220 rev chp 13 - chem PDF

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1 NMR Worksheet Draw the structures of the following compounds given the 1H-NMR data and the molecular formula. 1. Formula: C3H8O2, singlet),  3.3 (singlet) in a 1:3 ratio.

2. Formula: C4H10O2,  3.3 (singlet),  3.4 (triplet) in a 3:2 ratio.

3. Formula: C5H12O2,  3.1 (singlet),  1.2 (singlet) in a 1:1 ratio.

4. Formula: C4H10O a. Isomer 1H-NMR Data:  1.13 (doublet, 6H),  3.30 (singlet, 3H),  3.65 (septet, 1H)

b. Isomer 1H-NMR Data:  2.87 (broad singlet, 1H),  1.28 (singlet, 9H)

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c. Isomer 1H-NMR Data:  0.95 (triplet, 3H),  1.52 (sextet, 2H),  3.30 (singlet, 3H),  3.40 (triplet, 2H),

d. Isomer 1H-NMR Data:  0.90 (doublet, 6H),  1.78 (nonet, 1H),  2.45 (broad singlet, 3H),  3.30 (doublet, 2H),

e. Isomer 1H-NMR Data:  1.20 (triplet),  3.45 (quartet), ratio 3:2.

f. Isomer 1H-NMR Data:  0.92 (triplet, 3H),  1.18 (doublet, 3H),  1.45 (quintet, 2H),  1.80 (broad singlet, 1H), 3.75 (sextet, 1H)

© John Congleton, Orange Coast College

3 5. Which hydrogens exhibit the more downfield signal relative to TMS in the proton NMR? Explain your answer. a. (CH3)2O or (CH3)3N b. (CH3)2S or (CH3)2S=O c.

O

H3C

C

O

CH3

OR

d. CH3

CH2

CH2

OH

6. How many chemical shifts would you expect for the following compounds? a. CH3CH2CH2CH3

b. CH3CHBrCH3 c. HO-CH2CCl(CH3)2 d. (CH3)2CH-CH2-CH3

e. CH3

O

CH3

CH

CH3 CH2

C

CH3

CH3

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7. The following are isomeric esters derived from acetic acid, each with the formula C5H10O2. The peaks of the spectrum have been labeled to indicate the degree of splitting. With the first spectrum as an example. Use the integral curve traced on the spectrum to calculate the number of hydrogens in each multiplet. Spectrum (a) data: Chemical Integration Shift ~ 4.1 1.7 ~ 2.1 2.5 ~ 1.7 1.7 ~ 0.9 2.5 Spectrum (b) data: The second spectrum has a hydrogen pattern of 1:3:6. What are the structures of the two esters?

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8. Following are the NMR spectra of three isomeric esters with the formula C7H14O2, all derived from propanoic acid. Provide a structure for each of the spectra.

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