Alkenes do not undergo hydration upon treatment with water even at very high temperatures. There are two approaches to hydrating alkenes:
- Reaction of the alkene with water in the presence of a strong-acid catalyst.
- Using an indirect method, such as oxymercuration-reduction, also known as oxymercuration-demercuration or, simply, oxymercuration.
The protocol is carried out in two stages:
Stage 1: Oxymercuration: The alkene is treated with aqueous mercury (II) acetate, Hg(OAc)2, which converts the alkene into an organomercury compound (see organometallic compound).
Stage 2: Reduction (Demercuration): The organomercury compound is treated with a reducing agent, usually NaBH4, which converts the organomercury compound into an alcohol.
eg: Stage 1:
The reaction is an anti addition.
Stage 1 + Stage 2 =
The net reaction is a Markovnikov addition:
see also hydroboration-oxidation