Third Midterm Ian R. Gould

PRINTED FIRST NAME

Person on your LEFT (or Aisle)

H He

Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar

K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

CHEM 234, Spring 2010

PRINTED LAST NAME

H/H ~1.0

Eclipsing

H/Me ~1.4

Me/Me ~2.6

Me/Me ~0.9

Et/Me ~0.95

i-Pr/Me ~1.1

t-Bu/Me ~2.7

Gauche

Me/Et ~2.9

Interaction Energies, kcal/mol

ASU ID or Posting ID

Person on your RIGHT (or Aisle)

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1__________/18 .......................2__________/32.........................3__________/40.........................4__________/20.........................5__________/40 .........................6__________/25.........................

Extra Credit_____/5 Total (incl Extra)________/175+5

C NR2

RC CRR2C CR2

Aromatic

CR OHO

C X

R NH2R OH

aminealcohol

3Y > 2Y > 1Y

020406080100120140160180200220

–H2C X

–H2C NR2

–OCH2–

01234567891011

C CHC HO

CR OHO

Aromatic Ar HAlkylmainly 8 - 6.5

C CH2

C CH3

O

3Y > 2Y > 1YAlkyl–OCH2–

CO

(δ, ppm)

variable and condition dependent, ca. 2 - 6 δ

R C N

O H C N

CN

CC

H

C ON H

C H

C N

O

HCO

CH

C CH

COR

ON H

C H

CO

O H

C O HO

CNR2

O

3000–3100

2850–2960

3300

broad ~3300

broad with spikes ~3300

2200

broad ~30001710

2200

1650

2720–28202 peaks

1735

1600–1660

1680

range of valuesbroad peak

small range usuallystrong

1600

CH

CH

C CHH

CH

CH

CH

CH

H

H

H

H

Approximate Coupling Constants, J (Hz), for

1H NMR Spectra

~7

~10

~2

~15~2

~8

Infrared Correlation Chart

NMR Correlation Charts

3000 200025003500 1500(cm-1)

EASreactions

retro 1retro 2mxn 1

spect

ANSWER KEY

CHM 234, Spring 2010, Midterm #3 - 2 - NAME

Extra credit question (5 pts). β-carotene is synthesized using which reaction?

Clemmenson Grignard Wittig Aldol

from weekly work #12

Question 1 (18 pts). Rank the following reactions in order of increasing rate. Give a BRIEF explanation that includes discussions of Lewis acidity/basicity, nucleophilicity/ electrophilicity, substitution, addition, elimination or rearrangement as appropriate.

slowest fastest< <D B C

These are all electrophilic aromatic substitution, reaction at any position on a ring with a withdrawing group is slow because the W-group is deactivating, so reaction A is slower than both reactions B and C. Reaction B, meta with respect to the string donating group is slower than C (ortho-) because the positive charge in the intermediate in C is directly stabilized by the strong donating group whereas it is not in B.

NH2

O2NCl2

AlCl3NH2

O2N

Cl

A

NH2

O2NCl2

AlCl3NH2

O2NB

Cl

NH2

O2NCl2

AlCl3NH2

O2NC Cl

Question 2 (32 pts.) Provide the missing major organic products, you can IGNORE stereochemistry EXCEPT WHERE EXPLICITELY INCLUDED IN THE STARTING STRUCTURE, and you do NOT need to state what kinds of reactions these are or whether a solution of the product would be opticaly active.

CHM 234, Spring 2010, Midterm #3 - 3 - NAME

a)

c)

d)

b)

1. PhMgBr

2. Zn(Hg)/HCl/H2O

O

O

OOH

N

NH2

OHCl (cat.)

H

OO

KOH/heat

OBr HON2H4

O

HO

CO/HCl

AlCl3

O

HOCHO

Question 3 (40 pts.) In each case, synthesize the (target) molecules on the right from the starting molecules the left. this can not be done in one reaction. Give reagents and conditions and the intermediate molecules at each step. Do not show any mechanisms or transient intermediates.

a)

b)

CHEM 234, Spring 2010 MIDTERM #3- 4 -

NAME

O

Br

OH

O

H

N

H

NBS/hν

K+ –O-t-Bu

1. BH3.THF

2. –OH/H2O2

PCC

H2NMe/H+ (cat.)

Br

OO

OO OO

MgBr

OH

O

OH

OH

HO OH/ H+ cat. (not H3O+)

HBr/ROORMg.THF 1.

O

2. H3O+

NaBH4/EtOH

Question 5 (20 pts.) Synthesize the (target) molecule on the right from the starting molecule the left. this can not be done in one reaction. Give reagents and conditions and the intermediate molecules at each step. Do not show any mechanisms or transient intermediates.

CHM 234, Spring 2010, Midterm #3- 5 -

NAME

NO2

NO2

Br

NH2

Br

NH2

Br

HNO3H2SO4

Br2/FeBr3

H2/Pd/C

AlCl3separateisomers

NH2

Br

HO3S

O

O

Cl

O

SO3H2SO4

CHM 234, Spring 2010, Midterm #3 - 6 - NAME

Question 6 (20 pts.) Give a complete arrow-pushing mechanisms for the following reactions.Indicate the lewis acid/base for each INTERmolecular step (LB or LA) and whether they are also Brønsted bases/acids (LB/BB or LA/BA)a) DRAW ALL RELEVANT RESONANCE CONTRIBUTORS OF THE INTERMEDIATES

H

O

HOO OCH3

CH3OH

HCl (cat.)

ClH:

H

OH

HO:

O

OH

HCl

O

OH..

ClH

O

OH2

:

O

O

H

CH3:

O

O+

CH3

H

:

::

::

::

: :LB/BB

LA/BA

:

:

::

::: ::

..

.... :

:

:

:O: :

: :

: Cl

:: ::

LA/BA

LB/BB

LB/BB

LA/BA

LA/BALB/BB

LA LA LB

LB

TsOH (cat.)

OH2

OH

H

OTs

:: H-OTs

: :::

LB/BB LA/BA

LALB

LA/BA

LB/BB

b) DO NOT draw resonance contributors for the intermediates

CHM 234, Spring 2010, Midterm #3 - 7 - NAME

a) Give the degrees of unsaturation ________________0 degrees of unsaturation

Question 6 (25pts) Provided are spectra for a compound with molecular formula C6H14O

b) On the infrared spectrum, indicate which peaks correspond to which functional groups

3321

2981

2903

2846 1436

13561189

958

877

OH

Hsp3

3Htriplet

6Hsinglet

2Htriplet

1Hsinglet

2Hsextet

c) draw the structure and clearly indicate which hydrogens correspond to which signals in the proton nmr spectrum (only)

CH3CH2

CH2OH

CH3

H3Cc

a

a

b

b

cd

d

e

e