Styrene reactive oxygen species

Effects of hydroxylic solvents on epoxidation of styrene with H2O2 have been studied. Consistent results were obtained when the impact of a single molecule of water, ethanol, and t-BuOH on the reaction was simulated using the discrete model. Reactivity was greatest for /-BuOH followed by ethanol protic solvent molecules promote the heterolytic cleavage of H2O2 and form active oxygen species that reduce the reaction barrier. ... 

Thermal insertion occurs at room temperature when R is XCH2CHAr-, at 40° C when R is benzyl, allyl, or crotyl (in this case two isomeric peroxides are formed), but not even at 80° C when R is a simple primary alkyl group. The insertion of O2 clearly involves prior dissociation of the Co—C bond to give more reactive species. The a-arylethyl complexes are known to decompose spontaneously into CoH and styrene derivatives (see Section B,l,f). Oxygen will presumably react with the hydride or Co(I) to give the hydroperoxide complex, which then adds to the styrene. The benzyl and allyl complexes appear to undergo homolytic fission to give Co(II) and free radicals (see Section B,l,a) in this case O2 would react first with the radicals. 

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