MCPBA EPOXIDATION OF ALKENES - REINVESTIGATION OF CORRELATION BETWEENRATE AND IONIZATION-POTENTIAL

A kinetic equation provides relative rate constants from product analy sis under competition conditions. This has been applied to the epoxida tion of a large number of alkenes with m-chloroperbenzoic acid in meth ylene chloride. The rate constants are well correlated with ionization potentials, but there are separate linear correlations for aliphatic and aromatic alkenes. However, the extent of electron transfer to the peracid is minimal. These results can be interpreted in terms of trans ition-state imbalance (''nonperfect synchronization''), frontier-orbit al theory, and a transition state (1) that has little charge developme nt at carbon.