Halohydrin

General structure of a halohydrin, where X = I, Br, F, or Cl

Structure of the halohydrin 2-chloroethanol

A halohydrin is a type of chemical compound or functional group in which one carbon atom has a halogen substituent, and an adjacent carbon atom has a hydroxyl substituent.

Halohydrin formation:

• from an alkene in a halohydrin formation reaction
• from an epoxide by a hydrohalic acid

Halohydrin reactions:

• In presence of a base, such as potassium hydroxide, a halohydrin may undergo internal S_N2 reaction to form an epoxide. This is the reverse of the formation reaction from an epoxide.
• Epoxidation in biological systems can be catalyzed by halohydrin dehalogenase.