Treatment of an alkene with mercury acetate in presence of water produce the corresponding alcohol. This reaction is regioselective Markovnikov and stereoespecific anti.
Step 1. Mercuric acetate dissociation
Step 2. Mercury cation adds to alkene with form a mercurinium ion
Step 3. Water attacks the more substituted carbon to give an alkylmercuric acetate.
Step 4. Replacement of mercury by hidrogen (demercuration)
The product obtained by oxymercuration-demercuration is the same as hydration (H2SO4 /H2O). However, oxymercuration-demercuration is not susceptible to the rearrangements.