Organic Chemistry

PROBLEM 12

Using curved arrows, show the principal fragments that would be observed in the mass

spectrum of each of the following compounds:

a. d.

b. e.

c. f.

PROBLEM 13

Two products are obtained from the reaction of (Z)-2-pentene with water and a trace of

The mass spectra of these products are shown in Figure 13.10. Identify the com-

pounds responsible for the spectra.

H 2 SO 4.

CH 3

CH 3

CH 3 CBr

OH

CH 3 CH 2 CHCH 2 CH 2 CH 2 CH 3

CH 3

CH 3 CH 2 CHCl

O

CH 3 CCH 2 CH 2 CH 2 CH 3

CH 3

CH 2 CH 3

CH 3 CH 2 CH 2 CH 2 CH 2 OH CH 3 CH 2 OCCH 2 CH 2 CH 3

496 CHAPTER 13 Mass Spectrometry and Infrared Spectroscopy

0 20 40 60 80 100 120

0 20 40 60 80 100 120

100

80

60

40

20

0

59

45

27

41

31

100

80

60

40

20

0

27

31

55

73

45

m/z

m/z

b.

a.

Relative abundance

Relative abundance

Figure 13.10N
The mass spectra for Problem 13.

The molecular ion and the pattern of fragment ion peaks are unique for each com-

pound. A mass spectrum, therefore, is like a fingerprint of the compound. A positive

identification of a compound can be made by comparing its mass spectrum with that of

a known sample of the compound.