Pulse radiolysis investigations on electron-transfer reactions in aqueous solutions of substituted alkyl sulfides

The transient optical absorption band formed on pulse radiolysis of N2-saturated dilute neutral aqueous solutions of dimethy 3,3'-thiodipropionate (DTDP) is assigned to an OH-adduct. The rate constant for the reaction of OH radicals has been determined. At higher solute concentrations the OH-adduct is converted to sulfur-centred dimer radical cations. In acidic solutions, only dimer radical cations are formed. In neutral aqueous solutions of 3,3'-thiodipropanol (TDP) OH radicals are able to bring about one-electron oxidation, forming intramolecular radical cations with p-orbital overlap between the oxidized sulfur and oxygen. In acidic solutions, sulfur-centred dimer radical cations are formed. In the presence of halide ions, the oxidized sulfur in DTDP and TDP stabilizes by formation of an >S: X type species. (Author)