Hydroxylation by organic peroxy acids

Hydrolysis of the epoxide occurs by trans-ring fission e.g., fra .y-l,2-cyclo-hexanediol is formed from 1,2-epoxycyclohexane.104 

The usual reagents for such oxidation of olefins are peroxyacetic and peroxy-formic acid. Because of the inherent danger these peracids are not prepared in the pure state but are used in dilute solution. 

According to Swern et al.23 the olefin is treated with an almost stoichiometric amount of 25-30% hydrogen peroxide in glacial acetic acid containing a small amount of concentrated sulfuric acid. This method gives good yields of -glycols when the reaction temperature is about 40° and the reaction time a few hours. 

According to Greenspan,107 olefins can be hydroxylated in very high yield by a mixture of acetic acid and 90% hydrogen peroxide. A mixture of con- 

Trifluoroperoxyacetic acid is also an efficient reagent for oxidation of olefins to -glycols (preparation see the Section on Epoxides) 109 in this reaction the -glycols are first formed as monoesters with trifluoroacetic acid and are obtained therefrom by treatment with methanol. Excellent yields of -glycols are obtained by adding triethylammonium trifluoroacetate to the reaction mixture. 

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