Experimental and Theoretical Study of the OH Vibrational Spectra and Overtone Chemistry of Gas-Phase Vinylacetic Acid

In this study we present the gas-phase vibrational spectrum of vinylacetic acid with a focus on the v = 1-5 vibrational states of the OH stretching transitions. Cross sections for v = 1, 2, 4 and 5 of the OH stretching vibrational transitions are derived on the basis of the vapor pressure data obtained for vinylacetic acid. Ab initio calculations are used to assist in the band assignments of the experimental spectra, and to determine the threshold for the decarboxylation of vinylacetic acid. When compared to the theoretical energy barrier to decarboxylation, it is found that the v(OH) = 4 transition with thermal excitation of low frequency modes or rotational motion and v(OH) = 5 transitions have sufficient energy for the reaction to proceed following overtone excitation.