Radiolytic Oxidation of Xylenes by OH Radicals

•Studies of radiolytic oxidation of xylenes in aqueous solution.•Distribution of radiolytic products from irradiated xylenes in aqueous solution.•Concerted effects of methyl group in the reaction of OH radicals with xylenes.•Radiolytic oxidation of dimethylated benzenes in aqueous solution.

Studies of the radiolytic oxidation of xylenes in aqueous solutions show that, as in the case of toluene, OH radical predominantly adds to the unsubstituted ring positions of the xylenes. Abstraction of H from the methyl groups and addition at the substituted positions is only of minor importance. The distribution of phenolic products observed in the case of meta-xylene shows that OH radical preferentially adds at the positions ortho and para to the methyl substituents. The yield for addition at the position meta to both methyl substituents is significantly less than for addition at the meta position of toluene. This difference indicates that the methyl substituents in meta-xylene act in together to reduce the negative charge at the 5 position.