oksümerkuratsioondemercuration

Oksümerkuratsioondemercuration, known in English as oxymercuration–demercuration, is a two-step organic reaction sequence that converts alkenes into alcohols via hydroxymercuration followed by demercuration. The process provides Markovnikov hydration of alkenes without carbocation rearrangements, making it useful for substrates that would rearrange under acid-catalyzed hydration.

In the first step, mercuric acetate [Hg(OAc)2] adds across the carbon–carbon double bond in water to form a mercurinium ion, and a water molecule attacks the more substituted carbon to give an organomercury alcoholate. In the second step, the organomercury intermediate is reduced, typically with sodium borohydride (NaBH4), to replace the mercury with hydrogen. The net result is the selective formation of the alcohol with Markovnikov regioselectivity, while avoiding carbocation rearrangements.

The method is compatible with a broad range of alkenes and is tolerant of many functional groups, including esters, ethers, and halides. However, it relies on stoichiometric quantities of toxic mercury reagents and generates mercury-containing waste, which raises safety and environmental concerns. It is less suitable for substrates that are sensitive to mercury species or for highly hindered alkenes.

Oxymercuration–demercuration has historically served as a practical alternative to acid-catalyzed hydration and to hydroboration–oxidation when Markovnikov hydration without rearrangement is desired. It is primarily used in synthetic contexts where regioselectivity must be controlled and rearrangements are problematic.