Epoxides:
Epoxides can be synthesized through treating aldehydes or ketones along with sulfur ylides. They can as well be prepared from alkenes by reaction with m- chloroperoxybenzoic acid. Conversely they can be acquired from alkenes in a two-step process. The 1st step includes electrophilic addition of a halogen in aqueous solution to make a halohydrin. Treatment of the halohydrin along with base after that ionizes the alcohol group, which can then work as a nucleophile. The oxygen employs a lone pair of electrons to make a bond to the neighboring electrophilic carbon, so displacing the halogen by an intramolecular SN2 reaction.
Figure: Synthesis of an epoxide via a halohydrin.
Figure: Mechanism of epoxide formation from a halohydrin.