Alkene Epoxidation

Animation of alkene epoxidation with m-CPBA (meta-chloroperoxybenzoic acid), a peroxyacid. The -OOH group has a weak O-O bond, and the terminal oxygen is electron deficient.

1. The alkene and m-CPBA align such that the O-O bond of m-CPBA is positioned above the π bond.
2. In a concerted process, the π electrons of the alkene attack the electrophilic oxygen while the O-O bond cleaves. This yields the epoxide product and m-chlorobenzoic acid byproduct in a stereospecific syn addition.