Studies in decarboxylation. Part III. The thermal decarboxylation of 2,2-dimethyl-3-phenylbut-3-enoic acid

Abstract

The rates of decarboxylation of 2,2-dimethyl-3-phenylbut-3-enoic acid have been measured in the gas phase at five temperatures between 442·4 and 476·7°K. The reaction is of the first order and homogeneous, having ΔH^‡= 29·7 kcal./mole and ΔS^‡=– 14·69 e.u. at 460·3°K. The extrapolated rate of decarboxylation of this acid is 580 times faster than that of the isomeric 2,2-dimethyl-4-phenyl-but-3-enoic acid at 500°K.