Organic Chemistry

520 CHAPTER 13 Mass Spectrometry and Infrared Spectroscopy

42. What peaks in their mass spectra would be used to distinguish between 4-methyl-2-pentanone and 2-methyl-3-pentanone?


43. A compound is known to be one of those shown here. What absorption bands in the compound’s IR spectrum would allow you to
    identify the compound.


44. How could IR spectroscopy distinguish among 1-hexyne, 2-hexyne, and 3-hexyne?


45. For each of the IR spectra in Figures 13.38, 13.39, and 13.40, indicate which of the five given compounds is responsible for the
    spectrum.

a. CH 3 CH 2 CH CH 2 CH 3 CH 2 CH 2 CH 2 OH CH 2 CHCH 2 CH 2 OH CH 3 CH 2 CH 2 COH

O

CH 3 CH 2 CH 2 OCH 3

O

H

A

H

O

C

CH 3

CH 3

O

B

Wavelength (μm)

Wavenumber (cm−^1 )

2.52.6 2.7 2.8 2.9 3 3.5 4 4.5 5 5.5 6 7 8 9 10 11 12 13 14 15 16

4000380036003400320030002800260024002200 2000 1800 1600 1400 1200 1000 800 600

% Transmittance

% Transmittance

Wavelength (μm)

Wavenumber (cm−^1 )

2.52.6 2.7 2.8 2.9 3 3.5 4 4.5 5 5.5 6 7 8 9 10 11 12 13 14 15 16

4000380036003400320030002800260024002200 2000 1800 1600 1400 1200 1000 800 600

Figure 13.39

The IR spectrum for Problem 45b.

b.

O

COH

O

CH

O

OH CCH 3 CH 2 OH

Figure 13.38

The IR spectrum for Problem 45a.