Chapter 16: Ethers, Epoxides and Sulfides

Epoxidation of Alkenes
(review of Chapter 6)

Reaction type: Electrophilic Addition

Summary

• Overall transformation :  C=C to epoxide
• Reagent : a peracid, RCO₃H
• Regioselectivity : not relevant since both new bonds are the same, C-O
• Stereoselectivity : syn since the two new C-O s bonds form at the same time from the peracid.

Related reactions

• Addition Reactions of Alkenes
• Using Halohydrins to synthesise Epoxides

MECHANISM FOR REACTION OF ALKENES WITH PERACID
A single step reaction involving several changes. Start at the C=C as the nucleophile, make a bond to the slightly electrophilic O, break the weak O-O bond and form a C=O, break the original C=O to make a new O-H bond, break the original O-H to form the new C-O bond ! (phew !)

© Dr. Ian Hunt, Department of Chemistry