Pyrrole studies. VIII. The NH stretching frequencies of substituted pyrroles Acetyl and benzoyl substituents

Abstract

The infrared spectra of a number of acylpyrroles have been examined in the NH and CO stretching region under high resolution in carbon tetrachloride. Analysis of the data show-s that the effect of each group on the NH stretching frequency is independent of other substituents and additive. Pyrroles having the acyl substituent in the β-position show two concentration-independent bands. The lower frequency band arises from interaction with the out-of-plane deformation of the NH group, producing a hot band.