THE INFRARED CARBONYL STRETCHING BANDS OF ACETOPHENONES SUBSTITUTED IN THE METHYL GROUP

Abstract

Measurements have been made of the positions and intensities of the C==O stretching bands in the infrared spectra of compounds of the types C6H5—CO—CH2X, C6H5—CO—CHX2, and C6H5—CO—CX3 where X = —Cl, —Br, —I, —CN, —C6H5, and —OH. In most cases two bands are observed, and these are attributed to gauche and cis conformations associated with hindered rotation about the CO—CH2X and CO—CHX2 bonds. The relative positions and intensities of these bands are discussed in terms of the steric, electrical, and mass effects of the substituents.