organic chemistry NMR Problem Set

CHEM 242CHEM 242 IR / NMR Problem Set
1. Point out any significant signals on the IR spectra below.
OH
O
OH
O
OCH3
O
CHEM 242
2. Assign each NMR signal in the molecules below, and label each coupling constant with the interaction that
gives rise to it (e.g. Jab for the coupling constant between signal a and b). Some terminology: br = broad, s =
singlet, d = doublet, dd = doublet of doublets, dt = doublet of triplets, dq = doublet of quartets, m =
multiplet (number of lines not always clear or not all lines visible), q = quartet, t = triplet, tt = triplet of
triplets.
HO
5
4
3
PPM
2
1
0
d (ppm): 4.38, br s, 1H. 3.49, t, J = 7.1 Hz, 2H. 1.81, m, J = 7.0, 6.8 Hz, 1H. 1.43, dt, J = 7.1, 7.0 Hz, 2H.
0.97, d, J = 6.8 Hz, 6H.
O
OCH3
4
3
2
PPM
1
0
d (ppm): 3.62, t, J = 7.1 Hz, 2H. 3.23, s, 3H. 3.09, t, J = 7.1 Hz, 2H. 2.56, m, J = 6.8 Hz, 1H. 1.04, d, J =
6.8 Hz, 6H.
CHEM 242
N
3
2
1
PPM
0
d (ppm): 2.64, q, J = 8.0 Hz, 2H. 2.18, s, 3H. 2.09, d, J = 7.0 Hz, 2H. 1.67, m, J = 6.8 Hz, 1H. 1.02, t, J =
8.0 Hz, 3H. 0.85, d, J = 6.8 Hz, 6H.
Br
H3CO
7
6
5
4
PPM
3
2
1
0
d (ppm): 6.25, d, J = 15.1 Hz, 1H (ignore the triplet splitting, it’s due to unusual long-range coupling). 4.63,
dt, J = 15.1, 6.2 Hz, 1H. 3.80, s, 3H. 3.34, t, J = 7.1 Hz, 2H. 2.46, dt, J = 7.1, 6.2 Hz, 2H.
CHEM 242
O
7
6
5
4
3
PPM
2
1
0
d (ppm): 6.57, dq, J = 10.9, 6.4 Hz, 1H. 6.07, d, J = 10.9 Hz (ignore the small coupling), 1H. 2.98, q, J = 8.0
Hz, 2H. 2.35, d, J = 6.4 Hz, 3H. 1.08, t, J = 8.0 Hz, 3H.
O
O
9
8
7
6
5
PPM
4
3
2
1
0
d (ppm): 8.06, dd, J = 7.5, 1.5 Hz, 2H. 7.68, tt, J = 7.5, 1.5 Hz, 1H. 7.55, t, J = 7.5 Hz, 2H. 4.30, q, J = 8.0
Hz, 2H. 1.30, t, J = 8.0 Hz, 3H.