C=O Stretching vibrations in Raman and infrared spectra of simple esters

Abstract

Infrared and Raman spectra of methyl acetate, tert-butyl acetate, methyl pivalate and tert-butyl pivalate were measured in the liquid and crystalline states and solutions of different dielectric constants. In these molecules, the bands of the C=O str. vibrations are not affected by conformational structure. The shape and position of the band of the C=O str. vibration in methyl acetate are primarily determined by intermolecular order created by interactions of the permanent dipoles of the molecules. In methyl pivalate and in tert-butyl acetate, the shape of the carbonyl band is mainly determined by Fermi resonance.