LIGHT ABSORPTION STUDIES: PART XX. THE ULTRAVIOLET ABSORPTION SPECTRA AND INFRARED CARBONYL BANDS OF BENZOYL CHLORIDES

Abstract

The ultraviolet absorption spectra and infrared carbonyl bands of a number of substituted benzoyl chlorides are determined. It is found that as a first approximation the B-bands of the ultraviolet spectra are similar for benzoyl chlorides and for the corresponding benzaldehydes and acetophenones. The spectra are discussed in terms of previously stated hypotheses. In this way the order of the apparent negative mesomeric effect is deduced to be —NO2 > — COCl > —CHO > —COCH3, and the effective size of these substituents is confirmed to be in the order —NO2 > —COCH3 > —COCl > —CHO.The infrared carbonyl band occurs as a well-defined doublet in most of the ring-substituted benzoyl chlorides. The most probable explanation is that these doublets occur because of an intramolecular vibration.