A detailed mechanistic investigation of the epoxidation of styrene by chlorine dioxide and chlorite is described. A quantitative kinetic understanding of the underlying chlorine reactions allowed us to create an accurate model for the oxidation of styrene. With excess chlorite ion, HOCl (an indirect product of the styrene oxidation) is scavenged by chlorite, thereby minimizing side reactions between HOCl and the starting material, resulting in an epoxide selectivity of ~90%. Our investigation supports the mechanism originally proposed by Kolar and Lindgren to account for the formation of styrene oxide. A simple electron transfer mechanism is not supported by the stoichiometry observed for the epoxidation of styrene. However, an initial electron transfer from the alkene to chlorine dioxide (forming a radical cation), followed by addition of chlorite to the radical cation and subsequent elimination of the ClO radical, is consistent with the reaction stoichiometry and reasonable based on reaction enthalpy calculations.

Kinetics and mechanism of styrene epoxidation by chlorite: Role of chlorine dioxide

245th National Meeting (2013)

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