Alkenes can be hydrated with aqueous mercury acetate followed by reduction with sodium borohydride. This reaction produces alcohols and follows the Markovnikov rule.
![hydration with mercury acetate hidratación con acetato de mercurio](/images/stories/organica-i/alquenos-reacciones/oximercuriacion/oximercuriacion01.png)
The reaction mechanism begins with the attack of the double bond to the + HgOAc ion from the dissociation of mercury acetate, forming the mercurinium ion that opens by water attack. Sodium borohydride treatment replaces mercury with hydrogen.
Stage 1. Ionization of mercury acetate
![oxymercuration oximercuriación](/images/stories/organica-i/alquenos-reacciones/oximercuriacion/oximercuriacion02.png)
Stage 2. Electrophilic addition to the double bond
![oxymercuration oximercuriación](/images/stories/organica-i/alquenos-reacciones/oximercuriacion/oximercuriacion03.png)
Stage 3. Opening of the mercurinium ion
![oxymercuration oximercuriación](/images/stories/organica-i/alquenos-reacciones/oximercuriacion/oximercuriacion04.png)
Stage 4. Deprotonation of water
![oxymercuration oximercuriación](/images/stories/organica-i/alquenos-reacciones/oximercuriacion/oximercuriacion05.png)
Stage 5. Mercury reduction with sodium borohydride
![oxymercuration oximercuriación](/images/stories/organica-i/alquenos-reacciones/oximercuriacion/oximercuriacion06.png)
The regiochemistry of the reaction corresponds to a Markovnikov addition of water. Regarding stereochemistry, hydrogen and the hydroxyl group add to Anti.