Molybdenum‐catalysed epoxidation of olefins with alkyl hydroperoxides I. Kinetic and product studies

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Abstract
In the homogeneous molybdenum‐catalysed epoxidation of olefins bytert‐alkyl hydroperoxides two competing processes, epoxidation and hydroperoxide decomposition, have been delineated.Hydroperoxide decomposition involves free‐radical reactions initiated by electron‐transfer reactions of Mo(V) and Mo(VI) complexes with the hydroperoxide. The rates and products of hydroperoxide decomposition are dependent on the solvent and the presence or absence of an olefin.The rate of epoxidation depends on the structure of the olefin and, after an initial period during which the rate changes, it becomes independent of the structure of the molybdenum compound originally added as the catalyst. The active catalyst in the epoxidation reaction is a molybdenum(VI) compound. The active epoxidizing agent is most likely a complex of molybdenum(VI) with the hydroperoxide, which transfers an oxygen atom to the olefin via a cyclic transition state analogous to that for the epoxidation of olefins with organic peracids.