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472 Chapter 14
Copyright © 2017 Pearson Education, Inc.
52.
a.
Chemical shift in ppm is independent of the operating frequency.
b.
Chemical shift in hertz is proportional to the operating frequency.
c.
The coupling constant in hertz is independent of the operating frequency.
d.
The frequency required for NMR spectroscopy is lower than that required for IR spectroscopy, which
is lower than that required for UV/Vis spectroscopy.
53.
a.
The spectrum must be that of
2-bromopropane
, because the NMR spectrum has two signals—the
lowest frequency signal is a doublet, and the other signal is given by a single hydrogen.
CH
3
CH
3
CHBr
b.
The spectrum must be that of
1-nitropropane
, because the NMR spectrum has three signals—both the
lowest frequency and highest frequency signals are triplets.
CH
3
CH
2
CH
2
NO
2
c.
The spectrum must be that of
ethyl methyl ketone
, because the NMR spectrum has three signals—a
triplet, a singlet, and a quartet.
C
H
2
CH
3
C
H
3
C
O
54.
a.
CH
3
CH
2
CHBr
CH
3
b.
CH
3
CH
2
CH
2
CH
2
Br
c.
CH
3
CHCH
2
Br
CH
3
55.
a.
CH
3
CCH
2
Br
CH
3
Br
b.
CHCH
3
Br
c.
O
C
2
CH
3
OCH
CH
3
CH
2
56.
The singlet at 210 ppm indicates the carbonyl group of a ketone. The splitting of the other two
signals indicates an isopropyl group. The molecular formula indicates that the compound must have two
isopropyl groups.
O
C
CH
3
CH CHCH
3
CH
3
CH
3
and
three signals
two signals
Cl
Cl
Cl
H
CH
3
CCH
3
CH
3
CH
3
and
CH
2
CCH
3
the signals for the benzene ring protons
plus two signals with integration 3:1
CH
3
CH
3
the signals for the benzene ring protons
plus two signals with integration 4.5:1
j.