CH217 Additional Example NMR exam (half) question
2 a) Solutions of the following two molecules were subjected to proton NMR.
O
O
O
(A)
(B)
These gave rise to the spectra below.
Spectrum 1
Spectrum 2
Decide which molecule belongs to which compound, and on the basis of this, fully
assign the spectra. You may use a table to display your assignments if preferred.
(10 marks)
Answer
Spectrum 1 belongs to B and Spectrum 2 belongs to A.
Spectrum 1:
C
O
E
A
A
B
B
D
δ = 7.8 (2H, d, HA), 7.25 (2H, d, HB), 2.90 (2H, quartet, HC), 2.35 (3H, s , HD), 1.20
(3H, t, HE)ppm.
Could also be displayed as:
Shift
7.8
7.25
2.90
2.35
1.2
Integration
2H
2H
2H
3H
3H
Multiplicity
d
d
q
s
t
Assignment
HA
HB
HC
HD
HE
Spectrum 2:
O
O
C
A
A
B
B
D
δ = 7.9 (2H, d, HA), 7.25 (2H, d, HB), 3.85 (3H, s, HC), 2.4 (3H, s , HD)ppm.
Could also be displayed as:
Shift
7.9
7.25
3.85
2.35
Integration
2H
2H
3H
3H
Multiplicity
d
d
s
s
Assignment
HA
HB
HC
HD