Chemistry 332 - Spring 1996
Elements of Organic Chemistry II
Homework, Chapter 13 - Structure Determination
McMurry, pp 405 - 409:
Problems 13.18-20, 23, 26-36, 38-41, 49-52
See the Study Guide for answers for the textbook problems.
1. Predict the general features of the H and 13C NMR spectra of the following
compounds. Use the format of question 2 below.
a) diethyl ketone
H NMR:
1-2 ppm, area 6, triplet (methyls)
2-3 ppm, area 4, quartet (methylenes)
13C NMR (proton uncoupled):
three peaks: ~30 ppm (methyls), ~50 ppm (methylenes), ~200 ppm (carbonyl)
b) p-ethylbenzoic acid
H NMR:
1-2 ppm, area 3, triplet (methyl)
2-3 ppm, area 2, quartet (methylene)
7-8 ppm, area 4, multiplet (aromatic)
11-12 ppm, area 1, singlet (carboxylic acid)
13C NMR (proton uncoupled):
seven peaks: ~30 ppm (methyl), ~50 ppm (methylene), 120-180 ppm (4 different
aromatic carbons), ~200 ppm (carboxylic acid)
c) CH3-O-CH(CH3)-CH2-CH=O
H NMR:
1-2 ppm, area 3, doublet (methyl)
2-3 ppm, area 2, triplet (methylene) (actually a doublet of doublets)
3-4 ppm, area 3, singlet (methoxy)
3-4 ppm, area 1, multiplet (methine - CH) (actually a triplet of quartets)
9-10 ppm, area 1, triplet (aldehyde)
13C NMR (proton uncoupled):
five peaks: ~30 ppm (methyl), ~50 ppm (methylene), ~70 ppm (methoxy), ~80
ppm (methine - CH), ~200 ppm (carbonyl)
2. Identify the following compounds based on their
H NMR spectra:
a) C3H6O
2.72 ppm, area 2, quintet
4.73 ppm, area 4, triplet
b) C8H8O2
11.0 ppm, area 1, singlet
7.0 ppm, area 5, multiplet
3.0 ppm, area 2, singlet
c) C10H14
7.05 ppm, area 4, singlet
2.45 ppm, area 4, quartet
1.05 ppm, area 6, triplet
d) C3H6Br2
3.80 ppm, area 1, multiplet
3.50 ppm, area 2, doublet
1.12 ppm, area 3, doublet
e) C6H10
4.82 ppm, area 2, singlet
2.22 ppm, area 4, triplet
1.65 ppm, area 4, triplet
