Conformations of some αβ-unsaturated carbonyl compounds. Part V. Assignments of Raman and infrared spectra of methyl and [2H3]methyl acrylates and trans-crotonates

Abstract

Raman and i.r. spectra of methyl and [²H₃]methyl acrylates and trans-crotonates in the liquid state at room temperature and as frozen solids are presented together with vibrational assignments for particular conformers. Intensities of selected Raman bands at different temperatures lead to enthalpy differences (ΔH⁰± standard deviation) of 377 ± 56 cal mol^–1 between the high and low energy forms of methyl trans-crotonate, in very good agreement with a previous result based on i.r. measurements.