In theoretical study of the epoxidation of olefins by peracids

For the parent reacting system, HCOOOH + CH2=CH2 --> HCOOH + ethylene oxide, the overall potential energy surface has been determined using ab initio methods. The oxygen-addition transition state is found to be remarkably similar to that deduced experimentally. The O-H bond is retained in the transition state. Reasonable kinetic isotopic effects are obtained theoretically The transition state leads to an unprecedented transient intermediate. That intermediate is converted to a hydrogen-bonded system between ethylene oxide and formic acid. Substituent effects on transition-state geometries are small, but the effects on activation energies are large.