Hydroboration–oxidation is an anti-Markovnikov reaction, with the hydroxyl group attaching to the less-substituted carbon. In an oxymercuration–demercuration reaction, an alkene is treated with mercury(II) acetate, and the product is treated with sodium borohydride. The net result is a Markovnikov addition product in which the OH group bonds to the more substituted carbon atom of the alkene.





