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### Transcript of Answers for Student Exercise 3.1 to 3.3 1 - . semester/Spektroskopi/solutions_NMR_ch03.pdfآ ...

• Answers for Student Exercise 3.1 to 3.3

1

3.1(a) 1,2,3,4 are a spin system. Pople notation is A3M2S2X2. 1,2, and 3 are enantiotopic. 3.2 (a)

Spin Appr. δ Table Coupled with Multiplet (n+1) Integration 1 δ 3.40 Appendix A, Chart A.1 2 Triplet 2 2 δ 1.85 Appendix A, Chart A.2 1,3 Quintet 2 3 δ 1.20 Appendix A, Chart A.1 3, 4 Sextet 2 4 δ 0.85 Appendix A, Chart A.1 3 Triplet 3

3.3 (a)

Br

(a) 1-bromobutane

1 2

3 4

1 2 3 4

• Answers for Student Exercise 3.1 to 3.3

2

3.1 (b) 1,2,3,4,5,6,7 are one spin system, and 9 is the second. 4,4’ ; 5,5’ ; 6,6’and 7,7’ are diastereotopic. 3.2 (b)

Spin Appr. δ Table or Calculation Coupled with Multiplet (n+1) Integration 1 δ 2.80 Appendix A, Chart A.2 6,2,7 Sextet* 1 2 δ 5.59 Appendix D, Chart D2 3,1 Triplet* 1 3 δ 5.59 Appendix D, Chart D2 Quartet* 1 4 δ 1.96 Appendix D, Chart D2 Quartet** 2 5 δ 1.65 Appendix D, Chart D2 4,6 Quartet** 2 6 δ 1.80 Appendix A, Chart A.2 1,5 Triplet** 2 7 δ 4.05 Appendix A, Chart A.2 1 Doublet** 2 9 δ 2.10 Appendix A, Chart A.1 none Singlet 3

* Coupling constants may not be the same, but make the assumption that they are. **These are diastereotopic, and are coupled to diastereotopic protons, they would not be first order. We will assume they are first order for the drawn spectrum. 3.3 (b)

2 and 3 7 1 9 4 6 5

O

1

23

4

5 6

7 O

8 9

(b) (cyclohex-2-enyl)methyl acetate

2

• Answers for Student Exercise 3.1 to 3.3

3

3.1 (c) 2,3,4,5,6 are a spin system, and 8,9,10 another spin system. 3,3’ ; 4,4’ ; 9,9’ are diastereotopic. 3.2 (c)

Spin Appr. δ Table or Calculation Coupled with Multiplet (n+1) Integration 2 δ 6.68 Appendix D, Chart D.1 3 Triplet 1 3 δ 2.05 Appendix A, Chart A1 2,4 Quartet*** 2 4 δ 2.05 Appendix A, Chart A1 3,5 Quartet*** 2 5 δ 5.68 Appendix D, Chart D1 4,6 Quartet* 1 6 δ 6.22 Appendix D, Chart D1 5 Doublet 1 8 δ 2.65 Appendix A, Chart A.1 9,10 Sextet 1 9 δ 3.20 Appendix A, Chart A.1 8 Doublet** 2 10 δ 1.05 Appendix A, Chart A.2 8 Doublet 3 ΟΗ δ 0.5-4.0 Appendix E 1

* Coupling constants may not be the same, but make the assumption that they are. ** These are diastereotopic, and are coupled to diastereotopic protons; they would not be first order. We will assume they are first order for the drawn spectrum. 3.3 (c)

OH

O

1 2

3

4 5

6

7 8

(c) 1-(cyclohexa-1,5-dienyl)-3- hydroxy-2-methylpropan-1-one

9

10

2 6 5 9 8 3,4 OH 10

• Answers for Student Exercise 3.1 to 3.3

4

3.1 (d) 5,4,3 are a spin system and 1 is second. 5,4,3 is Pople notation is A3M2X2; may have long rang coupling. 3+4 are enantiotopic. 3.2 (d)

Spin Appr. δ Table or Calculation Coupled with Multiplet (n+1) Integration 5 δ 0.85 Appendix A, Chart A.2 4 Triplet 3 4 δ 1.50 Appendix A, Chart A2 3,5 Sextet 2 3 δ 2.20 Appendix A, Chart A1 4 Triplet 2 1 δ 1.80 Appendix D, Chart D3 none Singlet 1

3.3 (d)

H

(d) pent-1-yne

13 2 4

5

3 1 4 5

• Answers for Student Exercise 3.1 to 3.3

5

3.1 (e) 3,4,5,6 are a spin system, and 1 is another spin system. Pople notation is A3G2MX. 5 is enantiotopic. 3.2 (e)

Spin Appr. δ Table or Calculation Coupled with Multiplet (n+1) Integration 1 δ 1.86 Appendix D, Chart D.2 None Singlet 3 3 δ 6.09 Appendix D, Chart D.1 4 Doublet 1 4 δ 6.82 Appendix D, Chart D.1 3, 5 Quartet* 1 5 δ 2.05 Appendix A, Chart A1 4, 6 Quintet* 2 6 δ 1.00 Appendix A, Chart A2 5 Triplet 3

* Coupling constants may not be the same, but make the assumption that they are. 3.3 (e)

4 3 5 1 6

O

(e) hex-3-en-2-one

1 3 4

5 2 6

• Answers for Student Exercise 3.1 to 3.3

6

O

(f) 1-methoxybut-1-ene

1 2 3

4 5

3.1 (f) 3,4,5,6 are a spin system, and 1 is another spin system. Pople notation is A3G2MX. 4 is enantiotopic. 3.2 (f)

Spin Appr. δ Table or Calculation Coupled with Multiplet (n+1) Integration 1 δ 3.20 Appendix A, Chart A.1 None Singlet 3 2 δ 6.14 Appendix D, Chart D.1 3 Doublet 1 3 δ 4.63 Appendix D, Chart D.1 2, 4 Quartet* 1 4 δ 2.05 Appendix A, Chart A1 3, 5 Quintet* 2 5 δ 1.00 Appendix A, Chart A2 4 Triplet 3

* Coupling constants may not be the same, but make the assumption that they are. 3.3 (f)

2 3 1 4 5

• Answers for Student Exercise 3.1 to 3.3

7

N H

O

O

(g) propyl methylcarbamate

1

2 3 4

5

3.1 (g) 3,4,5 are a spin system, and 1 is another spin system. Pople notation is A3M2X2. 3 and 4 are enantiotopic. 3.2 (g)

Spin Appr. δ Table or Calculation Coupled with Multiplet (n+1) Integration 1 δ 2.95 Appendix A, Chart A.1 None Singlet 3 3 δ 4.10 Appendix D, Chart D.1 3 Triplet 2 4 δ 1.60 Appendix A, Chart A.2 2, 4 Sextet 2 5 δ 0.85 Appendix A, Chart A1 3, 5 Triplet 3

NH δ 4.5-7.5 Appendix E * Singlet 1 *See Section 3.6.2 for coupling between 1 and N-H. 3.3 (g)

NH 3 1 4 5

• Answers for Student Exercise 3.1 to 3.3

8

O O

(h) diethoxymethane

1 2 3

3.1 (h) 1 and 2 are a spin system, and 3 is another spin system. Pople notation is A3X2. 2 are enantiotopic. 3.2 (h)

Spin Appr. δ Table or Calculation Coupled with Multiplet (n+1) Integration 1 δ 1.20 Appendix A, Chart A.2 2 Triplet 3 2 δ 3.40 Appendix A, Chart A.1 1 Quartet 2 3 δ 4.95 Appendix B, Table B.1 none Singlet 2

3.3 (h)

3 2 1

• Answers for Student Exercise 3.1 to 3.3

9

HO

(i) 2-methylpentan-2-ol

1

2 3

4 5

6

1 and 6 Large singlet of 6 H

3.1 (i) 3,4 and 5 is a spin system. 1 and 6 are enantiotopic to each other and 3 and 4 are also enantiotopic. Pople notation is A3M2X2. 3.2 (i)

Spin Appr. δ Table or Calculation Coupled with Multiplet (n+1) Integration 1 and 6 δ 1.20 Appendix A, Chart A2 none Singlet 6

3 δ 1.50 Appendix A, Chart A2 4 Triplet 2 4 δ 1.20 Appendix A, Chart A1 3,5 Sextet 2 5 δ 0.85 Appendix A, Chart A2 4 Triplet 3

ΟΗ δ 0.5-4.0 Appendix E none Singlet 1 3.3 (i)

OH 3 1,6,4

• Answers for Student Exercise 3.1 to 3.3

10

S S

(j) 1,4-bis(methylthio)butane

1 2 3

3.1 (j) Not First order (no Pople). See Section 3.11.2. Protons 2 and 3 are enantiotopic. Protons on 1,2,3 are Chemical Shift Equivalent. 3.2 (j)

Spin Appr. δ Table or Calculation Coupled with Multiplet (n+1) Integration 1 δ 2.10 Appendix A, Chart A1 none Singlet 6 or 3 2 δ 2.60 Appendix A, Chart A1 3 Triplet* 4 or 2 3 δ 1.60 Appendix A, Chart A2 2,3 Quintet* 4 or 2

* Would not be first order. We will assume they are first order for the drawn spectrum. 3.3 (j) Actual spectrum would look like this!

012 PPM

• Answers for Student Exercise 3.1 to 3.3

11

N

O

(k) N,N,4-trimethylbenzamide

1

2

3

4

5

6

7 8

2' 3'

3.1 (k) 2,2’; 3,3’ are CSE but not ME. 6 and7 are diastereotopic. Pople notation for ring is AA’ XX’ 3.2 (k)

Spin Appr. δ Table or Calculation Coupled with Multiplet (n+1) Integration 2, 2’ δ 7.80 Appendix D, Chart D1 none Doublet** 2 3, 3’ δ 7.25 Appendix D, Chart D1 3 Doublet** 2 6,7 δ 2.95 Appendix A, Chart A1 none Singlet* 6* 8 δ 2.25 Appendix A, Chart A1 none Singlet 3

* There will be two singlets because of the restricted rotation of the NR2 ** These can not be first order. Not magnetically equivalent. 3.3 (k)

2,2’ 3,3’ 6,7 8

• Answers for Student Exercise 3.1 to 3.3