Dioxirane chemistry. Part15. Rate studies on epoxidations by dimethyldioxirane

Abstract

The relative rates of epoxidation by dimethyldioxirane, (1), of a series of 4-substituted (E)-ethyl cinnamates have been studied. The data were treated with the Hammett linear free energy relationship and give ρ=–1.53 indicating an electrophilic O-atom transfer. Second-order rate coefficients were determined for the epoxidation of (E)-ethyl cinnamate by (1) at several temperatures and the Arrhenius factors were determined, E_a= 14.1 kcal mol^–1, log (A/s^–1)= 7.41.