Study Guide
Organic Chemistry I Chapter 2 Solutions
-
University:
Whitman College -
Course:
CHEM-245 | Organic Chemistry I Academic year:
2022
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Views:
377
Pages:
12
Author:
Macy Escobar
Chapter 2 Solutions
Cl
NH2
+
1)
+
NH3
a) The M+ peak at 82 suggests that the spectrum is of cyclohexene.
CH2
H2C
CH
H2C
CH
H2C
H2C
CH
CH2
CH
H2C
CH
CH2
CH
CH
CH
CH
CH2
CH
CH2
CH2
H2C
CH2
CH2
CH
CH
H2C
H
CH2
CH
CH2
CH3
CH
CH
CH2
CH2
m/z 67
m/z 67
+
m/z 54
b) The odd M+ peak at 99 suggests the nitrogen containing compound cyclohexanamine.
NH2
NH2
NH2
NH2
m/z 43 NH2
NH2
m/z 56
hν
+
NBS
Br
2)
The pair of peaks at 121 and 123 as well as at 149 and 151 indicates that the compound
contains bromine. These, in combination with other prominent fragments, suggest that the
compound is 2-bromo-2-methlybutane.
Br
Br
m/z 121
Br
m/z 71
H2 O
+
OH
H2 SO4
3)
The peak at m/z 87 is deceiving because it is not the molecular ion in this case. By
utilizing other prominent peaks (m/z 73 and 45) and our knowledge of organic chemistry,
we can deduce that the mass spectrum is of 2-pentanol. H
O
O
m/z 87
OH
OH
OH
m/z 73
CH2
CH
H
H2 C
H
OH
CH2
OH
CH
m/z 55
OH
OH
OH
m/z 45
H
CH
OH
CH
CH2
H2C
OH
m/z 31
1. BH3 THF
OH
2. H2O2, OH
4)
The molecular ion is missing from the spectrum which is to be expected from a straight chain
alcohol. While it would be possible to determine the molecular weight from a soft ionization
technique, the existence of other prominent peaks indicates that the spectrum is of 1-pentanol. CH2
H2
C
CH2
H
O
CH2
H
O
H
H
m/z 70
CH2
H
CH
CH2
O
H
CH2
CH
CH2
CH
CH2
CH2
CH2
CH2
CH2
HC
m/z 55
H
O
H
CH2
CH
CH2
CH2
CH
CH2
m/z 42 2. H30+
O
+
Et
MgBr
OH
5)
The molecular ion is missing from the spectrum which is to be expected. The existence of other
prominent peaks indicates that the spectrum is of 2-methyl-2-butanol.
CH3
Et
Et
Et
OH
OH
OH
m/z 73
Et
OH
OH
OH
m/z 59
H
H2C
CH2
Et
OH
m/z 55
CH3
H2C
OH
m/z 31
+
HI
I
6)
The molecular ion at 184 as well as the large gap in the spectrum in combination with the peak at
127 indicates that the spectrum contains iodine and can be attributed to tert-butyl iodide.
CH3
I
I
m/z 169
I+
m/z 127
I I
m/z 57
O
1. O3
O
2. (CH3)2S
H
7)
a) The molecular ion at 86 doesn’t help distinguish compound a from b. The more intense
molecular ion suggests that a) is the ketone, 2-pentanone, rather than the aldehyde.
O
C
O
O
C
C
CH3
m/z 71
H
H2C
H
O
O
C
C
m/z 58
O
O
O
C
C
C
m/z 43
b) The presence of the M-1 peak helps to indicate that compound b) is the aldehyde, pentanal. O
C
O
H
O
C
m/z 85
H
O
H2C
CH2
O
C
CH2
H3C
C
H
H
m/z 58
H
CH
H
O
O
C
C
H
H
m/z 44
O
O
C
O
C
H
C
H
m/z 29
+
H
HCl
Cl
8)
While the molecular ion is absent from the spectrum, the peaks at m/z 77 and 63 indicate the
presence of a chlorine atom in the sample indicating that the compound is 2-chloro-butane.
Cl
Cl
m/z 77
Cl Cl
Cl
Cl
m/z 63
Cl
H
m/z 57
Cl
m/z 56
O
OH
O
+
Cl
O
9)
While the molecular ion is abscent, the other prominent peaks indicate both the functional group
and the hydrocarbon structure of the compound sec-butyl acetate.
O
O
O
O
O
O
m/z 101
O
O
O
O
m/z 87
O
O H
H
C
CH
O
CH
CH
O
m/z 56
O
O
O
O
m/z 43
O
CH3
m/z 15
O
OH
O
1. NaH
2. EtBr
10)
The molecular ion of this ether is stabilized by the aromatic group. At m/z 122 it indicates that
the spectrum is of ethoxybenzene.
O
O
CH2
O
H
CH2
H
H
H
H
H
m/z 94
O
m/z 77 O
C
1. KMnO 4, NaOH
O
2. H+
11)
OH
HO
a) The molecular ion at 102 fails to distinguish between the two expected carboxylic acids. The
prevelant peaks at m/z 87 and 57 as indicates that the compound is pivalic acid.
O
H3 C
O
C
OH
C
O
OH
C
OH
m/z 87
O
C
OH
m/z 57
b) The missing molecular ion can be expected from a carboxylic acid. The prevelant peaks at
m/z 73 and 60 indicates that the compound is pentanoic acid.
O
O
HO
HO
m/z 73
H
O
HO
H
H
C
O
HO
m/z 60
Br +
NaCN
N
C
12)
The lack of a molecular ion is to be expected from a nitrile. The base peak at m/z 41 indicates
that the compound is butanenitrile. H
H
N
CH2
N
C
C
m/z 41
CH3
N
CH2
C
m/z 29
O
O
NH3
+
C
C
NH2
O
13)
CH2
H2C
H3C
CH2
O
CH2
O
C
H2C
C
NH2
H2C
NH2
m/z 86
H
C
H
H
O
O
C
C
NH2
NH2
m/z 59
O
O
C
C
NH2
NH2
m/z 44
O
O
OH
14)
Et
+
CH3 OH
O
Et H
H2C
H
O
O
O
O
Et
Et
m/z 102
O
O
O
O
Et
Et
Et
m/z 99
O
O
O
O
O
Et
m/z 59
O
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Organic Chemistry I Chapter 2 Solutions
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