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Dihydroxylation of Alkenes

Cis-dihydroxylation of Alkenes: Reaction with Osmium Tetroxide

The reaction of alkenes with osmium tetroxide is similar to the one with potassium permanganate, but the yields are higher.

Originally, osmium tetroxide was used in stoichiometric amounts to yield cyclic osmate esters. These could be isolated and reductively hydrolyzed either with hydrogen sulfide or sodium hydrogensulfite.

Fig.1
Oxidation of osmium tetroxide
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Fig.2
3D model of osmium tetroxide adduct

Since osmium tetroxide is very expensive and highly toxic, a modified process using only catalytic amounts of osmium tetroxide together with stoichiometric amounts of hydrogen peroxide is being used today. The latter oxidizes the generated osmium trioxide to osmium tetroxide:

Fig.3
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