The gas-phase reaction of acetic acid with hydrogen bromide

Abstract

In the gas phase, acetic acid reacts with hydrogen bromide in the temperature range 412-492° to give methyl bromide, carbon monoxide, and water. The reaction is first order in each reagent, and the variation of rate constant with temperature is described by the equation                      k₂ = 10^11.67exp(-30400/RT) ml mole^-1 sec^-1 Possible transition states for the reaction are examined. A mechanism involving an intermediate of the type CH₃CO⁺Br^- is possible if the reaction is of the family represented by the hydrogen bromide catalysed decompositions of trimethylacetic, isobutyric, and propionic acids.