Problem 1
Using the data supplied, identify the unknown, accounting for the observed
coupling patterns as fully as possible.
IR spectrum (nujol mull)
Mass Spectrum (EI mode)
1
1
H NMR spectrum (300 MHz, CDCl3)
4.5
11
10
9
4.2
8
7
25.77
0.94
13
3.9
ppm
6
5
4
22.63 24.50
24.33
3
2
1
ppm
1.83
C NMR spectrum (175 MHz, CDCl3)
2
Problem 2 You need some 2,4-pentane diol as a starting material for a laboratory preparation.
After asking around, you track down two bottles of this material. One costs about £1 / ml, the
other costs £50 / ml. The IR and CI-MS (Chemical Ionisation Mass Spectrum) of both
reagents were identical, and are shown below together with the 1H and 13C NMR spectra of
both samples. Account for the differences in the spectra of the two samples (NMR in
methanol-d4) and comment upon the coupling patterns in the 1H NMR spectrum of the
expensive sample. What explanation can you offer for the difference in cost for the two
samples?
IR spectrum (neat liquid)
Mass Spectrum (CI mode – reagent gas ammonia)
MJ
MJDIOLC 356 (5.934) Cm (321:356-176:213)
100
Scan CI+
2.92e5
122
%
105
0
55
60
65
70
75
80
85
90
95
100
105
110
115
120
125
130
135
140
145
m/z
150
3
£50/ml sample
1
H NMR spectrum (500 MHz, CD3OD)
1.65
4.5
4.0
3.5
1.55
3.0
1.45
2.5
ppm
2.0
1.5
ppm
13
C NMR spectrum (125 MHz, CD3OD)
50.0
70
65
60
55
50
45
40
48.5
35
ppm
30
25
ppm
4
£1/ml sample
1
H NMR Spectrum (500 MHz, CD3OD)
1.66
4.5
4.0
13C
3.5
1.60
1.54
3.0
2.5
65
60
ppm
2.0
1.5
ppm
NMR spectrum (63 MHz, CD3OD)
50.0
70
1.48
55
50
45
40
48.5
35
ppm
30
25
ppm
5
Problem 3 Given the spectroscopic data attached, determine the structure of the unknown
(organic) liquid. You should assign the spectroscopic data fully, and clearly explain your
reasoning.
IR spectrum (neat liquid)
Mass Spectrum (CI mode – reagent gas ammonia)
MJ
MJCLDIOC 446 (7.434) Cm (413:447-940:1057)
58
100
Scan CI+
1.99e4
92
57
%
56
74
128
56
122
91
73
105
130
94
76
0
55
60
65
70
75
80
85
90
95
100
105
110
115
120
125
130
135
140
145
m/z
150
6
1
H NMR spectrum (500 MHz, CDCl3)
7.5
7.0
3.95
3.85
6.5
6.0
3.75
5.5
3.65
5.0
4.5
1.06
13
ppm
4.0
3.5
13.88
13.68 40.94
3.0
ppm
30.43
C NMR spectrum (63 MHz, CDCl3)
160
160
140
140
120
120
100
100
80
80
60
60
40
40
20
20
ppm
ppm
7
Problem 4
Given the spectroscopic data attached, determine the structure of the unknown
(organic) liquid. You should assign the spectroscopic data fully, and clearly explain your
reasoning.
Mass Spec (EI mode)
91
100
55
41
50
39
121
29
27
172
49 53
51
0
10
1
75
63
65
15
20
30
40
50
60
73
70
79
80
107
90
100
110
129
120
136
130
157
140
150
160
170
H NMR (500 MHz, CDCl3)
3.60
3.54
3.4
3.48
3.0
ppm
2.6
2.23
2.2
4.16
2.19
1.8
ppm
1.4
ppm
3.10
0.98
8
13
C NMR (125 MHz, CDCl3)
60
50
40
30
20
10
ppm
IR (neat liquid)
9