A computational study on the possible role of oxygen in the oxidation of methionine and dimethylsulfide initiated by OH radicals

► Molecular oxygen can oxidize sulfur radical cations to carbocations in solution. ► Molecular oxygen can oxidize peroxy radicals to carbonyl oxides in solution. ► Sulfur ylides are possible intermediates in the oxidation of DMS to DMSO. ► Reliable G3(MP2)//B3LYP heats of formation for several organo-sulfur compounds.