Instant Notes: Analytical Chemistry

The CH(methine) resonance in 1,1,2-trichloethane(Fig. 4) is at a much lower

field than the CH 2 (methylene) resonance because of the very strong deshielding

by two chlorines. The protons give an AX 2 coupling pattern of a triplet and

doublet, and an integral ratio of 1 : 2.

264 Section E – Spectrometric techniques

NH 2

N

Cytosine

N

HA

HX

HO

HOD peak from exchange with D 2 O

500 400 300 200 100 0

1.8 ppm

108 Hz at 60 MHz

8 Hz 8 Hz

HA HX

d 7.7 d 5.9

8.0 7.0 6.0 5.0 4.0

d (ppm)

3.0 2.0 1.0 0

(Hz)

Fig. 3.^1 H spectrum of cytosine.

500 400 300 200

(Hz)

100 0

CH CH 2

H

Cl

Cl C

8.0 7.0 6.0 5.0 4.0

d (ppm)

3.0 2.0 1.0 0

1:2:1 CH^2 Cl

1,1,2-Trichloroethane

Fig. 4.^1 H spectrum of 1,1,2-trichloroethane.