Reaction kinetics of hydrogen addition reactions to methyl butenoate

Abstract

To investigate the kinetics of hydrogen addition reactions of unsaturated methyl esters, we selected two representative molecules that are isomers with CC double bonds at different locations, i.e. methyl 2-butenoate and methyl 3-butenoate for study. An appropriate quantum chemical method was determined to compute the potential energy surfaces. The high-pressure limit rate constants were computed by applying multi-structural canonical variational transition state theory including tunneling by the multi-dimensional small-curvature tunneling approximation. The master equation analysis was followed to study the pressure-dependence of the rate constants of H addition and the subsequent dissociation reactions. The results show that it is easier for the H atom to add to the CC than to the CO bond because of the lower barrier heights, and the hydrogen addition reactions are faster for both methyl 2-butenoate and methyl 3-butenoate, except that the hydrogen abstraction is dominant at above 1700 K for methyl 2-butenoate. Using our computed rate constants, the prediction for methyl propanoate mole fraction agreed better with experimental data of methyl 2-butenoate combustion.