The reaction of methyl radicals with hydrogen peroxide

Methyl radicals (plus methanesulfinic acid) were generated radiolytically i n N2O-saturated aqueous solutions by reacting the OH radicals thus formed w ith dimethyl sulfoxide. Upon addition of hydrogen peroxide the methyl radic als abstract an H-atom from hydrogen peroxide. With increasing hydrogen per oxide concentrations the methane yield increases while that of ethane drops . The yield of methanesulfinic acid remains unaffected. At constant hydroge n peroxide concentration, the ethane yield increases with increasing dose r ate. The system has been successfully modelled using k((CH3)-C-. + H2O2) = 2.7 x 10(4) dm(3) mol(-1) s(-1). As the corresponding rate constant in the gas phase is reported to be 3.3 x 10(7) dm(3) mol(-1) s(-1), the water solv ent appears to have a dramatic effect. Some aspects of the mechanism of H-a bstraction from H2O2 are briefly discussed.