α,ß-Unsaturated Carboxylic Esters and Their Hydrogen Bond Complexes with Substituted Phenols: Vibrational Spectra-Structure Correlations

Abstract

The conformational freedom about the C_α—C bond in some α,ß-unsaturated carboxylic esters — methyl acrylate, methyl trans-crotonate and methyl trans-cinnamate — and the extent of hydrogen bonding between the carbonyl group of these ester compounds and some phenol derivatives in carbon tetrachloride solutions, are herein considered and studied. A linear relationship between △vC=0 due to the hydrogen bond and the enthalpy of complex formation is found, providing an indirect means of evaluating the strength of the hydrogen bond from the observed shift in the carbonyl stretching frequency.