Epoxidation of Alkenes with Peracids
Epoxidation of Alkenes with Peracids: General Procedure
MCPBA (meta-chloroperbenzoic acid) and the appropriate alkene in a ratio of 1:5 are dissolved in dichloromethane. The reaction mixture is heated with stirring under reflux for 24 hours. After completion, the mixture is washed with a saturated solution of sodium bicarbonate and 10% aqueous sodium bisulfite. Subsequently, the organic phase is dried over magnesium sulfate.
Frequent side products are 1,2-diols formed by acid-catalyzed opening of the epoxide or glycol esters produced by esterification with MCPBA
Often, opening of the epoxides can be reduced either by the addition of solid sodium bicarbonate with strong stirring or the use of ultrasound. In such cases, the oxidizing agent dioxirane is used advantageously in the laboratory.