Activation parameters and mechanism of the acid-catalysed hydrolysis of epoxides

Abstract

Rates of acid-catalysed hydrolysis of three epoxides have been measured over the temperature range 0–30°. The energies of activation are within the range 18–21 kcal mol^–1. The entropies of activation are –8 for epichlorohydrin, –5 for propylene oxide, and +8 cal mol^–1K^–1 for isobutylene oxide. The significance of these values and related factors are discussed in relation to the A-2 mechanism in the case of epichlorohydrin and propylene oxide and the A-1 mechanism in the case of isobutylene oxide.