Electron spin resonance study of organosulfur radicals produced in electron-irradiated aqueous solutions. Spin trapping with nitromethane aci-anion and 2-methyl-2-nitrosopropane

Free radicals produced by the reaction of hydroxyl radicals with a number of organosulfur compounds in N2O-saturated aqueous solutions have been studied by the in situ radiolysis-steady-state ESR method. Organosulfur radicals (RS.) and additional alkyl radicals have been detected indirectly by spin trapping experiments using nitromethane aci-anion (CH2=NO2-) and 2-methyl-2-nitrosopropane ((CH3)3CN=O) as spin trapping reagents in the in situ radiolysis system. The ESR parameters of the spin adducts RS-CH2NO2-. are as follows: a/sup N/ = 23.98-24.29 G, a/sup H/(CH2) = 5.70-7.10 G, a/sup H/(-CHS-CH2-) = 0.65-0.83 G, and g = 2.00557-2.00566. The inequivalent hyperfine coupling constants of methylene protons adjacent to the nitrogen and the selective line broadening can be attributed to the chiral carbon atom across a sulfur atom from the methylene group or hindered internal rotation around the C-N bond. The ESR parameters of the spin adducts RS-N(O.)C(CH3)3 are a/sup N/ = 17.91-18.40 G, a/sup H/(-CHS-N<) ≤ 1.36 G, and g = 2.00626-2.00656. The apparent differences in the trapping efficiency of RS from disulfides, thiols, and sulfides are discussed with the above two spin traps