Oxymercuration reaction

The Oxymercuration is a method for highly selective to convert alkenes into alcohols according to the Markovnikov rule. When Oxymercuration water is deposited with the aid of mercuric acetate to an alkene. This hydration is similar to the addition of hydrogen halides to alkenes and belongs to the type of reaction of the electrophilic addition.

Implementation

The alkene is reacted with water and mercuric acetate. Most of tetrahydrofuran is used as solvent, which can dissolve all components. The resulting mercury alcohol is reduced with sodium borohydride and sodium hydroxide to the alcohol.

The Oxymercuration generally produces very good yields under very mild conditions. Similarly, you can also alcohols, amines or other nucleophiles accumulate. Thus, instead of water, for example, also the alcohol side chain intramolecular attack to form a cyclic ether.

Mechanism

Mercuric acetate dissociates in water partially to H3C -COO-, H3C COOHg and Hg2 . The H3C COOHg ion binds to the double bond of the alkene and forms a Mercuriniumion. At this water is added, resulting in forming a mercury alcohol. The H3C COOHg residue at the alcohol can be cleaved with sodium borohydride and sodium hydroxide solution. This produces acetate, mercury and the desired alcohol.

Criticism

The oxymercuration is unsuitable because of the low atom economy of the reaction and the toxic properties of organic mercury compounds in industrial applications. Therefore, the application of the reaction to the laboratory scale limited. An alternative offer epoxidation, which run on an industrial scale with catalysis in sufficient yields.