use of these reagents in the order indicated.

A) (1) HBr; (2) NaOC2H5 B) (1) Br2; (2) NaOC2H5 C) (1) Br2; (2) H2O D) (1) NaNH2; (2) HBr E) (1) HBr; (2) H2SO4

Ans: B Topic: Synthetic Strategy

56. Cyclohexene is treated with cold dilute alkaline KMnO4. Assuming syn addition, the spatial arrangement of the two hydroxyl groups in the product would be:

A) equatorial-axial B) axial-axial C) equatorial-equatorial D) coplanar E) trans

Ans: A

Chapter 8

266

Topic: Synthetic Strategy

57. Which of the following reactions of cyclobutene would yield a meso product? A) Reaction with H3O+, H2O B) Reaction with Br2, CCl4 C) Reaction with Cl2, CCl4 D) Reaction with D2, Pt E) Reaction with hot, alkaline KMnO4, followed by acid workup

Ans: E Topic: Reaction Products

58. How many compounds are possible from the addition of bromine to CH2=CHCH2CH3 (counting stereoisomers separately)?

A) One B) Two C) Three D) Four E) Five

Ans: B Topic: Reaction Products

59. Which alkene would react with cold dilute alkaline permanganate solution to form an optically inactive and irresolvable product?

Ans: C

Chapter 8

267

Topic: Reaction Products

60. Which reaction of an alkene proceeds with anti addition? A) Hydroboration/oxidation B) Bromination C) Oxidation with cold KMnO4 D) Hydrogenation E) Oxymercuration-demercuration

Ans: B Topic: Reaction Products

61. A pair of enantiomers results from which of these reactions? A) cyclopentene + cold, dil. KMnO4 ⎯⎯⎯⎯→ B) trans-2-butene + Br2 ⎯⎯⎯⎯→ C) 1-pentene + HCl ⎯⎯⎯⎯→ D) cis-2-butene + D2/Pt ⎯⎯⎯⎯→ E) cyclobutene + OsO4, then Na2SO3 ⎯⎯⎯⎯→

Ans: C Topic: Reaction Products

62. Which reaction would yield a racemic product? A) cyclopentene + D2/Pt ⎯⎯⎯⎯→ B) Cyclopentene + OsO4, then Na2SO3 ⎯⎯⎯⎯→ C) cyclopentene + Br2/H2O ⎯⎯⎯⎯→ D) Cyclopentene + cold, dilute KMnO4 ⎯⎯⎯⎯→ E) Cyclopentene + dilute H2SO4 ⎯⎯⎯⎯→

Ans: C Topic: Reaction Products

63. 3,3-dimethylcyclohexene is subjected to reaction with cold, dilute KMnO4, to give 3,3-dimethyl-1,2-cyclohexanediol. In the most stable conformation of the product, the hydroxyl groups would be:

A) both axial B) both equatorial C) axial-equatorial D) coplanar E) None of these

Ans: B

Chapter 8

268

Topic: Reaction Products

64. Cyclohexene reacts with bromine to yield 1,2-dibromocyclohexane. Molecules of the product would:

A) be a racemic form and, in their most stable conformation, they would have both bromine atoms equatorial.

B) be a racemic form and, in their most stable conformation, they would have one bromine atom equatorial and one axial.

C) be a meso compound and, in its most stable conformation, it would have both bromine atoms equatorial.

D) be a meso compound and, in its most stable conformation, it would have one bromine atom equatorial and one axial.

E) be a pair of diastereomers and, in their most stable conformation, one would have the bromines equatorial and axial, and the other would have the bromines equatorial and equatorial. Ans: A

Topic: Reaction Products

65. Which reaction would yield a meso compound? A) Br2/CCl4cis-2-ButeneB)

cis-2-ButeneH2/Pd

C) cis-2-Butene i) OsO4 ii) NaHSO3

D) dil KMnO4

5oCtrans-2-Butene

E) None of these Ans: C

Topic: Reaction Products

66. Which reaction would give a meso compound as the product? A) Cyclopentene + Br2/CCl4 B) Cyclopentene + OsO4, then NaHSO3 C) Cyclopentene + RCO3H, then H3O+ D) Cyclopentene + Cl2, H2O E) More than one of these

Ans: B

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Topic: Reaction Products

67. Which of the following reactions would yield the final product as a racemic form? A) Cyclohexene + a peroxy acid, then H3O+ B) Cyclohexene + cold, dilute KMnO4 and OH- C) Cyclohexene + HCl D) Cyclohexene + OsO4, then NaHSO3 E) Cyclohexene + D2/Pt

Ans: A Topic: Reaction Products

68. (R)-3-Chloro-1-butene reacts with HCl by Markovnikov addition, and the products are separated by gas chromatography. How many total fractions would be obtained and how many would be optically active?

A) One optically active fraction only B) One optically active fraction and one optically inactive C) Two optically active fractions D) One optically active fraction and two optically inactive E) Two optically active fractions and one optically inactive

Ans: B Topic: Reaction Products

69. The interaction of the π bond of an alkene with an electrophile can initially result in the formation of a species termed a π complex. Which of these cannot combine with an alkene to form a π complex?

A) H+ B) NH3 C) Ag+ D) Hg2+ E) BF3

Ans: B Topic: Reaction Products

70. Markovnikov addition of HI to 2-methyl-2-butene involves: A) initial attack by an iodide ion. B) initial attack by an iodine atom. C) isomerization of 2-iodo-2-methylbutene. D) formation of a carbocation at C-2. E) formation of carbocation at C-3.

Ans: D

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Topic: Reaction Products

71. Which reaction is NOT stereospecific?

Br2/CCl4trans-2-Butene cis-2-Pentene

trans-2-Hexenedil KMnO4

5oC2-Methyl-2-heptene

1-MethylcyclohexeneH2/Pd

Br2/H2O

HBr

I II

VIV

III

A) I B) II C) III D) IV E) V

Ans: E

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Topic: Reaction Products

72. Which reaction is regioselective?

D2/Ni

ClI

OHH

IClI

III

KMnO4

Br2

A) I B) II C) III D) IV E) None of these

Ans: A Topic: General Information

73. The thermodynamic parameters at 298 K for the following reaction are given below.

CH2=CH2 + HClgas phase

CH3CH2Cl ΔHº = -64.9 kJ mol-1 ΔSº = -131 J K-1 mol-1 ΔGº = -25.8 kJ mol-1 Which of the following statements is true of the reaction?

A) Both ΔHº and ΔSº favor product formation. B) Neither ΔHº nor ΔSº favors product formation. C) The entropy term is unfavorable but the formation of ethyl chloride is favored. D) The entropy term is favorable but the formation of ethyl chloride is not favored. E) The sign of ΔGº indicates that the reaction cannot occur as written.

Ans: C

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Topic: Reaction Products

74. In general, when the addition of an unsymmetrical electrophilic reagent to an unsymmetrical alkene forms the product predicted by Markovnikov's rule, that occurs because:

A) the product is statistically favored. B) steric hindrance favors its formation. C) it is formed via the more/most stable carbocation. D) it is the more/most stable product. E) All of the above are reasons.

Ans: C Topic: General Information

75. Which of these compounds belongs to the class of substances commonly known as "halohydrins"?

A) BrCH2CH2Cl B) ClCH2CO2H C) ICH2CH2OH D) FCH2CH2NH2 E) HOCH2 COCl

Ans: C Topic: General Information

76. Which alkene would you expect to be most reactive toward acid-catalyzed hydration? A) 1 pentene B) trans-2-pentene C) cis-2-pentene D) 2-methyl-1butene E) All of these would be equally reactive.

Ans: D Topic: General Information

77. The most resistant compound to the action of hot alkaline KMnO4 is: A) Pentane B) 1-Pentene C) 2-Pentene D) 2-Pentyne E) Cyclopentene

Ans: A

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273

Topic: General Information

78. 2-Pentyne will not react with: A) H2, Pt B) Br2 C) NH3 D) H2SO4 E) KMnO4/H2O

Ans: C Topic: General Information

79. Consider the ozonolysis products obtained from all the unbranched and unsymmetrical isomers of heptene. The reaction product in each case would consist of:

A) a single aldehyde. B) an aldehyde and a ketone. C) two different ketones. D) two different aldehydes. E) a single ketone.

Ans: D SHORT ANSWER QUESTIONS Topic: General Information

80. The rule that correctly predicts the regiochemistry of most ionic additions to alkenes is called ____________________. Ans: Markovnikov's Rule

Topic: General Information

81. When a reaction that could potentially yield two or more constitutional isomers instead produces only one as the major product, the reaction is said to be _____________________. Ans: regioselective

Topic: General Information

82. When a particular stereoisomer reacts in such a way that it gives a particular stereoisomer as a product, even if more than one stereoisomer is theoretically possible, the reaction is said to be _____________. Ans: stereospecific

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Topic: General Information

83. A reaction in which the reactant is not necessarily chiral but still produces primarily one stereoisomeric form of the product (or a specific subset of the possible stereoisomers) is referred to as a _________________ reaction. Ans: stereoselective

Topic: General Information

84. Hydroboration-oxidation is a reaction with _________ stereochemistry and ________________ regiochemistry. Ans: syn, anti-Markovnikov

Topic: General Information

85. Even when one or more stereogenic centers are produced as the result of an addition reaction to an alkene, the product is always formed as a racemic mixture. Why is that? Ans: Because alkenes are planar, and the reagent can add from either face.

Topic: General Information

86. The “decolorization” of molecular bromine is often used as a functional group test to detect the presence of ________________. Ans: carbon-carbon multiple bonds; or, alkenes and alkynes

Topic: General Information

87. Neutral divalent carbon compounds are called ___________. Ans: carbenes

Topic: General Information

88. Carbenes are frequently produced by α-elimination reactions. These are reactions in which the proton being lost and the leaving group are ___________. Ans: both attached to the same carbon

Topic: General Information

89. π bonds are quite susceptible to reaction with electron-seeking reagents, also referred to as ____________________.

Ans: electrophiles

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Topic: Reaction Sequence

90. Predict the final product(s) obtained when (2R,3R)-2-bromo-3-methylpentane is subjected to the following sequence of reactions, briefly explaining your rationale. Provide regiochemical and stereochemical details as relevant.

i) NaOC2H5/C2H5OH, heat ii) BH3, THF iii) H2O2, OH−

Ans: Br

H3C

NaOC2H5C2H5OH (E2: anti elimination)(2R,3R)

CH3

E-3-methyl-2-hexene

H3C

CH3

Hydroboration/oxidation: overall Anti-Markovnikov, syn addition of H2O

(2S,3R) (2R,3S)3-methyl-2-pentanol

Heating with sodium ethoxide results in E2 elimination; the anti- elimination leads to the formation of E-3-methyl-2-hexene as the major product. Subsequent hydroboration oxidation is regioselective (anti-Markovnikov) and stereospecific (syn), resulting in the formation of racemic (2S,3R & 2R,3S) 3-methyl-2-pentanol. The other diastereomer pair (2S,3S & 2R,3R) is not expected to be obtained.

Topic: Reaction Products

91. Provide a mechanistic explanation for the following observation: The same major product is obtained when 2-ethyl-1-hexene and 3-methyl-2-heptene are allowed to react with HCl.

Ans: HCl

ClHCl

most stable carbocation

Both alkenes are unsymmetrically substituted: the major product is a consequence of regioselective addition to the double bond. Upon reaction with HCl, electrophilic addition of a proton results in the formation of the most stable intermediate carbocation, which then reacts with Cl−, to give the observed product.

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Topic: Reaction Products

92. Predict the major product(s) of the following reaction, giving regiochemical and/or stereochemical details as relevant.

Br2, H2O?

Ans:

HBrOH

HBrOH+

The reaction takes place with Markovnikov regioselectivity and anti stereospecificity, giving a racemic mixture of the halohydrin as the major product.

Topic: Reaction Products

93. Draw Fischer projection formula(s) of the major product(s) of the reaction between Z-2-methyl-3-hexene and cold, alkaline KMnO4.

Ans: CH(CH3)2

OHOH

C2H5

CH(CH3)2

HOHO

C2H5

cold, dil KMnO4

The reaction takes place with syn stereospecificity, giving a racemic mixture of the diol product.

Topic: Reaction Products

94. Draw Fischer projection formula(s) of the major product(s) of the reaction between Z-3-methyl-3-hexene and cold, alkaline KMnO4.

Ans: CH2CH3

OHOH

C2H5

H3CH

CH2CH3

HOHO

C2H5

CH3

Hcold, dil KMnO4

The reaction takes place with syn stereospecificity, giving a racemic mixture of the diol product.

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Topic: Reaction Products

95. Draw Fischer projection formulas of the major product of the reaction between E-2-methyl-3-hexene and aqueous Br2.

Ans: CH(CH3)2HBr

C2H5

HOH

CH(CH3)2

HBr

C2H5

OHH

CH(CH3)2

BrH

C2H5

HHO

CH(CH3)2

BrH

C2H5

HOH+ ++

Br2 H2O

The reaction takes place with anti stereospecificity. Since the alkene is symmetrically substituted, Markovnikov rule is not applicable, and the reaction is not regioselective. The product mixture would therefore consist of 2 pairs of enantiomers, that are constitutional isomers of each other.

Topic: Reaction Products

96. Give a mechanistic explanation for the formation of the following product in significant yield. What other product(s) might also be obtained? Explain clearly.

HI I

Ans: H+ + +fast I−

II−

The regioselective addition of a proton first generates a secondary carbocation, which can undergo rearrangement to a more stable 3o carbocation by two alternate pathways. One pathway results in ring expansion to a more stable 5-membered ring. This pathway is thus more likely, which would then lead to the observed product. The other pathway is less likely, since ring strain is not relieved; however, this could lead to a minor product, as shown above.

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Topic: Structure Elucidation

97. Deduce the structure of an unknown compound A, C8H16, from the following data. Briefly, but clearly explain your rationale. A decolorizes Br2/CCl4, and upon reaction with excess H2/Ni, affords 1-ethyl-2-methylcyclopentane. When A is subjected to ozonolysis, the following product is obtained.

Ans: A must be 3-ethyl-4-methylcyclopentene. This given data can be explained as shown below:

decolorizes Br2,CCl4: A must contain pi bonds

H2, Ni

ozonolysis

C8H14: Index of Hydrogen Deficiency of A = 2

A must contain some the same carbon skeleton and one pi bond

pi bond position in A deduced from the structure of the ozonolysis product

Topic: Reaction Products

98. Predict the product(s) of the oxidation of 2,3,4-trimethyl-1,5-heptadiene with hot, alkaline KMnO4.

Ans: O

OH O

OH+CO2 + H2O +hot, alkaline

KMnO4

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279

Topic: Reaction Products

99. Predict the structure of product obtained when cis-2-hexene is allowed to react with Zn/CH2I2. Ans:

Zn, CH2I2H

The Zn/CH2I2 produces a carbene which reacts with the alkene to give the corresponding cyclopropane derivative. The reaction proceeds with retention of alkene stereochemistry, resulting in a racemic mixture of the two cis enantiomers.

Topic: Reaction Products

100. Predict the structure of product obtained when 1-hexyne is allowed to react with aqueous H2SO4 in the presence of catalytic amounts of HgSO4.

Ans: HgSO4, H2SO4, H2O OH O

The reaction of 1-hexyne with aqueous H2SO4, in the presence of catalytic amounts of HgSO4, results in regioselective hydration to produce an enol, which tautomerizes to the more stable keto form.

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MULTIPLE CHOICE QUESTIONS Topic: Proton NMR- Chemical Shift, Splitting, Etc.

1. If all the protons of 1-fluoropentane could be discerned, which would you expect to be at the lowest field in the 1H NMR spectrum of this compound?

V IV III

CH3CH2CH2CH2CH2F

II I A) Protons on carbon I B) Protons on carbon II C) Protons on carbon III D) Protons on carbon IV E) Protons on carbon V

Ans: A Topic: Proton NMR- Chemical Shift, Splitting, Etc.

2. Which proton(s) of the compound below would appear as a septet in the 1H NMR spectrum?

V IV III

CH3CH2CH2-O-CHI

III

CH3

A) The protons on carbon I B) The proton on carbon II C) The protons on carbon III D) The protons on carbon IV E) The protons on carbon V

Ans: B

Chapter 9

281

Topic: Proton NMR- Chemical Shift, Splitting, Etc.

3. Which proton(s) of the compound below would appear as a doublet in the 1H NMR spectrum?

V IV III

CH3CH2CH2-O-CHI

III

CH3

A) The protons on carbon I B) The protons on carbon II C) The protons on carbon III D) The protons on carbon IV E) The protons on carbon V

Ans: A Topic: Proton NMR- Chemical Shift, Splitting, Etc.

4. Which proton(s) of the compound below would appear as a triplet in the 1H NMR spectrum?

V IV III

CH3CH2CH2-O-CHI

III

CH3

A) The protons on carbon II B) The protons on carbon I and V C) The protons on carbon III and V D) The protons on carbon III and IV E) The protons on carbon V

Ans: C Topic: Proton NMR- Chemical Shift, Splitting, Etc.

5. How many signals would you expect to find in the 1H NMR spectrum of CH3OCH2CH2OCH3?

A) 1 B) 2 C) 3 D) 4 E) 5

Ans: B

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282

Topic: Proton NMR- Chemical Shift, Splitting, Etc.

6. Predict the splitting pattern you would observe for the proton at C3 of 2,3-dimethyl-2-phenylbutane.

A) Doublet B) Singlet C) Quartet D) Septet E) Octet

Ans: D Topic: Proton NMR- Chemical Shift, Splitting, Etc.

7. Predict the splitting pattern you would observe for the proton at C1 of 2,3-dimethyl-2-phenylbutane.

A) Doublet B) Singlet C) Quartet D) Septet E) Octet

Ans: B Topic: Proton NMR- Chemical Shift, Splitting, Etc.

8. Predict the splitting pattern you would observe for the proton at C4 of 2,3-dimethyl-2-phenylbutane.

A) Doublet B) Singlet C) Quartet D) Septet E) Octet

Ans: A

Chapter 9

283

Topic: Proton NMR- Chemical Shift, Splitting, Etc.

9. What feature would you expect to see in the 1H NMR spectrum of B after subjecting A to the following reaction?

Cl2

A B

heat or light C8H9Cl + HCl(chief product)

A) There would be only 4 aromatic protons at low field. B) The signal for the protons on the benzylic carbon would be a doublet. C) The signal for the methyl protons would be a triplet. D) The signal for the methyl protons would be a doublet. E) The signal for the methyl protons would integrate for only 2 hydrogens.

Ans: D Topic: Proton NMR- Chemical Shift, Splitting, Etc.

10. How many 1H NMR signals would trans-1,2-dichlorocyclopropane give? A) 1 B) 2 C) 3 D) 4 E) 5

Ans: B Topic: Proton NMR- Chemical Shift, Splitting, Etc.

11. How many 1H NMR signals would the following compound give? ClCH2CHCH3

BrA) 1 B) 2 C) 3 D) 4 E) 5

Ans: D

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284

Topic: Proton NMR- Chemical Shift, Splitting, Etc.

12. How many 1H NMR signals would cis-1,2-dichlorocyclopropane give? A) 1 B) 2 C) 3 D) 4 E) 5

Ans: C Topic: Proton NMR- Chemical Shift, Splitting, Etc. 13. How many 1H NMR signals would you expect from this compound?

OCH3

OCH3 A) 1 B) 2 C) 3 D) 4 E) 5

Ans: B Topic: Proton NMR- Chemical Shift, Splitting, Etc.

14. The 1H NMR signal for which of the indicated protons occurs furthest downfield?

H C C C

CH3I

IIIV

III

A) I B) II C) III D) IV E) V

Ans: E

Chapter 9

285

Topic: Proton NMR- Chemical Shift, Splitting, Etc.

15. The 1H NMR spectrum of which of the compounds below, all of formula C7H12O2, would consist of two singlets only?

O O

IIIO

V A) I B) II C) III D) IV E) V

Ans: E Topic: Proton NMR- Chemical Shift, Splitting, Etc.

16. The 1H NMR spectrum of which of the compounds below, all of formula C7H12O2, would consist of three singlets only?

O O

IIIO

V A) I B) II C) III D) IV E) V

Ans: B

Chapter 9

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Topic: Proton NMR- Chemical Shift, Splitting, Etc.

17. The 1H NMR spectrum of which of the compounds below, all of formula C7H12O2, would consist of a singlet, a doublet and a triplet only?

O O

IIIO

V A) I B) II C) III D) IV E) V

Ans: D Topic: Proton NMR- Chemical Shift, Splitting, Etc.

18. The 1H NMR spectrum of which of these compounds would consist of a triplet, singlet and quartet only?

A) 2-chloro-4-methylpentane B) 3-chloro-2-methylpentane C) 3-chloropentane D) 1-chloro-2,2-dimethylbutane E) 3-chloro-3-methylpentane

Ans: E Topic: Proton NMR- Chemical Shift, Splitting, Etc.

19. In NMR terminology, protons Ha and Hb are said to be: H Cl

HaHb A) Identical B) Enantiotopic C) Diastereotopic D) Homotopic E) Mesotopic

Ans: C

Chapter 9

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Topic: Proton NMR- Chemical Shift, Splitting, Etc.

20. Consider the 1H NMR spectrum of very pure 1-propanol. Assuming the maximum multiplicity of signals and non-superposition of peaks, what is the expected signal splitting pattern for each signal, in the order (a, b, c, d) ?

CH3-CH2-CH2-OH a b c d

A) 3, 6, 4, 1 B) 3, 6, 4, 3 C) 3, 12, 3, 1 D) 3, 12, 3, 3 E) 3, 12, 6, 3

Ans: C Topic: Proton NMR- Chemical Shift, Splitting, Etc.

21. In the structure shown, Hb and Hc are classified as:

Hc A) homotopic protons. B) vicinal protons. C) enantiotopic protons. D) diastereotopic protons. E) isomeric protons.

Ans: D Topic: Proton NMR- Chemical Shift, Splitting, Etc.

22. In the structure shown, Hb and Hc are classified as:

HaHb

A) homotopic protons. B) vicinal protons. C) enantiotopic protons. D) diastereotopic protons. E) isomeric protons.

Ans: C

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Topic: Proton NMR- Chemical Shift, Splitting, Etc.

23. In the structure shown, Hb and Hc are classified as:

A) homotopic protons. B) vicinal protons. C) enantiotopic protons. D) diastereotopic protons. E) isomeric protons.

Ans: D Topic: Proton NMR- Chemical Shift, Splitting, Etc.

24. In the structure shown, Hb and Hc are classified as:

HO H

Ha Hb A) homotopic protons. B) vicinal protons. C) enantiotopic protons. D) diastereotopic protons. E) isomeric protons.

Ans: D Topic: Proton NMR- Chemical Shift, Splitting, Etc.

25. Distinction between the methine protons in the compounds I and II below should be possible in the 1H NMR spectra if:

C2H5H3C

A) a very high field instrument is used. B) the spectra are determined in a chiral solvent. C) a long scan time is used for each compound. D) a high amplitude setting is employed. E) Distinction between the enantiomers is impossible.

Ans: B

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289

Topic: Proton NMR- Unknown Identification.

26. A compound with the molecular formula C4H10O gives a 1H NMR spectrum consisting only of a quartet centered at δ 3.5 and a triplet at δ 1.1. The most likely structure for the compound is:

CH3COH

CH3

CH3OCHOH

CH3

C) CH3CH2CH2CH2OH D) CH3CH2OCH2CH3 E) CH3CHCH2OH

CH3

Ans: D Topic: Proton NMR- Unknown Identification.

27. Determine the most likely structure of a compound, with the molecular formula C9H12, which gave a 1H NMR spectrum consisting of: a doublet at δ 1.25 a septet at δ 2.90 and a multiplet at δ 7.25

I II III IV V]

A) I B) II C) III D) IV E) V

Ans: D

Chapter 9

290

Topic: Proton NMR- Unknown Identification.

28. A compound with the molecular formula C10H13Cl gave the following 1H NMR spectrum: singlet, δ 1.6 singlet, δ 3.1 multiplet, δ 7.2 (5H) The most likely structure for the compound is:

Cl Cl Cl

ClI II III

IV VA) I B) II C) III D) IV E) V

Ans: B Topic: Proton NMR- Unknown Identification.

29. A compound with the molecular formula C8H9BrO gave the following 1H NMR spectrum: triplet, δ 1.4 quartet, δ 3.9 multiplet, δ 7.0 (4H) There was no evidence of an -OH band in the IR spectrum. A possible structure for the compound is:

OBr

O Br

BrIII

A) I B) II C) III D) IV E) V

Ans: C

Chapter 9

291

Topic: Proton NMR- Unknown Identification

30. A compound with the molecular formula C6H15N gave the following 1H NMR spectrum: triplet, δ 0.90 quartet, δ 2.4 There were no other signals. The most likely structure for the compound is:

A) CH3NCH2CH3

CH2CH2CH3

B) CH3NCH2CH2CH2CH3

CH3

C) CH3CH2CH2CH2CH2CH2NH2 D) CH3CH2NCH2CH3

CH2CH3

E) CH3CH2CH2NCH2CH2CH3

Ans: D Topic: Proton NMR- Unknown Identification

31. A compound with the molecular formula C8H9ClO gave the following 1H NMR spectrum: triplet, δ 3.7 triplet, δ 4.2 multiplet, δ 7.1 There was no evidence of an -OH band in the IR spectrum. The most likely structure for the compound is:

OCl

ClIII

A) I B) II C) III D) IV E) V

Ans: A

Chapter 9

292

Topic: Proton NMR- Unknown Identification

32. A compound with the molecular formula C3H6Cl2 gave a 1H NMR spectrum consisting only of a triplet centered at δ 3.7 and a quintet centered at δ 2.2. The most likely structure for the compound is:

A) CH3CH2CHCl2 B) CH3CHClCH2Cl C) ClCH2CHClCH3 D) ClCH2CH2CH2Cl E) CH3CCl2CH3

Ans: D Topic: Proton NMR- Unknown Identification

33. A compound with the molecular formula C10H14 gave the following 1H NMR spectrum: doublet, δ 1.2 singlet, δ 2.3 septet, δ 2.8 multiplet, δ 7.1 A possible structure for the compound is:

I II III

IV VA) I B) II C) III D) IV E) V

Ans: B

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293

Topic: Proton NMR- Unknown Identification

34. A compound C5H10O gave the following spectral data: 1H NMR spectrum IR spectrum, doublet, δ 1.10 strong peak singlet, δ 2.10 near 1720 cm-1

septet, δ 2.50 Which is a reasonable structure for the compound?

III

A) I B) II C) III D) IV E) V

Ans: E Topic: Proton NMR- Unknown Identification

35. A compound C4H9Br gave the following 1H NMR spectrum: multiplet, δ 4.1 (1H); multiplet, δ 1.8; doublet, δ 1.7; triplet, δ 1.0 (3H) Which is a reasonable structure for the compound?

A) CH3CH2CHBrCH3 B) CH3CH2CH2CH2Br C) (CH3)2CHCH2Br D) (CH3)3CBr

Ans: A

Chapter 9

294

Topic: Proton NMR- Unknown Identification

36. Determine the likely structure for a compound A (C6H10O), which is found to decolorize bromine in carbon tetrachloride. Its spectral data is as follows: 1H NMR IR triplet, δ 1.0 singlet, δ2.4 2200 cm-1 (sharp) singlet, δ 1.4 singlet, δ3.4 3300 cm-1 (sharp) quartet, δ 1.6 3500 cm-1 (broad)

III

IV VOH

OH OH

A) I B) II C) III D) IV E) V

Ans: C

Chapter 9

295

Topic: C-13 NMR- Symmetry, Chemical shift.

37. The broadband proton-decoupled 13C NMR spectrum of a hexyl chloride exhibits five signals. Which of these structures could be the correct one for the compound?

CH3CCH2CH2Cl

CH3

CH3CH2CCH2CH3

CH3

CH3C CHCH3

CH3

CH3CHCHCH2CH3

CH3

CH3C CHCH3

CH3

CH3 Cl

Ans: D Topic: C-13 NMR- Symmetry, Chemical shift

38. How many signals will be recorded in the broadband proton-decoupled 13C spectrum of 4-chloro-1-ethylbenzene? Cl

A) 2 B) 3 C) 4 D) 6 E) 7

Ans: D

Chapter 9

296

Topic: C-13 NMR- Symmetry, Chemical shift

39. How will the methyl carbon appear in the proton off-resonance decoupled 13C spectrum of toluene?

A) Singlet B) Doublet C) Triplet D) Quartet E) Quintet

Ans: D Topic: C-13 NMR- Symmetry, Chemical shift

40. How many 13C signals would 1,4-dimethylbenzene give?

A) 1 B) 2 C) 3 D) 4 E) 5

Ans: C Topic: C-13 NMR- Symmetry, Chemical shift

41. How many 13C signals would 1,3-dichlorobenzene give?

A) 1 B) 2 C) 3 D) 4 E) 5

Ans: D

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297

Topic: C-13 NMR- Symmetry, Chemical shift

42. How many 13C signals would 1,2-dimethylbenzene give?

A) 1 B) 2 C) 3 D) 4 E) 5

Ans: D Topic: C-13 NMR- Symmetry, Chemical shift

43. How many 13C signals would you expect from C6H5OCH3? O

A) 1 B) 2 C) 3 D) 4 E) 5

Ans: E Topic: C-13 NMR- Symmetry, Chemical shift

44. The C7 compound which gives 3 signals in the broadband proton-decoupled 13C spectrum could be:

A) Heptane B) 2-Methylhexane C) 3,3-Dimethylpentane D) 2,4-Dimethylpentane E) 2,2,3-Trimethylbutane

Ans: D

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Topic: Proton NMR- Symmetry, Splitting, Chemical shift

45. Which of these compounds will not be represented by a singlet only in the 1H NMR spectrum?

A) Neopentane B) Hexamethylbenzene C) Isobutane D) (Z)-1,2-Dichloroethene E) (E)-1,2-Dichloroethene

Ans: C Topic: Proton NMR- Symmetry, Splitting, Chemical shift

46. For the C2 methylene group in 1-bromopropane, the theoretical multiplicity in the 1H NMR spectrum, presuming that Jab is sufficiently different from Jbc and that the instrument has sufficient resolving power, is which of these?

CH3 CH2 CH2 Br

c b aA) 2 B) 5 C) 6 D) 8 E) 12

Ans: E Topic: Proton NMR- Symmetry, Splitting, Chemical shift 47. A compound C5H11Cl which exhibits only two singlets in the 1H NMR spectrum must

be: A) 1-Chloropentane B) 1-Chloro-2,2-dimethylpropane C) 1-Chloro-2-methylbutane D) 3-Chloropentane E) 1-Chloro-3-methylbutane

Ans: B

Chapter 9

299

Topic: Proton NMR- Symmetry, Splitting, Chemical shift

48. A downfield (δ 9-10) singlet is observed in the 1H NMR spectrum of: A)

CH3CCH2CH3

C6H5CH2C O

(CH3)2CHC O

(CH3)3CC O

C6H5CH2CCH3

Ans: D Topic: Proton NMR- Symmetry, Splitting, Chemical shift 49.

Consider the expected splitting of signal “b” in the 1H NMR spectrum of N-methyl-1-propanamine, shown below. Presuming that Jab is sufficiently different from Jbc and that the instrument has sufficient resolving power, what is the theoretical multiplicity of signal “b”?

A) 2 B) 5 C) 6 D) 8 E) 12

Ans: E

Chapter 9

300

Topic: Proton NMR- Symmetry, Splitting, Chemical shift

50. Consider the expected splitting of signal “b” in the 1H NMR spectrum of 1-methoxy-2-methylpropane, shown below. Presuming that Jab is sufficiently different from Jbc and that the instrument has sufficient resolving power, what is the theoretical multiplicity of signal “b”?

a b c d

A) 8 B) 9 C) 12 D) 21 E) 24

Ans: D Topic: Proton NMR- Symmetry, Splitting, Chemical shift

51. Consider the expected splitting of signal “b” in the 1H NMR spectrum of 1,1-dichloro-3-methylbutane, shown below. Presuming that Jab is sufficiently different from Jbc and that the instrument has sufficient resolving power, what is the theoretical multiplicity of signal “b”?

Cla b c

a Cl

A) 8 B) 9 C) 12 D) 18 E) 21

Ans: E

Chapter 9

301

Topic: Proton NMR- Symmetry, Splitting, Chemical shift

52. Consider the expected splitting of signal “b” in the 1H NMR spectrum of 1,2-dimethoxypropane, shown below. Presuming that Jbc is sufficiently different from Jbd and that the instrument has sufficient resolving power, what is the theoretical multiplicity of signal “b”?

Oa b

A) 2 B) 5 C) 6 D) 8 E) 12

Ans: E Topic: Proton NMR- Symmetry, Splitting, Chemical shift

53.

Consider the expected splitting of signal “c” in the 1H NMR spectrum of 2-ethyl-1-butanol, shown below. Presuming that Jbc is sufficiently different from Jcd and that the instrument has sufficient resolving power, what is the theoretical multiplicity of signal “c”?

OHa

b dc e

A) 6 B) 7 C) 8 D) 12 E) 15

Ans: E

Chapter 9

302

Topic: Proton NMR- Symmetry, Splitting, Chemical shift

54.

Consider the expected splitting of the C2 proton signal in the 1H NMR spectrum of 2-ethyl-1,3-propanediol. Presuming that the coupling constants for neighboring protons are sufficiently different, and that the instrument has sufficient resolving power, what is the theoretical multiplicity of the C2 proton signal?

A) 6 B) 7 C) 8 D) 12 E) 15

Ans: E Topic: Proton NMR- Symmetry, Splitting, Chemical shift

55.

What is the theoretical multiplicity of the C-2 proton signal in the 1H NMR spectrum of 2-hydroxymethyl-1,3-propanediol, shown below?

OHHO

A) 1 B) 6 C) 7 D) 8 E) 9

Ans: C Topic: Proton NMR- Symmetry, Splitting, Chemical shift

56.

Consider the expected 1H NMR spectrum of 1,1,3,3-trimethylcyclopentane. Which of the following is likely to be observed?

A) 7 signals: all singlets B) 7 signals: 4 singlets, 3 doublets C) 3 signals: all singlets D) 3 signals: one singlet, 2 doublets E) 3 signals: two singlets, one doublet

Ans: E

Chapter 9

303

Topic: Proton NMR- Symmetry, Splitting, Chemical shift

57.

Consider the expected 1H NMR spectrum of 2,4-dimethyl-1,4-pentadiene. Which of the following is likely to be observed?

A) 7 signals: all singlets B) 4 signals: all singlets C) 3 signals: all singlets D) 3 signals: one singlet, 2 doublets E) 4 signals: two singlets, two doublets

Ans: B Topic: Proton NMR- Symmetry, Splitting, Chemical shift

58.

Consider the expected splitting of the C2 proton signal in the 1H NMR spectrum of 1,1-dibromopentane. Presuming that the coupling constants for neighboring protons are sufficiently different, and that the instrument has sufficient resolving power, what is the theoretical multiplicity of the C2 proton signal?

A) 3 B) 4 C) 5 D) 6 E) 8

Ans: D

Chapter 9

304

Topic: Carbon NMR- Symmetry, Chemical shift

59. A bromodichlorobenzene which gives four signals in the broadband proton-decoupled 13C spectrum could be:

III

IV V

A) I B) II C) III D) IV E) V

Ans: A Topic: Carbon NMR- Symmetry, Chemical shift

60. In 13C NMR spectroscopy, the signal due to this type of carbon occurs furthest downfield.

A) –C≡N B)

C O

C) C O

D) C X

E) –C≡C– Ans: B

Chapter 9

305

Topic: Mass Spectrometry. Use the following to answer Q 61-62

Topic: Mass Spectrometry.

61. Which is the base peak? A) 15 B) 29 C) 44 D) 45 E) 100

Ans: B Topic: Mass Spectrometry.

62. Which is the likely molecular ion (M+•)?

A) 15 B) 29 C) 44 D) 45 E) 100

Ans: C Topic: Mass Spectrometry.

63. What is the molecular formula of this compound? m/z intensity 84 M+

• 10.00 85 0.56 86 0.04

A) C5H10O B) C5H8O C) C5H24 D) C6H12 E) C4H6O2

Ans: B

Chapter 9

306

Topic: Mass Spectrometry.

64. What is the molecular formula of this compound? m/z intensity 78 M+

• 10.00 79 1 80 3.3 81 0.3

A) C6H6 B) C3H5Cl C) C6H8 D) C6H9 E) C3H7Cl

Ans: E Topic: Mass Spectrometry.

65. The mass spectra of alkyl bromides and chlorides are characterized by an unusually intense __________.

A) base peak B) parent peak C) M+

• +1 peak D) M+

• +2 peak E) None of these

Ans: D Topic: Mass Spectrometry. 66. Predict the base peak for 2-chloro-2-methylpropane

A) m/z 15 B) m/z 92 C) m/z 43 D) m/z 57 E) m/z 77

Ans: D

Chapter 9

307

Topic: Mass Spectrometry.

67. Select the structure of a compound C6H14 with a base peak at m/z 43. A) CH3CH2CH2CH2CH2CH3 B) (CH3CH2)2CHCH3 C) (CH3)3CCH2CH3 D) (CH3)2CHCH(CH3)2 E) None of these

Ans: D Topic: Mass Spectrometry.

68. The data below from the molecular ion region of the mass spectrum of a halogen-containing compound are consistent with the presence of what halogen(s) in the original compound? intensity M+

• 51.0 M+

• +2 100.0 M+

• +4 49.0

A) One Br B) One Cl C) One Br and one Cl D) Two Br E) Two Cl

Ans: D Topic: Mass Spectrometry.

69. A prominent (M+• -18) peak suggests that the compound might be a(n):

A) alkane B) alcohol C) ether D) ketone E) primary amine

Ans: B

Chapter 9

308

Topic: Structure Elucidation

70. An organic compound absorbs strongly in the IR at 1687 cm-1. Its 1H NMR spectrum consists of two signals, a singlet at 2.1 ppm and a multiplet centered at 7.1 ppm. Its mass spectrum shows significant peaks at m/z 120, m/z 105 and m/z 77. This information is consistent with which of the following structures?

III

IV VA) I B) II C) III D) IV E) V

Ans: A SHORT ANSWER QUESTIONS Topic: General

71. Which form of electromagnetic radiation possesses the least energy? Ans: radiofrequency radiation

Topic: General

72. “NMR” stands for _______________________. Ans: nuclear magnetic resonance

Topic: General; Signal Integration

73. When measuring the integral for a particular peak in the NMR spectrum, we are not interested in the peak height as much as in the ____________________. Ans: area under the peak

Chapter 9

309

Topic: General; Chemical Shift

74. A shielded proton will absorb at a higher frequency (this is the ________ end of the spectrum); and a deshielded proton will absorb at a lower frequency (the _____________ end of the spectrum). Ans: upfield; downfield

Topic: Reference Compound

75. What compound is used as the standard “zero” reference in both carbon and proton NMR? Ans: TMS or tetramethylsilane or (CH3)4 Si

Topic: General, Bond Rotation, Proton Exchange

76. Name two rapid processes that occur in organic molecules. Ans: Rotation about C-C single bonds; chemical exchange of protons attached to

electronegative atoms Topic: Molecular Ion

77. In electron impact mass spectrometry, a beam of high-energy electrons initially dislodges one electron from the compound being studied. This produces a positively charged ion called the ____________________. Ans: molecular ion

Topic: Nitrogen Rule

78. What is the nitrogen rule? Ans: If the molecular ion peak is even, the molecule must contain an even number of

nitrogen atoms (zero is an even number). If the molecular ion peak is odd, the molecule must contain an odd number of nitrogen atoms.)

Topic: Relative Abundance

79. What can be determined from the relative abundance of the M+• +1 peak?

Ans: An approximation for the number of carbon atoms in the molecule. Topic: Relative Abundance

80. What can be determined from the relative abundance of the M+• +2 peak?

Ans: The presence of a number of different elements, including S, Br, and Cl.

Chapter 9

310

Topic: Base Peak

81. In mass spectrometry, the most intense peak is assigned an intensity of 100%, and is referred to as the ______________. Ans: base peak

Topic: m/z Ratio

82. A mass spectrometer sorts ions on the basis of their _______________. Ans: mass to charge ratio

Topic: Structure Elucidation

83. Briefly explain how you might distinguish between the following substances by comparing their 1H-NMR spectra:

IIAns: The main difference would likely be in the chemical shift of the methine proton of

the isopropyl group. The methine proton in I is likely to be more deshielded, and produce a signal (septet) at about 3.5 ppm, while the analogous proton in II is likely to be found, also as a septet, at about 2.3 ppm.

I II

~3.5 ppm ~2.3 ppm

Chapter 9

311

Topic: Structure Elucidation

84. Briefly explain how you might distinguish between the following substances by comparing their 1H-NMR spectra:

OII

Ans: The main difference would likely be in the chemical shifts of the methine proton of the isopropyl group and the methylene proton closest to the ester function. The methine proton in I is likely to be more deshielded, and produce a signal (septet) at about 3.5 ppm, while the analogous proton in II is likely to be found, also as a septet, at about 2.3 ppm. By contrast, the methylene proton in II is likely to be more deshielded, and produce a signal (triplet) at about 3.4 ppm, while the analogous proton in II is likely to be found, also as a triplet, at about 2.2 ppm.

I II

~3.5 ppm(septet)

~2.3 ppm(septet)

~2.2 ppm(triplet)

~3.4 ppm(triplet)

Chapter 9

312

Topic: Structure Elucidation

85. Briefly explain how you might distinguish between the following substances by comparing their 1H-NMR spectra:

OII

Ans: The main difference would likely be in the chemical shifts of the methine proton of the isopropyl group and the methylene proton closest to the amide function. The methine proton in I is likely to be more deshielded, and produce a signal (septet) at about 3.5 ppm, while the analogous proton in II is likely to be found, also as a septet, at about 2.3 ppm. By contrast, the methylene proton in II is likely to be more deshielded, and produce a signal (triplet) at about 3.4 ppm, while the analogous proton in II is likely to be found, also as a triplet, at about 2.2 ppm.

O HN

I II

~3.2 ppm(septet)

~2.3 ppm(septet)

~2.2 ppm(triplet)

~3.1 ppm(triplet)

Chapter 9

313

Topic: Structure Elucidation 86.

An unknown compound, A, has the formula C7H14O. Elucidate the structure of A by scrutinizing its IR, 1H NMR and 13C NMR spectra, shown below.

Ans: O

4-Heptanone

Chapter 9

314

Topic: Structure Elucidation 87.

An unknown compound, C, has the formula C7H7Br. Elucidate the structure of C by scrutinizing its IR, 1H NMR and 13C NMR spectra, shown below.

Chapter 9

315

Ans:

Br 4-Bromotoluene

Chapter 9

316

Topic: Structure Elucidation

88. An unknown compound, E, has the formula C6H12O. Elucidate the structure of E by scrutinizing its IR, 1H NMR and 13C NMR spectra, shown below.

Ans: O

2-Hexanone

Chapter 9

317

Topic: Structure Elucidation

89. An unknown compound, F, has the formula C3H6O2. Elucidate the structure of F by scrutinizing its IR, 1H NMR and 13C NMR spectra, shown below.

Chapter 9

318

Ans:

Propanoic acid

Chapter 9

319

Topic: Structure Elucidation

90. An unknown compound, I, has the formula C3H7NO2. Elucidate the structure of I by scrutinizing its IR, 1H NMR and 13C NMR spectra, shown below.

Ans: NO2 1-Nitropropane

Chapter 9

320

Topic: Structure Elucidation

91. An unknown compound, L, has the formula C5H10O2. Elucidate the structure of L by scrutinizing its IR, 1H NMR and 13C NMR spectra, shown below.

Ans:

Methyl butyrate

Chapter 9

321

Topic: Structure Elucidation

92. An unknown compound, U, has the formula C6H4Cl2O. Elucidate the structure of U by scrutinizing its IR, 1H NMR and 13C NMR spectra, shown below.

Chapter 9

322

Ans: OH

Cl Cl

2,6-dichlorophenol

Chapter 9

323

Topic: Structure Elucidation

93. An unknown compound, V, has the formula C8H10O. Elucidate the structure of V by scrutinizing its IR, 1H NMR and 13C NMR spectra, shown below.

Chapter 9

324

Ans: OH

2,6-dimethylphenol

Chapter 9

325

Topic: Structure Elucidation

94. Examine the 1H NMR spectrum of 1-nitropropane, shown below. Assign the signals to the respective hydrogen atoms in the molecule.

Ans:

NO21.0 ppmtriplet

2.0 ppmsextet

4.3 ppmtriplet

Topic: 1H NMR

95. Predict the 1H NMR spectrum of 2-chloroethanal, CH2ClCHO.

Ans:

ClO>

4-5 ppmdoublet

9-10 ppmtriplet

Chapter 9

326

Topic: 1H NMR

96. Predict the number of signals in the 1H NMR spectrum of 2-methyl-2-pentanol. Ans: Five

1 2 4

Topic: 13C NMR, Structure Elucidation

97. Interpret the following 13C/DEPT spectrum of a compound C5H10Br2: elucidate the structure and assign all the 13C resonances.

Ans:

Br Br

32 ppm

27 ppm

33 ppm

Chapter 9

327

Topic: 1H NMR

98. Predict the 1H NMR spectrum of diethoxymethane, CH3CH2OCH2OCH2CH3.

Ans:

O O

>~4.9 ppmsinglet

~3.4 ppmquartet

~1.2 ppmtriplet

Chapter 10

328

MULTIPLE CHOICE QUESTIONS Topic: Delta H Calculations and Comparisons

1. The bond dissociation energies for the relevant bonds are given below each of the species involved in the following reaction. Calculate the overall ΔH° for the reaction. (CH3)3C-H + Cl-Cl (CH3)3C-Cl + H-Cl

ΔHo=400 kJ/mol ΔHo=243 kJ/mol ΔHo=349 kJ/mol ΔHo=432 kJ/mol

A) +243 kJ / mol B) -138 kJ / mol C) +138 kJ / mol D) -781 kJ / mol E) +781 kJ / mol

Ans: B Topic: Delta H Calculations and Comparisons

2. The bond dissociation energies for the relevant bonds are given below each of the species involved in the following reaction. Calculate the overall ΔH° for the reaction. CH3CH2CH2-H + Br-Br CH3CH2CH2-Br + H-Br

ΔHo=423 kJ/mol ΔHo=193 kJ/mol ΔHo=294 kJ/mol ΔHo=366 kJ/mol

A) +616 kJ / mol B) -101 kJ / mol C) -173 kJ / mol D) +57 kJ kJ / mol E) -44 kJ / mol

Ans: E

Chapter 10

329

Topic: Delta H Calculations and Comparisons

3. The bond dissociation energies for the relevant bonds are given below each of the species involved in the following reaction. Calculate the overall ΔH° for the reaction. CH3CH2-H + Cl-Cl CH3CH2-Cl + H-Cl

ΔHo=353 kJ/mol ΔHo=432 kJ/molΔHo=421 kJ/mol ΔHo=243 kJ/mol

A) -121 kJ / mol B) +121 kJ / mol C) +243 kJ / mol D) +664 kJ / mol E) -785 kJ / mol

Ans: A Topic: Delta H Calculations and Comparisons

4. The bond dissociation energies for the relevant bonds are given below each of the species involved in the following reaction. Calculate the overall ΔH° for the reaction. (CH3)2CH-H + F-F (CH3)2CH-F + H-F

ΔHo=413 kJ/mol ΔHo=159 kJ/mol ΔHo=439 kJ/mol ΔHo=570 kJ/mol

A) +437 kJ / mol B) -437 kJ / mol C) -411 kJ / mol D) +26 kJ / mol E) -1581 kJ / mol

Ans: B Topic: Delta H Calculations and Comparisons

5. Which of the reactions listed below would have a value of ΔH° equal to zero? A) H–H ⎯⎯⎯⎯→ 2H· B) H· + CH3–H ⎯⎯⎯⎯→ CH3–H + H· C) CH3· + CH3· ⎯⎯⎯⎯→ CH3–CH3 D) CH3· + CH3–H ⎯⎯⎯⎯→ CH3–H + CH3· E) Reactions (B) and (D)

Ans: E

Chapter 10

330

Topic: Delta H Calculations and Comparisons

6. Which of the reactions listed below would be exothermic? A) CH3–CH3 ⎯⎯⎯⎯→ 2CH3· B) CH3· + CH4 ⎯⎯⎯⎯→ CH4 + CH3· C) 2(CH3)2CH· ⎯⎯⎯⎯→ (CH3)2CH–CH(CH3)2 D) H· + (CH3)3CH ⎯⎯⎯⎯→ (CH3)3CH + H· E) None of the above

Ans: C Topic: Delta H Calculations and Comparisons

7. Which of the reactions listed below would be exothermic? A) H–H ⎯⎯⎯⎯→ 2H· B) H· + CH3–H ⎯⎯⎯⎯→ CH3–H + H· C) CH3· + CH3· ⎯⎯⎯⎯→ CH3–CH3 D) CH3· + CH3–H ⎯⎯⎯⎯→ CH3–H + CH3· E) All of the above

Ans: C Topic: Activation Energies

8. Which reaction would you expect to have the smallest energy of activation? ΔH°(kJ mol-1)

A) CH3· + CH3· ⎯⎯⎯⎯→ CH3CH3 -378 B) CH4 + F· ⎯⎯⎯⎯→ CH3· + HF -130 C) CH4 + I· ⎯⎯⎯⎯→ CH3· + HI +142 D) CH4 + Br· ⎯⎯⎯⎯→ CH3· + HBr +104 E) CH4 + Cl· ⎯⎯⎯⎯→ CH3· + HCl +8

Ans: A Topic: Activation Energies

9. Which of the following reactions would have an activation energy equal to zero? A) CH3–CH3 ⎯⎯⎯⎯→ 2CH3· B) H· + CH3CH3 ⎯⎯⎯⎯→ CH3CH3 + H· C) 2CH3CH2· ⎯⎯⎯⎯→ CH3CH2CH2CH3 D) CH3· + CH3CH3 ⎯⎯⎯⎯→ CH3CH3 + CH3· E) None of the above

Ans: C

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Topic: Activation Energies

10. Which of the following reactions would have the smallest energy of activation? A) CH4 + Br· ⎯⎯⎯⎯→ CH3· + HBr B) CH3CH3 + Br· ⎯⎯⎯⎯→ CH3CH2· + HBr C) CH3CHCH3

+CH3CHCH2

+ HBrBrCH3 CH3

D) CH3CHCH3

+CH3CCH3

+ HBrBrCH3 CH3

C CH2CH3

CH3

+ HBrC CH3CH3

CH3

+ Br

Ans: D Topic: Activation Energies

11. Which of the following reactions would have the smallest energy of activation? A) + Br + HBr.

B) + Br + HBr.

.C) + Br + HBr..

D) + Br + HBr..

E) + Br + HBr..

Ans: C Topic: Activation Energies

12. An example of a reaction having an Eact = 0 would be: A) Br· + Br–Br ⎯⎯⎯⎯→ Br–Br + Br· B) F· + CH4 ⎯⎯⎯⎯→ H–F + CH3· C) CH3· + CH3CH3 ⎯⎯⎯⎯→ CH4 + CH3CH2· D) Br· + H–Br ⎯⎯⎯⎯→ H–Br + Br· E) CH3· + CH3· ⎯⎯⎯⎯→ CH3–CH3

Ans: E

Chapter 10

332

Topic: Activation Energies

13. Which of the following reactions should have the smallest energy of activation? A) CH4 + Cl· ⎯⎯⎯⎯→ CH3· + HCl B) CH3CH3 + Cl· ⎯⎯⎯⎯→ CH3CH2· + HCl C) CH3CHCH3

+CH3CHCH2

+ HClClCH3 CH3

D) CH3CHCH3

+CH3CCH3

+ HClClCH3 CH3

C CH2CH3

CH3

+ HClC CH3CH3

CH3

+ Cl

Ans: D Topic: Activation Energies

14. Which reaction would you expect to have the largest energy of activation? ΔH° (kJ mol-1)

A) CH3· + CH3· ⎯⎯⎯⎯→ CH3CH3 -378 B) CH3· + Br· ⎯⎯⎯⎯→ CH3Br -130 C) CH4 + I· ⎯⎯⎯⎯→ CH3· + HI +142 D) CH4 + Br· ⎯⎯⎯⎯→ CH3· + HBr +104 E) CH4 + Cl· ⎯⎯⎯⎯→ CH3· + HCl +8

Ans: C Topic: Activation Energies

15. An example of a reaction having an Eact = 0 would be: A) Br· + Br–Br ⎯⎯⎯⎯→ Br–Br + Br· B) F· + CH4 ⎯⎯⎯⎯→ H–F + CH3· C) CH3· + Cl· ⎯⎯⎯⎯→ CH3Cl D) More than one of these E) None of these

Ans: C

Chapter 10

333

Topic: Activation Energies

16. Which of the following reactions would have an activation energy equal to zero? A) H–H ⎯⎯⎯⎯→ 2H· B) H· + CH3–H ⎯⎯⎯⎯→ CH3––H + H· C) CH3· + CH3· ⎯⎯⎯⎯→ CH3–CH3 D) CH3· + CH3–H ⎯⎯⎯⎯→ CH3–H + CH3· E) All of the above

Ans: C Topic: Activation Energies 1. Given the following bond dissociation energies:

ΔH° (kJ mol-1) CH3CH2–H 421 H–F 570 H–Cl 432 H–Br 366 H–I 298 predict which of the following reactions would have the highest energy of activation.

A) CH3CH3 + F· ⎯⎯⎯⎯→ CH3CH2· + HF B) CH3CH3 + Cl· ⎯⎯⎯⎯→ CH3CH2· + HCl C) CH3CH3 + Br· ⎯⎯⎯⎯→ CH3CH2· + HBr D) CH3CH3 + I· ⎯⎯⎯⎯→ CH3CH2· + HI E) ΔH° values are important, but not sufficient for this prediction Ans: D

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Topic: Activation Energies 18. Given the following bond dissociation energies:

ΔH°(kJ mol-1) CH3–H 440 H–F 570 H–Cl 432 H–Br 366 H–I 298 predict which of the following reactions would have the highest energy of activation.

A) CH4 + F· ⎯⎯⎯⎯→ CH3· + HF B) CH4 + Cl· ⎯⎯⎯⎯→ CH3· + HCl C) CH4 + Br· ⎯⎯⎯⎯→ CH3· + HBr D) CH4 + I· ⎯⎯⎯⎯→ CH3· + HI E) ΔH° values are important, but not sufficient for this prediction

Ans: D Topic: Activation Energies

19. For which of the following gas-phase reactions would the Eact be equal to ΔH°? A) Cl–Cl ⎯⎯⎯⎯→ 2Cl· B) 2 Cl· ⎯⎯⎯⎯→ Cl–Cl C) Cl· + CH4 ⎯⎯⎯⎯→ CH3· + H–Cl D) CH3· + CH3· ⎯⎯⎯⎯→ CH3–CH3 E) CH3· + Cl–Cl ⎯⎯⎯⎯→ CH3–Cl + Cl·

Ans: A Topic: Reaction Products (Isomers)

20. In the presence of light, ethane (1 mol) reacts with chlorine (1 mol) to form which product(s)?

A) CH2ClCHCl2 B) CH3CHCl2 C) CH3CH2Cl D) ClCH2CH2Cl E) All of these

Ans: E

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Topic: Reaction Products (Isomers)

21. How many different monochlorobutanes (including stereoisomers) are formed in the free radical chlorination of butane?

A) 1 B) 2 C) 3 D) 4 E) 5

Ans: C Topic: Reaction Products (Isomers)

22. The reaction of 2-methylbutane with chlorine would yield how many monochloro derivatives? (include stereoisomers)

A) 2 B) 3 C) 4 D) 5 E) 6

Ans: E Topic: Reaction Products (Isomers) 23. The reaction of 2,2-dimethylbutane with chlorine would yield how many monochloro

derivatives? (include stereoisomers) A) 1 B) 2 C) 3 D) 4 E) 5

Ans: D Topic: Reaction Products (Isomers)

24. The free radical chlorination of pentane produces this number of monochloro compounds, including stereoisomers.

A) 2 B) 3 C) 4 D) 5 E) 6

Ans: C

Chapter 10

336

Topic: Reaction Products (Isomers)

25. Free radical chlorination will produce but one monochloro derivative in the case of: A) Propane. B) Butane. C) Isobutane. D) Isopentane. E) Neopentane.

Ans: E Topic: Reaction Products (Isomers)

26. Free radical chlorination of hexane produces this number of monochloro derivatives (including stereoisomers):

A) 3 B) 4 C) 5 D) 7 E) 8

Ans: C Topic: Reaction Products (Isomers)

27. More than one monochloro compound can be obtained from the free radical chlorination of:

A) Cyclopentane B) Neopentane C) Isobutane D) Ethane E) Methane

Ans: C Topic: Reaction Products (Isomers)

28. What is the total number of trichloropropanes which can be produced by free radical chlorination of propane? Include all stereoisomers.

A) 4 B) 5 C) 6 D) 7 E) 8

Ans: C

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Topic: Reaction Products (Isomers)

29. If chlorocyclopentane were chlorinated to form all possible dichloro compounds and the product mixture subjected to precise fractional distillation, how many fractions would be obtained (ideally)?

A) 3 B) 4 C) 5 D) 7 E) 9

Ans: C Topic: Reaction Products (Isomers)

30. The free radical chlorination of (R)-2-chloropentane forms a mixture of dichloropentanes which includes:

A) three optically active compounds B) two achiral compounds. C) two meso compounds. D) one pair of diastereomers. E) one racemic mixture.

Ans: B Topic: Reaction Products (Isomers)

31. How many monochloro derivatives, including stereoisomers, can be formed in the chlorination of 1-bromobutane?

A) 4 B) 5 C) 6 D) 7 E) 8

Ans: D Topic: Reaction Products (Isomers)

32. The free radical chlorination of 3-chloropentane forms a mixture of dichloropentanes which, on precise fractional distillation, affords these fractions:

A) 4 fractions, none optically active B) 4 fractions, 2 optically active C) 7 fractions, 4 optically active D) 7 fractions, 6 optically active E) 7 fractions, all optically active

Ans: A

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Topic: Reaction Products (Isomers)

33. Consider the light-initiated chlorination of (S)-2-chlorobutane followed by careful fractional distillation (or separation by GLC) of all of the products with the formula C4H8Cl2. How many fractions (in total) would be obtained and how many of these fractions would be optically active?

A) Three fractions total; all optically active B) Four fractions total; three fractions optically active C) Five fractions total; all optically active D) Five fractions total; four fractions optically active E) Five fractions total; three fractions optically active

Ans: E Topic: Reaction Products

34. What is the product of the reaction

CH3CH2CH CH2 + CBr4peroxides

?A) CH3CH2CH=CHCBr3 B) CH3CH2CHCH2CBr3

C) CH3CH2CHCH2Br

CBr3

D) CH3CH2CH2CH2CBr3 E) No reaction occurs.

Ans: B

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Topic: Reaction Products

35. Select the structure of the major product formed in the following reaction.

I II III IV V

CH3

CH2Br CH3 Br CH3CH3BrBr

Br2

hν?

A) I B) II C) III D) IV E) V

Ans: B Topic: Reaction Products 36. What would be the major product of the following reaction?

I II III IV V

CH3

CH3Br

CH3

BrCH3

?HBr

peroxides

A) I B) II C) III D) IV E) V

Ans: A

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Topic: Reaction Products

37. In the presence of light at 25°C, isobutane (1 mol) and bromine (1 mol) yield which monobromo product(s)?

A) 2-Methyl-1-bromopropane (almost exclusively) B) 2-Methyl-2-bromopropane (almost exclusively) C) A mixture of 50% (A) and 50% (B) D) A mixture of 90% (A) and 10% (B) E) Butyl bromide

Ans: B Topic: Reaction Products

38. Which of these molecules is not expected to arise as a product of the high temperature chlorination of methane?

A) CCl4 B) HCCl3 C) CH2Cl2 D) CH3CH3 E) CH2=CH2

Ans: E Topic: Reaction Products 39. In a competition reaction, equimolar amounts of five alkanes compete for a deficiency

of chlorine at 300°C. The greatest amount of reaction would occur in the case of which of these alkanes?

A) Ethane B) Propane C) Butane D) Isobutane E) Pentane

Ans: D Topic: Reaction Products

40. Which of the following combinations of reactants can provide a demonstrable example of anti-Markovnikov addition?

A) CH2=CHCH3 + HCl + ROOR B) CH3CH=CH2 + H2O + Cl2 C) CH3CH=CHCH3 + HBr + ROOR D) CH3CH2CH=CH2 + HBr + ROOR E) CH3CH2CH=CH2 + Br2 + ROOR

Ans: D

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Topic: Reaction Products

41. 2-Methyl-2-butene reacts with HBr in the presence of peroxide to give (chiefly): A) (CH3)2CHCH2CH2Br B) (CH3)2CHCHCH3

C) (CH3)2CCH2CH3

BrCH2CHCH2CH3

CH3

(CH3)2CCHCH3

BrAns: B

Topic: Reaction Products

42. What product would result from the following reaction?

I II III IV V

Br Br HOO Br Br OOH

+ HBrperoxides ?

A) I B) II C) III D) IV E) V

Ans: A

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Topic: Synthesis

43. Which of the following would serve as the best synthesis of 2-bromohexane? A)

+ HBrperoxides

CH2 CHCH2CH2CH2CH3 heatB)

+ HBrheat

CH2 CHCH2CH2CH2CH3

C) + HBrCH3CH2 CHCH2CH2CH3

heat

D) peroxides

heat+ HBrCH3CH2 CHCH2CH2CH3

E) All of the above would be equally suitable. Ans: B

Topic: Synthesis

44. Which would be the best way to carry out the following synthesis? ?

(CH3)3COH (CH3)2CHCH2Br

A) (1) HA, heat; (2) HBr B) (1) HBr and peroxides; (2) Br2/CCl4 C) (1) HA, heat; (2) HBr and peroxides D) (1) Br2/CCl4; (2) HA, heat E) (1) HA, heat; (2) Br2/CCl4

Ans: C Topic: Reaction Products

45. What sequence of reactions could be used to prepare cis-1,2-cyclopentanediol from cyclopentane?

A) (1) Cl2, hν; (2) t-BuOK/t-BuOH; (3) OsO4; (4) NaHSO3/H2O B) (1) t-BuOK/t-BuOH; (2) Cl2, hν; (3) NaOH/H2O C) (1) Cl2, hν; (2) t-BuOK/t-BuOH; (3) H2O2 D) (1) NaOH/H2O; (2) Br2; (3) NaNH2(2eq.)/liq.NH3; (4) KMnO4, NaOH/H2O, 5°C E) (1) Cl2, hν; (2) t-BuOK/t-BuOH; (3) Hg(OAc)2, H2O (4) NaBH4, H3O+

Ans: A

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Topic: Mechanisms

46. Carbocations are NOT intermediates in which one of the following reactions? A)

+ HBrBr

B) + H2SO4

C) + BH3

HH2B

D) OSO3H+ H2SO4

E) Br+ HBr

R-O-O-R

Ans: E Topic: Mechanisms

47. A chain reaction is one that: A) involves a series of steps. B) involves two steps of equal activation energy. C) is one that can be initiated by light. D) involves a series of steps, each of which generates a reactive intermediate that brings

about the next step. E) involves free radicals that have an unusual stability and thereby cause a large quantum

yield. Ans: D

Topic: Mechanisms

48. Which of the following statements is true when used to compare the reaction of fluorine with 2-methylhexane and the reaction of bromine with 2-methylhexane?

A) Bromine is the less reactive and the less selective, giving 2-bromo-2-methyl hexane as one of several products.

B) Fluorine is the less reactive and the more selective, giving 2-fluoro-2-methyl hexane as the major product.

C) Fluorine is the more reactive and less selective, giving 2-fluoro-2-methyl hexane as one of several products.

D) Bromine is the more reactive and the more selective, giving 2-bromo-2-methyl hexane as the major product.

E) More than one of the above statements is true Ans: C

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Topic: Mechanisms

49. An alternate mechanism for the chlorination of methane is: Cl2 ⎯⎯⎯⎯→ 2Cl· Cl–Cl, ΔH° = 243 kJ mol-1

Cl· + CH4 ⎯⎯⎯⎯→ CH3Cl + H· CH3–H, ΔH° = 440 kJ mol-1

H· + Cl2 ⎯⎯⎯⎯→ HCl + Cl· CH3–Cl, ΔH° = 352 kJ mol-1

H–Cl, ΔH° = 432 kJ mol -1

This mechanism is unlikely because:

A) The overall ΔH° is highly endothermic. B) The probability factor is low. C) One of the chain propagating steps is non-productive. D) One of the chain propagating steps has a very high Eact. E) One of the chain propagating steps is highly exothermic.

Ans: D Topic: Mechanisms

50. Which statement(s) is(are) true about the reaction of bromine with isobutane? A) Bromine selectively abstracts the tertiary hydrogen. B) The transition state of the rate determining step is product-like. C) The major product formed from this reaction is 1-bromo-2-methylpropane. D) A) and B) E) A), B) and C)

Ans: D Topic: Mechanisms

51. For which reaction would the transition state be most product-like? A) CH4 + Br· ⎯⎯⎯⎯→ CH3· + HBr B) CH3CH3 + Br· ⎯⎯⎯⎯→ CH3CH2· + HBr C)

+CH3CHCH2

+ HBrBrCH3

CH3CHCH3

CH3

+CH3CCH3

+ HBrBrCH3

CH3CHCH3

CH3

+ CH3CCH2 + HBrBr

CH3

CH3CCH3

CH3

CH3 CH3

Ans: A

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Topic: Mechanisms

52. For which of the following reactions would the transition state most resemble the products? The following bond dissociation energies may be useful. (CH3)2CH–H CH3CH2CH2–H H–F (413 kJ mol-1) (423 kJ mol-1) (570 kJ mol-1) H–Cl H–Br (432 kJ mol-1) (366 kJ mol-1)

B) CH3CH2CH3 + F· ⎯⎯⎯⎯→ CH3CH2CH2· + HF C)

D) CH3CH2CH3 + Cl· ⎯⎯⎯⎯→ CH3CH2CH2· + HCl E) CH3CH2CH3 + Br· ⎯⎯⎯⎯→ CH3CH2CH2· + HBr

Ans: E Topic: Mechanisms

53. Which of the following gas-phase reactions is a possible chain-terminating step in the light-initiated chlorination of methane?

A) Cl–Cl ⎯⎯⎯⎯→ 2Cl· B) Cl· + CH4 ⎯⎯⎯⎯→ CH3· + H–Cl C) CH3· + CH3· ⎯⎯⎯⎯→ CH3–CH3 D) CH3· + Cl–Cl ⎯⎯⎯⎯→ CH3Cl + Cl· E) More than one of the above

Ans: C Topic: Mechanisms

54. The reaction of 1-butene with HBr in the presence of peroxides yields 1-bromobutane. The mechanism for the reaction involves:

A) attack on the alkene by a Br+ ion. B) attack on the alkene by a H+ ion. C) attack on the alkene by a bromine atom, Br·. D) attack on the alkene by a hydrogen atom, H·. E) isomerization of the 2-bromobutane produced initially.

Ans: C

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Topic: Mechanisms

55. The reaction of Cl2 with a methyl radical has a positive ΔH°. Which of these drawings is the best representation of the transition state of this reaction?

ClClδ - δ -

B) C

HClCl

C) C

HClClδ - δ -

D) C

HClCl +

E) C

Hδ - δ -

ClCl

Ans: E Topic: Free Radicals 56. The hybridization state of the carbon of a methyl radical is: A) sp B) sp2 C) sp3 D) sp4 E) p3 Ans: B Topic: Free Radicals

57. The p-orbital of a methyl radical carbon, CH3·, contains how many electrons? A) 1 B) 2 C) 3 D) 4 E) 0

Ans: A

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Topic: Free Radicals

58. Which of the following free radicals is the most stable? A)

CH3CHCH2CH3

CH2

CH3CHCH2CH2

CH3

CH2CHCH2CH3

CH3

CH3CHCHCH3

CH3

CH3CCH2CH3

CH3

Ans: E Topic: Free Radicals

59. Hydrogen atom abstraction from which position would yield the most stable free radical intermediate during the reaction of bromine with 2,2,3-trimethylpentane?

A) C1 B) C2 C) C3 D) C4 E) C5

Ans: C Topic: Free Radicals

60. Free radicals can be produced by: A) use of high temperatures. B) irradiation with light. C) reaction of a molecule with another free radical. D) both A) and B). E) all of A), B) and C).

Ans: E

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Topic: Free Radicals

61. The ΔH° value is expected to be least for which indicated C-H bond of isopentane? A) CH2CHCH2CH3

CH3

B) CH3CHCH2CH3

CH2 H

CH3CCH2CH3

CH3

CH3CHCHCH3

CH3

E) CH3CHCH2CH2

CH3

Ans: C Topic: Free Radicals

62. Which is true for a chain-terminating step? A) A new free radical is formed. B) The process is endothermic. C) Eact = 0. D) ΔH° is positive. E) A product is formed which is immune to further reaction.

Ans: C Topic: Free Radicals

63. At some temperatures, the relative reactivities of 3°, 2° and 1° alkane hydrogens in free radical chlorination are in the ratio of 5:3:1. Thus, monochlorination of isopentane should produce these percentages of 2-chloro-2-methylbutane (A), combined 1-chloro-2-methylbutane and 1-chloro-3-methylbutane (B), and 2-chloro-3-methylbutane (C):

A) 8% A, 75% B, 17% C B) 25% A, 45% B, 30% C C) 29% A, 44% B, 18% C D) 30% A, 35% B, 35% C E) 36% A, 43% B, 21% C

Ans: B

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Topic: Miscellaneous

64. According to the present explanation of the role of atmospheric chlorofluorocarbons in ozone depletion, it is this species which destroys, i.e., reacts irreversibly with, ozone.

A) F· B) Cl· C) O· D) ClO· E) FO·

Ans: B Topic: Miscellaneous

65. If propene polymerization is initiated by the use of diacyl peroxide, this is an intermediate species formed early in the process.

RCH2CHCH2CH

CH3 CH3

RCHCH2CHCH2

CH3 CH3

RCHCH2CH2CH

CH3 CH3

RCH2CHCHCH2

CH3

RCCH2CH

CH3

CH3CH3

Ans: A Topic: Miscellaneous

66. As the term "peroxide" is used in Chapter 10, it can refer to which structure(s)? A) ROOR B) ROOH C)

RCOOCR

O O

D) Answers A) and B) only E) Answers A), B) and C)

Ans: E

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Topic: Miscellaneous

67. When an alkane in which all hydrogen atoms are not equivalent is monosubstituted, use of this halogen produces a ratio of isomers which is essentially statistical, i.e., dependent only on the number of each type of hydrogen.

A) F2 B) Cl2 C) Br2 D) I2 E) All of the above

Ans: A Topic: Multistep Reactions

68. What is the final product, C, obtained via the following reaction sequence?

OH OH OHOHOH

I II III IV V

Br2hν

i) BH3, THF

ii) H2O2, OH−Bt-BuOK

t-BuOHheat

A) I B) II C) III D) IV E) V

Ans: A

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Topic: Multistep Reactions

69. What is the major product obtained from the following reaction sequence?

OH OH OHOHOH

I II III IV V

Br2

hνi) Hg(OAc)2, H2O, THF

ii) NaBH4, OH−Bt-BuOK

t-BuOHheat

A) I B) II C) III D) IV E) V

Ans: B Topic: Multistep Reactions

70. What is the major product obtained from the following reaction sequence?

SH SHSH

I II III IV V

Br2

hνHBrperoxidesBt-BuOK

t-BuOHheat

DNaSH

A) I B) II C) III D) IV E) V

Ans: A

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Topic: Multistep Reactions

71. What is the major product obtained from the following reaction sequence?

CN CN

CNI II III IV V

DBr2

hνHBrperoxides

NaCNBEtONaEtOHheat

A) I B) II C) III D) IV E) V

Ans: C Topic: Multistep Reactions

72. What is the major product obtained from the following reaction sequence?

I II III

IV V

HBrperoxides C

i) BH3, THF

ii) H2O2, OH−B

OH OH

t-BuOKt-BuOHheat

A) I B) II C) III D) IV E) V

Ans: E

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353

Topic: Multistep Reactions

73. What is the major product obtained from the following reaction sequence?

I II III IV V

Br2

hνi) O3ii) Zn, HOAc

OH OH

EtONaEtOHheat

A) I B) II C) III D) IV E) V

Ans: E SHORT ANSWER QUESTIONS Topic: General 74. Intermediates possessing unpaired electrons are called ______________.

Ans: radicals or free radicals Topic: General

75. A covalent bond breaking so that each of the resulting intermediates bears a single unpaired electron is an example of __________________ bond cleavage. Ans: homolytic

Topic: General

76. Bond formation is an ______________ process, and therefore ΔH° is ____________. Ans: exothermic; negative

Topic: General

77. Although alkyl radicals are uncharged, the carbon bearing the odd electron is electron ___________, and alkyl groups provide a __________________ effect. Ans: deficient; stabilizing

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Topic: General

78. The mechanism for a free-radical reaction consists of three types of steps. These are: _______________ Ans: initiation, propagation, termination – or chain-initiating, chain-propagating, chain-

terminating Topic: General

79. In a chain-initiating step, radicals are _____________. Ans: created or formed

Topic: General

80. In a chain-terminating step, radicals are ______________. Ans: used up or removed

Topic: General

81. In a chain-propagating step, one radical _______________. Ans: generates another

Topic: General

82. While the electrophilic addition of HBr to an alkene is ionic and follows Markovnikov's rule, if the reaction is done in the presence of peroxides it becomes a ___________ reaction and is ____________________ in regiochemistry. Ans: radical or free-radical; anti-Markovnikov

Topic: General

83. Macromolecules made up of many repeating subunits are called ____________. Ans: polymers

Topic: General

84. Two radicals that are very important in biological processes are ________________ and __________________. Ans: molecular oxygen; nitric oxide

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Topic: General

85. Chlorofluorocarbons, or freons, diffuse into the upper atmosphere. There, ultraviolet light initiates a radical chain reaction that has been shown to cause extreme damage to _______________. Ans: the ozone layer

Topic: General

86. Unsymmetrical alkenes give Markovnikov products through the most stable_______________ intermediates and anti-Markovnikov products through the most stable _______________ intermediates. Ans: Carbocation; free-radical

Topic: Reaction Products ( Isomers)

87. Draw bond-line formulas of all monochloro derivatives that might be formed when 2,3-dimethylbutane is allowed to react with Cl2 under UV irradiation. For each structure, indicate, with an asterisk, any stereocenters that might be present. Ans:

2,3-dimethylbutane

Cl2, hνCl

*Cl

monochloro derivatives Topic: Reaction Products ( Isomers)

88. Draw bond-line formulas of all monochloro derivatives that might be formed when 1,1-dimethylcyclobutane is allowed to react with Cl2 under UV irradiation. For each structure, indicate, with an asterisk, any stereocenters that might be present. Ans:

monochloro derivatives1,1-dimethylcyclobutane

Cl2, hνCl+ +

ClCl *

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356

Topic: Reaction Products ( Isomers)

89. Draw bond-line formulas of all monochloro derivatives that might be formed when 3-ethylhexane is allowed to react with Cl2 under UV irradiation. For each structure, indicate, with an asterisk, any stereocenters that might be present. Ans:

3-ethylhexane

Cl2 hν

monochloro derivatives

+Cl Cl

ClCl

* ** *

* ****

Topic: Structure Elucidation

90. Deduce the structure of a substance, C8H18, which gives only a single monochloro derivative upon reaction with Cl2 under UV irradiation. Ans:

C8H18

Cl2 hν

singlemonochloro derivative

Topic: Reaction Products ( Isomers)

91. Draw bond-line formulas of all dichloro derivatives that might be formed when 1-chloro-2,2,3,3,-tetramethylpentane is allowed to react with Cl2 under UV irradiation. For each structure, indicate, with an asterisk, any stereocenters that might be present. Ans:

1-chloro-2,2,3,3-tetramethylpentane

Cl2 hν

dichloro derivatives

Cl ClCl

ClCl

+ +

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357

Topic: Reaction Products ( Isomers)

92. Draw bond-line formulas of all monochloro derivatives that might be formed when 2,2,4-trimethylpentane is allowed to react with Cl2 under UV irradiation. For each structure, indicate, with an asterisk, any stereocenters that might be present. Ans:

2,2,4-trimethylpentane

Cl2 hν

monochloro derivatives

Cl +

Cl Cl

Topic: Multistep Reactions

93. Complete the following reaction sequence: indicate regiochemical/stereochemical details as relevant.

Methylcyclopentane

i) Br2, hν

ii) C2H5ONa/C2H5OH, heat

iii) BH3, THF

iv) H2O2, OH−

Ans: Br2

hν

Br C2H5ONaC2H5OHheat

BH3, THF

H3C H

BH2

H +

H3C H

BH2

H H2O2, OH−H3C H

H +

H3C H

Chapter 10

358

Topic: Multistep Reactions

94. Complete the following reaction sequence: indicate regiochemical/stereochemical details as relevant.

i) Br2, hνii) C2H5ONa/C2H5OH, heat iii) HBr, peroxidesiv) NaCN

Ans: CN

BrBr2

hν Br

C2H5ONaC2H5OHheat

HBr peroxides

NaCN

Topic: Multistep Reactions

95. Complete the following reaction sequence: indicate regiochemical/stereochemical details as relevant.

i) Br2, hνii) C2H5ONa/C2H5OH, heat iii) Ozonolysis ?1,1,2-trimethylcyclohexane

Ans: Br2

hνC2H5ONaC2H5OHheat

Ozonolysis OOBr

Topic: Multistep Synthesis

96. Suggest a reasonable strategy for the synthesis of 1-bromo-2-methylcyclohexane from methylcyclohexane Ans: Br2

hν BrC2H5ONaC2H5OHheat

HBr peroxides Br

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359

Topic: Mechanisms

97. Provide a reasonable mechanistic explanation for the formation of small amounts of 3,3,4,4-teramethylhexane during the free-radical bromination of 2-methylbutane. Ans: During the free radical bromination of 2-methylbutane, the most stable

intermediate is produced by abstraction of the tertiary hydrogen atom at C2. Two such radicals can couple together via a termination step to afford 3,3,4,4-teramethylhexane as a minor product.

Br2

hν

minor product

termination step: radical coupling Topic: Mechanisms

98. What product(s) might be obtained via chain-termination step(s) during the reaction of 2-methylpropene with HBr in presence of peroxides? Ans: The addition of HBr to 2-methylpropene takes place via the formation of the most

stable free radical intermediate, by addition of a bromine atom at C1. Two such radicals can couple together via a termination step to afford 1,4-dibromo-2,2,3,3-teramethylbutane as a minor product. Analogous coupling between this radical and a bromine radical leads to the formation of 1,2-dibromo-2-methylpropane as another minor product.

HBrperoxides Br most stable radical intermediate

Br Br BrBr

Br + Br BrBr

termination steps: radical coupling

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Topic: Reactivity / Selectivity

99. Briefly, but clearly, explain the following observation: While alkanes can be fluorinated, chlorinated and brominated easily, they do not easily undergo iodination. Ans: The energy of activation for the first propagation step in the free radical

mechanism for halogenation of alkanes determines the overall reactivity pattern for the various halogens. In contrast to the reaction with the other halogens, hydrogen atom abstraction from an alkane by an iodine atom has a very high energy of activation- since this is the first propagation step, the overall process is affected as well and iodination does not occur to any appreciable extent. I . + R-H H-I + R . Eact for this step very high: reaction very slow, further steps inhibited

Topic: Reactivity / Selectivity

100. Briefly, but clearly, explain the following observation: When 2-methylbutane reacts with Cl2/hν, the monochlorinated products consist of four constitutional isomers in significant yields. However, when the same alkane is allowed to react with Br2/ hν, there is only one major monobromination product. Ans: The final product distribution is a consequence of the relative ease of hydrogen

atom abstraction from primary, secondary and tertiary positions. Chlorine is highly reactive and therefore there is not much differentiation between the different kinds of hydrogen atoms- as a result, all the possible free radicals are formed, leading to the formation of all possible constitutional isomers. Bromine is less reactive and more selective than chlorine in its reaction with alkanes; this results in the selective abstraction of the tertiary hydrogen atom at C2, to give the most stable radical intermediate, a tertiary radical, leading to the selective formation of only one major monobromination product.

Br2

hν

Cl2, hν

ClCl

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361

MULTIPLE CHOICE QUESTIONS Topic: Nomenclature

1. What is the correct IUPAC name for the following compound? CH3

CH3CHOHCHCHCH(CH3)2

CH3A) 4-isopropyl-3,4-dimethyl-2-butanol B) 2,3,4-trimethyl-4-pentanol C) 1,1,2,3-tetramethyl-4-pentanol D) 3,4,5-trimethyl-2-hexanol E) 3,4,5,5-tetramethyl-2-pentanol

Ans: D Topic: Nomenclature

2. A correct IUPAC name for isobutyl alcohol is: A) 2-Methyl-1-propanol B) 2-Methyl-1-butanol C) 1-Methyl-1-propanol D) 1,1-Dimethyl-1-ethanol E) 3-Methyl-1-propanol

Ans: A Topic: Nomenclature

3. What is the correct IUPAC name for the following compound?

CH3CH2C=CCH2CH3

CH3

CH2CH2OH A) 3-methyl-4-ethyl-3-hexen-6-ol B) 4-ethyl-3-methyl-3,6-hexenol C) 3-ethyl-4-methyl-3-hexen-1-ol D) 3-methyl-4-(2-hydroxyethyl)-3-hexene E) 3-(2-hydroxyethyl)- 3-methyl-3-hexene

Ans: C

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362

Topic: Nomenclature

The correct IUPAC substitutive name for

CH3CCHCH

CH3

CH2

is: A) 4-Penten-2-methyl-2-ol B) 4-Methyl-1-penten-2-ol C) 2-Methyl-4-penten-2-ol D) 4-Methyl-1-penten-4-ol E) 4-Hydroxy-4-methyl-1-pentene

Ans: C Topic: Nomenclature

5. Which is a correct IUPAC name for CH3CH2OCH2CH2CH2OCH2CH3? A) 1,4-Dioxane B) Ethylene glycol diethyl ether C) 1,3-Diethoxypropane D) 1,2-Diethoxyethane E) 1,2-Diethoxymethane

Ans: C Topic: Nomenclature

The IUPAC name of compound

CH3CH2COH

CH2CH3

is: A) 1,1,1-Triethylmethanol B) 1,1-Diethyl-1-propanol C) 2-Ethyl-3-pentanol D) 3-Ethyl-3-pentanol E) tert-Heptanol

Ans: D

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363

Topic: Nomenclature

7. The correct IUPAC name for tert-butyl alcohol is: A) 1-Butanol B) 2-Methyl-1-propanol C) 2-Methyl-2-propanol D) 2-Butanol E) 1,1-Dimethyl-1-ethanol

Ans: C Topic: Nomenclature

8. Select the structure of benzyl methyl ether.

O CH3CH3

CH3O

CH3 O CH2

CHCH3

O CHCH3

CH3 CH2 O CH2 CH3

III

A) I B) II C) III D) IV E) V

Ans: C

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Topic: Nomenclature

is properly named: A) cis-1,2-Cyclopentanediol B) meso-1,2-Cyclopentanediol C) (1R,2R)-1,2-Cyclopentanediol D) (1R,2S)-1,2-Cyclopentanediol E) (1S,2S)-1,2-Cyclopentanediol

Ans: C Topic: Nomenclature

10. 2,2-Dimethyl-1-propanol has the common name: A) Isoamyl alcohol B) Isopentyl alcohol C) tert-Pentyl alcohol D) Neopentyl alcohol E) 2-Methylisobutyl alcohol

Ans: D Topic: Nomenclature

11. What is the most accurate name for the molecule represented by the following Fischer projection formula?

HOCH3

CH3

H3CH2C

A) sec-Butyl methyl ether B) Isobutyl methyl ether C) tert-Butyl methyl ether D) (R)-2-Methoxybutane E) (S)-2-Methoxybutane

Ans: E

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Topic: Nomenclature

12. A correct name for the following Fischer projection formula is:

C CH3C

CCH3

A) (R)-3-Pentyn-2-ol B) (S)-3-Pentyn-2-ol C) (R)-2-Pentyn-4-ol D) (S)-2-Pentyn-4-ol E) (S)-2-Hydroxy-3-pentyne

Ans: B Topic: Nomenclature

13. Which of these, though commonly used, is an incorrect name for CH3CHOHCH3? A) Isopropyl alcohol B) sec-Propyl alcohol C) 2-Propanol D) Isopropanol E) More than one of these.

Ans: D Topic: Nomenclature

14. Which of these, though commonly used, is an incorrect name for (CH3)3COH? A) tert-Butyl alcohol B) tert-Butanol C) 2-Methyl-2-propanol D) More than one is incorrect. E) Each is a correct name.

Ans: B Topic: Isomerism, Stereoisomers

15. Which of the following can be described as “optically active, primary alcohol”? A) CH3CH2CH2CH2CH2OH B) (CH3)2CHCH2CH2OH C) CH3CH2CH(CH3)CH2OH D) (CH3)2CHCHOHCH3 E) Two of the above

Ans: C

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Topic: Isomerism, Stereoisomers

16. What is the total number of pentyl alcohols, including stereoisomers? A) 7 B) 8 C) 9 D) 10 E) 11

Ans: E Topic: Isomerism, Stereoisomers

17. The number of primary alcohols corresponding to the formula C5H12O, counting stereoisomers separately, is:

A) 1 B) 2 C) 3 D) 4 E) 5

Ans: E Topic: Isomerism, Stereoisomers

18. The number of optically active pentyl alcohols (C5H12OH), i.e., the total number of individual enantiomers, is:

A) 0 B) 2 C) 3 D) 4 E) 6

Ans: E Topic: Alcohol Reactions

19. Which of the following reactions would serve as a synthesis of butyl bromide? A) CH3CH2CH2CH2OH + HBr reflux

B) CH3CH2CH2CH2OH + PBr3 ⎯⎯⎯⎯⎯→ C) CH3CH2CH2CH2OH + NaBr reflux

D) CH3CH2CH2CH2OH + Br2 ⎯⎯⎯⎯⎯→ E) Answers A) and B) only

Ans: E

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Topic: Ether Reactions

20. The product(s) of the following reaction

CH2CH2

CH2

CH3CH2OCH2CH3 CH3CH2CH2CH2OH and CH3CH2CH2CH2Br

BrCH2CH2CH2CH2OH and BrCH2CH2CH2CH2Br

CHBrCH2

CH2

excess HBr

heatis/are:

I II

III IV

A) I B) II C) III D) IV E) None of these

Ans: C

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Topic: Alcohol Synthesis

21. Which product(s) would you expect to obtain from the following sequence of reactions?

CH3

CH3 H3C CH2OHO

+enantiomer

I II III IV V

1. BH3-THF2. H2O2, NaOH

A) I B) II C) III D) IV E) V

Ans: C Topic: Alcohol Synthesis

22. Which would be the best way to carry out the following synthesis?

CH3CH2CHCH3

CH3CH2CH2CH2OH?

A) (1) HA, heat; (2) H3O+, H2O, heat B) (1) (CH3)3COK / (CH3)3COH; (2) BH3:THF, then H2O2, OH- C) (1) (CH3)3COK / (CH3)3COH; (2) H3O+, then H2O, heat D) (1) KOH, C2H5OH; (2) BH3:THF, then H2O2, OH- E) (1) KOH, C2H5OH; (2) HA, heat; (3) H3O+, H2O, heat

Ans: B

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Topic: Alcohol Synthesis

23. Select the structure of the major product formed from the following reaction.

CH3

CH3OH

CH3

CH2OH HO CH3CH3

I II III IV V

1. Hg(OOCCH3)2 THF, H2O

2. NaBH4, NaOH?

A) I B) II C) III D) IV E) V

Ans: D

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Topic: Alcohol Synthesis, Isotope Labeling

24. The hydroboration-oxidation procedure can be successfully employed for synthesis of deuterated derivatives, by using BD3 instead of BH3. What product would you expect from the following reaction?

CH3

DHOH CH3

DHH CH3

DBD2H CH3

OHDH CH3

BD2HD

1. (BD3)2

2. H2O2/NaOH?

+enantiomer

III

+enantiomer

VA) I B) II C) III D) IV E) V

Ans: A Topic: Ether Reactions, Isotope Labeling

25. Select the structure of the major product formed in the following reaction.

CH3CH

CH2 HA

H218O

A) CH3CH2CH218OH

B) CH3CHCH3

18OH

C) CH3CHCH2OH

18OH

D) CH3CH

CH2

18OH

E) CH3CHCH218OH

18OH

Ans: C

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Topic: Ether Reactions

26. What would be the major product of the following reaction

C6H5CH2OCH3 ?

Concd. HBr (xs)

heatA) C6H5Br + CH3OH B) C6H5CH2Br + CH3Br C) C6H5CH2OH + CH3Br D) C6H5CH2Br + CH3OH E) C6H5CH2CH2Br

Ans: B Topic: Ether Synthesis

27. Which is the best way to prepare 3-methoxypentane via the Williamson method? A) CH3OH + CH3CH2CHOHCH2CH3 + H2SO4, 140°C B) CH3OH + (CH3)2CHCH2CH2OH + H2SO4, 140°C C) CH3ONa + (CH3CH2)2CHBr D) CH3I + (CH3CH2)2CHONa E) CH3I + (CH3)2CHCH2CH2ONa

Ans: D Topic: Ether Synthesis

28. Which is the best method to prepare 2-ethoxy-5methylhexane? A) C2H5ONa + (CH3)2CHCH2CH2Br B) C2H5ONa + (CH3)2CHCH2CH2CH2CH2Br C) C2H5ONa + (CH3)2CHCH2CH2CHBrCH3 D) C2H5Br + (CH3)2CHCH2CH2CH(CH3)ONa E) C2H5OH + (CH3)2CHCH2CH2CHOHCH3 + H2SO4, 140°C

Ans: D Topic: Alcohol Reactions

29. Which of the following could be used to synthesize 2-bromobutane? A) CH3CH2C=CH2 + Br2 (aq) ⎯⎯⎯⎯→ B) CH3CH2CΗΟΗCH3 + HBr ⎯⎯⎯⎯→ C) CH3CH2C≡CH + HBr ⎯⎯⎯⎯→ D) CH3CH2C≡CH + Br2 ⎯⎯⎯⎯→ E) More than one of the above

Ans: B

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Topic: Alcohol Reactions

30. Which of the following could not be used to synthesize 2-bromopentane efficiently? A) 1-Pentene + HBr B) 2-Pentene + HBr C) 2-Pentanol + HBr D) 2-Pentanol + PBr3 E) All of the above would afford good yields of 2-bromopentane

Ans: B Topic: Alcohol Reactions

31. Which of the following could be used to synthesize 1-bromobutane efficiently? A) CH3CH2CH=CH2 + HBr ⎯⎯⎯⎯→ B) CH3CH2CH2CH2OH + PBr3 ⎯⎯⎯⎯→ C) CH3CH2CH2CH2OH + HBr ⎯⎯⎯⎯→ D) CH3CH2CH2CH2OH + Br2 ⎯⎯⎯⎯→ E) More than one of these

Ans: E Topic: Alcohol Synthesis

32. Which of the following would be a reasonable synthesis of 2-butanol? A)

1-ButeneH3O+, heat

B) 1-Butene

2. H2O2, NaOH

1. BH3-THF

C) 1-Butene

2. NaBH4, NaOH

1. Hg(OAc)2, THF, H2O

D) More than one of these E) None of these

Ans: D

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Topic: Epoxide Reactions

33. What would be the final product?

H3CC CH2

CH3RCOOH

product final productCH3OH, HA

A) (CH3)2CHCH2OCH3 B) (CH3)2CCH3

OCH3

C) (CH3)2CCH2OH

OCH3

D) (CH3)2CCH2OCH3

E) (CH3)2CCH2OCH3

OCH3

Ans: C Topic: Alcohol Synthesis

34. Which of the following would be a reasonable synthesis of CH3CH2CH2CH2OH? A)

1-ButeneH3O+, heat

B) 1-Butene

2. H2O2, NaOH

1. BH3-THF

C) 1-Butene

2. NaBH4, NaOH

1. Hg(OAc)2, THF, H2O

D) More than one of these E) None of these

Ans: B Topic: Alcohol Synthesis

35. Which would be the best method for converting 3,3-dimethyl-1-pentene into 3,3-dimethyl-2-pentanol?

A) H3O+, heat B) BH3:THF; then H2O2, OH- C) concd. H2SO4; then H2O, heat D) Hg(OAc)2/THF-H2O; then NaBH4,OH- E) HBr; then NaOH/H2O

Ans: D

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Topic: Alcohol Reactions

36. trans-3-Methylcyclopentanol is treated with CH3SO2Cl in the presence of base. The product of this reaction is then heated with KI in methanol. What is the final product?

A) trans-1-Iodo-3-methylcyclopentane B) cis-1-Iodo-3-methylcyclopentane C) 1-Methylcyclopentene D) 2-Methylcyclopentene E) 3-Methylcyclopentene

Ans: B Topic: Ether Synthesis

37. Which method would provide the best synthesis of ethyl isopropyl ether? A) (CH3)2CHONa + CH3CH2Br ⎯⎯⎯⎯⎯→ B) CH3CH2ONa + (CH3)2CHBr ⎯⎯⎯⎯⎯→ C)

CH3CH2OH + (CH3)2CHOHH2SO4, 140 oC

D) CH3CH2OH + (CH3)2CHOH

H2SO4, 180 oC

E) CH3CH2ONa + (CH3)2CHOH ⎯⎯⎯⎯⎯→ Ans: A

Topic: Alcohol Reactions

38. Which of the following could be used to synthesize 1-bromopentane? A) CH3CH2CH2CH=CH2 + HBr ⎯⎯⎯⎯→ B) CH3CH2CH2CH2CH2OH + PBr3 ⎯⎯⎯⎯→ C) CH3CH2CH2CH2CH2OH + NaBr ⎯⎯⎯⎯→ D) CH3CH2CH2CH2CH2OH + Br2 ⎯⎯⎯⎯→ E) CH3CH2CH2CH=CH2 + Br2 ⎯⎯⎯⎯→

Ans: B

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Topic: Epoxide Reactions

39. Which compound (or compounds) would be produced when trans-2-butene is treated first with a peroxy acid to form an epoxide, and then the epoxide is subjected to acid-catalyzed hydrolysis?

CH3HO

H CH3

HHO

HO CH3

CH3

OHH

H3C H

CH3

IIIA) An equimolar mixture of I and II B) An equimolar mixture of II and III C) I alone D) II alone E) III alone

Ans: E Topic: Ether Reactions

40. Heating 2-ethoxyhexane with excess concentrated HBr would produce: A) CH3CH2OCH2CH2CH2CH2CH2CH2Br B) BrCH2CH2OCH2CH2CH2CH2CH2CH3 C) CH3CH2OH and CH3CH2CH2CH2CHBrCH3 D) CH3CH2Br and CH3CH2CHOHCH2CH2CH3 E) CH3CH2Br and CH3CH2CH2CH2CHBrCH3

Ans: E Topic: Ether Synthesis

41. Which is the best method for the synthesis of tert-butyl methyl ether? A) CH3ONa + (CH3)3CBr ⎯⎯⎯⎯→ B) (CH3)3CONa + CH3I ⎯⎯⎯⎯→ C) CH3OH + (CH3)3COH + H2SO4 at 140° C ⎯⎯⎯⎯→ D) (CH3)3CONa + CH3OCH3 ⎯⎯⎯⎯→ E) CH3ONa + (CH3)3COH ⎯⎯⎯⎯→

Ans: B

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Topic: Alcohol Reactions

42. What would be the major product of the following reaction?

CH3

OSO2I

CH3

CH3SO2Cl

basemesylate

NaI

ethanol?

I II III IV

A) I B) II C) III D) IV E) An equimolar mixture of I and II

Ans: B Topic: Alcohol Reactions

43. cis-3-Methylcyclopentanol is treated with CH3SO2Cl in the presence of a base. The product of the reaction then is allowed to react with KI in methanol. What is the final product?

A) trans-1-Iodo-3-methylcyclopentane B) cis-1-Iodo-3-methylcyclopentane C) 1-Methylcyclopentene D) 2-Methylcyclopentene E) 3-Methylcyclopentene

Ans: A

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Topic: Alcohol Reactions

44. The major product of the following reaction would be:

CH3SO2Cl

baseProduct ?

I II III

C2H5

H OHCH3

CH3CO2-

C2H5

H3CCO2 HCH3

C2H5

H O2CCH3

CH3

C2H5

H3CCO2 OSO2CH3

CH3

A) I B) II C) III D) Equal amounts of I and II E) None of these

Ans: A

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Topic: Alcohol Synthesis

45. Which would be the major product of the reaction shown?

CH2CH3

CH2CH3OH

CH2CH3H

CH2CH2OHH

CH2CH3H

CH2CH3

2. NaBH4, NaOH

1. Hg(OAc)2, THF, H2O?

I II III IV V

A) I B) II C) III D) IV E) V

Ans: B Topic: Alcohol Reactions

46. Which reagent(s) would transform propyl alcohol into propyl bromide? A) Concd. HBr and heat B) PBr3 C) NaBr/H2O and heat D) More than one of these E) All of these

Ans: D

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Topic: Epoxide Reactions

47. Epoxidation followed by reaction with aqueous base converts cyclopentene into which of these?

I II III IV

A) I B) II C) III D) IV E) Equal amounts of III and IV

Ans: E Topic: Ether Synthesis

48. When 3-methyl-2-pentene is treated with mercuric acetate, Hg(O2CCH3)2, in a THF-ethanol mixture and the resulting product reacted with NaBH4 in basic solution, the principal product formed is which of these?

A) 3-methyl-3-pentanol B) 3-ethoxy-3-methylpentane C) 3-methyl-2-pentanol D) 2-ethoxy-3-methylpentane E) 1-ethoxy-3-methylpentane

Ans: B Topic: Alcohol Synthesis

49. Anti-Markovnikov hydration of the carbon-carbon double bond occurs when an alkene reacts with:

A) BH3:THF; then H2O2/OH- B) BH3:THF; then CH3COOH C) Hg(OAc)2, THF, H2O; then NaBH4, OH- D) Hg(OAc)2, THF, CH3OH; then NaBH4, OH- E) Hg(OAc)2, THF, H2O; then BH3:THF

Ans: A

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Topic: Alcohol Reactions

50.

The conversion of

CH CH3CH

H3C

CH3

to CH CH3CH

H3C

CH3

is best achieved through use of which of these reagents in a low temperature reaction?

A) Concd. HBr B) Br2 C) NaBr, H2SO4 D) PBr3 E) HBr, peroxide

Ans: D Topic: Alcohol Reactions

51. The conversion of 3-methyl-1-octanol to 1-chloro-3-methyloctane is best achieved through use of which of these reagents?

A) Concd. HCl B) SO2Cl2 C) NaCl, H2SO4 D) PCl3 E) SOCl2

Ans: D Topic: Alcohol Reactions

52. What is the product of the reaction of propyl alcohol with (CH3)3SiCl in the presence of a tertiary amine?

A) CH3CH2CH2Si(CH3)3 B) (CH3)2CHSi(CH3)3 C) CH3CH2CH2OSi(CH3)3 D) (CH3)2CHOSi(CH3)3 E) (CH3CH2CH2)3SiOH

Ans: C

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Topic: Alcohol Synthesis

53. What is the major product of the reaction:

i) BH3, THFii) H2O2,NaOH

CH3

OH OH

CH3

I II III IV

CH3OH

+enantiomer

A) I B) II C) III D) IV E) Both III and IV

Ans: D Topic: Alcohol Synthesis

54. What is the major product of the reaction when (R)-3-methylcyclohexene is subjected to the hydroboration-oxidation sequence?

A) (1R,2R)-2-methylcyclohexanol + (1S,2R)-2-methylcyclohexanol B) (1S,2R)-2-methylcyclohexanol + (1S,2S)-2-methylcyclohexanol C) (1R,3R)-3-methylcyclohexanol + (1S,3R)-3-methylcyclohexanol D) (1S,3R)-3-methylcyclohexanol (1S,3S)-3-methylcyclohexanol E) Two of the above

Ans: E

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Topic: Alcohol Synthesis

55. Oxymercuration-demercuration of 3-methylcyclopentene produces this/these product(s):

I II III IV

HO CH3CH2OH CH3 CH3

A) I B) II C) III D) IV E) Both III and IV

Ans: E

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Topic: Alcohol Reactions

56.

Methanesulfonic acid,

OH,

CH3

is treated, in turn, with PCl5 and (R)-2-butanol. Which of the following Fischer formulas is a stereochemically correct representation of the final product?

I II III

IV V

CH3 C

CH3

CH2

CH3

CH3 C

CH3

CH2

CH3

CH3 C

CH2

CH3

CH3 C

CH2

CH3

CH3 C

CH3

CH2

CH3

A) I B) II C) III D) IV E) V

Ans: A

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Topic: Epoxide Reactions

57. cis-3-Hexene is treated with magnesium monoperoxyphthalate and the product is then subjected to acid-catalyzed hydrolysis. What is the final product?

CH2CH3

HHOHH

I II

CH2CH3

HHHHO

CH2CH3

OHHHHO

III IV

CH2CH3

HHOOHH

CH2CH3

OHHOHH

A) equal amounts I and II B) equal amounts I, II and V C) equal amounts III, IV and V D) equal amounts, III and IV E) Only V

Ans: D Topic: Chemical Tests

58. Which of the following reagents might serve as the basis for a simple chemical test that would distinguish between pure 1-butene and CH3CH2CH2CH2OH?

A) Bromine in carbon tetrachloride B) Dilute aqueous potassium permanganate C) Chromic oxide in aqueous sulfuric acid D) All of these E) None of these

Ans: D Topic: Chemical Tests

59. Which of the reagents listed below would serve as the basis for a simple chemical test to distinguish between

Oand ?

A) AgNO3 in alcohol B) NaOH in H2O C) Br2 in CCl4 D) Cold concd. H2SO4 E) KMnO4 in H2O

Ans: D

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Topic: Chemical Tests

60. Which of the reagents listed below would serve as the basis for a simple chemical test to distinguish between

Oand

Br?

A) AgNO3 in C2H5OH B) Dilute HCl C) Br2 in CCl4 D) NaOH in H2O E) KMnO4 in H2O

Ans: A Topic: Physical Properties, Comparison

61. Which of the compounds listed below would you expect to have the highest boiling point? (They all have approximately the same molecular weight.)

A) CH3CH2CH2CH2CH3 B) CH3CH2CH2CH2OH C) CH3CH2CH2OCH3 D) CH3CH2CH2Cl E) CH3CH2OCH2CH3

Ans: B Topic: Physical Properties, Comparison

62. Which compound would have the highest boiling point? A) CH3CH2CH2CH3 B) CH3CH2OCH3 C) CH3CH2CH2OH D) (CH3)2CHOH E) HOCH2CH2OH

Ans: E Topic: Physical Properties, Comparison

63. Which compound would have the lowest solubility in water? A) Diethyl ether B) Methyl propyl ether C) 1-Butanol D) 2-Butanol E) Pentane

Ans: E

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Topic: Physical Properties, Comparison

64. Which compound would have the lowest boiling point?

I II III IV V

OOH

OH CH2OHOH

A) I B) II C) III D) IV E) V

Ans: A Topic: Physical Properties, Comparison

65.

Which compound would have the highest boiling point?

I II III

IV V

O O O O

A) I B) II C) III D) IV E) V

Ans: E Topic: Alcohol Reaction Rates

66. Which of the alcohols listed below would you expect to react most rapidly with HBr? A) CH3CH2CH2CH2CH2CH2OH B) (CH3CH2)2CH2CH2OH C) (CH3CH2)2CHOHCH3 D) CH3CH2CH2CH2CH2OH E) (CH3CH2)2C(CH3)OH

Ans: E

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Topic: Alcohol Reaction Rates

67. Which alcohol would undergo acid-catalyzed dehydration most rapidly? A) 3,3-dimethyl-1-butanol B) 2,2-dimethyl-1-butanol C) 3,3-dimethyl-2-butanol D) 2-methyl-2-butanol E) All would undergo dehydration equally rapidly.

Ans: D Topic: Ether Reaction Rates

68. Which of these ethers is most resistant to peroxide formation on exposure to atmospheric oxygen?

A) CH3OCH2CH3 B) CH3CH2OCH2CH3 C) (CH3)2CHOCH(CH3)2 D) (CH3)2CHOCH2CH3 E) CH3OC(CH3)3

Ans: E Topic: Ether Reaction Rates

69. Which of these ethers is least likely to undergo significant cleavage by hot aqueous H2SO4 ?

I II III

IV V

CH3OCH3 CH3OCH(CH3)2 (CH3)2CHOCH(CH3)2

(CH3)3COC(CH3)3 O

A) I B) II C) III D) IV E) V

Ans: A

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Topic: Alcohol Reaction Rates

70. Which of these alkyl halide syntheses is predicted to occur at the greatest rate? A) CH3CH2CH2CH2OH + HI ⎯⎯⎯⎯→ B) (CH3)2CHCH2OH + HBr ⎯⎯⎯⎯→ C) CH3CHOHCH2CH3 + HCl ⎯⎯⎯⎯→ D) CH3CHOHCH2CH3 + HBr ⎯⎯⎯⎯→ E) (CH3)3COH + HI ⎯⎯⎯⎯→

Ans: E Topic: Reaction Mechanisms

71. The following reaction,

CH3CH2CH2CH2OH CH3CH2CH2CH2Br + H2O

HBr

heat

is probably: A) An SN1-type reaction involving the protonated alcohol as the substrate. B) An SN2-type reaction involving the protonated alcohol as the substrate. C) An E1-type reaction involving the protonated alcohol as the substrate. D) An E2-type reaction involving the protonated alcohol as the substrate. E) An epoxidation reaction.

Ans: B Topic: Reaction Mechanisms

72. The reaction between 1-pentanol and HBr to yield 1-bromopentanol is probably:

A) an SN1-type reaction involving the protonated alcohol as the substrate. B) an SN2-type reaction involving the protonated alcohol as the substrate. C) an E1-type reaction involving the protonated alcohol as the substrate. D) an E2-type reaction involving the protonated alcohol as the substrate. E) an epoxidation reaction.

Ans: B Topic: Reaction Mechanisms

73. The reaction between 2-methyl-2-pentanol and HBr to yield 2-bromo-2-methylpentane is probably:

Ans: A

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389

Topic: Reaction Mechanisms

74. The reaction between 2-methyl-2-pentanol and HBr to yield 2-methyl-2-pentene is probably:

Ans: C Topic: Reaction Mechanisms

75. The reaction between 4-methyl-1-pentanol and HBr to yield 4-methyl-1-pentene is probably:

Ans: D Topic: Reaction Mechanisms

76. Which statement is true concerning the formation of alcohols by the hydroboration-oxidation sequence?

A) Overall, the process results in syn addition and anti-Markovnikov orientation. B) Overall, the process results in anti addition and anti-Markovnikov orientation. C) Overall, the process results in syn addition and Markovnikov orientation. D) Overall, the process results in anti addition and Markovnikov orientation. E) The stereochemistry and orientation are unpredictable.

Ans: A

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390

Topic: Reaction Mechanisms

77. What is the electrophilic species involved in the initial step of the reaction below?

OHHgOAc

Hg(OAc)2

THF, H2OA) +OH B) +HgOAc C) H3O+ D) THF E) the THF/H2O complex

Ans: B Topic: Reaction Mechanisms

78. The following reaction,

2 CH3CH2CH2CH2OH (CH3CH2CH2CH2)2O + H2O

H2SO4

heat

is probably: A) an SN1-type reaction involving the protonated alcohol as the substrate. B) an SN2-type reaction involving the protonated alcohol as the substrate. C) an E1-type reaction involving the protonated alcohol as the substrate. D) an E2-type reaction involving the protonated alcohol as the substrate. E) an epoxidation reaction.

Ans: B Topic: Stereoisomerism

79. What is the relationship between alcohols I and II?

CH3OH

CH3H

I II

They are: A) different conformations of the same compound. B) constitutional isomers. C) enantiomers. D) diastereomers. E) identical.

Ans: D

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Topic: Stereoisomerism

80. What is the relationship between alcohols I and II?

CH3OH

CH3

I II

They are: A) different conformations of the same compound. B) constitutional isomers. C) enantiomers. D) diastereomers. E) identical.

Ans: C Topic: Ether Reactivity

81. Which of the following statements is NOT true of ethers? A) Ethers are generally unreactive molecules toward reagents other than strong acids. B) Ethers generally have lower boiling points than alcohols of a corresponding molecular

weight. C) Ethers generally have much lower water solubilities than alcohols with a corresponding

molecular weight. D) Ethers can generally be cleaved by heating them with strong acids. E) Ethers form peroxides when allowed to stand in the presence of oxygen.

Ans: C

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Topic: General

82. Which compound is a tosylate?

CH3 S O

CH3 Br S O

CH2 CH3 S O

CH3

CH3 S CH3

CH3 S

CH3

I II III

IV VA) I B) II C) III D) IV E) V

Ans: A Topic: General

83. The major industrial process in use today for the production of methanol is the: A) hydration of ethyne. B) distillation of wood. C) hydrogenation of carbon dioxide. D) reduction of methanal. E) catalytic reduction of carbon monoxide.

Ans: E Topic: General

84. Today, most industrial ethanol is made in the U.S. by the: A) fermentation of grain. B) hydrolysis of ethyl bromide. C) hydration of ethylene. D) reduction of acetaldehyde. E) hydration of acetylene.

Ans: C

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Topic: Ether Reactivity

85. Long-term storage of ethers can be dangerous, because most ethers react slowly with oxygen by a radical process called __________________. This process forms peroxides and hydroperoxides which are dangerously _______________. Ans: autooxidation, explosive

Topic: General, Alcohol Synthesis

86. We have learned three different methods to convert alkenes into alcohols. a. The method that takes place with Markovnikov regioselectivity but is prone to rearrangement is ________________. b. The method that takes place with Markovnikov regioselectivity and does not lead to rearrangement is _____________. c. The method that takes place with anti-Markovnikov regioselectivity and syn stereoselectivity is _______________. Ans: a. acid-catalyzed hydration; b. oxymercuration-demercuration; c. hydroboration-

oxidation Topic: General, Alcohol Reactions

87. Reactions of alcohols can be broadly categorized into three types. a. Those that utilize the hydroxyl oxygen as a ____________. b. Those that utilize the hydroxyl proton as an _________. c. Those that convert the hydroxyl group into a _____________. Ans: a nucleophile or base; b. acid; c. leaving group

Topic: General

88. Stereochemically speaking, conversion of an alcohol into a tosylate occurs with _____________ of configuration. Ans: retention

Topic: General

89. When an alcohol in which the OH is attached to a stereogenic carbon reacts with thionyl chloride (SOCl2) in the presence of a 3° amine, the resulting alkyl chloride is produced with _____________ of configuration. Ans: inversion

Topic: General

90. The SN2 reaction between an alkoxide and an alkyl halide is commonly referred to as the _________________ synthesis. Ans: Williamson

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Topic: General

91. Three-membered rings containing oxygen are called _______________ or ______________. Ans: oxiranes; epoxides

Topic: General

92. The development of a procedure called __________________ has made the use of nonpolar solvents possible in reactions involving polar reagents. Ans: phase transfer catalysis

Topic: General

93. The relationship between a crown ether and the ion it transports is known as the ____________________ relationship. Ans: host-guest

Topic: General

94. A compound or ion that prefers a nonpolar environment to an aqueous one is said to be ______________. Ans: lipophilic

Topic: Isomerism

95. Draw structures for all possible ethers having the formula C4H10O Ans:

C4H10O: ethers

O OO

Topic: Ether Synthesis

96. Which is the most efficient way to prepare isopropyl methyl ether via the Williamson method? Ans: CH3I + (CH3)2CHONa

Topic: Ether Synthesis

97. Which is the best method to prepare ethoxycyclopentane via the Williamson method? Ans: ONa I

O+

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Topic: Alcohol Synthesis

98. Draw the structures of all the products formed when (3R)-3-methylcyclopentene is subjected to the hydroboration-oxidation sequence. Ans: The alkene is symmetrically substituted: thus, Markovnikov rule does not apply.

Hence, all four products shown below are likely to be formed in roughly equal proportions.

H3C H

(3R)-3-methylcyclopentene

hydroboration-oxidation

H3C H H3C H H3C H H3C HOH OH

OH OH+ + +

Topic: Ether Synthesis

99. Provide a reasonable synthetic strategy for the synthesis of trans-1,2-cyclohexanediol from bromocyclohexane Ans: CH3ONa

CH3OHheat

Br MMPPO H3O+ OH

OH +enantiomer

Topic: Nomenclature

100. Give the correct IUPAC name corresponding to the following structure:

OH Ans: 6-cyclohexyl-2,7-dimethyl-3-octanol

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Topic: Nomenclature

101. Give the correct IUPAC name corresponding to the following structure:

Ans: (R)-3-ethyl-2-methyl-3-hexanol

Topic: Nomenclature

102. Give the correct IUPAC name corresponding to the following structure:

O O Ans: 1,3-diethoxyhexane

Topic: Nomenclature

103. Give the correct IUPAC name corresponding to the following structure:

CH3

Br H

Ans: (1R,2R)-2-bromo-1-methylcyclopentanol

Topic: Multistep Synthetic Strategy

104. Provide a reasonable synthetic strategy for the synthesis of a racemic mixture of (1R,2R) and (1S,2S)-2-bromo-1-methylcyclopentanol from methylcyclohexane. Ans:

CH3

Br H

CH3

BrBr2

hνCH3ONaCH3OHheat

CH3

Br H

Br2, H2O

2-bromo-1-methylcyclopentanol(1R,2R) (1S,2S)

CH3CH3

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Topic: Multistep Reactions

105. Complete the following reaction sequence, giving structural details of all key intermediates:

i) Li, NH3

ii) KMnO4 ,OH−, H2O

iii) H3O+

Ans: LiNH3

i) KMnO4 ,OH−, H2O

ii) H3O+

2S,3R 2R,3S Topic: Multistep Reactions

106. Complete the following reaction sequence, giving structural details of all key intermediates:

i) H2, Lindlar catalyst

ii) KMnO4 ,OH−, H2O

iii) H3O+

Ans: i) KMnO4 ,OH−, H2O

ii) H3O+

meso

H2 Lindlar catalyst

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Topic: Multistep Reactions

107. Complete the following reaction sequence, giving structural details of all key intermediates:

i) Li, NH3

ii) MMPP

iii) H3O+, H2O

Ans: LiNH3

2S, 3S 2R, 3R

i) MMPP

ii) H3O+, H2O

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MULTIPLE CHOICE QUESTIONS Topic: General Carbonyl Information

1. Which of the following resonance structures is not a significant contributor to the hybrid for the carbonyl group?

C O C O C O

I II IIIA) I B) II C) III D) Neither II nor III is important. E) All are significant contributors.

Ans: B Topic: General Carbonyl Information

2. When nucleophilic addition to a carbonyl group occurs, the carbon attacked undergoes this hybridization change:

A) sp2 ⎯⎯⎯⎯→ sp3 B) sp ⎯⎯⎯⎯→ sp2 C) sp ⎯⎯⎯⎯→ sp3 D) sp3 ⎯⎯⎯⎯→ sp2 E) sp2 ⎯⎯⎯⎯→ sp

Ans: A Topic: Functional Group Tests

3. Which reagent(s) will distinguish between cyclopentanol and cyclopentane? A) Br2/CCl4 B) KMnO4 (cold) C) CrO3/aqueous H2SO4 D) NaOH (aq) E) A) and B)

Ans: C

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Topic: Functional Group Tests

4. Which reagent(s) will distinguish between 2-methylcyclopentanol and 1-methylcyclopentanol?

A) Br2/CCl4 B) KMnO4 C) CrO3/aqueous H2SO4 D) NaOH (aq) E) B) and C)

Ans: E Topic: Functional Group Tests

5. Which of the following reagents might serve as the basis for a simple chemical test that would distinguish between CH3CH=CHCH3 and CH3CHOHCH2CH3?

A) CrO3 in H2SO4 B) KMnO4 C) Br2 in CCl4 D) Two of these E) All of these

Ans: D Topic: Functional Group Tests

6. Which of the reagents listed below would serve as the basis for a simple chemical test to distinguish between CH3CH=CHCH2OH and CH3CH2CH2CH2OH ?

A) CrO3 in H2SO4 B) Cold conc. H2SO4 C) Br2 in CCl4 D) NaOH/H2O E) NaBH4

Ans: C Topic: Functional Group Tests

7. Which of the reagents listed below would serve as the basis for a simple chemical test to distinguish between (CH3)2C=CHCH2CH2OH and (CH3)2CHCH2CH2CH2OH ?

A) CrO3 in H2SO4 B) Cold conc. H2SO4 C) Br2 in CCl4 D) NaOH/H2O E) NaBH4

Ans: C

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Topic: Functional Group Tests

8. Which of the reagents/techniques listed below would serve as the basis for a simple chemical test to distinguish between 2-methyl-3-hexyn-1-ol and 2-methyl-5-hexyn-1-ol?

A) CrO3 in H2SO4 B) Cold conc. H2SO4 C) Br2 in CCl4 D) NaBH4 E) IR spectroscopy

Ans: E Topic: Functional Group Tests

9. Which of the reagents/techniques listed below would serve as the basis for a simple chemical test to distinguish between 2-methyl-3-hexyn-2-ol and 2-methyl-5-hexyn-1-ol?

A) CrO3 in H2SO4 B) IR spectroscopy C) Br2 in CCl4 D) A) and B) E) All of the above

Ans: D Topic: Functional Group Tests

10. Which of the reagents/techniques listed below would serve as the basis for a simple chemical test to distinguish between CH3CH2CH=CHCH2CH2CHO and CH3CH2CH=CHCH2CH2CH2OH?

A) KMnO4 B) IR spectroscopy C) Br2 in CCl4 D) A) and B) E) All of the above

Ans: B Topic: Functional Group Tests

11. Which of the reagents listed below would serve as the basis for a simple chemical test to distinguish between (CH3)3COH and (CH3)2CHCH2OH ?

A) NaH B) NaOH/H2O C) Br2 in CCl4 D) Cold conc. H2SO4 E) CrO3 in H2SO4

Ans: E

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Topic: Functional Group Tests

12. CrO3 in H2SO4/H2O will fail to give a positive test with which of these compounds? A) CH3CH2CH2CH2OH B) CH3CHCH2CH3

C) (CH3)3COH D)

CH3CH2CH2C O

E) More than one of these Ans: C

Topic: Functional Group Tests

13.

Consider the molecule CH3CHC CHCH2OH.

CH3

Which reagent will not give a positive test with this compound? A) Cold conc. H2SO4 B) Br2/CCl4 C) NaOH (aq) D) CrO3/H2SO4 E) Dilute KMnO4/H2O

Ans: C

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Topic: Reactions and Reaction Sequences

14. The final product, D, in the following reaction sequence,

CH3CHOH

CH3

CH2

PBr3 Aether

B CH3O+

DMg

, would be?

A) CH3CHOCH2CH2OH

CH3

B) CH3CHCH2CH2Br

CH3

C) CH3CHCH2CH2OH

CH3

D) CH3CHOCH2CH3

CH3

E) CH3CHCH2CH3

CH3

Ans: C

Chapter 12

404

Topic: Reactions and Reaction Sequences

15. What is the product, A, that would be obtained from the following reaction sequence?

CH3CH

CHCH3CH3CH2MgBr H3O+

C CH A

C CCH2CH3 C CCH

CH3

CHOCH2CH3

CH3

C CCH

CH3

CHOH

CH3

CH3CH2

C CCH

CH3

CHOH

CH3

C C CHCH2CH3

CH3

I II III

IV VA) I B) II C) III D) IV E) V

Ans: D

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Topic: Reactions and Reaction Sequences

16. What is the product, A, that would be obtained from the following reaction sequence?

CH2

CH3CH2MgBr H3O+

C CH A

C CCH2CH3 C CCH2CH2OCH2CH3 C CCH2CH2OHCH3CH2

C CCH2CH2OCH3 C COCHCH2CH3

I II III

IV V

CH3

A) I B) II C) III D) IV E) V

Ans: C Topic: Reactions and Reaction Sequences

17. What would be the product, C, of the following reaction sequence?

CH3CCH2Br

CH3

etherA

CuIB

CH3CHCH2CH2Br

CH3

CLi

A) 2,6-Dimethylheptane B) 2,2-Dimethylpropane C) 2-Methylpentane D) 2,2,5-Trimethylhexane E) 2,2,6-Trimethylheptane

Ans: E

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Topic: Reactions and Reaction Sequences

18. What would be the product, O, of the following reaction sequence?

CH3CH2CHCH3

Br etherN

D2OO

A) CH3CH2CH2CH3 B) CH3CH2CHCH3

C) CH3CH2CHCH3

D) CH3CH2CH2CH2OD E) CH3CH2CH2CH2D

Ans: B Topic: Reactions and Reaction Sequences

19. What is the product, A, that would be obtained from the following reaction sequence?

PBr3 Li NH4Cl

10oC(CH3)2C=OOH

I II

IV V

OHOH

III

A) I B) II C) III D) IV E) V

Ans: D

Chapter 12

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Topic: Reactions and Reaction Sequences

20.

What is the product, A, that would be obtained from the following reaction sequence?

PBr3 Mg, Et2O H3O+ heat

(CH3)2C=OOH

I II

IV V

OHOH

III

A) I B) II C) III D) IV E) V

Ans: C Topic: Reactions and Reaction Sequences

21. What would be the final product, A, in the following reaction sequence?

PBr3 Mg, Et2O H3O+ heat

IV V

I II III

O OH

BrO

OHO

A) I B) II C) III D) IV E) V

Ans: C

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Topic: Reactions and Reaction Sequences

22. What is the final product of the following reaction sequence?

Mg, Et2O

IV V

I II III

OH O

ii) H3O+CH3I H2CrO4

acetoneA

A) I B) II C) III D) IV E) V

Ans: E

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Topic: Reactions and Reaction Sequences

23. What would be the alkane C that is the product of the following reaction sequence?

CH3CHBr

CH3ether

ACuI

BCH3CHCH2Br

CH3

CLi

CH3CHCHCH2CH3

CH3

B) CH3CH CHCH2CH3

CH3 CH3

CH3CHCH2CHCH3

CH3

CH3CH CCH3

CH3 CH3

CH3

CH3CH2CH2CH2CHCH3

CH3

Ans: C

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Topic: Reactions and Reaction Sequences

24. What would be the major product of the following reaction?

O O

III

IV V

OHO OH O

O OH

I II

HO O OH

O Ai) NaBH4 ii) ethylene oxide, HA

A) I B) II C) III D) IV E) V

Ans: A Topic: Reactions and Reaction Sequences

25. What would be the major product of the following reaction?

S OO

OCH2CH3

Ai) NaBH4 ii) NaH, Et2Oiii)

A) CH3CH2OCH(CH3)CH2CH2CH2CH3 B) (CH3CH2O)2CHCHOHCH2CH2CH3 C) (CH3CH2)2CHOHCH2CH2CHOHCH3 D) CH3OCH(C2H5)CH2CH2CH2CH3 E) CH3CH2CH(OCH3)CH2CH2CHOHCH3

Ans: A

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Topic: Reactions and Reaction Sequences

26.

What would be the major product of the following reaction?

Li, Et2O ABr

CH3Cl

HCuI

A) (R)-3-ethyl-5-methylheptane B) (R,S)-3-ethyl-5-methylheptane C) (S)-3-ethyl-5-methylheptane D) (3R,5S)-5-ethyl-3-methylheptane E) (3S,5R)-5-ethyl-3-methylheptane

Ans: C Topic: Reactions and Reaction Sequences

27. What is the principal product(s) formed when 1 mol of methylmagnesium iodide reacts with 1 mol of p-hydroxyacetophenone ?

CH3MgI

IV V

I II IIIIMgO

OMgI

O MgI IMgO

+ CH4

A) I B) II C) III D) IV E) V

Ans: A

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Topic: Reactions and Reaction Sequences

28.

What is (are) the principal product(s) formed when 1 mol of ethylmagnesium bromide reacts with 1 mol of 3-(N-methylamino)cyclopentanone ?

CH3CH2MgBr

IV V

I II III

OHN

H3C

OBrMgNCH3 H

NH3C

CH2CH3

OMgBr

ONH3C

H3CH2COMgBr

H3C

CH2CH3

OHN

H3C CH2CH3+ CH4

A) I B) II C) III D) IV E) V

Ans: A Topic: Reactions and Reaction Sequences

29.

What would be the product, A, of the following reaction ?

i) NaBD4 ii) H2O

OD B)

OHD

C) ODD

D) OH

E) O

Ans: B

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Topic: Reactions and Reaction Sequences

30. What is the predominant product from the reaction of 2-hexanol with H2CrO4? A) CH3CO2H B) CH3(CH2)3CO2H C)

CH3(CH2)3CCH3

D) CH3(CH2)4CO2H E) A) and B)

Ans: C Topic: Synthetic Strategy, Redox 31. Which of the reagents listed below would efficiently accomplish the transformation of

CH3CH2CH=CHCH2CH2CHO into CH3CH2CH=CHCH2CH2CH2OH? A) KMnO4 B) NaBH4 C) Br2 in CCl4 D) H2, Ni E) Two of the above

Ans: B Topic: Synthetic Strategy, Redox 32. Which of the reagents listed below would efficiently accomplish the transformation of

CH3CH2CH=CHCH2CH2CHO into CH3CH2CH2CH2CH2CH2CH2OH? A) KMnO4 B) NaBH4 C) Br2 in CCl4 D) H2, Ni E) Two of the above

Ans: D Topic: Synthetic Strategy, Redox 33. Which of the reagents listed below would efficiently accomplish the transformation of

CH3CH2C≡CCH2CH2CHO into CH3CH2C≡CCH2CH2CH2OH? A) KMnO4 B) NaBH4 C) Br2 in CCl4 D) H2, Ni E) Two of the above

Ans: B

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Topic: Synthetic Strategy, Redox

34. Which of the reagents listed below would efficiently accomplish the transformation of CH3CH2CH=CHCH2CH2CH2OH into CH3CH2CH=CHCH2CH2CHO ?

A) KMnO4(aq, alkaline) B) CrO3 / H2SO4 C) PCC in CH2Cl2 D) Br2, CCl4 E) Two of the above

Ans: C Topic: Synthetic Strategy

35. Which of the reagents listed below would efficiently accomplish the transformation of 2-methyl-3-cyclopentenol into 2-methyl-3-cyclopentenone?

OH O?

A) KMnO4(aq, alkaline) B) CrO3/H2SO4 C) H2, Pt D) Br2, CCl4 E) Two of the above

Ans: B Topic: Synthetic Strategy, Redox

36. Which of the reagents listed below would efficiently accomplish the transformation of 3-methyl-3-cyclopentenone into 3-methyl-3-cyclopentenol?

O OH?

A) i) LiAlH4; ii) H2O B) NaBH4,H2O C) H2, Pd D) A) and B) E) A), B) and C) of the above

Ans: D

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Topic: Synthetic Strategy, Redox

37. Which of the reagents listed below would efficiently accomplish the transformation of ethyl-3-pentenoate into 3-penten-1-ol?

A) i) LiAlH4; ii) H2O B) NaBH4,H2O C) H2, Pd D) A) and B) E) A), B) and C) of the above

Ans: A Topic: Reactions and Reaction Sequences

38. When 2-pentanol is treated with chromic acid, A) The color changes from orange to blue B) The color changes from purple to colorless C) The color changes from blue to red D) The color changes from orange to green E) The color changes from green to orange

Ans: D Topic: Reactions and Reaction Sequences

39. When 1-pentanol is treated with alkaline potassium permanganate, A) The color changes from orange to blue B) The color changes from purple to colorless C) The color changes from blue to red D) The color changes from orange to green E) The color changes from green to orange

Ans: B Topic: Reactions and Reaction Sequences

40. When 3-methyl-3-pentanol is treated with chromic acid, A) The color changes from orange to blue B) The color changes from purple to colorless C) The purple color remains unchanged D) The color changes from orange to green E) The orange color remains unchanged

Ans: E

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Topic: Reactions and Reaction Sequences

41. What is the final product?

NaNH2 CH3I?

CH3CCH3

CH3C CHliq. NH3

CH3CC

CH3

CCH3

CH3CC

CH3

CCH3

OCH3

CH3C COCH2CHCH3

OCH3

CH3CC

CH3

CONa

CH3

E) None of these Ans: B

Topic: Reactions and Reaction Sequences

42. What product(s) is/are formed in the following reaction?

D2OLiAlD4 ?etherCH3CH2CH2COCH2CH3

A) CH3CH2CH2CH2OD + CH3CH2OD B) CH3CH2CH2CD2OD + CH3CH2OD C) CH3CH2CH2CD2OH + CH3CH2OH D) CH3CH2CH2CHDOD + CH3CH2OD E)

CH3CH2CH2CDOCH2CH3

Ans: B

Chapter 12

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Topic: Reactions and Reaction Sequences

43. What product(s) is/are produced in the 1:1 reaction of sec-butylmagnesium bromide with

CH3CHCH2CH2C

HOH

A) CH3CHCH2CH2CHCCH2CH3

OMgBrOH

CH3

CH3CHCH2CH2C

HOMgBr

O + CH3CH2CH2CH3C)

CH3CHCH2CH2CHCH2CH(CH3)2

OMgBrOH

CH3CHCH2CH2C

HOMgBr

O + (CH3)3CHE)

CH3CHCH2CH2C

OCHCH2CH3

CH3

Ans: B

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Topic: Reactions and Reaction Sequences

44. What is the principal product of the following reaction:

CH3CH CH2

+ CH3CH2CH2CH2MgBr/ether; then H2O ⎯⎯⎯⎯→ ? A) CH3CHCH2CH2CH2CH3

CH2OH

CH3CHCH2CH2CH2CH2CH3

CH3CHCH2OCH2CH2CH2CH3

D) CH3CHOCH2CH2CH2CH3

CH2OH

E) CH3CHCH2OCH2CH2CH2CH3

OCH2CH2CH2CH3

Ans: B Topic: Reactions and Reaction Sequences

45. The reaction of lithium di-sec-butylcuprate with isopentyl bromide yields: A) 2,5-Dimethylheptane B) 2,6-Dimethylheptane C) 3,5-Dimethylheptane D) 3,4-Dimethylheptane E) 3,6-Dimethylheptane

Ans: A Topic: Reactions and Reaction Sequences

46. The reaction of lithium diethylcuprate with 1-bromo-4,4-dimethylhexane yields: A) 3,3-Dimethylheptane B) 3,3-Dimethyloctane C) 1-Ethyl-4,4-dimethylhexane D) Di-4,4-dimethylhexylcuprate E) None of the above

Ans: B

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Topic: Reactions and Reaction Sequences

47. What compound(s) result(s) from the reaction of CH3CH2CH2MgBr with CH3CH2CH2CH2CO2H (1:1 mole ratio)?

A) (CH3CH2CH2)2CCH2CH2CH2CH3

OHB)

CH3CH2CH2CCH2CH2CH2CH3

CH3CH2CH2CH2COCH2CH2CH3

D) CH3CH2CH3 + CH3CH2CH2CH2CO2MgBr E)

CH3CH2COCCH2CH2CH2CH3

Ans: D Topic: Synthetic Strategy

48.

Your task is to synthesize

CH3CH2CH2CCH3

C6H5

OH through a Grignard synthesis. Which pairs of compounds listed below would you choose as starting materials?

CH3CC6H5CH3CH2CH2Br and

CH3CH2CH2CH and C6H5Br

C6H5CH

CH3CH2CHCH3

Brand

D) More than one of these E) None of these

Ans: A

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Topic: Synthetic Strategy

49. Which of the following synthetic procedures would be employed most effectively to transform ethanol into ethyl propyl ether?

A) Ethanol + HBr, then Mg/ether, then H3O+, then NaH, then CH3CH2Br B) Ethanol + HBr, then Mg/ether, then HCHO, then H3O+, then NaH, then CH3CH2Br C) Ethanol + CH3CH2CH2OH + H2SO4/140°C D) Ethanol + NaH, then HCHO, then H3O+, then HBr, then Mg/ether, then CH3CH2CH2BrE) Ethanol + H2SO4/180°C, then CH3CH2CH2Br

Ans: B Topic: Synthetic Strategy

50. Your task is to synthesize 2-phenyl-2-hexanol through a Grignard synthesis. Which pair(s) of compounds listed below would you choose as starting materials?

CH3CC6H5CH3CH2CH2Br and

B) CH3CHCH2Br

CH3CC6H5

andO

CH3

CH3CH2CH2CH2CCH3 and C6H5Br

D) Answers A) or B) E) Answers A) or C)

Ans: E Topic: Synthetic Strategy

51. How could the following synthesis be accomplished?

OH CH2CH

(1) SOCl2, (2) Mg, ether, (3) CH3CH,

then H3O+ B) (1) SOCl2, (2) Li, ether, (3) (CH3CH2)2CuLi, (4) KMnO4, OH- C)

1) PBr3, (2) Mg, ether, (3) CH2 CH2,

then H3O+ (4) PCC,CH2Cl2 D) More than one of the above E) None of the above

Ans: C

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Topic: Synthetic Strategy, Redox

52. Select the correct reagent(s) for the following reaction:

CH3CCH2CH2CO2CH3

CH3CHCH2CH2CH2OH

A) LiAlH4/ether; then H3O+ B) NaBH4; then H3O+ C) H2 with Pt/C D) A) and B) E) A), B) and C)

Ans: A Topic: Synthetic Strategy, Redox

53. Select the correct reagent(s) for the following reaction:

CH3CCH2CH2CO2CH3

CH3CHCH2CH2CO2CH3

A) LiAlH4/ether; then H3O+ B) NaBH4; then H3O+ C) H2 with Pt/C D) B) and C) E) A), B) and C)

Ans: D Topic: Synthetic Strategy, Redox

54. Which reagent(s) would you use to convert CH3(CH2)6CO2H to CH3(CH2)6CH2OH? A) NaBH4/H2O B) LiAlH4/ether, then H3O+ C) PCC/CH2Cl2 D) Zn, H3O+ E) H2, Pt

Ans: B

Chapter 12

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Topic: Synthetic Strategy

55.

Which method would give (CH3)2CC CH

A) CH3CHCH3

H2CrO4

aceticacid

HC CNa NH4+

B) CH3CCH3

CH3CH2Li H3O+ H2CrO4

acetoneC) CH3CC

2 CH3MgBr NH4+CH

D) More than one of the above E) None of the above

Ans: D Topic: Synthetic Strategy

56. Which synthesis of a Grignard reagent would fail to occur as written? A)

CH3OCH2CH2BrMg, ether

CH3OCH2CH2MgBrB)

CH3CH2CH2IMg, ether

CH3CH2CH2MgIC)

HO2CCH2CH2IMg, ether

HO2CCH2CH2MgID)

C6H5BrMg, ether

C6H5MgBrE) All of the above will succeed.

Ans: C Topic: Synthetic Strategy

57. Which combination of reagents is to be preferred for the synthesis of 2,4-dimethylhexane by the Corey-Posner, Whitesides-House procedure?

A) Lithium diisobutylcuprate + sec-butyl bromide B) Lithium dimethylcuprate + 2-bromo-4-methylhexane C) Lithium dimethylcuprate + 4-bromo-2-methylhexane D) Lithium diisopropylcuprate + 1-bromo-2-methylbutane E) Lithium di(2-methylbutyl)cuprate + isopropyl bromide

Ans: D

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Topic: Synthetic Strategy

58. Which of these reactions will not produce a 1° alcohol? A)

(CH3)2CHCH2CH2MgBr1. LiAlH4, Et2O

2. H3O+

B) CH2

CH2

(CH3)2CHCH2CH2MgBr

2. H3O+

C6H5CCH3

O 1. NaBH4

2. H3O+

D) CH3CH2CH2CH2Li

1. H2C=O

2. H3O+

E) CH3(CH2)5COOH

1. LiAlH4, Et2O

2. H3O+

Ans: C

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Topic: Synthetic Strategy, Stereochemistry

59. Which of the following would serve as a synthesis of racemic 2-methyl-1-phenyl-2-butanol?

CCH2CH3

CH2MgCl

CH2CCH3

III

CH3CH2CCH3

O 2. NH4+

CH3

+1. Et2O

O+ CH3CH2MgBr

2. NH4+

1. Et2O

CH2CCH2CH3

+ CH3MgI2. NH4

1. Et2O

A) I B) II C) III D) All of the above E) None of the above

Ans: D

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Topic: Synthetic Strategy, Stereochemistry

60. Which of the following reactions would serve as a reasonable synthesis of the following racemic alcohol (2-phenyl-2-butanol)?

CH3CC6H5

C2H5

CH3CC6H5

O+ C2H5MgBr

2. NH4+

1. Et2O

C2H5CC6H5

+ CH3MgBr2. NH4

1. Et2OO

CH3CC2H5

+ C6H5MgBr2. NH4

1. Et2OO

D) Answers A) and B) only E) Answers A), B) and C)

Ans: E Topic: Synthetic Strategy, Stereochemistry

61. Which Grignard synthesis will produce an optically active product or product mixture?

A) MgBr

O+

B) OClMg+

C) O

MgI+

D) O

MgI

H CH3+

H3C HMgBr+

Ans: E

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Topic: Synthetic Strategy, Stereochemistry

62. Which reaction leads to an optically active product? A)

O+ NaBH4

B) OClMg+

C) +

H CO2HH2, Pt

+H OH

KMnO4

E) O

H3C CHO

LiAlH4 / Et2O (excess)+

Ans: C Topic: Acid/Base

63. Which of the following is the strongest acid? A) RMgX B) Mg(OH)X C) RH D) H2O

Ans: D Topic: Acid/Base

64. Which of the following is the strongest base? A) RMgX B) Mg(OH)X C) RH D) H2O

Ans: A Topic: Acid/Base

65. In which of the following series are the compounds arranged in order of decreasing basicity?

A) CH3CH2MgBr > NaNH2 > HC≡CNa > NaOH > CH3CH2ONa B) CH3CH2MgBr > NaNH2 > HC≡CNa > CH3CH2ONa > NaOH C) HC≡CNa > CH3CH2MgBr > NaNH2 > CH3CH2ONa > NaOH D) NaNH2 > CH3CH2MgBr > HC≡CNa > CH3CH2ONa > NaOH E) None of these

Ans: B

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Topic: Redox

66. Which reaction is an oxidation? A) RCHO ⎯⎯⎯⎯→ RCO2H B) RCH2OH ⎯⎯⎯⎯→ RCHO C) RCH2OH ⎯⎯⎯⎯→ RCO2H D) Two of these E) All of these

Ans: E Topic: Synthetic Strategy, Redox

67. Which of these compounds will not be reduced by LiAlH4? A) CH3CH2CH2CH=CH2 B)

CH3CH2CH2C

CH3CH2CH2COH

CH3CH2CH2COCH3

CH3CH2CH2CCH3

Ans: A Topic: Synthetic Strategy, Redox

68. Which reagent(s) is/are capable of reducing the following ester to a primary alcohol ? O

O A) LiAlH4 / ether B) NaBH4 / H2O C) Na / C2H5OH D) H2 / Ni, atmospheric pressure E) All can be used successfully.

Ans: A

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Topic: Synthetic Strategy, Redox

69. Which reagent(s) is/are capable of reducing the following ester to an aldehyde ? O

O A) LiAlH4 / ether B) NaBH4 / H2O C) Na / C2H5OH D) H2 / Ni, atmospheric pressure E) None of the above can be used successfully.

Ans: E Topic: Redox

70. Which of these transformations cannot be classified as a reduction? A) RCH2Cl ⎯⎯⎯⎯→ RCH3 B) RCH=CH2 ⎯⎯⎯⎯→ RCH2CH3 C) RCOOH ⎯⎯⎯⎯→ RCH2OH D)

RCOR'

RCH2OH + R'OHE) All of these are reductions.

Ans: E Topic: Synthetic Strategy, Redox

71. Which of these compounds cannot be reduced by sodium borohydride? A)

(CH3)2CHC

CH3CH2CCH3

C6H5COH

CH3(CH2)4COCH3

E) Neither C) nor D) can be reduced. Ans: E

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Topic: Redox, Reaction Mechanisms

72. In the reaction of carbonyl compounds with LiAlH4, the effective reducing species is: A) Li+ B) Al+3 C) AlH4

- D) AlH3 E) H-

Ans: E Topic: Redox, Reaction Mechanisms

73. The success in converting low molecular weight 1° alcohols to aldehydes by use of K2Cr2O7/H2SO4 as oxidant can be attributed to the fact that:

A) dichromate is a relatively weak oxidizing agent. B) the presence of H2SO4 limits the oxidation. C) the aldehyde can be separated, as formed, by distillation. D) aldehydes are not oxidized by the K2Cr2O7/H2SO4 mixture. E) hydrogen bonding occurs between the alcohol and the acid present.

Ans: C Topic: Redox, Reaction Mechanisms

74. Fundamentally, 2-methyl-2-pentanol does not undergo oxidation by H2CrO4 because: A) the intermediate chromate ester is not formed. B) the oxidant isn't in a sufficiently high oxidation state. C) the alcohol undergoes dehydration. D) the intermediate chromate ester cannot lose hydrogen. E) Actually, this oxidation does occur.

Ans: D

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Topic: Synthetic Strategy, Redox

75. Which of these reduction reactions is unsuccessful? A)

CH3CH2CH2COCH2CH2CH3

+ LiAlH4, etherB)

+ NaBH4, CH3OHC6H5CH2C O

CH3(CH2)10COH + H2, Pt, high pressure

C6H5CCH2CH2CH2CH3 + NaBH4, CH3CH2OH

E) All of these are successful reductions. Ans: C

Topic: Synthesis of Grignards and Other Organometallics

76. Grignard reagents react with oxirane (ethylene oxide) to form 1° alcohols but can be prepared in tetrahydrofuran solvent. Why is this difference in behavior observed?

A) Steric hindrance in the case of tetrahydrofuran precludes reaction with the Grignard. B) There is a better leaving group in the oxirane molecule. C) The oxirane ring is the more highly strained. D) It is easier to obtain tetrahydrofuran in anhydrous condition. E) Oxirane is a cyclic ether, while tetrahydrofuran is a hydrocarbon.

Ans: C Topic: Synthesis of Grignards and Other Organometallics

77. Which of these compounds cannot be used to prepare the corresponding Grignard reagent?

A) CH3OCH2CH2CH2Br B) (CH3)3CCl C) CH2=CHCH2Br D) (CH3)2NCH2CH2Br E)

O CCH2CH2I

Ans: E

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Topic: Synthesis of Grignards and Other Organometallics

78. Which of these compounds can be used to prepare the corresponding Grignard reagent? A) CH3CHOHCH2CH2CH2CH2Br B) (CH3)3CHCHBrCH2CH2CO2H C) BrCH=CHCH2CH2CH3 D) CH3NHCH2CH2Br E) None of the above can be used to prepare the corresponding Grignard reagent

Ans: C Topic: Reactivity of Grignards and Other Organometallics

79. Which of these is the least reactive type of organometallic compound? A) RK B) R2Hg C) RLi D) R2Zn E) R3Al

Ans: B Topic: Synthesis of Grignards and Other Organometallics

80. If the role of the solvent is to assist in the preparation and stabilization of the Grignard reagent by coordination with the magnesium, which of these solvents should be least effective?

CH3CH2OCH2CH3 O(CH3CH2)3N

CH3(CH2)4CH3 CH3OCH2CH2OCH3

I II III

IV VA) I B) II C) III D) IV E) V

Ans: D

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Topic: Synthesis of Grignards and Other Organometallics

81. Which of these is most likely to be a successful synthesis of an organometallic compound?

A) CH3CH2CH2MgBr + LiCl ⎯⎯⎯⎯→ CH3CH2CH2Li + MgBrCl B) 2 CH3CH2CH2CH2Li + ZnCl2 ⎯⎯⎯⎯→ (CH3CH2CH2CH2)2Zn + 2 LiCl C) 3 (CH3CH2)2Hg + 2 AlCl3 ⎯⎯⎯⎯→ 2 (CH3CH2)3Al + 3 HgCl2 D) (CH3CH2)3Al + 3 NaCl ⎯⎯⎯⎯→ 3 CH3CH2Na + AlCl3 E) (CH3)2Cu + MgBr2 ⎯⎯⎯⎯→ (CH3)2Mg + CuBr2

Ans: B SHORT ANSWER QUESTIONS Topic: General

82. Because the carbonyl carbon bears a partial positive charge, it is susceptible to ________________ attack. Ans: nucleophilic

Topic: General, Redox

83. A reaction which increases the hydrogen content or decreases the oxygen content of an organic molecule is called a(n) _____________. Ans: reduction

Topic: General, Redox

84. A reaction which increases the oxygen content or decreases the hydrogen content of an organic molecule is called a(n) _____________. Ans: oxidation

Topic: General, Redox

85. LAH is the abbreviation for the powerful reducing agent ______________. Ans: lithium aluminum hydride

Topic: General, Redox

86. A negatively charged hydrogen atom is called a ______________. Ans: hydride ion

Topic: General, Redox Reagents

87. A solution of CrO3 in aqueous acetone is called the _______________. Ans: Jones reagent

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Topic: Functional Group Tests

88. Primary and secondary alcohols can be distinguished from most other compounds (with the exception of aldehydes) because they will react rapidly with a solution of CrO3 in aqueous sulfuric acid, causing a color change from ______________ to _____________. Ans: orange; green

Topic: General

89. Compounds that contain carbon-metal bonds are known as _________________. Ans: organometallic compounds

Topic: General

90. Organomagnesium halides are known as _______________. Ans: Grignard reagents

Topic: Synthesis of Grignards and Other Organometallics

91. Why can we not prepare a Grignard reagent from a molecule such as 4-bromo-1-butanol? Ans: Because Grignard reagents are extremely strong bases and will react with the

alcohol's acidic proton. Topic: Reactions of Grignards and Other Organometallics

92. A Grignard reagent will produce a primary alcohol when reacted with ____________. Ans: Formaldehyde and ethylene oxide

Topic: Reactivity of Grignards and Other Organometallics

93. The reactivity of organometallic compounds increases with the _____________ of the carbon-metal bond. Ans: percent ionic character

Topic: Reactions of Grignards and Other Organometallics

94. A Grignard reagent will produce a secondary alcohol when reacted with ____________.Ans: Any aldehyde except formaldehyde

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Topic: Reactions of Grignards and Other Organometallics

95. Reaction of an alkyllithium with a ketone produces, after acid work-up, a _____________ alcohol. Ans: tertiary

Topic: Reactions of Grignards and Other Organometallics

96. Reaction of excess methyllithium with ethyl acetate (CH3CO2C2H5) produces, after acid work-up, ____________. Ans: t-butyl alcohol: (CH3)3COH

Topic: Reactions of Grignards and Other Organometallics

97. Reaction of excess ethyl magnesium bromide with ethyl benzoate (C6H5CO2C2H5) produces, after acid work-up, ____________. Ans:

3-phenyl-3-pentanol:

Topic: Reactions of Grignards and Other Organometallics

98. Reaction of excess ethyl magnesium iodide with a ethyl acetate (CH3CO2C2H5) produces, after acid work-up, ____________ . Ans: 3-methyl-3-pentanol CH3CH2C(CH3)(OH)CH2CH3

Topic: Redox Reactions

99. In the reaction of carbonyl compounds with LiAlH4, the effective reducing species is: Ans: H− (hydride)

Topic: Redox Reactions

100. In the reaction of carbonyl compounds with NaBH4, the effective reducing species is: Ans: H− (hydride)

Topic: Grignard Reactions

101. NH4Cl is sometimes preferred instead of HCl or H2SO4 for “acid” work-up after Grignard reactions, particularly when the expected and desired product is a tertiary alcohol: why? Ans: NH4Cl provides mildly acidic conditions via partial hydrolysis of NH4Cl. Under

strongly acid conditions, a tertiary alcohol product can undergo facile dehydration to an alkene.

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Topic: Synthesis of Grignards and Other Organometallics

102. Diethyl ether, the most commonly used solvent for Grignard reactions, also acts as an ‘internal cooling agent’, preventing the overheating of the reaction mixture: what specific property of diethyl ether is exploited here and why is it important to prevent the overheating of the reaction mixture? Ans: Diethyl ether is very volatile (35-36oC): its low boiling point ensures that

reactions carried out in diethyl ether solvent cannot become overheated (the maximum temperature cannot exceed the b.p. of the solvent): this is important in Grignard reactions, because Grignard reagents decompose at higher temperatures. Thus, the decomposition of the newly formed Grignard reagent is minimized by use of this ‘internal cooling agent’.

Topic: General

102. When nucleophilic addition to a carbonyl group occurs, the carbon attacked undergoes this hybridization change: Ans: sp2 sp3

Topic: General, Redox

103. PCC and CrO3 are both Cr(VI) reagents. However, PCC/CH2Cl2 is useful in oxidizing primary alcohols to aldehydes, while the analogous reaction with CrO3/H2SO4 will typically produce carboxylic acids. Why? Ans: Both reagents first oxidize the alcohol to the corresponding aldehyde. Further

oxidation of aldehydes, to carboxylic acids, is facilitated in aqueous solutions, via formation of the intermediate aldehyde hydrates (CrO3/H2SO4). When the solvent is non-aqueous, such as CH2Cl2, these key intermediates cannot be formed, thereby preventing further oxidation of aldehydes (with PCC/CH2Cl2).

Topic: Multistep Reactions

104. What would be the major product, A, of the following reaction?

OCF3

S OO

OCH2CH3

Ai) NaBH4 ii) NaH, Et2Oiii)

Ans:

Chapter 12

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Topic: Multistep Synthetic Strategy

105. Suggest a reasonable synthetic strategy for the synthesis of 3-methyl-3-hexanol from 3-hexanol. Ans: 3-hexanol- i) PCC; ii) CH3MgBr (or CH3Li); iii) NH4Cl

OHPCC CH2Cl2

Oi) CH3MgBr, Et2O ii) NH4Cl

Topic: Multistep Synthetic Strategy

106. Suggest a reasonable synthetic strategy for the synthesis of 2-methyl-3-hexanol from 1-butanol. Ans: 1-butanol i) PCC; ii) (CH3)2CHMgBr (or (CH3)2CHLi); iii) NH4Cl (H3O+)

HOPCC CH2Cl2 O

i) (CH3)2CHMgBr, Et2O ii) NH4Cl

Topic: Multistep Synthetic Strategy

107. Suggest a reasonable synthetic strategy for the synthesis of 4-heptanol from 1-pentene. Ans: 1-pentene i)MMPP; ii) CH3CH2MgBr (or CH3CH2Li); iii) NH4Cl (H3O+)

MMPP O i) CH3CH2MgBr, Et2O ii) NH4Cl

Topic: Multistep Synthetic Strategy

108. Suggest a reasonable synthetic strategy for the synthesis of 3-ethyl-3-heptanol from pentanoic acid, CH3CH2CH2CH2CO2H. Ans: CH3CH2CH2CH2CO2H i)SOCl2; ii) 2 equivalents CH3CH2MgBr (or

CH3CH2Li); iii) NH4Cl (H3O+)

OSOCl2

O OHi) CH3CH2MgBr (2 equivalents), Et2Oii) NH4Cl

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Topic: Multistep Reaction Sequence

109. Complete the following reaction sequence, giving structural details of all key intermediates. 1-hexene------------------ i) HBr ii) Li iii) (CH3CH2)2C=O iv) C2H5I Ans: Li

OLi

C2H5I

BrHBr

Topic: Multistep Reaction Sequence

110. Complete the following reaction sequence, giving structural details of all key intermediates. 2-methyl-1-pentene------------------ i) BH3, THF ii) H2O2,NaOH iii) PCC, CH2Cl2 iv) CH3CH2C≡C:−Na+ v) NH4Cl Ans: i) BH3,THF

ii) H2O2, NaOHHO

PCC,CH2Cl2

:− Na+

ii) NH4Cl

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Topic: Multistep Reaction Sequence

111. Complete the following reaction sequence, giving structural details of all key intermediates. 4-methyl-1-hexene------------------ i) BH3, THF ii) H2O2,NaOH iii) SOCl2 iv) Mg, Et2O iv) ethylene oxide v) NH4Cl Ans:

ClMgMgEt2O

i) BH3,THFii) H2O2, NaOH

ii) NH4Cl

SOCl2

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Topic: Multistep Reaction Sequence

112. Complete the following reaction sequence, giving structural details of all key intermediates. Bromocyclohexane------------------ i) Li ii) CuI iii) 4-methyl-1-bromohexane Ans:

CuLiLi CuIBr Li

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MULTIPLE CHOICE QUESTIONS Topic: Nomenclature

What is an IUPAC name for A) 2,3-methylhept-2-en-4-yne B) 1,1,3-trimethylhex-3-yn-1-ene C) 1,1,3-trimethyl-3-hexyn-1-ene D) 2,3-dimethyl-2-hepten-4-yne E) 5,6-dimethyl-5-hepten-3-yne

Ans: D Topic: Nomenclature

2. What is an IUPAC name for this triene?

CH3CH2H H

CH3

A) (2E,4Z,6E)–2,4,6–Nonatriene B) (2Z,4E,6Z)–2,4,6–Nonatriene C) (2E,4Z,6Z)–2,4,6–Nonatriene D) (3Z,5Z,7E)–3,5,7–Nonatriene E) (3Z,5E,7E)–3,5,7–Nonatriene

Ans: C Topic: Nomenclature

3. What is an IUPAC name for this triene?

A) (2E,4Z,6E)–3,4,7,8–tetramethyl-2,4,6–Nonatriene B) (2Z,4E,6E)–3,4,7,8–tetramethyl-2,4,6–Nonatriene C) (2E,4Z,6E)–2,3,6,7–tetramethyl-3,5,7–Nonatriene D) (2E,4Z,6E)– 2,3,6,7–tetramethyl-3,5,7–Nonatriene E) (2E,4E,6E)–3,4,7,8–tetramethyl-2,4,6–Nonatriene

Ans: E

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Topic: Nomenclature

A correct IUPAC name of the compound below is:

A) 1-Bromo-1-methyl-2,5-cyclohexadiene B) 3-Bromo-3-methyl-1,4-cyclohexadiene C) 6-Bromo-6-methyl-1,4-cyclohexadiene D) 2-Bromo-2-methyl-1,3-cyclohexadiene E) None of these

Ans: B Topic: Stability (Alkenes, Cations, Radicals)

5. Which of the following dienes would you expect to be the most stable? A) CH3CH=CHCH=CHCH3 B) CH3CH=CHCH2CH=CH2 C) CH2=CHCH2CH2CH=CH2 D) CH2=CHCH(CH3)CH=CH2 E) CH3CH=C=CHCH2CH3

Ans: A Topic: Stability (Alkenes, Cations, Radicals)

6. Which of the following dienes would you expect to be the most stable? A) CH3CH2CH=CHCH2CH=CHCH3 B) CH3CH=CHCH=CHCH2CH3 C) CH2=CHCH2CH2CH2CH=CH2 D) CH2=CHCH=CHCH2CH2CH3 E) CH3CH2CH=C=CHCH2CH3

Ans: B

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Topic: Stability (Alkenes, Cations, Radicals)

7. Which of the following compounds would be the most stable?

I II III IVA) I B) II C) III D) IV E) They are all of equal stability.

Ans: A Topic: Stability (Alkenes, Cations, Radicals)

8. Considering both configurational and conformational factors, select the most stable form of 2,4-hexadiene.

CH3 H

CH3

H H

CH3 HCH3

CH3

CH3H

CH3CH3H

CH3

I II III IV V

A) I B) II C) III D) IV E) V

Ans: A

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Topic: Stability (Alkenes, Cations, Radicals)

9. Which alkene would you expect to be most stable? A) CH2=CHCH2CH2CH=CH2 B)

C CH

CH3H

CHCH2CH2

C) C C

CH3 CH2CH

H H

CH2

C CC

CH3 CH

CH3

E) C C

CH3

H C

CH3

Ans: E Topic: Stability (Alkenes, Cations, Radicals) 10. Which diene would be least stable?

I II III IV V

A) I B) II C) III D) IV E) V

Ans: C

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Topic: Stability (Alkenes, Cations, Radicals)

11. Arrange these hexadienes in order of expected decreasing stability.

I II

IV V

III

A) V > II > I > III > IV B) III > IV > II > I > V C) IV > III > II > V > I D) IV > III > I > II > V E) I > II > IV > III > V

Ans: D Topic: Stability (Alkenes, Cations, Radicals)

12. Which carbocation would be most stable? A)

Ans: C

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Topic: Stability (Alkenes, Cations, Radicals)

13. Which carbocation would be most stable?

I II III IV V

CH2 CH3 CH3 CH3 CH3

A) I B) II C) III D) IV E) V

Ans: C Topic: Stability (Alkenes, Cations, Radicals)

14. Which free radical would be most stable? A)

CH3CC CH2

CH3

CCH2CH2

CH3

CH2

CH3CCH2CH3

CH3

CH2CHC CH2

CH3

CH3CHCHCH3

CH3

Ans: A

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Topic: Stability (Alkenes, Cations, Radicals)

15.

Which hydrogen atom(s) of

CH CHCHCH3 CH

CH3

CH CH3

I II III IV

is/are most susceptible to abstraction by free radicals?

A) I B) II C) III D) IV E) V

Ans: D Topic: Heat of Hydrogenation

16. Which alkene would you expect to have the smallest heat of hydrogenation? A) CH2=CHCH2CH2CH=CH2 B)

C CH

CH3H

CHCH2CH2

C) C C

CH3 CH2CH

H H

CH2

C CC

CH3 CH

CH3

E) C C

CH3

H C

CH3

Ans: E

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Topic: Bond Lengths

17. Which compound would have the shortest carbon-carbon single bond? A) CH3–CH3 B) CH2=CH–CH3 C) HC≡C–C≡CH D) CH2=CH–C≡CH E) CH2=CH–CH=CH2

Ans: C Topic: Bond Lengths

18. Which compound would have the shortest carbon-carbon single bond?

A) CH≡C–CH=CH–CH2–CH3 B) CH2=CH–CH=CH–CH3 C) HC≡C–CH2–C≡C–CH3 D) CH2=CH–C≡C–CH2–CH3 E) CH3–C≡C–C≡C–CH3

Ans: E Topic: Bond Lengths

19. Which carbon-carbon bond in the following compound would you expect to be shortest?C C CHH CH2 CH3CH

I II III IV VA) I B) II C) III D) IV E) V

Ans: A

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Topic: Bond Lengths

20. Which carbon-carbon bond in the following compound would you expect to be longest? C C CHH CH2 CH3CH

I II III IV VA) I B) II C) III D) IV E) V

Ans: E Topic:Alkene Classification

21. Select the structure of the conjugated diene.

I II III IV VA) I B) II C) III D) IV E) V

Ans: B

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Topic:Alkene Classification

22.

Select the structure(s) of the conjugated diene(s).

I II

IV V

III

A) I and II B) II and III C) III and IV D) I, II and V E) V

Ans: B Topic: Alkene Classification

23. Which of the following dienes is a cumulated diene? A) CH2=CHCH2CH2CH=CH2 B) CH2=CHCH=CHCH2CH3 C) CH3CH=C=CHCH2CH3 D) CH3CH=CHCH=CHCH3 E) CH3CH=CHCH2CH=CH2

Ans: C Topic: Alkene Classification

24. Which of the following dienes is a cumulated diene? A) CH2=CHCH2CH2CH2CH=CH2 B) CH2=CHCH=CHCH2CH2CH3 C) CH3CH=C=CHCH2CH2CH3 D) CH3CH=CHCH=CHCH2CH3 E) CH3CH2CH=CHCH2CH=CH2

Ans: C

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Topic: Molecular Orbitals

25. The allyl radical has how many bonding π molecular orbitals? A) 1 B) 2 C) 3 D) 4 E) 5

Ans: A Topic: Molecular Orbitals

26. The allyl cation has how many electrons in bonding π molecular orbitals? A) 1 B) 2 C) 3 D) 4 E) 5

Ans: B Topic: Molecular Orbitals

27. 1,3-Pentadiene has how many bonding π molecular orbitals? A) 1 B) 2 C) 3 D) 4 E) 0

Ans: B

Chapter 13

451

Topic: Heat of Hydrogenation

28. Estimate the stabilization energy for 1,3-butadiene using the heats of hydrogenation in Table 1. Table 1. Heats of Hydrogenation for Selected Compounds Compound Moles H2 ΔH(kJ mol-1) 1-Butene 1 -127 1-Pentene 1 -126 1,3-Butadiene 2 -239 1,3-Pentadiene 2 -226

A) 13 kJ mol-1 B) 15 kJ mol-1 C) 28 kJ mol-1 D) 239 kJ mol-1 E) 112 kJ mol-1

Ans: B Topic: Resonance

29. Which is not an example of resonance? I

III

II CH2

CH2

CH2=CH−CH2

CH2=CH−CH−CH2CCl3

CH2

CH3

CH2−CH=CH2

CH2−CH=CH−CH2CCl3

. .

A) I B) II C) III D) IV E) None of these are examples of resonance

Ans: C

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452

Topic: Resonance

30. Which is not a proper resonance structure for 1,3-butadiene? A) CH2=CH–CH=CH2 B)

CH CH2CHCH2

C) CH CH2CHCH2

D) CHCH2 CH CH2

E) All are correct Ans: B

Topic: Resonance

31. Which pair does not represent a pair of resonance structures?

III

CH2 CH2

CH2 CH3

and

A) I B) II C) III D) IV E) All of these represent pairs of resonance structures.

Ans: D

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Topic: Reaction Mechanisms and Control

32. A thermodynamically-controlled reaction will yield predominantly: A) the more/most stable product. B) the product whose formation requires the smallest free energy of activation. C) the product that can be formed in the fewest steps. D) the product that is formed at the fastest rate. E) the product which possesses the greatest potential energy.

Ans: A Topic: Reaction Mechanisms and Control

33. A reaction under kinetic (or rate) control will yield predominantly: A) the most stable product. B) the product that can be formed in the fewest steps. C) the product whose formation requires the smallest free energy of activation. D) the product with the greatest potential energy. E) the product with the least potential energy.

Ans: C Topic: Reaction Mechanisms and Control

34. The accompanying diagram, which describes the fate of the intermediate in a reversible reaction, implies that:

reaction coordinate A) the less stable product forms more rapidly. B) the more stable product forms more rapidly. C) product B will predominate at equilibrium. D) the intermediate has a short lifetime. E) No conclusions can be drawn as to either reaction rate or product stability.

Ans: B

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Topic: Reaction Mechanisms and Control

35. The accompanying diagram implies that:

reaction coordinate A) The formation of B from A would be favored at high temperature. B) The more stable product forms more rapidly from the intermediate species. C) The formation of the intermediate from A is the rate-limiting step in the transformation

of A into B D) The formation of B from A is not a concerted reaction. E) All of the above statements are true

Ans: E Topic: Diels-Alder Reaction

36. Which is an untrue statement concerning the Diels-Alder reaction? A) The reaction is a syn addition. B) The diene must be in the s-cis conformation to react. C) Most Diels-Alder reactions are reversible. D) Generally, the adduct formed most rapidly is the exo product. E) Depending on the nature of the dienophile, both electron-releasing and electron-

withdrawing groups in the diene can favor adduct formation. Ans: D

Topic: Diels-Alder Reaction

37. does not undergo the Diels-Alder reaction because:

A) ring systems cannot function as the diene component. B) it cannot adopt the s-cis conformation. C) it lacks electron-withdrawing groups. D) it lacks strong electron-releasing groups. E) the two double bonds are further apart than in a non-cyclic conjugated system.

Ans: B

Chapter 13

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Topic: Diels-Alder Reaction

38. does not undergo the Diels-Alder reaction because:

Ans: B Topic: Diels-Alder Reaction

39. Which of these dienes is the most reactive in the Diels-Alder reaction? A) 1,3-Butadiene B) 1,4-Pentadiene C) Cyclopentadiene D) 1,2-Butadiene E) 1,4-Cyclohexadiene

Ans: C Topic: Diels-Alder Reaction

40. Which of these dienes can undergo the Diels-Alder reaction? A) 1,3-Pentadiene B) 1,4-Pentadiene C) 1,2-Butadiene D) 1,4-Cyclohexadiene E) All of the above can undergo the Diels-Alder reaction

Ans: A Topic: Diels-Alder Reaction

41. Which of these dienes can undergo the Diels-Alder reaction? A) 1,2-Heptadiene B) 1,3-Heptadiene C) 1,4-Heptadiene D) 1,5-Heptadiene E) 1,6-Heptadiene

Ans: B

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Topic: Diels-Alder Reaction

42. Which diene and dienophile would you choose to synthesize the following compound?

COCH3

and CH2 CH2 and

and and

HC CCOCH3

CH2 CHCOCH3

I II

III IVA) I B) II C) III D) IV E) None of these

Ans: C Topic: Diels-Alder Reaction

43. Which diene would be least reactive toward Diels-Alder addition of maleic anhydride?

CH CH2CHCH2 C CH2CHCH2

CH3

C CH2CCH2

CH3CH3

I II III

IV VA) I B) II C) III D) IV E) V

Ans: E

Chapter 13

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Topic: Diels-Alder Reaction

44. What would be the product of the following reaction?

CHCCH3CH2

I II III IV

O+

heat

CCH

CH3

CH2C C

CH3

A) I B) II C) III D) IV E) All of these

Ans: C

Chapter 13

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Topic: Diels-Alder Reaction

45. How would you synthesize:

III

COCH3

1,3-Cyclohexadiene + CHCOCH3,CH2

then RCOOH

1,3-Cyclohexadiene + CHCOCH3,CH2

thenRCOOH,

COCH3

CH2

CH2+

1,4-Cyclohexadiene + CHCOCH3,CH2

thenCH2

CH2

COCH3

OCH2CH2+V

A) I B) II C) III D) IV E) V

Ans: A

Chapter 13

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Topic: Diels-Alder Reaction

46. Which of the following would afford a synthesis of the following compound?

CHO

CH3CH CHCH32 +CHO

CH3CH CH2

CHO

CH2 CHCHO+

III

A) I B) II C) III D) IV E) None of these

Ans: D

Chapter 13

460

Topic: Diels-Alder Reaction

47. Which diene would you expect to react most rapidly with maleic anhydride?

CH3

CH3C

OI II III IV V

A) I B) II C) III D) IV E) V

Ans: D Topic: Diels-Alder Reaction

48. Which of these conjugated dienes can undergo a Diels-Alder reaction?

CH2 CH2

C(CH3)3CH2

(CH3)3C

I II III IV VA) I B) II C) III D) IV E) V

Ans: C

Chapter 13

461

Topic: Diels-Alder Reaction

49. Which of these conjugated dienes can undergo a Diels-Alder reaction?

I II III

IV V

A) I and V B) I, II and V C) III D) IV E) III and IV

Ans: D

Chapter 13

462

Topic: Diels-Alder Reaction

50. Which diene and dienophile would you choose to synthesize the following compound?

OHCOCH3

COCH3

O O

and O2and

CH2 CH COCH3

Oand and

HC C COCH3

I II

III IVA) I B) II C) III D) IV E) None of these

Ans: C

Chapter 13

463

Topic: Diels-Alder Reaction

51. Which diene and dienophile would you choose to synthesize the following compound?

CHO

CHOH

CHO

OHC

CHO

II III

V VIA) I and VI B) II and V C) III and IV D) IV and V E) I and III

Ans: E

Chapter 13

464

Topic: Diels-Alder Reaction

52. Which compounds could be used in a Diels-Alder synthesis of

CH2 CHCO2CH3 HC CCO2CH3

CH3

CO2CH3

CH3

CH3 CH3

CH3

I II III IVA) I and III B) I and IV C) II and III D) II and IV

Ans: C Topic: Diels-Alder Reaction

53. Which is the major product of the following reaction?

H C

CO2H

CO2HCO2H

CO2H

I II III IV

+ ?

A) I B) II C) III D) IV E) None of these

Ans: D

Chapter 13

465

Topic: Diels-Alder Reaction

54. Which is the major product of the following reaction?

CHO

III III V

HCHO

CHO

CHOH

CHOCHO

HCHO

CHO

+ ?

A) I B) II C) III D) IV E) V

Ans: A Topic: Diels-Alder Reaction

55. Which is the major product of the following reaction?

CHO

III III V

HCHO

CHO

CHOH

CHOCHO

CHO

CHOOHC+ ?

A) I B) II C) III D) IV E) V

Ans: D

Chapter 13

466

Topic: Diels-Alder Reaction

56. Which is the major product of the following reaction?

CHO

III III V

HCHO

CHO

CHOH

H CHO

CHO

CHO+ ?

A) I B) II C) III D) IV E) V

Ans: III

Chapter 13

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Topic: Diels-Alder Reaction

57. Which diene and dienophile would you choose to synthesize the following compound?

COCH3

and O2and

CH2 CH COCH3

Oand and

HC C COCH3

I II

III IV

OCOCH3

A) I B) II C) III D) IV E) None of these

Ans: B Topic: Diels-Alder Reaction

58.

Which of the following can undergo the Diels Alder reaction?

III

A) I and II B) II and III C) III and IV D) I, II and V E) V

Ans: C

Chapter 13

468

Topic: Diels-Alder Reaction

59. From the standpoint of reactivity, which is the poorest choice of dienophile to react with 2,3-dimethyl-1,3-butadiene in a Diels-Alder reaction?

I II

O O

III

H3CO

OCH3O

OCH3H3CO

A) I B) II C) III D) IV E) V

Ans: B

Chapter 13

469

Topic: Diels-Alder Reaction

60. What is the product of the following reaction?

CH CH2+

CH3C C C CCH3

OO?

COCH3

COCH3COCH3

COCH3

COCH3 COCH3

COCH3

I II III

IV VA) I B) II C) III D) IV E) V

Ans: A

Chapter 13

470

Topic: Diels-Alder Reaction

61. Which would be the best synthesis of the following compound?

CO2CH3CO2CH3

CO2CH3

+CO2CH3

CO2CH3

+CO2CH3

+CH3O2C

CO2CH3

+ + 2 HCO2CH3

I II III

IV V

A) I B) II C) III D) IV E) V

Ans: B

Chapter 13

471

Topic: Diels-Alder Reaction

62. Which reaction would produce the following compound?

CO2CH3

+CO2CH3

CO2CH3

+CO2CH3

CH3O2C

I II

III IV

CO2CH3

+CO2CH3

CO2CH3

A) I B) II C) III D) IV E) None of the above

Ans: D

Chapter 13

472

Topic: Diels-Alder Reaction

63. Which of the following pairs of compounds could be used as the basis for a Diels-Alder synthesis of the compound shown below?

CO2CH3

CH3CH CHCH32 +CO2CH3

CH3CH CH2

CO2CH3

CH2 CHCO2CH3+

III

A) I B) II C) III D) IV E) More than one of the above

Ans: D

Chapter 13

473

Topic: Multi-step Synthesis

64. How could the following synthesis be carried out?

CH2CH3

A) (1) Br2/CCl4; (2) CH3CH2MgCl, ether; (3) CH3ONa/CH3OH B) (1) HBr, 80°C; (2) (CH3CH2)2CuLi, ether C) (1) HBr, 80°C; (2) Mg, ether; (3) CH3CH2OH, then H3O+ D) More than one of the above E) All of the above

Ans: B Topic: Multi-step Reaction Sequence

65. How could the following synthesis be carried out?

A) (1) Br2/CCl4; (2) CH3MgCl, ether; (3) CH3ONa/CH3OH B) (1) HBr (1 eq); (2) (CH3)2CuLi, ether C) (1) HBr (1eq); (2) Li, ether; (3) CuI; (4) CH3Br D) More than one of the above E) All of the above

Ans: C Topic: Allylic Substitution

66. What product(s) would you expect from the following substitution reaction of 14C-labeled propene?

14CH2 CH CH3

Cl2

500 oC?

A) 14CH2=CH–CH2Cl alone B) 14CH2=CH–CH2Cl and CH2=CH–14CH2Cl, in equal amounts C) CH2=CH–14CH2Cl alone D) more 14CH2=CHCH2Cl, but a little CH2=CH–14CH2Cl E) more CH2=CH–14CH2Cl, but a little 14CH2=CHCH2Cl

Ans: B

Chapter 13

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Topic: Allylic Substitution

67. What product(s) would you expect from the following substitution reaction?

ClCl Cl Cl

I II III IV

* * * *

Cl2500oC

* ?

A) I B) II C) III D) IV E) More than one of the above

Ans: E Topic: Synthesis of Allylic Halides

68. Which of the following could be used to synthesize 3-bromopropene? A)

CH3CH CH2 + Br225 oC

CCl4B)

CH3CH CH2 + N-bromosuccinimideCCl4

ROOR

C) CH2=CHCH2OH + PBr3 ⎯⎯⎯⎯→ D) More than one of these E) None of these

Ans: D Topic: Synthesis of Allylic Halides

69. Which of the following could be used to synthesize 3-bromocyclopentene? A) Cyclopentene + Br2, CCl4 , 25o B) Cyclopentene + NBS, CCl4 (ROOR) C) 3-Cyclopentenol + PBr3 D) Both A) and B) E) Both B) and C)

Ans: E

Chapter 13

475

Topic: Synthesis of Allylic Halides

70. Treatment of 2-butene (cis or trans) with N-bromosuccinimide in CCl4 would yield mainly:

A) CH3CHBrCHBrCH3 alone B) CH3CH=CBrCH3 alone C) CH3CH=CHCH2Br alone D) CH2BrCH2CH=CH2 and CH3CH=CHCH2Br E) CH3CHBrCH=CH2 and CH3CH=CHCH2Br

Ans: E Topic: Synthesis of Allylic Halides

71. Treatment of 4-methylcyclohexene with N-bromosuccinimide in CCl4 would yield mainly:

Br Br

I II III IV A) I B) II C) III D) IV E) All of the above

Ans: E

Chapter 13

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Topic: Multistep Reactions

72. Which would be the best synthesis?

CH2 CHCH3

?CH2CHCH2Cl

Br BrA)

PropeneBr2, CCl4 Cl2, hν

B) Propene

Cl2, 400 oC Br2, CCl4

C) Br2, hνPropene

HCl

D) Propene

Cl2, CCl4NBS, CCl4

E) Propene

Cl2, CCl4 NBS, CCl4

Ans: B Topic: Ozonolysis of Polyenes

73. Which is the diene that yields on ozonolysis (O3, followed by Zn/HOAc) an equimolar

mixture of CH2O, CH3CHO, and

CHO

CH2

CHO

CH2 CH

CH3

CH CH CH2 CH3

CH2 CH CH2 CH CH CH3 CH2 CH CH2 CH2 CH CH2

I II III

IV V

A) I B) II C) III D) IV E) V

Ans: D

Chapter 13

477

Topic: Allylic Halogenation

74. What is (are) the product(s) of the following reaction?

Cl ClCl

I II III

Cl2400oC

A) I B) II C) III D) a mixture of I and II E) a mixture of II and III

Ans: E Topic: Allylic Halogenation

75. Which set of conditions does not result in allylic halogenation of an alkene? A) Cl2 at 400°C B) Cl2 in CCl4 at 25°C C) Cl2, ROOR,hν D) Br2 at low concentration in CCl4 E) N-Bromosuccinimide in CCl4, ROOR

Ans: B Topic: Allylic Halogenation

76.

Which carbon of

CH3 CH CH2 CH CH2

CH3

V IV III II I is predicted to be the major site of substitution when this alkene reacts with chlorine at 400°C?

A) I B) II C) III D) IV E) V

Ans: C

Chapter 13

478

Topic: Allylic Halogenation

77. Which carbon is predicted to be the major site of substitution when this alkene reacts with NBS?

IIII IV

A) I B) II C) III D) IV E) V

Ans: B Topic: Diene Synthesis

78. Which of these is not a useful method for the synthesis of 1,3-pentadiene? A) 1,4-pentanediol + H2SO4 at 180oC B) 2,4-dibromopentane + (CH3)3COK , (CH3)3COH at 75oC C) 2,4-pentanediol + H2SO4 at 180oC D) HC≡CCH=CHCH3 + H2, Ni2B (P-2) E) 1,4-dibromopentane + CH3CH2ONa , CH3CH2OH at 75oC

Ans: B

Chapter 13

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Topic: Conjugate Addition Reactions

79. Ignoring stereochemistry, the 1:1 reaction of bromine with 1,3-cyclohexadiene at 25°C in the dark and in the absence of peroxide forms which of these?

Br Br Br

Br Br

I II III IVA) I B) II C) III D) IV E) Both I and II

Ans: E Topic: Conjugate Addition Reactions

80. Which is the only compound which can be completely ruled out as a product of the reaction of 1,3-butadiene with HCl?

A) (S)-3-chloro-1-butene B) (R)-3-chloro-1-butene C) (E)-1-chloro-2-butene D) (Z)-1-chloro-2-butene E) (Z)-2-chloro-2-butene

Ans: E Topic: Diene Synthesis

81. Hot alumina can be used as an effective dehydrating agent: when 3-methyl-2,3-pentanediol vapor is passed over hot alumina (Al2O3), the chief product to be expected is which of these?

A) 2-Ethyl-1,3-butadiene B) 3-Methyl-1,3-pentadiene C) 3-Methyl-1,2-pentadiene D) 3-Methyl-2,3-pentadiene E) 3-Methyl-1,4-pentadiene

Ans: B

Chapter 13

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Topic: Allylic Halogenation

82. An unsaturated product results from the reaction of cyclohexene with which of these? A) Br2/CCl4 at 25°C B) NBS/CCl4, ROOR C) HCl, ROOR D) HCl, no peroxides E) More than one of these

Ans: B Topic: Conjugate Addition Reactions

83. Which of the following dienes might react with bromine in CCl4 to yield 2,5-dibromo-3-hexene?

A) CH2=CHCH2CH2CH=CH2 B) CH2=CHCH=CHCH2CH3 C) CH3CH=C=CHCH2CH3 D) CH3CH=CHCH=CHCH3 E) CH3CH=CHCH2CH=CH2

Ans: D Allylic Halogenation

84. What product(s) would you expect from the following substitution reaction of 14C-labeled propene?

14CH2 CH CH3

N-bromosuccinimide

ROOR, CCl4?

A) 14CH2=CH–CH2Br alone B) 14CH2=CH–CH2Br and CH2=CH–14CH2Br in equal amounts C) CH2=CH–14CH2Br alone D) More 14CH2=CHCH2Br but a little CH2=CH–14CH2Br E) More CH2=CH14CH2Br but a little 14CH2=CHCH2Br

Ans: B

Chapter 13

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Allylic Halogenation

85. Treatment of 2-butene (cis or trans) with Cl2 at 400°C would yield mainly: A) CH2ClCHClCH2CH3 B) CH3CHClCH2CH3 C) CH3CH=CClCH3 D) CH3CH=CHCH2Cl and CH3CHClCH=CH2 E) CH3CHClCHClCH3

Ans: D Topic: Conjugate Addition Reactions

86. Indicate which products would be obtained from the chlorination of 1,5-hexadiene at high temperature (500°C), using a 1:1 mole ratio of the reactants.

ClCH2CHCH2CH2CH CH2

CHCH CHCH2ClClCH2CH

CHCH2CH CH2ClCH2CH

CHCH2CHCH CH2CH2

ClCH2CHCH2CH2CHCH2Cl

Cl Cl

I II

III

IVA) I and II B) II and III C) III and IV D) IV and V E) V and I

Ans: C

Chapter 13

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Topic: 1,2 Reactions of Conjugated Dienes

87. Which reagent would convert 1,3-pentadiene into 3-penten-2-ol?

A) KMnO4/-OH B) OsO4 C) H2O2, then H3O+ D) Cl2/H2O E) H3O+

Ans: E Topic: 1,2 Reactions of Conjugated Dienes

88. Which reagent would convert 1,3-octadiene into 3-octen-2-ol? A) KMnO4/-OH B) OsO4 C) H2O2, then H3O+ D) Cl2/H2O E) H3O+

Ans: E Topic: UV-Vis Spectroscopy

89. Which compound would have an UV absorption band at longest wavelength?

CH CHCH3

CHCH CH CHCH3

CH2CH CH2 CH CHCH3

CH2

I II III

IV VA) I B) II C) III D) IV E) V

Ans: B

Chapter 13

483

Topic: UV-Vis Spectroscopy

90. Select the most energetically favorable UV transition for 1,3-butadiene. A) n ⎯⎯⎯→ σ* B) n ⎯⎯⎯→ π* C) π2 ⎯⎯⎯→ π3* D) σ ⎯⎯⎯→ σ* E) π1 ⎯⎯⎯→ π4*

Ans: C Topic: UV-Vis Spectroscopy

91. Which compound would have an UV absorption band at longest wavelength?

CH CH CH

CHCH2CH2CH

CHCH CH2 CHCH CH2 CHCH CH2

CH2 CHCH CH2

I II III

IV VA) I B) II C) III D) IV E) V

Ans: A Topic: UV-Vis Spectroscopy

92. Which of these symbols is used in connection with the intensity of absorption in the UV-visible region?

A) ∝ B) ν C) ε D) λ E) θ

Ans: C

Chapter 13

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Topic: Allylic Halogenation

93. Which of the following compounds is not formed as a result of a chain-termination step in the free radical chlorination of propene?

A) CH2=CHCH2Cl B) Cl2 C) CH2=CHCH2CH2CH=CH2 D) HCl E) All can be formed in chain-termination steps.

Ans: D SHORT ANSWER QUESTIONS Topic: General

94. Systems that have a p orbital on an atom adjacent to a double bond are called ______________ systems. Ans: conjugated unsaturated

Topic: General

95. The hydrogen atom on a saturated (sp3) carbon adjacent to a double bond is called an ______________ hydrogen. Ans: allylic

Topic: General 96. The hydrogen atom on a carbon that is part of a double bond is called a ___________

hydrogen. Ans: vinyl or vinylic

Topic: General

97. Allylic radicals are ___________ stable than tertiary radicals. Ans: more

Topic: General 98. Vinyl cations are _____________ stable than tertiary cations.

Ans: less

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Topic: General

99. There are three types of polyenes (molecules containing two or more double bonds). They are: _________________. Ans: conjugated, cumulated, isolated

Topic: General

100. Polyenes in which single and double bonds alternate along the carbon chain are called ___________. Ans: conjugated

Topic: General

101. UV-vis spectroscopy can be used to indicate whether _________________ is present. Ans: conjugation

Topic: General

102. When the product distribution for a particular reaction reflects the relative stabilities of the products, the reaction is said to be under ______________ control. Ans: thermodynamic

Topic: General

103. When the product distribution for a particular reaction reflects the relative rate at which the products are formed, the reaction is said to be under _______________ control. Ans: kinetic

Topic: General

104. The Diels-Alder reaction is a cycloaddition between a conjugated ________ and a ___________. Ans: diene; dienophile

Topic: General

105. A thermodynamically-controlled reaction will yield predominantly:___________. Ans: the more/most stable product.

Topic: General

106. A reaction under kinetic (or rate) control will yield predominantly:___________. Ans: the product whose formation requires the smallest free energy of activation.

Chapter 13

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Topic: General

107. Stereochemically speaking, the Diels-Alder reaction is ___________ and occurs with ___________ of the dienophile stereochemistry. Ans: stereospecific; retention

Topic: General

108. Conjugated dienes routinely undergo 1,2 and 1,4 addition reactions with a variety of electrophilic reagents; this suggests that ___________ are likely intermediates during these reactions. Ans: allylic carbocations

Topic: Diels –Alder Reactions

109. During Diels Alder reactions, when two stereoisomer products, exo and endo, are possible, the ___________ product is typically obtained as the major product. Ans: endo

Topic: Nomenclature

110. Draw the structural formula for (2E,4Z,6E)–3,4,7,8–tetramethyl-2,4,6–nonatriene, clearly indicating stereochemical details. Ans:

Topic: Nomenclature

111. Draw the structural formula for (2Z,4Z,6Z)-3,4,8-trimethyl-2,4,6-nonatriene,clearly indicating stereochemical details. Ans:

Topic: Nomenclature

112. Draw the structural formula for (R)-5-bromo-2,5-dimethyl-1,3-cyclopentadiene, clearly indicating stereochemical details. Ans: CH3

Chapter 13

487

Topic: Multistep Reactions

113. Complete the following sequence of reactions, giving structural details of all key intermediates.

O+

heatA B

H2Ni

Ans: O

O+ heat

H2, Ni

+ +

Chapter 13

488

Topic: Multistep Reactions

114. Complete the following sequence of reactions, giving structural details of all key intermediates.

i) NBSii) (CH3)3COK, (CH3)3COH, heatiii) trans CH3CH=CHCHO

Ans:

NBSBr

O O

(CH3)3COK,(CH3)3COH, heat

Topic: Multistep Reactions

115. Complete the following sequence of reactions, giving structural details of all key intermediates.

i) cis-CH3CH=CHCHO

ii) CH3CH2MgBr

iii) H3O+

Ans: CHO CH3

HCH3

Hi) CH3CH2MgBr

ii) H3O+

Topic: Diels Alder Reaction

116. What reagents would be needed to synthesize the following substance via the Diels-Alder reaction? Give stereochemical details, as relevant.

O Ans:

Chapter 14

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MULTIPLE CHOICE QUESTIONS Topic: Bonding and Resonance

1. Which of the following is NOT true of benzene? A) Benzene tends to undergo substitution rather than addition reactions, even though it has

a high index of hydrogen deficiency. B) All of the hydrogen atoms of benzene are equivalent. C) The carbon-carbon bonds of benzene are alternately short and long around the ring. D) Only one o-dichlorobenzene has ever been found. E) Benzene is more stable than the hypothetical compound 1,3,5-cyclohexatriene.

Ans: C Topic: Bonding and Resonance

2. Which of the following is true of benzene? A) Benzene tends to undergo addition rather than substitution reactions. B) All of the hydrogen atoms of benzene are equivalent. C) The carbon-carbon bonds of benzene are alternately short and long around the ring. D) The benzene ring is a distorted hexagon. E) Benzene has the stability expected for cyclohexatriene.

Ans: B Topic: Bonding and Resonance

3. The carbon-carbon bonds in benzene are: A) of equal length and are shorter than the double bond of ethene. B) of equal length and are intermediate between a double bond and a single bond. C) of unequal length and are alternately short and long around the ring. D) due only to p-orbital overlap. E) of equal length and intermediate between the carbon-carbon bond lengths in ethene and

ethyne. Ans: B

Topic: Nomenclature, Bonding and Resonance

4. In which of the following compounds would the shortest carbon-carbon bond(s) be found?

A) Toluene B) 2-Ethylcyclopentene C) 4-Methyl-1,3-cyclohexadiene D) 3-Methyl-1-hexyne E) 3-Methyl-1,3-hexadiene

Ans: D

Chapter 14

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Topic: Bonding and Resonance

5. We now know that the two Kekule structures for benzene are related in the following way:

A) They are each equally correct as a structure for benzene. B) Benzene is sometimes one structure and sometimes the other. C) The two structures are in a state of rapid equilibrium. D) Neither of the two structures adequately describes benzene; benzene is a resonance

hybrid of the two. E) None of the above

Ans: D Topic: Nomenclature, Bonding and Resonance

6. In which of the following compounds would the longest carbon-carbon bond(s) be found?

A) 2-bromobenzaldehyde B) Vinylbenzene C) 1,3,5-heptatriene D) 2,4,6-octatriene E) 2-Ethylbenzoic acid

Ans: D Topic: Aromatic/ Antiaromatic/ Nonaromatic

7. Which of the following statements regarding the cyclopentadienyl radical is correct? A) It is aromatic. B) It is not aromatic. C) It obeys Huckel's rule. D) It undergoes reactions characteristic of benzene. E) It has a closed shell of 6 pi-electrons.

Ans: B

Chapter 14

491

Topic: Aromaticity, Huckel Rule

8. Which of the following would you expect to be aromatic?

I II III IV V

A) I B) II C) III D) IV E) V

Ans: E Topic: Aromaticity, Huckel Rule

9. Which of these would you expect to have significant resonance stabilization energy?

I II III

NNH

A) I B) II C) III D) All of the above E) None of the above

Ans: D

Chapter 14

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Topic: Aromaticity, Huckel Rule

10. Of the following C-10 compounds, which is expected to possess the greatest resonance (delocalization) energy?

I II III IV VA) I B) II C) III D) IV E) V

Ans: C Topic: Aromaticity, Huckel Rule

11. Which of the following would you expect to be aromatic?

IVI II III

H H

A) I B) II C) III D) IV E) None of these

Ans: B

Chapter 14

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Topic: Aromaticity, Huckel Rule

12. Which compound would you NOT expect to be aromatic?

IVI II III V

NS N O B

H R

A) I B) II C) III D) IV E) V

Ans: E Topic: Aromaticity, Huckel Rule

13. Which annulene would you NOT expect to be aromatic? A) [6]-Annulene B) [14]-Annulene C) [16]-Annulene D) [18]-Annulene E) [22]-Annulene

Ans: C Topic: Aromaticity, Huckel Rule

14. Which of the following would you expect to be aromatic?

IVI II IIIA) I B) II C) III D) IV E) All of these

Ans: A

Chapter 14

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Topic: Aromaticity, Huckel Rule

15. Which of these species is aromatic?

IVI II III V

NH O N

A) I B) II C) III D) IV E) V

Ans: B Topic: Aromaticity, Huckel Rule

16. Which of the following structures would be aromatic?

IVI II III V

-2

KK Br Br

A) I B) II C) III D) IV E) V

Ans: B

Chapter 14

495

Topic: Aromaticity, Huckel Rule

17. Which of the following would you expect to be antiaromatic?

IVI II III VA) I B) II C) III D) IV E) V

Ans: C Topic: Aromaticity, Huckel Rule

18. Which of the following would you expect to be aromatic?

IVI II III

H H

A) I B) II C) III D) IV E) None of the above

Ans: C

Chapter 14

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Topic: Aromaticity, Huckel Rule

19. On the basis of molecular orbital theory and Huckel's rule, which molecules and/or ions should be aromatic?

IVI II III V

H H H H

VI VII VIII IX

A) I and V B) III and VIII C) IV, VII and IX D) IV, VI, VII and IX E) All of the structures, I-IX

Ans: D Topic: Aromaticity, Huckel Rule

20. On the basis of molecular orbital theory and Huckel's rule, which of these compounds should be aromatic?

I II III IV VA) I B) II C) III D) IV E) V

Ans: E

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Topic: Aromaticity, Huckel Rule

21. Of Huckel's requirements for aromatic character, only this one is waived in the case of certain compounds considered to be aromatic.

A) The ring system must be planar. B) The system must be monocyclic. C) There must be (4n + 2) π electrons. D) The Huckel number of electrons must be completely delocalized. E) None. All of these rules must apply in every case.

Ans: B Topic: Aromaticity, Huckel Rule

22. Which of these is an aromatic molecule?

I II III IV V

N O BS

CH3 CH3 ONH

A) I B) II C) III D) IV E) V

Ans: A Topic: Aromaticity, Huckel Rule

23. In which case is the indicated unshared pair of electrons NOT a contributor to the π aromatic system?

I II III IV

N OH

A) I B) II C) III D) IV E) None of these

Ans: B

Chapter 14

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Topic: Chemical Tests and Reactions

24. Which reagent(s) would serve as the basis for a simple chemical test that would distinguish between benzene and 1-hexene?

A) NaOH in H2O B) Br2 in CCl4 C) AgNO3 in C2H5OH D) NaHSO3 in H2O E) None of these

Ans: B Topic: Chemical Tests and Reactions

25. Which reagent(s) would serve as the basis for a simple chemical test that would distinguish between ethylbenzene and vinylcyclohexane?

A) H2CrO4 B) LAH C) NaBH4, H2O D) KMnO4, OH−, H2O E) Two of the above

Ans: D Topic: Chemical Tests and Reactions

26. Which reagent(s) would serve as the basis for a simple chemical test that would distinguish between naphthalene and 2,4,6-decatriene?

A) NaOH in H2O B) KMnO4, OH−, H2O C) NaBH4, H2O D) H2CrO4 E) None of these

Ans: B Topic: Chemical and Spectroscopic Analysis

27. Which reagent(s)/technique would serve to distinguish between azulene and bicyclo[5.3.0]decane?

A) Br2, CCl4 B) KMnO4, OH−, H2O C) NMR Spectroscopy D) UV Spectroscopy E) Two of these

Ans: E

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Topic: Chemical Tests and Reactions

28. Which is the only one of these reagents which will react with benzene under the specified conditions?

A) Cl2, FeCl3, heat B) H2, 25°C C) Br2/CCl4, 25°C, dark D) KMnO4/H2O, 25°C E) H3O+, heat

Ans: A Topic: Nomenclature and Isomerism

29. Which dibromobenzene can, in theory, yield three mononitro derivatives? A) o-Dibromobenzene B) m-Dibromobenzene C) p-Dibromobenzene D) All of these E) None of these

Ans: B Topic: Nomenclature and Isomerism

30. If thiophene is an aromatic molecule and reacts similarly to benzene, how many (neutral) monobromothiophenes could be obtained in the following reaction?

S Br2FeBr3

A) 1 B) 2 C) 3 D) 4 E) 5

Ans: B

Chapter 14

500

Topic: Nomenclature and Isomerism

31. 2-Bromo-4-nitroaniline is:

I II

III

NO2

BrOCH3

NH2

NO2

NH2

NO2

H2N

NO2

H3COBr

A) I B) II C) III D) IV E) V

Ans: C Topic: Nomenclature and Isomerism

32. 4-Bromo-2-nitroaniline is:

I II

III

NO2

BrOCH3

NH2

NO2

NH2

NO2

H2N

NO2

H3COBr

A) I B) II C) III D) IV E) V

Ans: A

Chapter 14

501

Topic: Nomenclature and Isomerism

33. 4-Amino-2-chlorophenol is:

I II

III

NH2

ClOH

NO2

ClNH2

Cl OHO

H2N

NO2

ClOH

A) I B) II C) III D) IV E) V

Ans: D Topic: Nomenclature and Isomerism

34. 4-Chloro-3-nitro-benzaldehyde is:

I II

III

NH2

ClOH

NO2

ClNH2

Cl OHO

H2N

NO2

ClOH

A) I B) II C) III D) IV E) V

Ans: B

Chapter 14

502

Topic: Nomenclature and Isomerism

35. 4-amino-2-chlorobenzaldehyde is:

I II

III

NH2

ClOH

NO2

ClNH2

Cl OHO

H2N

NO2

ClOH

A) I B) II C) III D) IV E) V

Ans: C Topic: Nomenclature and Isomerism 36. 4-amino-2-bromoanisole is:

I II

III

NH2

BrOCH3

NO2

H3CONH2

Br OCH3O

H2N

NO2

BrOCH3

A) I B) II C) III D) IV E) V

Ans: D

Chapter 14

503

Topic: Nomenclature and Isomerism

37. 4-bromomethyl-2-nitroanisole is:

I II

III

NH2

BrOCH3

NO2

H3CONH2

Br OCH3O

H2N

NO2

BrOCH3

A) I B) II C) III D) IV E) V

Ans: B Topic: Nomenclature and Isomerism

38. How many different dibromophenols are possible? A) 8 B) 7 C) 6 D) 5 E) 4

Ans: C Topic: Nomenclature and Isomerism

39. The correct name for the compound shown below is:

NH2

A) 3,4-Dibromoaniline B) 2,4-Dibromoaniline C) 2,5-Dibromoaniline D) 3,6-Dibromoaniline E) 2,6-Dibromoaniline

Ans: C

Chapter 14

504

Topic: Nomenclature and Isomerism

40. Which dibromobenzene can yield only one mononitro derivative? A) o-Dibromobenzene B) m-Dibromobenzene C) p-Dibromobenzene D) More than one of these E) None of these

Ans: C Topic: Nomenclature and Isomerism

41. A dichlorobenzene that on reaction with nitric acid and sulfuric acid might theoretically yield three mononitro products would be:

A) o-Dichlorobenzene B) m-Dichlorobenzene C) p-Dichlorobenzene D) None of these E) All of these

Ans: B Topic: Nomenclature and Isomerism

42. In theory, a single molecule of this compound will rotate plane-polarized light. A) Butylbenzene B) Isobutylbenzene C) sec-Butylbenzene D) tert-Butylbenzene E) None of these

Ans: C

Chapter 14

505

Topic: Nomenclature and Isomerism

43. Which of the following is NOT 2-bromo-5-nitrobenzoic acid?

I II

III

NO2

O2N OH

NO2HO

NO2

HO O

A) I B) II C) III D) IV E) V

Ans: D Topic: Nomenclature and Isomerism

44. Toluene is the name commonly assigned to: A) Hydroxybenzene B) Aminobenzene C) Methylbenzene D) Ethylbenzene E) Methoxybenzene

Ans: C Topic: Nomenclature and Isomerism

45. Anisole is the name commonly assigned to: A) Hydroxybenzene B) Aminobenzene C) Methylbenzene D) Ethylbenzene E) Methoxybenzene

Ans: E

Chapter 14

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Topic: Nomenclature and Isomerism

46. Phenol is the name commonly assigned to: A) Hydroxybenzene B) Aminobenzene C) Methylbenzene D) Ethylbenzene E) Methoxybenzene

Ans: A Topic: Nomenclature and Isomerism

47. Aniline is the name commonly assigned to: A) Hydroxybenzene B) Aminobenzene C) Methylbenzene D) Ethylbenzene E) Methoxybenzene

Ans: B Topic: Nomenclature and Isomerism

48.

The complete name for the following compound is:

CH3

A) sec-Hexylbenzene B) 2-Phenylhexane C) (R)-2-Phenylhexane D) (S)-2-Phenylhexane E) Butylmethylphenylmethane

Ans: D Topic: Nomenclature and Isomerism

49. How many dichloronaphthalenes are possible? A) 7 B) 8 C) 9 D) 10 E) 12

Ans: D

Chapter 14

507

Topic: Nomenclature and Isomerism

50. Which of these is the single best representation for naphthalene?

III

A) I B) II C) III D) IV E) V

Ans: A Topic: Molecular Orbital Theory

51. How many equivalent resonance structures can be written for the cyclopentadienyl anion?

A) 3 B) 4 C) 5 D) 6 E) 7

Ans: C Topic: Molecular Orbital Theory

52. In the molecular orbital model of benzene, the six p-orbitals combine to form how many molecular orbitals?

A) 6 B) 5 C) 4 D) 3 E) 2

Ans: A

Chapter 14

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Topic: Molecular Orbital Theory

53. Consider the molecular orbital model of benzene. In the ground state how many molecular orbitals are filled with electrons?

A) 1 B) 2 C) 3 D) 4 E) 5

Ans: C Topic: Molecular Orbital Theory

54. In the molecular orbital model of benzene, how many pi-electrons are delocalized about the ring?

A) 2 B) 3 C) 4 D) 5 E) 6

Ans: E Topic: Molecular Orbital Theory

55. In the molecular orbital model of benzene, how many pi-electrons are in bonding molecular orbitals?

A) 6 B) 5 C) 4 D) 3 E) 2

Ans: A Topic: Molecular Orbital Theory

56. Consider the molecular orbital model of cyclopentadienyl anion. In the ground state how many molecular orbitals are filled with electrons?

A) 1 B) 2 C) 3 D) 4 E) 5

Ans: C

Chapter 14

509

Topic: Molecular Orbital Theory

57. In the molecular orbital model of cyclopentadienyl anion, how many pi-electrons are delocalized about the ring?

A) 2 B) 3 C) 4 D) 5 E) 6

Ans: E Topic: Molecular Orbital Theory

58. In the molecular orbital model of cyclopentadienyl anion, how many pi-electrons are in bonding molecular orbitals?

A) 6 B) 5 C) 4 D) 3 E) 2

Ans: A Topic: Molecular Orbital Theory

59. In the molecular orbital model of cycloheptadienyl cation, how many pi-electrons are in bonding molecular orbitals?

A) 6 B) 5 C) 4 D) 3 E) 2

Ans: A Topic: Molecular Orbital Theory

60. In the molecular orbital model of cycloheptadienyl cation, how many pi-electrons are delocalized about the ring?

A) 6 B) 5 C) 4 D) 3 E) 2

Ans: A

Chapter 14

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Topic: Molecular Orbital Theory

61. In the molecular orbital model of 1,3-cyclobutadiene, how many electrons are in non-bonding molecular orbitals?

A) 6 B) 5 C) 4 D) 3 E) 2

Ans: E Topic: Molecular Orbital Theory

62. In the molecular orbital model of which of the following substance(s) are non-bonding orbitals found?

A) 1,3-Cyclobutadiene B) Cyclopentadienyl anion C) 1,3,5,7-Cyclooctatetraene D) Two of the above E) All of the above

Ans: D Topic: Molecular Orbital Theory

63. Which cyclization(s) should occur with a decrease in pi-electron energy?

III

CH2 CH CH CH2 + H2

CH2 CH CH2 + H2

A) I B) II C) III D) IV E) All of the above

Ans: B

Chapter 14

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Topic: Molecular Orbital Theory

64. Application of the polygon-and-circle technique reveals that single electrons occupy each of the two nonbonding orbitals in the molecular orbital diagram of:

A) Cyclobutadiene B) Benzene C) Cyclopropenyl cation D) Cyclopentadienyl anion E) Cycloheptatrienyl cation

Ans: A Topic: Explanations and Predictions

65. Why would 1,3-cyclohexadiene undergo dehydrogenation readily? A) It is easily reduced. B) Hydrogen is a small molecule. C) 1,3-Cyclohexadiene has no resonance energy. D) It would gain considerable stability by becoming benzene. E) It would not undergo dehydrogenation.

Ans: D Topic: Explanations and Predictions

66. Which of the following statements about cyclooctatetraene is NOT true? A) The compound rapidly decolorizes Br2/CCl4 solutions. B) The compound rapidly decolorizes aqueous solutions of KMnO4. C) The compound readily adds hydrogen. D) The compound is nonplanar. E) The compound is comparable to benzene in stability.

Ans: E Topic: Explanations and Predictions

67. Cyclopentadiene is unusually acidic for a hydrocarbon. An explanation for this is the following statement.

A) The carbon atoms of cyclopentadiene are all sp2-hybridized. B) Cyclopentadiene is aromatic. C) Removal of a proton from cyclopentadiene yields an aromatic anion. D) Removal of a hydrogen atom from cyclopentadiene yields a highly stable free radical. E) Removal of a hydride ion from cyclopentadiene produces an aromatic cation.

Ans: C

Chapter 14

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Topic: Explanations and Predictions

68. Recalling that benzene has a resonance energy of 152 kJ mol-1 and naphthalene has a resonance energy of 255 kJ mol-1, predict the positions which would be occupied by bromine when phenanthrene (below) undergoes addition of Br2.

23 4 5 6

910

A) 1, 2 B) 1, 4 C) 3, 4 D) 7, 8 E) 9, 10

Ans: E Topic: Spectroscopy

69. Which isomer of C7H7Cl exhibits strong IR absorbances at 690 and 750 cm1?

I II III IV

CH3Cl

CH3

CH2Cl

A) I B) II C) III D) IV E) II and IV

Ans: E

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Topic: Spectroscopy

70. Which of these compounds absorbs at the longest wavelength in the UV-visible region?

I II III IV VA) I B) II C) III D) IV E) V

Ans: B Topic: Spectroscopy

71. A compound has the formula C8H9Br. Its 1H NMR spectrum consists of: doublet, δ 2.0 quartet, δ 5.15 multiplet, δ 7.35 The IR spectrum shows two peaks in the 680-840 cm-1 region; one is between 690 and 710 cm-1 and the other is between 730 and 770 cm-1. Which is a possible structure for the compound?

III

VBr

A) I B) II C) III D) IV E) V

Ans: D

Chapter 14

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Topic: Spectroscopy

72. Which of the following substances, formula C8H9Br, might exhibit the following 1H NMR spectrum ? triplet, δ 2.8 triplet, δ 4.65 multiplet, δ 7.2

III

VBr

A) I B) II C) III D) IV E) V

Ans: C

Chapter 14

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Topic: Spectroscopy

73. Which of the following substances, formula C8H9Br, might exhibit the following 1H NMR spectrum ? triplet, δ 1.2 quartet, δ 2.45 multiplet, δ 7.4

III

VBr

A) I B) II C) III D) IV E) V

Ans: A

Chapter 14

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Topic: Spectroscopy

74. Which of the following substances, formula C8H9Br, might exhibit the following 1H NMR spectrum ? singlet, δ 2.45 singlet, δ 2.5 multiplet, δ 7.35

III

VBr

A) I B) II C) III D) IV E) V

Ans: E Topic: Spectroscopy

75. Which of the following substances, C8H9Cl, would exhibit five signals in its 13C NMR spectrum?

I II

III

VCl

ClCl

A) I B) II C) III D) IV E) V

Ans: C

Chapter 14

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Topic: Spectroscopy

76. Which of the following substances, C9H10O, would exhibit seven signals in its 13C NMR spectrum?

I II III

IV V

HO O

A) I B) II C) III D) IV E) V

Ans: A Topic: Spectroscopy

77. For which of the following substances, C9H10O, would the aromatic multiplet, in its 1H NMR spectrum, consist of two doublets?

I II III

IV V

HO O

A) I B) II C) III D) IV E) V

Ans: A

Chapter 14

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Topic: Spectroscopy

78. In the 1H NMR spectra of which of the following substances, C9H10O, would you expect to see two singlets in the range of δ 2.0-2.5 ppm?

I II III

IV V

HO O

A) I and III B) I, II, and III C) IV D) V E) All of the above substances would exhibit two singlets δ 2.0-2.5 ppm in their 1H NMR

spectra Ans: B

SHORT ANSWER QUESTIONS Topic: General Concepts

79. A compound that reacts like an alkane, alkene, alkyne, or one of their derivatives, is called an _____________ compound, while one that reacts like benzene is called an _____________ compound. Ans: aliphatic, aromatic

Topic: Nomenclature

80. When a benzene ring is used as a substituent, it is called a _________ group. Ans: phenyl

Topic: General Concepts

81. The difference between the amount of heat actually released upon hydrogenation of benzene and that calculated on the basis of the Kekule structure is called the ____________________ of benzene. Ans: resonance energy

Chapter 14

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Topic: General Concepts

82. Molecular orbitals of equal energy are referred to as _________ orbitals. Ans: degenerate

Topic: Huckel’s rule

83. Hückel's Rule requires _________ π electrons for an aromatic compound. Ans: 4n+2

Topic: General Concepts

84. Monocyclic compounds with alternating single and double bonds are called __________. Ans: annulenes

Topic: General Concepts

85. Cagelike molecules with the geometry of a truncated icosahedron are called ___________. Ans: fullerenes

Topic: Aromaticity, Reactivity

86. Pyrrole is not particularly basic, because the lone pair on the nitrogen is ______________. Ans: part of the aromatic system

Topic: General Concepts

87. Humans do not have the biochemical ability to synthesize the benzene ring. Therefore, two amino acids, _____________ and ___________, are essential to the human diet. Ans: tryptophan, phenylalanine

Topic: Aromaticity, Reactivity

88. Benzene, while unusually unreactive, will react under certain conditions. However, when it does react, it does so by ___________ rather than by addition. Ans: substitution

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Topic: Nomenclature

89. Draw the structure corresponding to the following name: 2-bromo-5-nitrophenol Ans: OH

O2N Topic: Nomenclature

90. Draw the structure corresponding to the following name: 3-bromo 5-phenylacetophenone Ans: NH2

Topic: Nomenclature

91. Draw the structure corresponding to the following name: 2-hydroxy-4-(3-methylcyclopentyl)benzoic acid Ans: HO

HO2C

Topic: Nomenclature

92. Draw the structure corresponding to the following name: 3-nitro-4-iodoanisole Ans: OO2N

I Topic: Nomenclature

93. Give the IUPAC name for the following substance:

Ans: 2-methyl-4-(3-methylbutyl)benzoic acid

Topic: Resonance

94. Draw all significant resonance structures for pyridine, C6H5N Ans:

N N....

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Topic: Resonance

95. Draw all significant resonance structures for azulene, C10H8 Ans:

Topic: Aromaticity

96. Briefly explain why the aromatic hydrocarbon azulene, C10H8, possesses a significant dipole moment. Use diagrams as needed to illustrate/clarify your answer. Ans: Azulene has the bicyclic structure shown below. Since the “non-polar” resonance

hybrid meets the Huckel rule for aromaticity, it accounts for the observed aromatic properties of azulene. However, closer scrutiny suggests that a shift in electron density, in which the 7-membered ring is electron deficient and the 5-membered ring is electron-rich would be especially stable: each ring is now independently aromatic, an aromatic cycloheptatrienyl cation fused with an aromatic cyclopentadienyl anion. Thus, the most stable pi-electron distribution would suggest a polar structure for azulene, accounting for this substance having a significant dipole moment.

non-polar polar Topic: Aromaticity, Molecular Orbital Theory

97. Use the “polygon-in-circle” method to draw an MO diagram showing the pi-electron distribution pattern in the cyclopentadienyl anion. How is this diagram useful in explaining the aromatic properties of this anion? Ans: The following MO diagram can be generated using the polygon-in-circle method.

The six pi electrons of the cyclopentadienyl anion in the bonding molecular orbitals form a closed bonding shell, accounting for its aromatic properties.

Bonding MO

Antibonding MO

6 pi electrons"closed bonding shell"

Chapter 14

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Topic: Aromaticity, Reactivity

98. Explain briefly why cyclopentadiene readily reacts with strong bases. Ans: The acidity of a substance can be often be correlated with the stability of its

conjugate base: substances that have exceptionally stable conjugate bases tend to be strong acids. The conjugate base of cyclopentadiene, formed during reaction with a base, is exceptionally stable, by virtue of being an aromatic anion (6 pi electrons, planar ring), thus accounting for the readiness with which cyclopentadiene reacts with bases.

B:−

..Aromaticanion

Topic: Resonance, Bond Lengths

99. Although all bond lengths in benzene are identical, that is not always true for all aromatic compounds. In naphthalene, for instance, the C1-C2 bond is shorter than the C2-C3 bond. Explain, using resonance theory. Ans: The major resonance structures for naphthalene are drawn below. The observed

bond lengths reflect the contribution of each structure to the overall resonance hybrid: The C1-C2 bond: two double bonds (I and II), and one single bond (III) The C2-C3 bond: one double bond (III), and two single bonds (I and II) Overall: C1-C2 bond more double-bond-like, thus shorter.

II III IVI

123

shorter

longer

Chapter 14

523

Topic: Aromaticity, Resonance Stabilization Energy

100. The heats of hydrogenation for cyclohexene and benzene are given below. Calculate the resonance stabilization energy of benzene. C6H10 + H2 C6H12 ΔHo = -120 kJ/mol C6H6 + 3H2 C6H12 ΔHo = -208 kJ/mol Ans: The resonance stabilization energy of benzene is the difference between the

theoretical and observed ΔHo values. Hydrogenation of three double bonds should release 3 times the energy released when one double bond is hydrogenated. Thus, the theoretical ΔHo for benzene can be calculated as [3x (-120)] kJ/mol = -360 kJ/mol Therefore, Resonance stabilization energy of benzene = (-208) – (-360) kJ/mol = 152 kJ/mol

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Topic: Aromaticity, Reactivity

101. The Lewis structures of both pyridine and pyrrole have an electron pair on the nitrogen atom, suggesting that both substances might possess basic properties. However, only pyridine reacts readily with HCl to form pyridinium chloride, while pyrrole is rather unreactive. Explain clearly, using relevant diagrams to illustrate/clarify your answer. Ans:

N..sp2

+ HClNH

+ Cl−

pyridinium chloride

N H..p

+ HCl X

pyrrole electron pair:part of aromatic pi sextet

pyridinium chloride

not aromatic

+ Cl−

Both pyridine and pyrrole are known to exhibit aromatic properties; the nitrogen atom must therefore be sp2 hybridized in both cases. In the pyridine molecule, this places the electron pair in an sp2 hybrid orbital, and not involved in the aromatic π sextet needed for aromatic stability; the electron pair is thus “available” for reacting with HCl, forming pyridinium chloride, while preserving aromatic stability. By contrast, the electron pair in pyrrole must be placed in the p orbital, since all three sp2 orbitals are used in sigma bonds with neighboring atoms. This allows the electron pair to contribute to aromatic stability by becoming part of the aromatic sextet. Thus, the electron pair on nitrogen is not “available” for reacting with HCl, because doing so would destroy the aromaticity of the ring.

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Topic: Aromaticity, Bonding

102. Consider the oxygen atom in the molecules of furan and tetrahydrofuran. Bearing in mind that furan exhibits aromatic properties, compare the hybridization of oxygen in both species, explaining why it must be different, although at first glance, it may appear identical.

O O.. ..

....

THFFuran Ans:

Tetrahydrofuran: sp3 hybridized both electron pairs in sp3 orbitals

O..p

Furan: sp2 hybridizedone electron pair in p orbital:part of aromatic pi sextet

.. sp2....

sp3

Oxygen has 2 lone electron pairs in both species and, at first glance, it might appear that the hybridization patterns are identical. In THF, the oxygen atom is sp3 hybridized and both pairs can be placed in sp3 hybrid orbitals. In furan, there are two possibilities that must be considered: i) the oxygen may be sp3 hybridized, with both electron pairs sp3 hybrid orbitals, as in THF, or, ii) oxygen may be sp2 hybridized, with one electron pair in an sp3 hybrid orbital, the other in a p orbital. In the latter case, the electrons in the p orbital can then become part of an aromatic sextet, allowing the molecule to gain aromatic stability. Since furan is known to exhibit markedly aromatic properties, the oxygen must be sp2 hybridized.

Chapter 15

Page 526

MULTIPLE CHOICE QUESTIONS

Topic: Reaction Products

1. The major product(s), A, of the following reaction,

CH3CH2Cl2, hν

400 - 600 oC

CH3CH2 CH3CH2 CH3CHClCH2CH2Cl

Cl ClI II III IV

would be: A) I B) II C) A mixture of I and II D) III E) IV Ans: E

Topic: Reaction Products

2. What would be the major product(s) of the following reaction?

CO2H

NO2

I II III

CO2H

NO2NO2

CO2H

NO2

CO2H

NO2O2N

O2NCO2H

NO2

HNO3H2SO4, heat

A) I B) II C) III D) IV E) Equal amounts of II and IV Ans: C

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Topic: Reaction Products

3. The major product(s), C, of the following reaction,

SO3H2SO4

SO3H

SO3HHO3S

I II III

would be: A) I B) II C) III D) Equal amounts of I and II E) Equal amounts of I and III Ans: B

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Topic: Reaction Products

4. The major product(s), D, of the following reaction,

CH2

CH2 CO

CH2

CH2 CO

CH2

Br2

FeBr3D

I II

III IV

would be: A) I B) II C) III D) IV E) Equal amounts of I and II Ans: D

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Topic: Reaction Products

5. What would be the product of the following reaction sequence?

I II

III

OO OH

i) SOCl2ii) C6H6, AlCl3iii) Zn(Hg), HCl, heat

A) I B) II C) III D) IV E) V Ans: E

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Topic: Reaction Products

6. What would you expect to be the major product obtained from the following reaction?

COOH

SO3H

COOH

SO3H

COOH

SO3H

COOH

SO3H

COOH

SO3H

BrBr

I II III IV

Br2

FeBr3?

A) I B) II C) III D) IV E) Equal amounts of II and IV Ans: C

Topic: Reaction Products

7. What would be the major product of the following reaction?

CH2CH2CH3

CH2CH2CH3 CH2CH2CH3 CHCH2CH3

CH2CHCH3 CH2CH2CH2Cl

Cl Cl

Cl2400 oC

I II III

IV VA) I B) II C) III D) IV E) V Ans: C

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Topic: Reaction Products

8. What would you expect to be the major product obtained from the following reaction?

NO2

SO3H

NO2

SO3H

NO2

SO3H

NO2

SO3H

NO2

SO3H

BrBr

I II III IV

Br2

FeBr3?

A) I B) II C) III D) IV E) Equal amounts of II and IV Ans: C

Topic: Reaction Products

9. What would you expect to be the major product obtained from the following reaction?

OO2N

O2N

NO2

III

ONO2

?HNO3H2SO4, heat

A) I B) II C) III D) IV E) V Ans: E

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Topic: Reaction Products

10. What would be the major product(s) of the following reaction?

NO2

I II III

NO2SO3H

NO2

SO3HO

NO2HO3S

OHO3S

NO2

?H2SO4

A) I B) II C) III D) Equal amounts of IV E) Equal amounts of II and IV Ans: C

Topic: Reaction Products

11. What would you expect to be the major product obtained from the mononitration of m-dichlorobenzene?

I II III

ClNO2

NO2

ClO2N

A) I B) II C) III D) Equal amounts of I and II E) Equal amounts of I, II and III Ans: B

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Topic: Reaction Products

12. What would you expect to be the major product obtained from the following reaction?

I IIIII IV

SO3HNO2

HO O

SO3H

NO2

HO O

SO3HO2N

HO OO2N

SO3H

HO O

SO3H

HO OHNO3 H2SO4 , heat

A) I B) II C) III D) IV E) Equal amounts of I and II Ans: C

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Topic: Reaction Products

13. What product would result from the following series of reactions,

i) AlCl3ii) N-Bromosuccinimide, peroxidesiii) CH3ONa, CH3OH, heativ) MMPPv) CH3MgBrvi) NH4Cl

+Cl

IIIHO

HO HO

A) I B) II C) III D) IV E) V Ans: D

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Topic: Reaction Products

14. The major product(s), D, of the following reaction

O O

O2N

NO2

HNO3

H2SO4D

I II

III IV

would be: A) I B) II C) III D) IV E) Equal amounts of I and II Ans: D

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Topic: Reaction Products

15. What would be the major product of the following reaction?

BrBr

III

?NBS, ROORlight

A) I B) II C) III D) IV E) V Ans: C

Topic: Reaction Products

16. Which would be the major product(s) of the following reaction? HO O

HNO3 H2SO4

HO ONO2

NO2

HO O

HO3S

HO O

III

A) I B) II C) III D) I and II in roughly equal amounts E) I and III in roughly equal amounts Ans: A

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Topic: Reaction Products

17. Which would be the product, X, of the following reaction sequence?

I II

SO2 CO2

CH2

III

?i) SOCl2ii) benzene, AlCl3iii) Zn(Hg), HCl

A) I B) II C) III D) IV E) V Ans: C

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Topic: Reaction Products

18. Toluene is subjected to the action of the following reagents in the order given: (1) KMnO4,OH-, heat; then H3O+ (2) HNO3, H2SO4 (3) Br2, FeBr3 What is the final product of this sequence?

I II III

CO2H

BrNO2

CO2H

Br NO2

CO2HNO2

IV VNO2

CO2H

NO2BrCH3

A) I B) II C) III D) IV E) V Ans: A

Topic: Reaction Products

19. When toluene is reacted in turn with 1) Cl2 (large excess), heat, and light and 2) Br2,FeBr3, the chief product is:

CCl3

III

CCl3Br

CCl3

A) I B) II C) III D) IV E) A mixture of III and IV Ans: B

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Topic: Reaction Products

20. The reaction of benzene with (CH3)3CCH2Cl in the presence of anhydrous aluminum chloride produces principally which of these?

IV V

I II III

A) I B) II C) III D) IV E) V Ans: E

Topic: Reaction Products

21. What might be predicted to happen when the following substance undergoes Friedel-Crafts acylation?

CH2O2N

A B A) Substitution occurs in ring B, p- to the methylene group B) Substitution occurs in ring A, o- to the nitro group C) Substitution occurs in ring A, o- to the methylene group D) Substitution occurs in ring B, m- to the methylene group E) None of the above. No reaction will occur. Ans: A

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Topic: Nomenclature, Reaction Products

22. A mixture of chlorobenzene (1 mol) and acetanilide (1mol) is allowed to react with Br2 (0.5 mol) in the presence of trace amounts of FeBr3. What is the principal product of the competing reactions? A) 1-bromo-4-chlorobenzene B) 1-bromo-2-chlorobenzene C) 1-bromo-3-chlorobenzene D) 4-bromoacetanilide E) 3-bromoacetanilide Ans: D

Topic: Nomenclature, Reaction Products

23. What is the chief product of the Friedel-Crafts alkylation of benzene with 1-butene and AlCl3? A) butylbenzene B) 2-phenylbutane C) 2-methyl-1-phenylpropane D) t-butylbenzene E) 2,2-diphenylbutane Ans: B

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Topic: Reaction Products

24. Which of the following reactions would give the product(s) indicated in substantial amounts (i.e., in greater than 50% yield)?

+ CH3Cl

NH2AlCl3

NH2 NH2

and

CH3

NH2 NH2

+ CH3ClAlCl3

CH3

+ CH3CH2CH2ClAlCl3 CH2CH2CH3

III

A) I B) II C) III D) All of these E) None of these Ans: E

Topic: Reagents

25. Which reagent(s) would you use to carry out the following transformation? toluene ⎯⎯⎯→ benzoic acid A) Br2, heat, and light B) Cl2, FeCl3 C) KMnO4, OH-, heat (then H3O+) D) HNO3/H2SO4 E) SO3/H2SO4 Ans: C

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Topic: Reagents

26. Which reagent(s) would you use to carry out the following transformation? ethylbenzene ⎯⎯⎯→ 1-chloro-1-phenylethane A) Cl2, light, and heat B) Cl2, FeCl3 C) SOCl2 D) C2H5Cl, AlCl3 E) HCl, O2 Ans: A

Topic: Reagents

27. Which reagent(s) would you use to carry out the following transformation? isopropylbenzene ⎯⎯⎯→ 2- and 4-chloro-1-isopropylbenzene A) Cl2, light, and heat B) Cl2, FeCl3 C) SOCl2 D) C2H5Cl, AlCl3 E) HCl, peroxides Ans: B

Topic: Reagents

28. Which reagent would you use to carry out the following transformation? tert-butylbenzene ⎯⎯⎯→ p-tert-butylbenzenesulfonic acid + o-tert-butylbenzenesulfonic acid

A) HNO3/H2SO4 B) tert-C4H9Cl/AlCl3 C) H2SO3/peroxides D) SO3/H2SO4 E) SO2/H2SO3 Ans: D

Topic: Reagents

29. Which reagent(s) would you use to carry out the following transformation? ethylbenzene ⎯⎯⎯⎯→ benzoic acid A) Cl2, light, and heat B) Cl2, FeCl3 C) KMnO4, OH-, heat (then H3O+) D) HNO3/H2SO4 E) SO3/H2SO4 Ans: C

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Topic: Reagents

30. Which reagent(s) would you use to carry out the following transformation? ethylbenzene ⎯⎯→ 2- and 4-chloro-1-ethylbenzene A) Cl2, light, and heat B) Cl2, FeCl3 C) SOCl2 D) C2H5Cl, AlCl3 E) None of these Ans: B

Topic: Reagents

31. Which reagent(s) would you use to carry out the following transformation? t-butylbenzene ⎯⎯⎯→ p-chloro substitution product A) Cl2, light, and heat B) Cl2, FeCl3 C) SOCl2 D) C2H5Cl, AlCl3 E) HCl, peroxide Ans: B

Topic: Reagents

32. Which reagent(s) would you use to carry out the following transformation? toluene ⎯⎯⎯→ benzyl bromide A) Br2, FeBr3 B) N-Bromosuccinimide, ROOR, hν C) HBr D) Br2/CCl4 E) NaBr, H2SO4 Ans: B

Topic: Reagents

33. Which reagent(s) would you use to synthesize 2- and 4-bromo-1-cyclopentylbenzene from cyclopentylbenzene? A) N-Bromosuccinimide (NBS), CCl4, light B) PBr3 C) Br2, FeBr3 D) CH3CH2Br, AlBr3 E) HBr, ROOR Ans: C

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Topic: Reagents

34. The compound 4-bromo-1-propylbenzene is best made from benzene by the application of these reagents in the order shown: A) (1) Br2,Fe (2) CH3CH2CH2Cl, AlCl3 B) (1) CH3CH2CH2Cl, AlCl3 (2) Br2,Fe C) CH3CH2CCl

1) , AlCl3 2) Br2, Fe 3) Zn(Hg), HCl

D) CH3CH2CCl

1) , AlCl3 3) Br2, Fe2) Zn(Hg), HCl

E) (1) (CH3)2CHCl, AlCl3 (2) Br2,Fe Ans: D

Topic: Functional Group Tests

35. Which reagent would you use as the basis for a simple chemical test that would distinguish between toluene and vinylbenzene (C6H5CH=CH2)? A) NaOH/H2O B) Br2/CCl4 C) NaBH4 D) HCl/H2O E) NaI in acetone Ans: B

Topic: Nomenclature, Functional Group Tests

36. Which reagent or test could you use to distinguish between phenylacetylene and vinylbenzene? A) NaOH/H2O B) Br2/CCl4 C) IR Spectroscopy D) CrO3/H2SO4 E) Concd. H2SO4 Ans: C

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Topic: Nomenclature, Synthesis

37. Which of the following would be the best synthesis of 1,4-dimethyl-2-nitrobenzene? A)

BenzeneHNO3

H2SO4

product2 CH3Cl

2 AlCl3B)

TolueneHNO3

H2SO4

productCH3Cl

AlCl3C)

p-XyleneHNO3

H2SO4D) CH3Cl

AlCl3m-Nitrotoluene

E) All of these are equally good. Ans: C

Topic: Synthesis

38. Starting with benzene, the best method for preparing p-nitrobenzoic acid is: A) HNO3/H2SO4; then CH3Cl/AlCl3; then separation of isomers; then KMnO4/

-OH/heat, followed by H3O+. B) CH3Cl/AlCl3; then HNO3/H2SO4; then separation of isomers; then KMnO4/

-OH/heat, followed by H3O+. C) CH3Cl/AlCl3; then KMnO4/-OH/heat, followed by H3O+; then HNO3/H2SO4. D) HNO3/H2SO4; then KMnO4/-OH/heat, followed by H3O+; then CH3Cl/AlCl3. E) HNO3/H2SO4; then CO2, followed by H3O+. Ans: B

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Topic: Synthesis

39. A good synthesis of

(CH3)3C CCH3

would be: A)

BenzeneCH3CCl

AlCl3

(CH3)3CCl

AlCl3B)

BenzeneCH3CCl

AlCl3

(CH3)3CCl

AlCl3C)

BenzeneCH3CCl

AlCl3 HF

(CH3)2C CH2

D) More than one of these E) None of these Ans: B

Topic: Synthesis

40. Which would be a good synthesis of m-nitrobenzoic acid? A)

BenzeneHNO3/H2SO4

heat AlCl3

CH3Cl 1. KMnO4, NaOH, heat

2. H3O+

B) Toluene

HNO3/H2SO4

heat

1. KMnO4, NaOH, heat

2. H3O+

C) Toluene

HNO3/H2SO4

heat

1. KMnO4, NaOH, heat

2. H3O+

D) More than one of the above E) None of the above Ans: C

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Topic: Synthesis

41. Benzoic acid can be prepared by the oxidation of all of the following compounds except this one: A) C6H5CH=CH2 B) C6H5C≡CH C) C6H5COCH3 D) C6H5CH2CH2CH3 E) C6H5C(CH3)3 Ans: E

Topic: Synthesis

42. Which of the following reactions would yield isopropylbenzene as the major product? A)

BenzeneH2SO4

CH3CH CH2

BenzeneH2SO4

CH3CHCH3

BenzeneAlCl3

CH3CHCH3

D) Benzene

AlCl3

CH3CH2CH2Cl

E) All of these Ans: E

Topic: Synthesis

43. Which of the following reactions could be used to synthesize tert-butylbenzene? A) H2SO4

C6H6 + CH2=C(CH3)2B) H2SO4

C6H6 + (CH3)3COHC) AlCl3

C6H6 + (CH3)3CClD) All of the above E) None of the above Ans: D

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Topic: Synthesis

44. Which of these is a satisfactory synthesis of 1-chloro-2-phenylethane? A) C6H5CH2CH3 + Cl2, Fe ⎯⎯→ B) C6H5CH2CH3 + Cl2, 400°C ⎯⎯→ C) C6H5CH2CH2OH + SOCl2 ⎯⎯→ D) C6H5CH=CH2 + HCl, peroxide ⎯⎯→ E) C6H6 + CH3CH2Cl, AlCl3 ⎯⎯→ Ans: C

Topic: Synthesis

45. Which of the following reactions would produce isopropylbenzene? A) Cl

AlCl3Benzene

B) Benzene

HFC) OH

H2SO4Benzene

D) Br

AlCl3Benzene

E) All of these Ans: E

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Topic: Synthesis

46. How might the following synthesis be carried out:

Benzene

CH2CH3

severalsteps

A) CH3CH2ClC6H6

AlCl3

Cl2FeCl3

product

B) CH3CH2ClC6H6

AlCl3

Cl2FeCl3

product

C6H6AlCl3

Cl2FeCl3

productCH3CCl

Zn(Hg)

HCl

C6H6AlCl3

Cl2FeCl3

productCH3CCl

Zn(Hg)

HCl

E) None of these syntheses is satisfactory. Ans: C

Topic: Synthesis

47. Which is the best sequence of reactions for the preparation of p-bromostyrene from ethylbenzene? A) Br2

Feproductethylbenzene

NBS, hν

CCl4

KOH

CH3CH2OHB) Br2

Feproductethylbenzene

NBS, hν

CCl4

KOH

CH3CH2OHC) Br2

Feproductethylbenzene

NBS, hν

CCl4

KOH

CH3CH2OHD) Br2

Feproductethylbenzene

630 oC

ZnO

E) None of these syntheses is satisfactory. Ans: B

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Topic: Synthesis

48. Which is the best sequence of reactions for the following transformation?

NO2

A) i) HNO3, H2SO4; ii) CH3MgBr, Et2O; iii) H3O+, heat B) i) CH3MgBr, Et2O; ii) H3O+, heat; iii) HNO3, H2SO4 C) i) HNO3, H2SO4; ii) NaBH4, H2O; iii) H3O+, heat D) i) HNO3, H2SO4; ii) NaBH4, H2O; iii) H3O+, heat E) None of these syntheses is satisfactory. Ans: A

Topic: Synthesis

49. Which is the best sequence of reactions for the following transformation?

OCH3

NO2

A) i) HNO3, H2SO4; ii) 2EtMgBr, Et2O; iii) NH4Cl B) i) 2EtMgBr, Et2O; ii) H3O+; iii) HNO3, H2SO4 C) i) HNO3, H2SO4; ii) NaBH4, H2O; iii) 2EtMgBr, Et2O D) i) LAH; ii) 2EtLi, Et2O; iii) HNO3, H2SO4, heat E) None of these syntheses is satisfactory. Ans: A

Topic: Synthesis

50. Which is the best sequence of reactions for the following transformation?

NO2

A) i) SOCl2; ii) C6H6, AlCl3; iii) Zn(Hg),HCl; iv) HNO3, H2SO4 B) i) SOCl2; ii) HNO3, H2SO4; iii) C6H6, AlCl3; iv) H2, Ni C) i) HNO3, H2SO4; ii) SOCl2; iii) C6H6, AlCl3; iv) Zn(Hg),HCl D) i) PBr3; ii) HNO3, H2SO4; iii) C6H6, AlCl3; iv) NaBH4, H2O E) two of these syntheses are satisfactory. Ans: C

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Topic: Relative Reactivities

51. Which of the following compounds would be most reactive toward electrophilic substitution?

OH CH3 Br CHO NO2

I II III IV V A) I B) II C) III D) IV E) V Ans: A

Topic: Relative Reactivities

52. Which of the following compounds would be most reactive to ring bromination? CH3 NO2 CF3 Cl NH2

I II III IV V A) I B) II C) III D) IV E) V Ans: E

Topic: Relative Reactivities

53. Which of the following compounds would you expect to be most reactive toward ring nitration? A) Benzene B) Toluene C) m-Xylene D) p-Xylene E) Benzoic acid Ans: C

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Topic: Relative Reactivities

54. Which of the following compounds would be least reactive toward electrophilic substitution?

NO2

O NH

I II III IV V A) I B) II C) III D) IV E) V Ans: B

Topic: Relative Reactivities

55. Which of the following compounds would be most reactive toward ring nitration?

CF3 OH NH

I II III IV V A) I B) II C) III D) IV E) V Ans: D

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Topic: Relative Reactivities

56. Which of the compounds listed below would you expect to give the greatest amount of meta-product when subjected to ring bromination?

OH HO O NH2 OCH3 CH3

I II III IV V A) I B) II C) III D) IV E) V Ans: B

Topic: Relative Reactivities

57. Which of the following compounds would be most reactive toward ring bromination?

OHO O NH2 OCH3

O O

I II III IV V A) I B) II C) III D) IV E) V Ans: C

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Topic: Relative Reactivities

58. Which of the compounds listed below would you expect to give the greatest amount of meta-product when subjected to ring nitration?

O NHO OCH3 CH3

I II III IV V A) I B) II C) III D) IV E) V Ans: B

Topic: Mechanisms and Intermediates

59. Which of the following structures contribute(s) to the resonance hybrid of the intermediate formed when bromobenzene undergoes para-chlorination?

H Cl

H ClI II III IV

++ +

.. .. .. ..: : : : : : :+

A) I B) II C) III D) IV E) All of the above Ans: E

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Topic: Mechanisms and Intermediates

60. Which of the following contributors to the resonance stabilized hybrid formed when aniline undergoes para-chlorination would be exceptionally stable?

NH2

H Cl

NH2

H Cl

NH2

H Cl

NH2

H ClI II III IV

++ +

: : :+

A) I B) II C) III D) IV E) None of these Ans: B

Topic: Mechanisms and Intermediates

61. Consider the structures given below. Which of them would be a relatively stable contributor to the hybrid formed when toluene undergoes para bromination?

CH3

BrII

CH3

H BrIII

+CH3

H BrIV

CH3

BrIV

CH3

H BrI

A) I B) II C) III D) IV E) V Ans: C

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Topic: Mechanisms and Intermediates

62. Which of the following structures does not contribute to the resonance hybrid of the intermediate formed when nitrobenzene undergoes meta-chlorination?

N N N

I II III

O O O OO O

ClH

+ +

::: : : ::::.. .. .. .. .. ..

A) I B) II C) III D) None of these contribute E) All of these contribute. Ans: E

Topic: Mechanisms and Intermediates

63. Which of these is the rate-determining step in the nitration of benzene? A) Protonation of nitric acid by sulfuric acid B) Protonation of sulfuric acid by nitric acid C) Loss of a water molecule by the protonated species to produce the nitronium ion D) Addition of nitronium to benzene to produce the arenium ion E) Loss of a proton by arenium ion to form nitrobenzene Ans: D

Topic: Directing Effects

64. The ortho/para product ratio is expected to be the smallest for the bromination of which of these? A) Toluene B) Isopropylbenzene C) Butylbenzene D) sec-Butylbenzene E) tert-Butylbenzene Ans: E

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Topic: Directing Effects

65. Which of the following is not a meta-directing substituent when present on the benzene ring? A) -NHCOCH3 B) -NO2 C) -N(CH3)3

+ D) -C≡N E) -CO2H Ans: A

Topic: Directing Effects

66. Each of the five disubstituted benzenes shown below is nitrated. In which of these cases does the arrow not indicate the chief position of nitration.

COOH Cl NHCOCH3

CH3

CCH3

CH2CH3

NO2

I II III IV V

A) I B) II C) III D) IV E) V Ans: C

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Topic: Directing Effects

67. Which of the following compounds would yield the greatest amount of meta product when subjected to ring nitration?

I II III IV V

HO O OH

OHO

HO O

A) I B) II C) III D) IV E) V Ans: A

Topic: Directing Effects

68. Which of the following is not an ortho-para director in electrophilic aromatic substitution? A) -CF3 B) -OCH3 C) -CH3 D) -F E) -NH2 Ans: A

Topic: Directing Effects

69. Which of these compounds gives essentially a single product on electrophilic substitution of a third group? A) p-chlorotoluene B) m-ethylanisole C) 1-bromo-2-chlorobenzene D) m-xylene E) 3-hydroxybenzoic acid Ans: D

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Topic: Directing Effects

70. What is a feature found in all ortho-para directing groups? A) An oxygen atom is directly attached to the aromatic ring. B) The atom attached to the aromatic ring possesses an unshared pair of electrons. C) The group has the ability to delocalize the positive charge of the arenium ion. D) The atom directly attached to the aromatic ring is more electronegative than

carbon. E) The group contains a multiple bond. Ans: C

Topic: Directing Effects

71. Which is the best prediction of the site(s) of substitution when 3-methylphenol is nitrated? A) C-2 B) C-4 C) C-5 D) C-6 E) C-4 and C-6 Ans: E

Topic: Directing Effects

72. (Trifluoromethyl)benzene, C6H5CF3, will A) nitrate rapidly in the ortho-para positions. B) nitrate slowly in the ortho-para positions. C) nitrate rapidly in the meta position. D) nitrate slowly in the meta position. E) fail to nitrate under any conditions. Ans: D

Topic: Directing Effects

73. What feature is common to all meta-directing groups? A) The atom directly attached to the ring has a full or well-developed partial positive

charge. B) The atom directly attached to the ring is doubly bonded to oxygen. C) One or more halogen atoms are present in the group. D) One or more oxygen atoms are present in the group. E) The group is attached to the ring through a carbon atom. Ans: A

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Topic: Directing Effects

74. Arrange the following compounds in order of decreasing reactivity in electrophilic substitution:

O O Br NO2

I II III IV V A) V > II > I > III > IV B) II > V > III > I > IV C) IV > I > III > V > II D) III > II > I > IV > V E) IV > V > II > I > III Ans: B

Topic: Other EAS Considerations

75. Which of these liquids would be unsuitable as an inert solvent for a Friedel-Crafts reaction? A) Chlorobenzene B) Nitrobenzene C) Acetophenone D) (Trifluoromethyl)benzene E) All could be used. Ans: A

Topic: Other EAS Considerations

76. Undesired polysubstitution of an aromatic nucleus is most likely to be encountered in the case of: A) Friedel-Crafts alkylation B) Friedel-Crafts acylation C) Nitration D) Sulfonation E) Chlorination Ans: A

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Topic: Other EAS Considerations

77. This molecule cannot participate as a reactant in a Friedel-Crafts reaction. A) Benzene B) Chlorobenzene C) Nitrobenzene D) Toluene E) tert-Butylbenzene Ans: C

Topic: Other EAS Considerations

78. Which one of these molecules can be a reactant in a Friedel-Crafts reaction? A) Aniline B) Nitrobenzene C) Chloroethene D) Bromobenzene E) p-Bromonitrobenzene Ans: D

Topic: Other EAS Considerations

79. This substituent deactivates the benzene ring towards electrophilic substitution but directs the incoming group chiefly to the ortho and para positions. A) -OCH2CH3 B) -NO2 C) -F D) -CF3 E) -NHCOCH3 Ans: C

Topic: Other EAS Considerations

80. In electrophilic aromatic substitution, the attacking species (the electrophile) necessarily is a: A) Neutral species. B) Positively charged species. C) Lewis acid. D) Proton. E) Carbocation. Ans: C

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562

Topic: Other EAS Considerations

81. The electrophilic bromination or chlorination of benzene requires, in addition to the halogen: A) Hydroxide ion. B) A Lewis base. C) A Lewis acid. D) Peroxide. E) Ultraviolet light. Ans: C

Topic: Non-EAS Reactions

82. What is the Birch reduction product of the following reaction?

I II III IV V

Na, NH3(l)EtOH ?

A) I B) II C) III D) IV E) V Ans: D

Topic: Non-EAS Reactions

83. SN1 solvolysis of C6H5CH=CHCH2Cl in water produces: A) C6H5CH2C(OH)=CH2 B) C6H5CH=CHCH2OH C) C6H5CHOHCH=CH2 D) A mixture of B) and C) E) A mixture of A), B) and C) Ans: D

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563

Topic: Non-EAS Reactions

84. Which compound is capable of undergoing both SN1 and SN2 reactions in ordinary nonacidic solvents?

Br Br

I II III IV VA) I B) II C) III D) IV E) V Ans: D

Topic: Non-EAS Reactions

85. Which alkyl halide can undergo both SN1 and SN2 reactions in nonacidic solvents? A) CH3Br B) CH3CH2CH2Br C) CH2 CHCHCH3

D) C6H5CH2CH2CH2Br E)

C6H5CCH2Br

CH3

Ans: C

Topic: Non-EAS Relative Rates and Intermediates

86. The rate of solvolysis in ethanol is least for which of these compounds? A) C6H5CH2Cl B) C6H5C(CH3)2

C) (C6H5)2CHCl D) C6H5CHCl

CH3

E) (C6H5)3CCl Ans: A

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564

Topic: Non-EAS Relative Rates and Intermediates

87. Which of the following structures would not be a contributor to the resonance hybrid of the benzyl cation?

CH3

CH2

III

CH2

CH3

H+

A) I B) II C) III D) IV E) V Ans: A

Topic: Non-EAS Relative Rates and Intermediates

88. Which of these species is/are proposed as intermediate(s) in the mechanism for the Birch reduction? A) Radical B) Carbanion C) Radical anion D) Both A) and B) E) All of A), B) and C) Ans: E

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Topic: Non-EAS Relative Rates and Intermediates

89. Which of the following carbocations would be most stable? A)

C6H5CH2CH2CHCH2

CH3

C6H5CH2CH2CHCH3

CH2

C6H5CH2CH2CCH3

CH3

C6H5CH2CHCHCH3

CH3

E) C6H5CHCH2CHCH3

CH3

Ans: E

Topic: Non-EAS Relative Rates and Intermediates

90. Which alkyl halide would be most reactive in an SN2 reaction? A) C6H5CH2CH2CH2Br B) C6H5CHCH2Br

CH3

C) C6H5CH2CHCH3

C6H5CCH2Br

CH3

E) C6H5CCH3

CH3

Ans: A

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Topic: Non-EAS Relative Rates and Intermediates

91. Which alkyl halide would be most reactive in an SN1 reaction? A) C6H5CH2CH2CH2Br B) C6H5CH2CHCH3

C6H5CH2CBr

CH3

D) C6H5CCH3

CH3

E) C6H5CCH2Br

CH3

Ans: D SHORT ANSWER QUESTIONS Topic: General

92. Aromatic hydrocarbons are generally known as ____________. Ans: arenes

Topic: General Reactivity

93. Benzene is susceptible to electrophilic attack primarily because of its _____________. Ans: exposed π system

Topic: General Reactivity

94. Although benzene is susceptible to electrophilic attack, its special stability causes it to undergo ______________ rather than ____________ reactions. Ans: substitution; addition

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567

Topic: EAS Mechanism

95. In general, there are three steps to an electrophilic aromatic substitution reaction. These are: a) formation of an _____________; b) reaction with an aromatic ring to form an ___________; and c) loss of a _________ to reform the aromatic system. Ans: electrophile; arenium ion; proton

Topic: General Reactivity

96. Aryl and vinyl halides cannot be used in the Friedel-Crafts alkylation because they do not __________. Ans: form carbocations readily

Topic: General EAS Reactivity

97. Substituent groups affect both _____________ and _______________ in electrophilic aromatic substitution reactions. Ans: reactivity; orientation

Topic: General EAS Reactivity

98. Electron-donating groups increase the electron density on the aromatic ring, causing it to be more reactive than benzene itself towards EAS. These types of groups are called _____________ groups. Ans: activating

Topic: General EAS Reactivity

99. Electron-withdrawing groups decrease the electron density on the aromatic ring, causing it to be less reactive than benzene itself towards EAS. These types of groups are called _____________ groups. Ans: deactivating

Topic: General EAS Reactivity

100. With the exception of halogens, activating groups are ____________ directors and deactivating groups are _________ directors. Ans: ortho/para; meta

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568

Topic: General EAS Reactivity

101. When two different groups are present on a benzene ring, the ____________ generally determines the outcome of an EAS reaction. Ans: more powerful activating group

Topic: EAS/non-EAS Reactivity

102. When toluene reacts with Cl2, the identity of the major product(s) obtained depends on whether the reaction is carried out in the presence of catalytic amounts of FeCl3, or without catalyst, at high temp. Explain clearly. Ans: Reaction with Cl2/FeCl3 results in electrophilic aromatic substitution at the o- and

p- positions, since the methyl group in toluene is an activating, o-,p- director. In contrast, when the reaction is carried out without catalyst, at high temperature, the methyl group undergoes free-radical halogenation via the benzyl radical intermediate.

ClCl

Cl2FeCl3

Cl2heat

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569

Topic: General EAS Reactivity

103. When the following substance is treated with Br2/FeBr3, the major product is obtained in good yield, and only very small amounts of minor products are found. What is this major product and why are the minor products not formed to any significant degree? Explain clearly.

Br2FeBr3

Ans: The major products are produced by brominating Ring B. Ring B is more electron-rich due to the electron-donation of both the nitrogen and methyl groups attached versus the two electron-withdrawing carbonyl groups attached to Ring A, which make it inherently electron-poor. Therefore, bromination mainly occurs on the more electron-rich benzene ring affording a mixture of the following two compounds. Due to steric effects, bromination ortho to both the nitrogen and methyl group would lead to a minor product. Also, because Ring A is electron-poor, bromination of this ring would also lead to minor products.

OBr

RingA

RingB

major productsHN

RingA

RingB

Topic: Synthetic Strategy

104. Suggest a reasonable synthetic strategy for the synthesis of 3,5-dinitrobenzyl alcohol from benzaldehyde. Ans:

O OO2N

NO2

OHO2N

NO2HNO3 (excess)H2SO4heat

benzaldehyde 3,5-dinitrobenzyl alcohol

NaBH4 H2O

Topic: Synthetic Strategy

105. Suggest a reasonable synthetic strategy for the synthesis of 4-methyl-1-phenyl-1-pentanol from 4-methylpentanoyl chloride, (CH3)2CHCH2CH2COCl Ans: O OH

O AlCl3

4-methylpentanoyl chloride 4-methyl-1-phenyl-1-pentanol

NaBH4 H2O

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570

Topic: Synthetic Strategy

106. Suggest a reasonable synthetic strategy for the synthesis of 6-methyl-3-phenyl-3-heptanol from 4-methylpentanoyl chloride, (CH3)2CHCH2CH2COCl Ans: O OH

Oi) C2H5MgBrii) NH4ClAlCl3

4-methylpentanoyl chloride 6-methyl-3-phenyl-3-heptanol Topic: Mechanism, Carbocation Stability

107. Acid-catalyzed hydration of 1-phenyl-1-pentene gives 1-phenyl-1-pentanol almost exclusively; the other possible hydration product, 1-phenyl-2-pentanol, is not detected at all. Explain clearly. Ans: Acid catalyzed hydration of an alkene occurs through a carbocation intermediate.

Although 1-phenyl-1-pentene is symmetrically substituted at the C=C, the relative stabilities of the two possible carbocation intermediates is significantly different: although both are secondary carbocations, one is also benzylic and thus stabilized by resonance. The observation that 1-phenyl-1-pentene gives 1-phenyl-1-pentanol, almost exclusively, is in accordance with the general trend that acid catalyzed hydration chiefly tends to afford products formed via the most stable intermediate carbocation.

H3O+

H2O

H++

2o, benzylic:stabilized by resonance,formed almost exclusively

2o, but not benzylic:less stable, not formed to any appreciable degree

chief product not detected

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571

Topic: Spectroscopic Analysis

108. How might 1H NMR spectroscopy be useful in distinguishing between the following two substances?

OOO

BA Ans: The chemical shift of the methyl protons is likely to be markedly different in the

two substances. In A, the signal may be expected at about 3.5-4.0 ppm (attachment to O), while in B, it is likely to show up at about 2.0 ppm (attachment to >C=O).

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572

MULTIPLE CHOICE QUESTIONS

Topic: Nomenclature

1. What is the correct IUPAC name for the following compound?

O A) 2-Methyl-5-heptanone B) 7-Methyl-4-octanone C) 6-Isopropyl-4-octanone D) Isobutyl propyl ketone E) 1,1-Dimethyl-4-heptanone Ans: B

Topic: Nomenclature

2. What is the correct IUPAC name for the following compound?

O A) 5,5-Dimethyl-2-heptanone B) 5-Ethyl-5,5-dimethyl-Methyl-2-octanone C) 5-Ethyl-5-methyl- 2-hexanone D) 5,5-Dimethyl-2-octanone E) 3,3-Dimethyl-6-heptanone Ans: A

Topic: Nomenclature

3. What is the correct IUPAC name for the following compound?

O A) 1,1,2-Trimethyl-1,3-hexenone B) 1,2-Dimethyl-1,3-hexenone C) 2,3-Dimethyl-1,3-heptenone D) 2,3-Dimethyl-2-hepten-4-one E) 5,6-Dimethyl-5-hepten-4-one Ans: C

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573

Topic: Nomenclature

A correct name for C6H5CH2CH2CH

is? A) 3-Benzylpropanone B) 3-Phenylpropanal C) 3-Benzylpropanal D) Nonanone E) Nonanal Ans: B

Topic: Nomenclature

5. A correct name for the following compound would be which of those below?

A) 2,5-Dimethyl-6-hexanal B) 2,5-Dimethylhexanal C) 2-Aldehydoisohexane D) 3,5-Dimethylheptanone E) 1-Hydro-2,5-dimethyl-1-hexanone Ans: B

Topic: Nomenclature

What is the IUPAC name for

CH3 CH

CH2 C CH

C6H5

CH3

? A) 4-Oxo-5-phenyl-2-hexanol B) 5-Hydroxy-2-phenyl-3-hexanone C) 2-Hydroxy-5-phenyl-4-hexanone D) 2-Hydroxypropyl-1-phenylethyl ketone E) 5-Hydroxy-3-keto-2-phenylhexane Ans: B

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574

Topic: Nomenclature

7. Which is the proper name for the structure shown?

CHO

CH3

A) 2-Chloro-5-aldehydotoluene B) 6-Chloro-3-aldehydotoluene C) 2-Methyl-4-aldehydochlorobenzene D) 4-Chloro-3-methylbenzaldehyde E) 4-Methyl-5-chloro-2-benzaldehyde Ans: D

Topic: Nomenclature

8. Which is the proper name for the structure shown?

O2N

NO2

A) 3-Methyl-5-(1,4-dinitrobenzyl)-1-pentanal B) 3-Methyl-1-(2,5-dinitrophenyl)-5-pentanal C) 3-Methyl-5-(2,5-dinitrophenyl)pentanal D) 3-Methyl-5-(2,5-dinitrophenyl)pentanaldehyde E) 3-Methyl-5-(2,5-dinitrophenyl)pentaldehyde Ans: C

Topic: Nomenclature

9. Which is the proper name for the structure shown?

Cl A) 3,5-Dimethyl-5-(4-chlorobenzyl)-1-pentanal B) 3-Methyl-5-(4-chlorophenyl)hexanol C) 3,5-Dimethyl-5-(4-chlorophenyl)-1-pentanaldehyde D) 3-Methyl-5-(4-chlorophenyl)-hexanaldehyde E) 3-Methyl-5-(4-chlorophenyl)hexanal Ans: E

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575

Topic: Nomenclature

10. Which is the proper name for the structure shown below?

BrO

A) 7-Bromo-1,4-octynal B) 7-Bromo-1,4-octynone C) 2-Bromo-5,7-octynal D) 7-Bromo-7-methyl-1-heptyne-3-ketone E) 7-Bromo-1-octyn-4-one Ans: E

Topic: Nomenclature

11. Which is the IUPAC name for the structure shown below?

Br H

A) (R)-5-Bromo-2-heptanal B) (S)-5-Bromo-2-heptanal C) (R)-5-Bromo-2-heptanone D) (S)-5-Bromo-2-heptanone E) (R)-3-Bromopentyl methyl ketone Ans: C

Topic: Nomenclature

12. Which is the IUPAC name for the structure shown below?

O A) 5-Cyclohexyl-2-hexanal B) 5-Cyclohexyl-2-hexanone C) 5-Cyclohexyl-5-methyl-2-pentanone D) 5-(1-Methylcyclohexyl)-2-pentanone E) 4-(1-Methylcyclohexyl)-2-butanone Ans: E

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576

Topic: New Functional Groups

13. Which of the following compounds is an acetal?

OCH3

O O

O OH

III

O O

A) I B) II C) III D) IV E) None of these Ans: C

Topic: New Functional Groups

14. Which is the general formula for a thioacetal? A)

RC S

B) RCHSR'

C) RCHSR'

D) RCHSR'

SR'

E) RCHOR'

SR'

Ans: D

Topic: New Functional Groups

15. Which compound is an acetal?

O OH

III

O OH

O OCH3

A) I B) II C) III D) IV E) All of the above Ans: B

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577

Topic: Reaction Products

16. The product, C, of the following reaction sequence,

CH3CCH3

CN+HCN

C4H7NOH2O

H2SO4heat

would be: A)

CH2 CCOOH

CH3

B) CH3CH2COOCH3 C) CH3CHCH3

D) CH3CH=CHCOOH E) None of these Ans: A

Topic: Reaction Products

17. The product, H, of the following reaction sequence,

FC6H5Li

etherGC6H5CH2Br + (C6H5)3P

C6H5CCH3

would be: A)

C6H5CH2CC6H5

CH3

C6H5CH2CC6H5

C) C6H5CH CHCC6H5

D) C6H5CH2CH=CHC6H5 E) C6H5CH CCH3

C6H5

Ans: E

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578

Topic: Reaction Products

18. What would be the product of the following reaction sequence?

I II

III

OO OH

i) PCl3ii) C6H6, AlCl3iii) Zn(Hg), HCl, heat

A) I B) II C) III D) IV E) V Ans: E

Topic: Reaction Products

19. What new compound will be formed when HCl is added to a solution of pentanal in methanol? A) O

O B) O

Cl C) OH

OH D) O

O E) Cl

O Ans: A

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579

Topic: Reaction Products

20. What would be the product of the following reaction sequence?

I II

IIIOH

O OH

i) PCl3ii) C6H6, AlCl3iii) NaBH4, H2O

A) I B) II C) III D) IV E) V Ans: D

Chapter 16

580

Topic: Reaction Products

21. The product, K, of the following sequence of reactions

ICH3CH2MgBr

etherJBenzene

CH3CHCOClK

CH3

AlCl3

H3O+

would be:

OH HO

OH O

I II III IV VA) I B) II C) III D) IV E) V Ans: B

Topic: Reaction Products

22. Dissolving benzaldehyde in methyl alcohol establishes an equilibrium with what compound? A)

C6H5CHOCH3

C6H5COCH3

C) C6H5C(OCH3)3 D) Answers A) and B) E) Answers B) and C) Ans: A

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581

Topic: Reaction Products

23. Predict the major organic product of the following reaction:

HO2C O

H3C O

H3C

OH3C

OHO

I II III IV V

Ag(NH3)2+

H2O?

A) I B) II C) III D) IV E) V Ans: B

Topic: Reaction Products

24. The product, E, of the following reaction sequence,

CH3CH2COOHPCl5 C6H6

AlCl3

NaBH4

CH3OHC D E

would be:

CH2CH2CH3 COCH2CH3

CCH2CH3

CHCH2CH3

CH(CH3)2

I II III IV VA) I B) II C) III D) IV E) V Ans: C

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582

Topic: Reaction Products

25. Select the structure of the major product in the following reaction.

?i) BH3

ii) H2O2,OH-, H2O A) Ethylbenzene B) 1-Phenylethanol C) Acetophenone D) 2-Phenylethanal E) Vinylbenzene Ans: D

Topic: Reaction Products

26. Select the structure of the major product in the following reaction.

?H2SO4 HgSO4, H2O

A) Ethylbenzene B) 1-Phenylethanol C) Acetophenone D) 2-Phenylethanal E) Vinylbenzene Ans: C

Topic: Reaction Products

27. Select the structure of the major product in the following reaction.

?i) H2, Lindlar catalystii) O3iii)Zn, CH3CO2H

A) 4-methylhexanal B) 4-methyl-1-hexanol C) 3-methylhexanal D) 4,10-dimethyldodecane-6,7-dione E) 4,10-dimethyldodecane-6,7-diol Ans: A

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583

Topic: Reaction Products

28. The product, J, of the following reaction sequence, CH3CHCOOH

CH3

SOCl2 I(CH3)2CuLi

etherJ

would be: A)

CH3CHCOCH3

CH3

B) CH3C

CH3

CCH3

C) CH3CHCOCu

CH3

D) CH3CHCCH3

CH3

E) CH3CHCCHCH3

CH3

Ans: D

Chapter 16

584

Topic: Reaction Products

29. What is the major product of the following reaction sequence?

NOSO3H COHO

CN OSO3H

CNH2

HCN H2SO4

H2Oheat

I II III IV V

A) I B) II C) III D) IV E) V Ans: B

Chapter 16

585

Topic: Reaction Products

30. The product, D, of the following sequence of reactions

CH3CH2COH

O SOCl2A

tolueneAlCl3

BZn(Hg)

HClD

C (discard)

would be:

CH3 CH2CH2CH3 CH3CH2CCH2

CH3 CH2CH2CCl

CH3 CH2CH2CH2Cl CH3 CHCH3

CH3

I II III

IV VA) I B) II C) III D) IV E) V Ans: A

Topic: Reaction Products

31. What new compound will be formed when gaseous HCl is added to a solution of propanal in methanol? A)

CH3CH2COCH3

B) CH3CH2COH

C) CH3CH2CH(OCH3)2 D) CH3CH2CHOCH3

E) None of the above Ans: C

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586

Topic: Reaction Products

32. What is the product of the following reaction sequence?

C6H5CH2OH

PCC

CH2Cl2

BrCH2CO2Et, Zn

benzene

H3O+

A) C6H5CH2OCH2CO2Et B)

C6H5COCH2CO2Et

C6H5CHCH2CO2Et

C6H5CHOCH2CO2Et

E) C6H5CH2CH2CO2Et Ans: C

Topic: Reaction Products

33. What would be the final product?

C6H5CCH3

CH3I(C6H5)3P

ether

C6H5Li?

A) C6H5C CH2

CH3

C6H5CCH3

C6H5

CH3

C) C6H5CH=CHCH3 D)

C6H5CCH3

CH3

E) C6H5CH CC6H5

CH3

Ans: A

Chapter 16

587

Topic: Reaction Products

34. What is the major product of the following reaction sequence? OCH3

I II III

HO HO

O OH

IV V

ii) LAH, Et2O

iii) H2O, H3O+

HOOH, HCl

A) I B) II C) III D) IV E) V Ans: E

Topic: Reaction Products

35. An aldehyde results from the reaction of which of these compounds with aqueous base? A) CH3CH2CH2Cl B) CH3CHClCH2Cl C) CH3CH=CCl2 D) CH3CH2CHCl2 E) CH3CCl2CH3 Ans: D

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588

Topic: Reaction Products

36. The Baeyer-Villiger oxidation of propiophenone (ethyl phenyl ketone) produces chiefly:A)

CH3CH2OCC6H5

B) CH3CH2OCOC6H5

C) p-HOC6H4CCH2CH3

D) C6H5OCCH2CH3

E) C6H5CCH2CH2OH

Ans: D

Topic: Reaction Products

37. What is compound V in the following synthesis?

Cl+ V

1. ether

2. H3O+

(C6H5)3P + WC6H5Li

etherWittigreagent

A) CH3CH2COCl B) CH3CH2MgBr C) CH3COCl D) (CH3)2CuLi E) (CH3CH2)2CuLi Ans: E

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589

Topic: Reaction Products

38. What is the reactant W in the synthesis given below? O

Cl+ V

1. ether

2. H3O+

(C6H5)3P + WC6H5Li

etherWittigreagent

A) Cyclopentanone B) Cyclopentene C) Cyclopentanol D) Bromocyclopentane E) Triphenylphosphine oxide Ans: D

Topic: Reaction Products

39. What is the final product, Z, of the following synthesis?

CH3

COAl(t-Bu)2

COCH3

COLi

COH

1. KMnO4, OH-, heat2. H3O+

SOCl21. LiAlH(O-t-Bu)3 ether, -78 oC2. H2O

X Y Z

I II III IV VA) I B) II C) III D) IV E) V Ans: C

Chapter 16

590

Topic: Reaction Products

40. What is the final product of this synthetic sequence?

Benzene

Br2

FeCl3

ether

1. C6H5CHO

2. H3O+

H2Cr2O4

acetone?

C6H5CC6H5

B) p-BrC6H4CH2C6H5 C) C6H5CH2COOH D)

C6H5CH2CC6H5

E) C6H5CH2C6H5 Ans: A

Topic: Reaction Products

41. The reaction of tert-butyl methyl ketone with a peroxy acid produces which of these as the principal product(s)? A)

(CH3)3COCCH3

(CH3)3CCOCH3

(CH3)2C

COCH3

CH3

D) (CH3)3COH + HO2CCH3 E)

(CH3)3COCOCH3

Ans: A

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591

Topic: Synthesis

42. Which of the following reactions would yield benzaldehyde? A)

C6H5CH2ClOH-

H2Oheat

B) C6H5CH(OCH3)2

H3O+

C) C6H5COOH

1. LiAlH4, ether

2. H2OD) Answers A) and B) E) Answers A), B), and C) Ans: B

Topic: Synthesis

43. Which of the reactions listed below would serve as a synthesis of acetophenone,

C6H5CCH3

C6H5CCl

+ (CH3)2CuLiB)

C6H6 + CH3COClAlCl3

C) C6H5CN + CH3Li

ether H3O+

D) Answers A) and B) only E) Answers A), B), and C) Ans: E

Topic: Synthesis

44. Which of the following would yield 3-pentanone as the major product? A)

CH3CH2CN + CH3CH2Liether H3O+

Product

B) CH3CH2CO2H + 2 CH3CH2Li

ether H3O+Product

CH3CH2CCl + (CH3CH2)2CuLiether

D) Two of these E) All of these Ans: E

Chapter 16

592

Topic: Synthesis

45.

Which of the following procedures would not yield (CH3)2CHCH

as a product?

CO2H

PCC

CH2Cl2

SOCl2ether, -78 oC

O3 Zn

HOAc

KMnO4

NaOH

H3O+

III

LiAlH(O-t-Bu)3

A) I B) II C) III D) IV E) V Ans: D

Chapter 16

593

Topic: Synthesis

46. Which of the following procedures would not yield 3-pentanone as a major product? A) H3O+

CH3CH2CNCH3CH2MgBr

etherB)

H2O2 CH3CH2Li

etherCH3CH2COH

C) H3O+CH3CH2CN

CH3CH2Li

etherD)

(CH3CH2)2CuLi

etherCH3CH2CCl

E) H3O+CH3CH2CO2H

CH3CH2MgBr

etherAns: E

Topic: Synthesis

47. How could the following synthetic conversion be accomplished?

CH3CH2CCH3

CH3CH2CH2CHOA) HgSO4/H2SO4; then PCl5/0°C; then NaNH2, liq. NH3 B) PCl5/0°C; then NaNH2, liq. NH3; then Sia2BH; then H2O2 C) PCl5/0°C; then NaNH2, liq. NH3; then HgSO4, H2SO4/H2O D) NaNH2, liq. NH3; then PCl5/0°C; then HgSO4, H2SO4/H2O E) H2O2; then PCl5/0°C; then NaNH2, liq. NH3; then Sia2BH Ans: C

Chapter 16

594

Topic: Synthesis

48. Which sequence of reactions would be utilized to convert

O CO2CH3 O C

CH3CH3

into ?

A) 2CH3MgBr, then NH4+

B) HOCH2CH2OH, H3O+; LiAlH4, ether; 2CH3MgBr, then NH4+

C) HOCH2CH2OH, H3O+; 2CH3MgBr, then NH4+

D) HOCH2CH2OH, H3O+; H2, Pt; CH3OH, NH4+

E) None of the above Ans: C

Topic: Synthesis

49. Which reaction sequence would be used to prepare

MgBr+1. ether

2. H3O+

NiI

+ 2 CH3MgBr1. ether

2. H3O+

NiII

III(C6H5)3P C6H5Li cyclopentanone H2

IVCH3MgBr

ether

H3O+

A) I B) II C) III D) IV E) All of the above would yield the product. Ans: C

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595

Topic: Synthesis

50. Which Wittig reagent would be used to synthesize

CH=P(C6H5)3 P(C6H5)3CH3CH=P(C6H5)3 CH3CH2CH=P(C6H5)3

I II III IV

A) I B) II C) III D) IV E) Either I or II could be used. Ans: E

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596

Topic: Synthesis

51. A good synthesis of

H2O, H2SO4

HgSO4I

II1. Sia2BH

2. H2O2, NaOH

III1. O3

2. Zn, HOAc

1. KMnO4, NaOH, heat

2. H3O+IV

would be:

A) I B) II C) III D) IV E) All of these are equally useful. Ans: B

Chapter 16

597

Topic: Synthesis

52. Which of the following is not a synthesis of benzophenone,

C6H5CC6H5

C6H5CCl

C6H6 +AlCl3

B) (C6H5)2CHOH

H2CrO4

acetoneC)

(C6H5)2CH=CH21. O3

2. Zn, HOAcD)

(C6H5)2CO2H + 2 C6H5Li1. ether

2. H2OE) All of the above will give benzophenone. Ans: E

Topic: Synthesis

53. Which of the following is a synthesis of 3-heptanone? A)

CH3CH2CH2CH2CH2OHPCC

CH2Cl2

1. CH3CH2MgBr

2. H3O+

H2Cr2O4

acetoneB)

CH3CH2CNCH3(CH2)2CH2Li H3O+

etherC)

CH3CH2CH2CH2OHPBr3 CH3CH2MgBrNaCN

ether

H3O+

etherD)

CH3CH2CH2CH2CH2OHKMnO4

OH-,

2 CH3CH2LiH3O+

ether

H2O

E) All of the above are syntheses of 3-heptanone. Ans: E

Chapter 16

598

Topic: Synthesis

54. Which synthesis or syntheses would yield propanal? A)

CH3CH2CH2OHPCC

CH2Cl2B)

CH3CH2CCl

OLiAlH[OC(CH3)3]3

ether, -78 oCC)

CH3C CH1. Sia2BH

2. H2O2, OH-

D) All of these E) None of these Ans: D

Topic: Reagents

55. LiAlH4 (LAH) cannot be used to convert carboxylic acids to the corresponding aldehydes because: A) LAH is not sufficiently reactive. B) RCOOH is converted into RCOOLi. C) RCOOH is reduced to RCH2OH. D) RCOOH is reduced to RCH3. E) RCOOH is converted into R2C=O. Ans: C

Topic: Reagents

56. The following reduction can be carried out with which reagent(s)?

A) Zn(Hg), HCl B) i) HSCH2CH2SH, BF3 ; ii)Raney Ni (H2) C) NaBH4, CH3OH D) A & B E) A & C Ans: D

Chapter 16

599

Topic: Reagents

57. Identify the reagent(s) that would bring about the following reaction: CH3CH2CH2COCl ⎯⎯⎯→ CH3CH2CH2CHO A) H2/Ni B) Li/liq.NH3 C) LiAlH[OC(CH3)3]3, ether D) NaBH4, CH3OH E) LiAlH4, ether Ans: C

Topic: Reagents

58. Which reagent will not differentiate between 3-butenal and 2-butanone? A) Br2/CCl4 B) Ag2O,OH- C) H2NNHC6H5 D) KMnO4,OH- E) None of these Ans: C

Topic: Reagents

59. The Reformatsky reaction involves the reaction of an aldehyde or ketone with: A) RLi B) R2CuLi C)

XZnCHCO2R'

D) RC≡CNa E) R3P Ans: C

Topic: Reagents

60. Acetals are unstable in the presence of an aqueous solution of which of these? A) HCl B) NaOH C) KHCO3 D) Na2CO3 E) NaCl Ans: A

Chapter 16

600

Topic: Reagents

61.

The compound C6H5C N N CC6H5

is produced by the reaction of an excess of benzaldehyde with which compound? A) Ammonia B) Hydrazine C) Nitrogen D) Phenylhydrazine E) Hydroxylamine Ans: B

Topic: Reagents

62. Which of these will not catalyze the reaction of a weak nucleophile with the carbonyl group of an aldehyde or ketone? A) I- B) H3O+ C) AlCl3 D) BF3 E) ZnCl2 Ans: A

Topic: Reagents

63. Which reagent(s) could be used to carry out the following transformation?

A) Zn(Hg), HCl, reflux B) LiAlH4, ether C) HSCH2CH2SH, BF3; then Raney Ni (H2) D) All of the above E) Two of the above Ans: E

Chapter 16

601

Topic: Physical Properties, Relationships, Stereochemistry

64. Which of the compounds listed below would you expect to have the highest boiling point? (They all have approximately the same molecular weight.) A) pentane B) 1-butanol C) Butanal D) 1-fluorobutane E) diethylether Ans: B

Topic: Physical Properties, Relationships, Stereochemistry

65. What is the order of decreasing reactivity of aldehydes, esters and ketones towards the organozinc compounds used in the Reformatsky reaction? A) Aldehydes > esters > ketones B) Esters > aldehydes > ketones C) Ketones > esters > aldehydes D) Ketones > aldehydes > esters E) Aldehydes > ketones > esters Ans: E

Topic: Physical Properties, Relationships, Stereochemistry

66. What, in general, is the order of decreasing reactivity of these carbonyl compounds towards nucleophilic reagents?

CH3CCH3 CH3C O (CH3)3CCCH3 HC O (CH3)3CCC(CH3)3

O H O OH

I II III IV VA) I > III > V > II > IV B) IV > II > I > III > V C) V > III > I > II > IV D) II > I > V > III > IV E) III > V > IV > II > I Ans: B

Chapter 16

602

Topic: Physical Properties, Relationships, Stereochemistry

67. Which of these gem-diols is expected to be the most stable? A)

CF3CCF3

B) CH3CH(OH)2 C)

CH3CCH3

D) C6H5CH(OH)2 E) ClCH2CH(OH)2 Ans: A

Topic: Physical Properties, Relationships, Stereochemistry

68. The relationship of 3-methyl-2-heptanone and 3-methyl-2-hepten-2-ol is designated by the term: A) Tautomers B) Conformational isomers C) Diastereomers D) Resonance structures E) Stereoisomers Ans: A

Chapter 16

603

Topic: Physical Properties, Relationships, Stereochemistry .

69. In which of the following reactions is the final product expected to be formed as a racemic mixture? A)

C6H5C O

C6H5MgBr +B)

CH3CCH3

HCN +

C) CH3CH2C O BrZnCH2COC2H5

H O

+D)

CH3C O

+ xs CH3OH + HClE)

CH3CHCH2COC2H5

CH3

+ (i-Bu)2AlH

Ans: C

Topic: Physical Properties, Relationships, Stereochemistry

70. Stereoisomers can exist in the case of which of the following? A) The hydrazone of butanone B) The oxime of acetone C) The phenylhydrazone of cyclohexanone D) The cyclic acetal formed from propanal and ethane-1,2-diol E) The imine of cyclopentanone Ans: A

Topic: Physical Properties, Relationships, Stereochemistry

71. Stereoisomers can exist in the case of which of the following? A) The hydrazone of acetophenone B) The oxime of 2-methylcyclopentanone C) The phenylhydrazone of 4-methylcyclohexanone D) The imine of cyclopentanone E) Two of the above Ans: B

Chapter 16

604

Topic: Reactions of Aldehydes and Ketones

72. Which of the following is formed when 3-methylcyclopentanone reacts with hydroxylamine?

N-NH-C6H5 N-NH2 N-OH

I II III

NNH

NH2

NNH NO2

NO2

VA) I B) II C) III D) IV E) V Ans: C

Topic: Reactions of Aldehydes and Ketones

73. Which of the following is formed when 3-methylcyclopentanone reacts with semicarbazide?

N-NH-C6H5 N-NH2 N-OH

I II III

NNH

NH2

NNH NO2

NO2

VA) I B) II C) III D) IV E) V Ans: D

Chapter 16

605

Topic: Reactions of Aldehydes and Ketones

74. Which of the following is formed when 4-methylpentanal reacts with phenylhydrazine?

N-NH-C6H5 N-C6H5 N-NH2

I II III

IV V

NNH

NH2

ON=N-C6H5

A) I B) II C) III D) IV E) V Ans: A

Topic: Reactions of Aldehydes and Ketones

75. Which of the following is formed when 2,2,3-trimethylcyclohexanone reacts with hydroxylamine?

N-NH-C6H5 N-NH2

N-OH

IIII

NNH

NH2

NNH NO2

NO2

VA) I B) II C) III D) IV E) V Ans: C

Chapter 16

606

Topic: Reactions of Aldehydes and Ketones

76. Which of the following is formed when 2,2,3-trimethylcyclohexanone reacts with semicarbazide?

N-NH-C6H5 N-NH2

N-OH

IIII

NNH

NH2

NNH NO2

NO2

VA) I B) II C) III D) IV E) V Ans: D

Topic: Reactions of Aldehydes and Ketones

77. Which of the following is formed when 2,2,3-trimethylcyclohexanone reacts with hydrazine?

N-NH-C6H5 N-NH2

N-OH

IIII

NNH

NH2

NNH NO2

NO2

VA) I B) II C) III D) IV E) V Ans: B

Chapter 16

607

Topic: NMR

78. A compound with formula C5H10O gives two signals only, both singlets, in the 1H NMR spectrum. Which of these structures is a possible one for this compound? A)

CH3CH2CCH2CH3

B) (CH3)2CHCCH3

C) (CH3)3CC O

D) CH3CH2CHC O

CH3

E) (CH3)2CHCH2C O

Ans: C

Topic: NMR

79. The 1H NMR spectrum of a compound with formula C7H14O gives three signals. Which of these structures is a possible one for this compound? A) 2-heptanone B) 3-heptanone C) 2,4-dimethyl-3-pentanone D) 2,2-dimethyl-3-pentanone E) two of the above Ans: E

Chapter 16

608

Topic: NMR

80. The 13C NMR spectrum of a compound with formula C7H14O gives three signals. Which of these structures is a possible one for this compound? A) 2-heptanone B) 3-heptanone C) 2,2-dimethyl-3-pentanone D) 2,4-dimethyl-3-pentanone E) two of the above Ans: D

Topic: NMR

81. The 1H NMR spectrum of a compound with formula C7H14O gives a doublet at 9.2 ppm. Which of these structures is a possible one for this compound? A) 2-methyl-3-hexanone B) 2-methylhexanal C) 2,2 -dimethylpentanal D) 2,2-dimethyl-3-pentanone E) two of the above Ans: B

SHORT ANSWER QUESTIONS Topic: Relative Reactivity

82. Aldehydes are more reactive than ketones towards nucleophilic substitution because of both steric and electronic factors. Briefly explain. a. Steric reasons: ______________. b. Electronic reasons: __________. Ans: a. aldehydes have the small hydrogen substituent on one side, so less steric

crowding than ketones b. aldehydes have only one electron-releasing group to partly neutralize/stabilize the partial positive charge at the carbonyl carbon while ketones have two

Topic: General

83. A compound with an OH and OR group attached to the same carbon is known as a(n) _____________. Ans: hemiacetal

Chapter 16

609

Topic: General

84. A compound with two OH groups attached to the same carbon is known as a(n) _________. Ans: hydrate or gem-diol

Topic: General

85. A compound with two OR groups attached to the same carbon is known as a(n) _________. Ans: acetal

Topic: General

86. A compound containing a C=N double bond is known as a(n) __________. Ans: imine

Topic: General

87. A compound with an OH and CN group attached to the same carbon is known as a(n) _____________. Ans: cyanohydrin

Topic: Wittig Reaction

88. The reaction between a phosphorus ylide and an aldehyde or ketone is called the ___________ reaction. Ans: Wittig

Topic: Wittig Reaction

89. The driving force for the Wittig reaction is the formation of the very strong _______________ bond in _______________. Ans: P-O bond; triphenylphosphine oxide

Topic: General

90. A “green” version of the __________________ uses a tin-zeolite catalyst with hydrogen peroxide. Ans: Baeyer-Villiger oxidation

Chapter 16

610

Topic: Functional Group Tests

91. 2,4-DNP is a reagent frequently used for functional group tests; it detects the presence of _____________. Ans: aldehydes and ketones

Topic: Functional Group Tests

92. The Tollens test, used in conjunction with 2,4-DNP, can distinguish between ______________ and _______________. Ans: aldehydes and ketones

Topic: Functional Group Tests

93. What reagent would help you distinguish between acetophenone and 2-methylbenzaldehyde? Ans: Tollen’s Reagent

Topic: Functional Group Tests

94. Oximes are formed when aldehydes and ketones react with _______________. Ans: Hydroxylamine, NH2OH

Topic: Synthetic Strategy

95. Suggest a synthetic strategy for the synthesis of 3-heptanone from 1-bromobutane. Ans:

Br CNNaCN

i. C2H5Li, Et2O

ii. H3O+

Topic: Synthetic Strategy

96. Suggest a synthetic strategy for the synthesis of 4-methylpentanal from 3-methyl-1-bromobutane. Ans:

Br CNNaCN i. DIBAL-H

ii. H2OO

Chapter 16

611

Topic: Synthetic Strategy

97. Suggest a synthetic strategy for the synthesis of 6-methyl-3-heptanol from 4-methylpentanenitrile, (CH3)2CHCH2CH2CN. Ans:

i. DIBAL-H

ii. H2O

iii. C2H5MgBr, Et2O

iv. H3O+

i. C2H5MgBr, Et2O

ii. H3O+

iii. NaBH4, H2O Topic: Reaction Sequence

98. Complete the following reaction sequence, giving structural details of all significant intermediates.

?i. Br2, hν

ii. Mg, CH3CH2CN

iii. H3O+

iv. RCO3HAns:

BrO

RCO3H

Br2, hν i. Mg, CH3CH2CN

ii. H3O+

Chapter 16

612

Topic: Reaction Sequence

99. Complete the following reaction sequence, giving structural details of all significant intermediates.

i. EtMgBrii. H3O+, heat

i. O3ii.Zn, CH3CO2H

Ans:

O HO

i. EtMgBrii. H3O+, heat

i. O3ii.Zn, CH3CO2H

Topic: NMR

100. Explain clearly how you might use 1H NMR to distinguish between 2-phenylacetaldehyde and acetophenone Ans: A quick inspection of 1H NMR of the two substances would allow easy

identification and distinction between them: the expected 1H NMR spectra of the two substances are described below. 2-Phenylacetaldehyde Acetophenone C6H5CH2CHO and C6H5COCH3 3 signals 2 signals approximate δ ppm approximate δ ppm doublet (-CH2-) 2.5 singlet (-CH3) 2.0 multiplet (C6H5) 7 multiplet (C6H5) 7.2 doublet (-CHO) 9

Chapter 17

613

MULTIPLE CHOICE QUESTIONS

Topic: Acid/Base

1. Which compound would be most acidic? A) CH3CH2CH3 B) CH3CH=CH2 C) Cyclohexane (CH3)2C=O D) (CH3)2C=O E) Benzene Ans: D

Topic: Reaction Products

2. What would be the major product of the following reaction?

C6H5CH

CH3CH

+OH-

heatA)

C6H5CH2CCH3

B) C6H5CCH2CH

O O

C) C6H5CHCH2CH2

OH OH

D) C6H5CH2CH2CH

E) C6H5CH=CHCH

Ans: E

Chapter 17

614

Topic: Reaction Products

3. The product, C, of the following sequence of reactions,

OH-CH3CCHO

CH3

+ CH3CH2CHO AH3O+

(-H2O)B

NaBH4

CH3OHC

would be: A)

CH3CCH=CHCH2CH2OH

CH3

CH3CCH=CCH2OH

CH3

CH3 CH3

CH3CCH2CH2CH2OH

CH3

CH3CCH2CH2CH2CH2OH

CH3

CH3CCH2CHCHO

CH3

CH3 CH3

Ans: B

Chapter 17

615

Topic: Reaction Products

4. What would be the major product of the following reaction?

CH3 CH

+ OH-CH3CCH3

100 oC?

CH CH

CH3

CH3 CH CCH3

CH3CH3 CHCH2CCH3

CH3 CH CHCCH3

CH3 CHC(CH3)2

I II III

IV VA) I B) II C) III D) IV E) V Ans: D

Topic: Reaction Products

5. What would be the major product of the following reaction?

CH3CH2CHOH-

H2O?

A) CH3CH2CH2OH + CH3CH2COO- B) CH3CH2CHCH2CHO

CH3CH2CH2OCCH2CH3

D) CH3CH2CHCHCHO

HO CH3

E) CH3CH2CHCCH2CH3

Ans: D

Chapter 17

616

Topic: Reaction Products

6. What would be the major product of the following reaction?

I II

III

?O + O

OHOH

OH-

A) I B) II C) III D) IV E) V Ans: D

Chapter 17

617

Topic: Reaction Products

7. What would be the major product of the following reaction?

I II

III

OH-

heat?+

A) I B) II C) III D) IV E) V Ans: D

Chapter 17

618

Topic: Reaction Products

8. What would be the major product, B, of the following reaction sequence?

I II

III

O OH O

OH-

heat+

i. CH3Cu ii H3O+

A B

A) I B) II C) III D) IV E) V Ans: C

Chapter 17

619

Topic: Reaction Products

9. What would be the major product, B, of the following reaction sequence?

I II

III

OHOH

OH OH

OH-

heatNaBH4 H2O+ A B

A) I B) II C) III D) IV E) V Ans: C

Chapter 17

620

Topic: Reaction Products

10. What would be the major product of the following reaction? OD-

roomtemp.

?C6H5C CHCH3

O CH3+ D2O

A) C6H5C CHCH3

O CD3

B) C6H5C CDCH3

O CH3

C) CDCH3

CH3

C6D5C

D) CDCD3

CD3

C6H5C

C6H5CDCHCH3

CH3

Ans: B

Topic: Reaction Products

11. What would be the product of the following reaction?

CH3CH=CO2C2H5

NaCN

C2H5OH, CH3COOH?

A) CH3CH2CHCO2C2H5

B) CH3CH=CHCO2CN C) CH3CH=CHCN D) CH3CHCH2CO2C2H5

CH3CH=CHCOC2H5

Ans: D

Chapter 17

621

Topic: Reaction Products

12. Select the structure of the major product formed in the following reaction.

(CH3)2C=CHCCH3

1. CH3Cu

2. H2OA) (CH3)3CCH2COCH3 B) (CH3)2C=CHC(CH3)2

C) (CH3)2CHCHCOCH3

CH3

D) CH3CCH3

E) (CH3)2C=CHCCH3

Ans: A

Topic: Reaction Products

13. What would be the product of the following reaction?

C6H5CH

+ CH3CH2CNEtO-, EtOH

?A) C6H5CH=CHCH2CN B)

C6H5CCHCN

CH3

C) C6H5CH=CCN

CH3

D) C6H5CHCH2CH2CN

E) C6H5CCH2CH2CN

OCH2CH3

Ans: C

Chapter 17

622

Topic: Reaction Products

14. What would be the final product of the following reaction sequence?

C6H5CH

OOH-, heat

+ CH3CCH3

ALiAlH4

etherFinal

Product

A) C6H5CH2CH2CH2CH3 B)

C6H5CHCH2CCH3

OH O

C6H5CH2CH2CCH3

C6H5CH=CHCHCH3

C6H5CHCH2CHCH3

OH OH

Ans: D

Chapter 17

623

Topic: Reaction Products

15. What would be the major product of the following reaction?

C6H5CCHCH2CH3

CH3

+ Br2H3O+

C6H5CCBrCH2CH3

CH3

C6H5CCHCHCH3

CH3

C6H5CCHCHCH3

CH3

D) C6H5CBr2CHCH2CH3

CH3

E) m-BrC6H4CCHCH2CH3

CH3

Ans: A

Chapter 17

624

Topic: Reaction Products

16. What would be the major product of the following reaction?

C6H5CH

+ CH3CCH3

?OH-

heatA)

C6H5CCH2CHCH3

O OH

C6H5CCH2CCH3

O O

C6H5CHCH2CHCH3

OH OH

C6H5CCH2CCH3

O O

C6H5CH=CHCCH3

Ans: E

Topic: Reaction Products

17. What would be the product, C, of the following reaction sequence?

(CH3)3CCH + CH3CH2CH

OO OH- H3O+

heatA B

NiC

A) (CH3)3CCH2CH2CH2OH B)

(CH3)3CCHCH2CH2CH

OOH

C) (CH3)3CCH2CHCH2OH

CH3

D) (CH3)3CCH=CCH2OH

CH3

(CH3)3CCH=CCH

CH3

Ans: C

Chapter 17

625

Topic: Reaction Products

18. What would be the product, C, of the following reaction sequence?

(CH3)3CCH + CH3CH2CH

OO OH- H3O+

heatA B C

CH2 P(C6H5)3

A) (CH3)3CCH2CH2CH2OH B)

(CH3)3CCHCH2CH=CH2

C) (CH3)3CCH2C=CH2

CH3

D) (CH3)3CCH=CCH=CH2

CH3

(CH3)3CCHCHCH=CH2

CH3

Ans: D

Topic: Reaction Products

19. What would be the product, B, of the following reaction sequence?

C6H5CH + CH3CNEtO-, EtOH A (C9H7N)

H3O+

heatB

A) C6H5CH=CHCO2H B)

C6H5CCH2CO2H

C) C6H5CH2CH2CO2H D)

C6H5CHCH2CO2H

E) C6H5CHCH2CN

Ans: A

Chapter 17

626

Topic: Reaction Products

20. What would be the product, C, of the following reaction sequence?

C6H5CHOH- H3O+, heat

A B CO

CH3CH2CH

+25 oC (-H2O)

NaBH4

CH3OHA)

C6H5CCHCH2OH

CH3

B) C6H5CHCHCH2OH

HO CH3

C) C6H5CH2CHCH

CH3

D) C6H5CH=CCH

CH3

E) C6H5CH=CCH2OH

CH3hi

Ans: E

Chapter 17

627

Topic: Reaction Products

21. What would be the product, C, of the following reaction sequence?

C6H5CHOH- H3O+, heat

A B CO

CH3CH2CH

+25 oC (-H2O)

H2, Ni

highpressure

A) C6H5CCHCH2OH

CH3 B) C6H5CH2CHCH2OH

CH3

C) C6H5CH2CHCH

CH3

C6H5CH=CCH

CH3

E) C6H5CH=CCH2OH

CH3 Ans: B

Chapter 17

628

Topic: Reaction Products

22. What would be the major product of the following reaction?

C6H5CH=CHCCH3

+ CN-CH3CH2OH

CH3COOH?

A) C6H5CH2CHCCH3

C6H5CHCH2CCH3

C6H5CH2CH2CCH3

C6H5CH2CH2CCN

C6H5CHCH=CCH3

Ans: B

Chapter 17

629

Topic: Reaction Products

23. What would be the major product(s) of the following reaction? O

Cui.ii. H3O+ ?

I II

III

O OH O

OH O

A) I and V B) II and IV C) I and III D) III and IV E) None of these Ans: A

Chapter 17

630

Topic: Reaction Products

24. What would be the major product of the following reaction?

I II

III

O O

OHO

OH-

A) I B) II C) III D) IV E) V Ans: E

Chapter 17

631

Topic: Reaction Products

25. What would be the major product of the following reaction?

I II

III

?i. Br2, NaOH

ii. H3O+

A) I B) II C) III D) IV E) V Ans: B

Chapter 17

632

Topic: Reaction Products

26. What would be the major product of the following reaction sequence?

I II

IIIO

?i. LDAii. C2H5I

O O

A) I B) II C) III D) IV E) V Ans: I

Topic: Synthetic Strategy

27. What synthetic strategy would accomplish the following transformation?

O O?

A) i) Br2, H3O+; ii) NaOC2H5, C2H5OH, heat B) i) Cl2, FeCl3; ii) NaOC2H5, C2H5OH, heat C) i) HCN; ii) H3O+

, heat D) i) Br2, hν; ii) (CH3)3COK, (CH3)3COH, heat E) i) Br2, H3O+; ii) (CH3)3COK, (CH3)3COH, heat Ans: A

Chapter 17

633

Topic: Reaction Products

28. What would be the major product of the following reaction?

CCHCH3

CH3

+ Br2OH-

CCHCH3

CH3Br

CCHCH3

CH3

Br CCBrCH3

CH3

CCHCH2Br

CH3

CCHCH2Br

CH2Br

I II III

IV V

A) I B) II C) III D) IV E) V Ans: C

Topic: Reaction Products

29. Which compound would be formed when 2-methylbutanal is treated with a solution of NaOD in D2O? A) CH3CH2CDCHO

CH3

B) CH3CH2CHCDO

CH3

C) CH3CHDCHCHO

CH3

D) CH2DCH2CHCHO

CH3

E) CH3CH2CDCDO

CH3

Ans: A

Chapter 17

634

Topic: Reaction Products

30. Which compound would be formed when 2,3-dimethylhexanal is treated with a solution of NaOD in D2O? A)

E) O

D Ans E

Topic: Reaction Products

31. What is the final product of this reaction sequence?

H2C=OCH3CH2NO2

OH-

H2, Ni?

CH3C=CH2

NH2

B) CH3CH2CH2NH2 C)

CH3CHCH3

NH2

D) CH3CH2CH2NO2 E)

CH3CHCH3

NO2

Ans: C

Chapter 17

635

Topic: Reaction Products

32. Which of these is a product of the reaction of C6H5MgBr with

C6H5CH=CHCCH3

C6H5CH=CCCH3

C6H5

C6H5CH=CHCCH3

C6H5

C6H5CH=CHCCH2C6H5

CH=CHCCH3

C6H4p-C6H5

C6H5CH=CHCHCH3

OC6H5

Ans: B

Topic: Reaction Products

33. What is the product of the reaction below?

OC6H5

C6H5

OC6H5

HO C6H5

I II III IV V

1. (C6H5)2CuLi

2. H2O?

A) I B) II C) III D) IV E) V Ans: B

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Topic: The Aldol Reaction/Condensation (Explicitly Identified)

34. Which reagents would you use to synthesize this compound by an aldol condensation?

C6H5CH=CHCC6H5

A) C6H5CH

C6H5CH2CH

andB)

C6H5CH2CH

and C6H5CCH3

C6H5CH=CHCH

and C6H5OHD)

C6H5CH

andC6H5CCH3

(C6H5)2CuLi and CH2=CHCC6H5

Ans: D

Topic: The Aldol Reaction/Condensation (Explicitly Identified)

35. What starting compound(s) would you use in an aldol reaction to prepare

CH3CHCH2CH2CCH3

OH O

CH3CCH2CH2CCH3

O O

CH3CCH2CH2CH2CH

O O

HCCH2CH2CH2CH

O O

+ H2C=O

I II III

IV VA) I B) II C) III D) IV E) V Ans: D

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Topic: The Aldol Reaction/Condensation (Explicitly Identified)

36.

Which reagents would you use to synthesize this compound by an aldol condensation?

C6H5CH=CCH

C6H5

A) C6H5CH

C6H5CH2CH

andB)

C6H5CH2CH

and C6H5CCH3

C6H5CH=CHCH

and C6H5OHD)

C6H5CH

andC6H5CCH3

E) C6H5CHCH

C6H5CH2Cl and

ONaAns: A

Topic: The Aldol Reaction/Condensation (Explicitly Identified)

37. The aldol condensation product formed from 3-pentanone in the presence of base has the IUPAC name: A) 5-Ethyl-4-methyl-4-hepten-3-one B) 5-Ethyl-4-methyl-5-hepten-3-one C) 4-Methyl-4-nonen-3,7-dione D) 3-Ethyl-4-methyl-3-hepten-5-one E) 3-Ethyl-4-methyl-2-hepten-5-one Ans: A

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Topic: The Aldol Reaction/Condensation (Explicitly Identified)

38. Which of these is not among the reaction products when a crossed aldol addition occurs between ethanal and butanal? A)

CH3CHCH2C=O

OH H

B) CH3CH2CH2CHCHCH2C=O

CH2CH3

C) CH3CHCHC=O

OH H

CH2CH3

D) CH3CH2CH2CHCH2C=O

HOH

E) CH3CH2CH2CHCHC=O

HOH

CH2CH3

Ans: B

Topic: The Aldol Reaction/Condensation (Explicitly Identified)

39.

The retro-aldol reaction of

C6H5CH=CC=O

CH2CH3 gives: A)

C6H5CH2CH2C=O

+ CH3C=O

C6H5CH2C=O + CH3CH2C=O

H H

C6H5C=O + CH3CH2CC=O

C6H5CH2CCH2CH3

+ H2C=OE)

C6H5C=O + CH3CH2CH2C=O

H H

Ans: E

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Topic: The Aldol Reaction/Condensation (Explicitly Identified)

40. If butanal is added slowly to an aqueous solution of sodium hydroxide and 2,2-dimethylpropanal at 25°C, the principal product is which of these? A)

(CH3)3CCHCHC=O

OH H

CH2CH3

CH3CH2CH2CHCHC=O

CH2CH3

(CH3)3CCHCC(CH3)3

CH3CH2CH2CHC(CH3)3

CH3CH2CH2CHCHC=O

C(CH3)3

Ans: A

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Topic: The Aldol Reaction/Condensation (Explicitly Identified)

41. What compound results from the aldol cyclization of

CH3CCH2CH2CHCH2CCH3

CH3

CH3 O

CH3

CH3 O

CH3

I II III IV A) I B) II C) III D) IV E) Both III and IV Ans: E

Topic: The Aldol Reaction/Condensation (Explicitly Identified)

42.

The aldol cyclization of CH3CCH2CH2CH2C=O

O H

produces which of these?

I II III IV

CH3 C=O

H OC=O

H OO O

CH3CH3

A) I B) II C) III D) IV E) V Ans: D

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Topic: The Aldol Reaction/Condensation (Explicitly Identified)

43. What product results from the intramolecular aldol reaction of 2,5-hexanedione?

I II III IV V

CH3 CCH3

CH3

A) I B) II C) III D) IV E) V Ans: A

Topic: The Aldol Reaction/Condensation (Explicitly Identified)

44.

The reaction of CH3CCH2CH2CH2CCH3

O O

with base affords which of these products?

I II III IV

C=O

HCH3

C=O

HCH3

CH3

O O

A) I B) II C) III D) IV E) V Ans: D

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Topic: The Aldol Reaction/Condensation (Explicitly Identified)

45. The aldol reaction of cyclohexanone produces which of these self-condensation products?

I II III IV V

O O O O OO

A) I B) II C) III D) IV E) V Ans: B

Topic: The Aldol Reaction/Condensation (Explicitly Identified)

46. Which is the only one of these compounds which cannot self-condense in the presence of dilute aqueous alkali? A) Phenylethanal B) Propanal C) 2-Methylpropanal D) 3-Methylpentanal E) 2,2-Dimethylpropanal Ans: E

Topic: The Aldol Reaction/Condensation (Explicitly Identified)

47. Which is the only one of these compounds which cannot self-condense in the presence of dilute aqueous alkali? A) Phenylethanal B) 2-methyl-3-pentanone C) 2-Methylpentanal D) Acetophenone E) 2,2-Dimethylpentanal Ans: E

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Topic: The Aldol Reaction/Condensation (Explicitly Identified)

48. Which of these compounds cannot self-condense in the presence of dilute aqueous alkali? A) 3-(4-Nitrophenyl)propanal B) 2-methyl-3-pentanone C) 2-(4-Nitrophenyl)propanal D) 3-(4-Nitrophenyl)-2-butanone E) All of the above compounds can self-condense Ans: E

Topic: The Aldol Reaction/Condensation (Explicitly Identified)

49. Which of these compounds can react with 4-methylhexanal to afford good yields of the crossed aldol product? A) 3-(4-Nitrophenyl)propanal B) 2-methyl-3-pentanone C) 2-(4-Nitrophenyl)propanal D) 3-(4-Nitrophenyl)-2-butanone E) None of the above compounds will give good yields of the crossed aldol product

with 4-methylhexanal Ans: E

Topic: The Aldol Reaction/Condensation (Explicitly Identified)

50. Which of these compounds can react with 4-methylpentanal to afford good yields of the crossed aldol product? A) 3-(4-Nitrophenyl)propanal B) 2ethyl-2-methylheptanal C) 2-(4-Nitrophenyl)propanal D) 3-(4-Nitrophenyl)-2-butanone E) None of the above compounds will give good yields of the crossed aldol product

with 4-methylhexanal Ans: B

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Topic: The Aldol Reaction/Condensation (Explicitly Identified)

51.

When CH3CCH2CH2CH2CH2CH2CCH3

O O

cyclizes in basic solution, which of these compounds will be formed?

I II III IV V

CH3

CCH3O

CH3CH3

CH2

CCH3O CH3

A) I B) II C) III D) IV E) V Ans: A

Topic: The Aldol Reaction/Condensation (Explicitly Identified)

52. What final product is obtained when 2,8-nonanone is treated with base, followed by reaction with sodium borohydride?

I II

III

OH OH

A) I B) II C) III D) IV E) V Ans: A

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Topic: Chemical Tests

53. Which reagent would best serve as the basis for a simple chemical test to distinguish between 2-pentanone and 3-pentanone? A) NaOI (I2 in NaOH) B) Br2/CCl4 C) CrO3/H2SO4 D) NaHCO3/H2O E) Ag(NH3)2

+ Ans: A

Topic: Chemical Tests

54. Which reagent would best serve as the basis for a simple chemical test to distinguish between CH3CHO and CH3COCH3? A) NaOI (I2 in NaOH) B) Br2/CCl4 C) C6H5NHNH2 D) NaHCO3/H2O E) Ag(NH3)2

+ Ans: E

Topic: Chemical Tests

55. Which reagent would best serve as the basis for a simple chemical test to distinguish between

CH3C

CH3and ?

A) NaOI (I2 in NaOH) B) Br2/CCl4 C) CrO3/H2SO4 D) NaHCO3/H2O E) Ag(NH3)2

+ Ans: B

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Topic: Chemical Tests

56. Which of the reagents listed below would serve as the basis for a simple chemical test to distinguish between 2-methyl-1-propanol and 2-butanol? A) NaOI (I2 in NaOH) B) KMnO4 in H2O C) Br2 in CCl4 D) Cold concd H2SO4 E) CrO3 in H2SO4 Ans: A

Topic: Chemical Tests

57. A compound, C5H10O, reacts with phenylhydrazine and gives a positive iodoform test. The compound could be which of these? A)

CH3CH2CH2CH2C=O

CH3CHCH2C=O

CH3

C) CH2=CHCH2CHOHCH3 D)

CH3CHCCH3

CH3

CH3CH2CCH2CH3

Ans: D

Topic: Chemical Tests

58. A negative iodoform test will be observed in the case of which of these? A) Acetone B) Ethanal C) Ethanol D) 2-Butanol E) All of these will give a positive test. Ans: E

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647

Topic: Tautomerization and Keto-Enol Equilibrium

59. Which of the following represent tautomers? A)

CH3CH=CH O CH3CH CH=OandB) andCH3 CH=CH2

CH3 C

CH2

C) andCH3 CH=CH2

CH3 C

CH3

HD) All of these E) None of these Ans: C

Topic: Tautomerization and Keto-Enol Equilibrium

60. Which of these compounds would exist in an enol form to the greatest extent? A)

CH3COC2H5

CH3CCH2CCH3

O O

CH3CCH3

D) CH3CH

E) CH3CCH2CH2CCH3

O O

Ans: B

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Topic: Tautomerization and Keto-Enol Equilibrium

61. Which of the following is a keto-enol tautomeric pair?

O OH O OH O OH

O OH O OH

and and and

and and

I II III

IV VA) I B) II C) III D) IV E) V Ans: B

Topic: Tautomerization and Keto-Enol Equilibrium

62. Which of the following would undergo racemization in base?

C6H5CC6H5

CH3CH2CH2

CH3CH2

CH3

CC6H5

CH3

CH3CH2

CC6H5

CH3

CCH2C6H5

I II

III IV

A) I B) II C) III D) IV E) Both III and IV Ans: C

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Topic: Tautomerization and Keto-Enol Equilibrium

63. Which of the following would undergo racemization in base?

I II

III

OH3C H

OH3C CH3

H3C CH3

A) I B) II and III C) IV and V D) I and V E) I, IV and V Ans: D

Topic: Tautomerization and Keto-Enol Equilibrium

64. Which of the following would not undergo racemization in base? A) (R)-3-methyl-4-heptanone B) (R)-3-methyl-2-heptanone C) (R)-4-methyl-2-heptanone D) (R)-2,4-dimethyl-3-heptanone E) All of the above will undergo racemization in base Ans: C

Topic: Tautomerization and Keto-Enol Equilibrium

65. Which of the following would not undergo racemization in base? A) (S)-2-phenylbutanal B) (S)-3-phenylbutanal C) (S)-3-phenyl-2-butanone D) (S)-3-methyl-2-phenylbutanal E) All of the above will undergo racemization in base Ans: C

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Topic: Tautomerization and Keto-Enol Equilibrium

66. Which of the following represent keto-enol tautomers? A)

CH3CCH2CH3

CH3C=CHCH3

andB)

CH3CCH2CH3

andCH2=CCH2CH3

CH3CCH2CH3

andHOCH2CCH=CH2

D) More than one of these E) None of these Ans: D

Topic: Tautomerization and Keto-Enol Equilibrium

67. Simple enols are less stable than the tautomeric keto forms because: A) severe angle strain exists in the enol forms. B) fewer atoms are coplanar in the keto form. C) the enol cannot be chiral. D) the C-C π bond is weaker than the C-O π bond. E) Actually, simple enols are the more stable. Ans: D

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651

Topic: Tautomerization and Keto-Enol Equilibrium

68. Which would be formed when 2-methylpropanal is dissolved in D2O containing NaOD?A)

CH3CHCD

CH3

CH3CHCH

CH2D

CH3CDCH

CH3

CH3CDCD

CH3

CH3CHCHOD

CH3

Ans: C

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652

Topic: Reagents, Intermediates, and Spectroscopy

69. A compound, X, C9H10O, which reacts with I2/NaOH to give a pale yellow precipitate, gives the following 1H NMR spectrum. Singlet, δ 2.0 Singlet, δ 3.0 Multiplet, δ 7.7 Which is a possible structure for X?

I II

III

A) I B) II C) III D) IV E) V Ans: B

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653

Topic: Reagents, Intermediates, and Spectroscopy

70. What is the missing reagent?

OH-

heat?

OA)

CH3CCH2CH2CCH3

O O

B) CH3CCH2CH2CH2CH

O O

C) CH3CCH2CH2CH2CH2CH

O O

D) CH3CCH2CH2CH2COEt

O O

O=CCH2CH2CH2CH2COEt

H O

Ans: B

Topic: Reagents, Intermediates, and Spectroscopy

71.

The conversion of C6H5CCH3

to C6H5COH

is accomplished by the use of which oxidizing agent? A) Ag(NH3)2

+ B) O3 C) NaOI (I2 in NaOH) D)

RCOOH

E) Cu++ Ans: C

Use the following to answer questions 72-73:

O OHA

OH-,warm(-H2O)

B (C11H12O)H2/Ni

highpressure

Chapter 17

654

Topic: Reagents, Intermediates, and Spectroscopy

72. Consider the synthesis above in answering this question. What is compound A? A) Butanone B) Butanal C) Propanal D) 1-Butanol E) 2-Methylpropanal Ans: B

Topic: Reagents, Intermediates, and Spectroscopy

73. What is the intermediate B in the synthesis shown above?

OH OH O O O

I II III IV VA) I B) II C) III D) IV E) V Ans: D

Topic: Reagents, Intermediates, and Spectroscopy

74. Which of these would not be an intermediate or final product when C6H5CH2CN and HCHO react in basic solution and the product is treated with acid? A)

C6H5CHCN

CH2OH

C6H5CCN

CH2

C) C6H5CH2C=NH

C6H5CHCN

D) C6H5CH2C=O

C6H5CHCN

E) Each of these would be either an intermediate or a final product. Ans: E

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Topic: Reagents, Intermediates, and Spectroscopy

75. The Robinson annulation reaction which produces

CH3

O uses which of the following as starting materials?

CH3

CH2

CH3

O O

CH2

CH3CH=CH2

CH2=CHC=O

H+

CH2=CHCCH3

O+ HCHO +

CH3CH=CHCCH3

O+

CH3CH=CHCCH3

O+

I II III

IV VA) I B) II C) III D) IV E) V Ans: B

Topic: Reagents, Intermediates, and Spectroscopy

76. Which compound could be subjected to a haloform reaction to produce m-chlorobenzoic acid?

CH2OH

CO2H CCH2CH3

CCH3

CH2Cl

I II III IV V

A) I B) II C) III D) IV E) V Ans: D

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656

SHORT ANSWER QUESTIONS

Topic: General, Active Hydrogens

77. The α-hydrogens on carbonyl carbons are unusually acidic (pKa 19-20) because: _____________. Ans: the corresponding anion is resonance-stabilized by the carbonyl

Topic: Keto-Enol Tautomerism

78. The keto and enol forms of carbonyl compounds are a special type of __________ isomer called ___________. Ans: constitutional; tautomers

Topic: Keto-Enol Tautomerism

79. The interconversion of the keto and enol forms of a carbonyl compound is called _____________. Ans: tautomerization

Topic: Epimers

80. Diastereomers that differ in configuration at only one stereogenic center are sometimes called ___________, and their interconversion is called __________. Ans: epimers; epimerization

Topic: General

81. Dissolving a halogen in aqueous sodium hydroxide provides a solution of _____________. Ans: sodium hypohalite, NaOX

Topic: Haloform Reaction

82. The haloform reaction is an efficient method for converting methyl ketones to ____________. Ans: carboxylic acids

Topic: General

83. The initial product of the aldol reaction is a β-hydroxycarbonyl compound. These dehydrate readily when heated because the product _______________. Ans: is stabilized by having conjugated double bonds

Chapter 17

657

Topic: Aldol Reaction

84. An aldol reaction that starts with two different carbonyl compounds is called a _______________. Ans: crossed aldol reaction

Topic: Kinetic/Thermodynamic Enolates

85. An unsymmetrical ketone can form two possible enolates. The enolate with the more highly substituted double bond is called the ____________. Ans: thermodynamic enolate

Topic: Kinetic/Thermodynamic Enolates

86. The kinetic enolate (the less highly substituted double bond) is favored when __________ is used as a base. Ans: LDA or lithium diisopropylamide

Topic: 1,2- /1,4- Addition

87. When α,β-unsaturated aldehydes and ketones react with nucleophiles, they do so in one of two ways. What are the two ways? Ans: simple or 1,2-addition; conjugate or 1,4-addition

Topic: Kinetic/Thermodynamic Enolates

88. When α,β-unsaturated aldehydes and ketones react with nucleophiles, simple addition is favored when _________ nucleophiles are used, while conjugate addition is preferred by ___________ nucleophiles. Ans: strong; weaker

Topic: Kinetic/Thermodynamic Enolates

89. The sequence of a Michael addition followed by an intramolecular aldol condensation is known as a ___________. Ans: Robinson annulation

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658

Topic: 1,2- /1,4- Addition

90. When 5-methyl-3-hepten-2-one reacts with CH3Cu, the major product expected is___________ (structure and IUPAC name). Ans: The 1,4-addition product:

O4,5-dimethyl-2-heptanone

Topic: Reaction Products: Stereochemical Outcomes

91. When optically active 2-methyl-1-phenyl-1-butanone undergoes reaction with Br2/H3O+, the product is observed to exhibit no optical activity. Explain clearly. Ans: An achiral enol is formed in presence of H3O+, which can then undergo reaction

with Br2 from both faces, to produce a racemic mixture of the brominated product; hence, no observed optical activity. The reaction with (R)-2-methyl-1-phenyl-1-butanone is shown below; the same enol and products can be formed from the (S) enantiomer.

CH3

H CH3

CH3

(S)

Br2

CH3

(R)

achiral enol

H3O+

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659

Topic: Multistep Reaction Sequence:

92. What is the final product of the following reaction sequence? Give structural details of all significant intermediates.

O O

Bri. Zn,

ii. H3O+, heat

iii. DIBAL-H

iv. H2O

v. (CH3)2CuLi

vi. H2O

Ans: O O

Oi. Zn,

ii. H3O+, heati. DIBAL-Hii. H2O

i. (CH3)2CuLiii. H2O

Topic: Multistep Reaction Sequence:

93. What is the final product of the following reaction sequence? Give structural details of all significant intermediates.

CNO

?i. , EtO-, EtOH

ii.H3O+, heatAns:

CN CO2HEtO-, EtOHH3O+

heat

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660

Topic: Multistep Reaction Sequence:

94. What is the final product of the following reaction sequence? Give structural details of all significant intermediates.

ONO2

?i. Cl2, FeCl3

ii. , EtO-, EtOH

iii.H3O+

Ans: O O

NO2

Cl2, FeCl3 i.

ii. H3O+ EtO-, EtOH

Topic: Synthetic Strategy

95. Suggest a reasonable synthetic strategy to carry out the following transformation. O

BrOH

Ans: O O

OCH3

BrOH

BrOCH3O

Br2, FeBr3 i.

ii. H3O+, heat EtO-, EtOH

i. LAHii. H2O

Chapter 17

661

Topic: Multistep Reaction Sequence

96. What is the final product of the following reaction sequence? Give structural details of all significant intermediates.

O i. EtO-, EtOH

ii. CH3CH2NH2

Ans:

O EtO-, EtOH

O O

HN CH3CH2NH2

Topic: Reaction Products

97. There are several possible cyclization products that might be formed when 5-methyl-6-oxoheptanal undergoes intramolecular aldol condensation in presence of ethoxide. Draw the structures of all these possible products. Comment on which of these is likely to be the major product, clearly explaining your rationale. Ans: There are 3 possible products (I-III) that might be formed from the 3 theoretically

possible enolates. The rationale for predicting the major product is the following: i) aldehydes are typically more reactive toward nucleophilic addition than ketones, so I and III are more likely than II; ii) since 5-membered rings are formed much more readily than 7-membered rings, I is more likely than III.

EtO-, EtOHO

O HO

HOO

IIImajor product

Topic: Reaction Products

98. What is the product of the following reaction?

OH-

Ans:

OH-

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662

Topic: Reaction Products

99. What is the product of the following reaction? O

?i. LDA, THFii. O

Ans: O i. LDA, THFii. O

O OH

Topic: Multistep Reaction Sequence

100. What is the product of the following reaction sequence? Give structural details of all significant intermediates.

Oi. OH-

ii. heat

Ans:

OH-

heatO

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663

MULTIPLE CHOICE QUESTIONS

Topic: Nomenclature 1. Which of the following is the best name for the following compound?

A) Isobutyl ethanoate B) Ethyl isopropanoate C) 3-methylbutyl ethanoate D) Ethoxy isobutyl ketone E) Ethyl 3-methylbutanoate Ans: C

Topic: Nomenclature

A correct name for O

is: A) 2-Methylbutyl 2-methylbutanoate B) 2-Methylbutyl 3-methylbutanoate C) 3-Methylbutyl isovalerate D) Isopentyl isovalerate E) Isopentyl isobutyrate Ans: B

Topic: Nomenclature

What is the IUPAC name for

ClCl

O A) ∝-Chlorovaleryl chloride B) 2-Chloropentanoyl chloride C) 1-Chloropentanoyl chloride D) 1,2-Dichloropentanal E) 1-Chloro-1-butanecarbonyl chloride Ans: B

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664

Topic: Nomenclature 4.

What is the IUPAC name for O O

A) 2,3−dimethylbutyl acetate B) 2,3−dimethyl-4-oxoethanal C) 2,3−dimethylbutyl methanoate D) 2,3−dimethylbutyl methylate E) 2,3−dimethylbutyl formylate Ans: C

Topic: Nomenclature

5. Which of the following structures is 3,4-dimethylpentyl chloroformate?

H O

O Cl

Cl O

III

O Cl

Cl O

VA) I B) II C) III D) IV E) V Ans: E

Chapter 18

665

Topic: Nomenclature 6. Which of the following structures is N-benzyl-N-propyl-2,3-dimethylbutanamide?

III

IV V

A) I B) II C) III D) IV E) V Ans: E

Topic: Acidity

7. In which of the following sequences are the compounds listed in order of decreasing acidity? A) CH3COOH > H2O > CH3CH2OH > HC≡CH > NH3 B) CH3CH2OH > CH3COOH > H2O > HC≡CH > NH3 C) CH3COOH > CH3CH2OH > H2O > NH3 > HC≡CH D) H2O > CH3COOH > CH3CH2OH > HC≡CH > NH3 E) CH3CH2OH > H2O > CH3COOH > HC≡CH > NH3 Ans: A

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666

Topic: Acidity 8. Which compound would be the strongest acid?

A) CHCl2CH2CH2CO2H B) ClCH2CHClCH2CO2H C) CH3CCl2CH2CO2H D) CH3CHClCHClCO2H E) CH3CH2CCl2CO2H Ans: E

Topic: Acidity

9. Which of the following would be the strongest acid?

IIII II

CO2H

IV VCl

CO2H

CO2H CO2H

Cl Cl

CO2HCl

A) I B) II C) III D) IV E) V Ans: C

Topic: Acidity

10. Which of the following acids would have the smallest value for pKa? A) BrCH2CH2CH2COOH B) ClCH2CH2CH2COOH C) Cl2CHCH2CH2COOH D) ICHBrCH2CH2COOH E) BrCCl2CH2CH2COOH Ans: E

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667

Topic: Acidity 11. Which compound would be most acidic?

Acetone A) Acetic acid B) Ethanol C) Phenol D) Acetone E) Water Ans: A

Topic: Acidity

12. In which of the following are the compounds listed in order of decreasing acidity? A) CH3CO2H > CH3CH2OH > C6H5OH > H2O B) C6H5OH > CH3CO2H > H2O > CH3CH2OH C) CH3CO2H > H2O > C6H5OH > CH3CH2OH D) H2O > CH3CO2H > C6H5OH > CH3CH2OH E) None of the above Ans: E

Topic: Acidity

13. Which of the following would be the strongest acid? A) Benzoic acid B) 4-Nitrobenzoic acid C) 4-Methylbenzoic acid D) 4-Methoxybenzoic acid E) 4-Iodobenzoic acid Ans: B

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668

Topic: Acidity 14. Which of the following would be the strongest acid?

A) 2,3-dimethylhexanoic acid B) 3,3-diiodopentanoic acid C) 3-iodo-4-bromopentanoic acid D) 3-chloro-4-bromohexanoic acid E) 2-fluoro-4-bromopentanoic acid Ans: E

Topic: Acidity

15. A 0.2505 g sample of an organic acid is titrated to the stoichiometric endpoint with 20.10 mL of 0.0750 M NaOH. Which of these is a possible structure for the acid? A) C6H5CO2H B) p-CH3C6H4CO2H C) m-ClC6H4CO2H D) o-NO2C6H4CO2H E) p-BrC6H4CO2H Ans: D

Topic: Chemical Tests, Relative Reactivities, and Physical Properties

16. Which reagent would serve as the basis for a simple chemical test to distinguish between benzoic acid and benzamide? A) Cold dilute NaOH B) Cold dilute NaHCO3 C) Cold concd H2SO4 D) More than one of these E) None of these Ans: D

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Topic: Chemical Tests, Relative Reactivities, and Physical Properties 17. Which reagent would best serve as a basis for a simple chemical test to distinguish

between CH3CH2COOH and CH3COOCH3? A) Concd H2SO4 B) Br2/CCl4 C) CrO3/H2SO4 D) NaHCO3/H2O E) KMnO4/H2O Ans: D

Topic: Chemical Tests, Relative Reactivities, and Physical Properties

18. Which reagent would best serve as the basis for a simple chemical test to distinguish between C6H5CH=CHCOOH and C6H5CH=CHCH3? A) Concd. H2SO4 B) Br2/CCl4 C) CrO3/H2SO4 D) NaHCO3/H2O E) KMnO4/H2O Ans: D

Topic: Chemical Tests, Relative Reactivities, and Physical Properties

19. Which compound would be most reactive toward nucleophilic acyl substitution? (CH3CO)2O A) CH3CO2Na B) CH3COCl C) (CH3CO)2O D) (CH3CONH2 E) CH3CO2CH3 Ans: B

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Topic: Chemical Tests, Relative Reactivities, and Physical Properties 20. The relative reactivity of acyl compounds toward nucleophilic substitution is:

A) Amide > ester > acid anhydride > acyl chloride B) Acyl chloride > ester > acid anhydride > amide C) Ester > acyl chloride > acid anhydride > amide D) Acyl chloride > acid anhydride > ester > amide E) Acid anhydride > acyl chloride > ester > amide Ans: D

Topic: Chemical Tests, Relative Reactivities, and Physical Properties

21. Alkaline hydrolysis of an ester involves initial attack by hydroxide ion on the carbonyl carbon. The presence of substituents on the aromatic ring of ethyl benzoate may be expected to increase/decrease the rate of hydrolysis of this ester. In what order should the five substituents below be arranged to represent the decreasing order of the rates of hydrolysis when these substituents are present in the para- position of the aromatic ring in ethyl benzoate? A) -NO2 > -H > -Cl > -CH3 > -OCH3 B) -NO2 > -Cl > -H > -CH3 > -OCH3 C) -OCH3 > -CH3 > -Cl > -H > -NO2 D) -Cl > -NO2 > -H > -OCH3 > -CH3 E) -H > -Cl > -CH3 > -OCH3 > -NO2 Ans: B

Topic: Chemical Tests, Relative Reactivities, and Physical Properties

22. Which of the following will not undergo hydrolysis, whether acid or base is present? A) CH3COCl B) CH3CONH2 C) (CH3CO)2O D) CH3CO2CH2CH3 E) CH3COCH2CH2CH3 Ans: D

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Topic: Chemical Tests, Relative Reactivities, and Physical Properties 23. Which of these compounds could not be formed by nucleophilic attack by an

appropriate reagent on acetyl chloride? A) CH3CONH2 B) CH3CO2CH2CH3 C) ClCH2COCl D) CH3CO2H E) (CH3CO)2O Ans: C

Topic: Chemical Tests, Relative Reactivities, and Physical Properties

24. In which of these species are all the carbon-oxygen bonds of equal length? A) Diethyl carbonate B) Methyl butanoate C) Lithium acetate D) Propionic anhydride E) Pentanoic acid Ans: C

Topic: Reaction Products

25. What is the expected product, A, of the following reaction sequence? i. NaCNii. 70% H2SO4, reflux

A + NH4+Cl

A) HCO2CH2C6H5 B) C6H5CH2COOH C) C6H5CH2OSO3H D) C6H5CHClCOOH E) O=C(CH2C6H5)2 Ans: B

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Topic: Reaction Products 26. Predict the major organic product of the reaction sequence below:

I II III

IV V

OHOH

CO2H

CHO

+ KMnO4 heat

H2O, OH−?

H3O+

A) I B) II C) III D) IV E) V Ans: B

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Topic: Reaction Products 27. What would be the product of the following reaction ?

O O

I II III

II III

HA+ ?18

18 18

\ A) I B) II C) III D) IV E) V Ans: A

Topic: Reaction Products

28. What would be the final product, F, of the following sequence of reactions?

CO2H

Br Br CO2H CO2H CO2HO

OI II III IV V

i. LAH, Et2Oii. H2O

i. Mg, Et2O

ii. CO2

iii. H3O+

FPBr3

A) I B) II C) III D) IV E) V Ans: D

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Topic: Reaction Products 29. The product, Z, of the following sequence of reactions is which compound?

i. KMnO4, OH−, heat

ii. H3O+

iii. SOCl2iv. CH3CH2OH, base

I II III

IV V

Zp-Chlorotoluene

Cl Cl

OCl

A) I B) II C) III D) IV E) V Ans: B

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Topic: Reaction Products 30. Predict the major organic product, P, of the following sequence of reactions:

CO2H

ClO

O CO2H

O O

ClO

I II III

IV V

H2 cat.

Pi. SOCl2ii. CH3OH

i. OH− (2eq.), H2O heat

ii. H3O+

A) I B) II C) III D) IV E) V Ans: D

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Topic: Reaction Products 31. Predict the major organic product of the reaction sequence,

OO O

OOH

OHO

ONH2

OH2N

ONH2

OHN O

I II III

IV V

HNO O

Mi. NH3, H2O ii. dilute HCl, cold

A) I B) II C) III D) IV E) V Ans: B

Topic: Reaction Products

32. (R)-3-hexanol is subjected to the following sequence of reactions: i) acetyl chloride, pyridine; ii) NaOH(aq), heat. What is(are) the likely final product(s)? A) (R)-3-hexanol B) (S)-2-hexanol C) Equal amounts of A) and B) D) 2-Hexene (cis and trans) E) 1-Hexen-2-ol Ans: A

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Topic: Reaction Products 33. What would be the final product?

C6H5CH2CONH2i. CH3MgI, Et2O

ii. H3O+P4H10heat

A) C6H5CH2CO2CH3 B) C6H5CH2CH2NHCH3 C) C6H5CH2COCH3 D) C6H5CH2CH(CH3)CN E) C6H5CH2CH=NCH3 Ans: C

Topic: Reaction Products

34. Predict the final product likely to be obtained when (S)-2-methyl-3-pentanol is subjected to the following sequence of reactions: i) benzoyl chloride; ii) NaOH (aq), heat A) (S)-2-methyl-3-pentanol B) (R)-2-methyl-3-pentanol C) (R,S)-2-methyl-3-pentanol D) 2-methyl-2-pentene E) (R,S)-2-methyl-3-pentanol and 2-methyl-2-pentene in more or less equal amounts Ans: A

Topic: Reaction Products

35. Predict the final product likely to be obtained when (S)-2-methyl-3-pentanol is subjected to the following sequence of reactions: i) Tosyl chloride; ii) NaOH (aq), heat A) (S)-2-methyl-3-pentanol B) (R)-2-methyl-3-pentanol C) (R,S)-2-methyl-3-pentanol D) 2-methyl-2-pentene E) (R,S)-2-methyl-3-pentanol and 2-methyl-2-pentene in more or less equal amounts Ans: B

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Topic: Reaction Products 36. The product of the following reaction is:

I II III

IV V

OCO2H

ClH

CO2H

OCl

O OHO O

OH+ heat

(1 mol) (1 mol)

A) I B) II C) III D) IV E) V Ans: A

Topic: Reaction Products

37. What final product, Q, would be obtained via the following reaction sequence?

H3C

OHClC6H5

OC6H5

OQ +pyridine

OH−/ H2O

heat

A) cis-3-Methylcyclopentanol B) trans-3-Methylcyclopentanol C) Equal amounts of A) and B) D) 3-Methylcyclopentanone E) None of these Ans: B

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Topic: Reaction Products 38. What would be the final organic product of the following reaction?

C6H5 ClNaCN i. excess LAH, Et2O

ii. H2O?

A) C6H5CH2CH2CO2H B) C6H5CH2CH2NH2 C6H5CH2CH(CH3)CN C) C6H5CH2CH(CH3)CN D) C6H5CH2CH=NH E) C6H5CH2NH2 Ans: B

Topic: Reaction Products

39. What would be the final organic product of the following reaction?

i. LAH, Et2Oii. H2OBr ?

i. Mg, Et2O

ii. CO2

iii. H3O+

A) (CH3)3CCO2H B) (CH3)3CCOCH3 C) (CH3)3CCH2OH D) (CH3)3COCH3 E) (CH3)3CCO2CH3 Ans: C

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Topic: Reaction Products 40. Identify the product(s) of the following reaction.

OCO2H

OH O

CO2H

I II III

IV V

CO2H

heat?

+ CO2

+ CO 2

A) I B) II C) III D) IV E) V Ans: C

Topic: Reaction Products

41. What would be the final product? CO2H i. PCl5

ii. NH3iii. P4H10, heat

A) CH3CH2CH2NH2 B) CH3CH2CONH2 C) CH3CH2CONHCOCH2CH3 D) CH3CH2CN E) CH3CH2COO-NH4

+ Ans: D

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Topic: Reaction Products 42.

What is the final product of this sequence of reactions?

I II III

IV V

ONH2 CN

NH2NHCl

NH2

i. SOCl2ii. excess NH3

?i. Mg, Et2O

ii. CO2

iii. H3O+

A) I B) II C) III D) IV E) V Ans: C

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Topic: Reaction Products 43. What is the product of the reaction of 1-propanol with phenyl isocyanate, C6H5N=C=O?

A) C6H5

HN O

B) C6H5

NCO2H

C6H5N

CHO

C6H5

HN O

O E)

C6H5

O Ans: A

Topic: Reaction Products

44. What would be the final product of this reaction sequence?

I II III

CN NH2

NH2

CO2H

CO2 NH4

i. PCl3ii. NH3iii. P4O10

A) I B) II C) III D) IV E) V Ans: A

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Topic: Reaction Products 45. What is the ultimate product of this sequence of reactions?

Cl NH

O Cl

OO N

Cl Cl

I II III

O O

CH3NH2CH3CH2OH (1 eq.)

A) I B) II C) III D) IV E) V Ans: A

Topic: Reaction Products

46. What is the product of this reaction?

CO2HO HOO

IIII II

O O

IV V

OOHO

?CH3OH

A) I B) II C) III D) IV E) V Ans: B