Catalysis by hydrogen halides in the gas phase. Part XII. Trimethylacetic acid and hydrogen bromide

Abstract

In the presence of hydrogen bromide at 340–460°, trimethylacetic acid decomposes in the gas phase into carbon monoxide, isobutene, and water. Hydrogen bromide is not consumed. Individual runs are of the first order, and the rate constants are proportional to the pressures of hydrogen bromide. The rate constant is k₂(sec.^–1cc.mole^–1)= 10^12·28exp(–31,660/RT), and the reaction is a molecular one. The suitabilities of seven-membered ring and heterolytic transition states are discussed.