Final answer:
The oxymercuration-demercuration mechanism is a two-step process that converts alkenes to alcohols, with anti-Markovnikov addition of water. It begins with oxymercuration to form a mercurium ion, followed by nucleophilic attack by water resulting in a mercurial alcohol. Lastly, a demercuration step yields the final alcohol while removing the mercury group.
Step-by-step explanation:
The mechanism of alcohol production via oxymercuration-demercuration is a process in organic chemistry that converts alkenes into alcohols. The reaction proceeds initially through the addition of mercuric acetate in the presence of water, where the alkene undergoes oxymercuration to form a mercurinium ion intermediate. This intermediate is then attacked by a water molecule, leading to the formation of a mercurial alcohol. In the second step, demercuration takes place through the treatment with sodium borohydride (NaBH4) or thiosulfate, which removes the mercury (II) acetate, regenerating the corresponding alcohol.
Here is a simplified version of the reaction steps:
-
- Oxymercuration: Alkene + Hg(OAc)2 + H2O -> Mercurium ion intermediate.
-
- Nucleophilic attack by water: Mercurium ion + H2O -> Mercurial alcohol.
-
- Demercuration: Mercurial alcohol + NaBH4 -> Alcohol + Hg + NaBH3Ac.
This method is preferred over direct hydration because it tends to give anti-Markovnikov addition of water across the double bond, which means that the hydroxy group ends up on the more substituted carbon atom.