Interaction between the carbonyl group and an α-sulphur atom. Part III. Infrared and nuclear magnetic resonance measurements of carbonyl group basicities for some α-ethylthio-substituted carbonyl compounds

Abstract

The replacement of an α-hydrogen by an ethylthio-group in ketones, esters, thioesters and NN-dimethylamides leads to a slight decrease of basicities as is shown by i.r. and n.m.r. measurements. Although for the series of α-ethylthio-substituted carbonyl compounds the decrease of basicities is followed by an increase in the frequency of carbonyl absorption, comparison of the α-ethylthio- with the corresponding unsubstituted compounds shows that the decrease of basicities is accompanied by a decrease in the frequency of carbonyl absorption. This abnormal relationship is discussed.