The gas-phase reaction of methyl acetate and hydrogen bromide

Abstract

In the gas phase methyl acetate reacts with hydrogen bromide over the range 419-497� to give methyl bromide, carbon monoxide, and methanol. Rate constants first order in both ester and hydrogen bromide are calculated from initial slopes, and are described by the equation �������������������� k2 = 1012.29exp(-32312/RT) ml mol-1 s-1 Kinetic data depart from this second-order form at early stages of the reaction. The addition of methanol can reduce the value of k2 to zero. A mechanism involving the reversible step : ������������������������ CH3COOCH3+HBr ↔ CH3OH+A* is proposed. The intermediate reacts with isobutene to form mesityl oxide, and is considered identical with that formed in the reaction of acetic acid with hydrogen bromide.