engleski

Oxidation of Organic Sulfur Compounds by Peroxyl Radicals

Halogenated alkyl peroxyl radicals have been found to engage in multi-electron oxidations as has been shown for organic sulfides or iodide as reactants. For example, 3 I- were oxidized per each peroxyl through a 2e-transfer in the first step, followed by a 1e-oxidation through the thereby liberated alkoxyl radical. The proposed reaction mechanism considered formation of an adduct intermediate between the peroxyl radical and the molecule, followed by an intramolecular electron transfer into the hydroperoxide moiety and heterolysis of the O-O and O-X bonds involving protons and/or water from the solvent. The following results from time-resolved and steady-state radiolysis experiments will be presented: (a) direct spectral evidence for the intermediate adduct and its existence as a species with a definitive life-time; (b) kinetic data for its formation and further reactions; (c) influence of the degree of halogenation of the peroxyl radical, solvent polarity and pH on the overall reaction kinetics; (d) quantitative evidence for iodide, tert-butyl sulfide, methyl disulfide and lipoic acid, as representatie examples, to undergo multi-electron transfer oxidation reactions with halogenated but also with slowly reacting non-halogenated alkyl peroxyl radicals.

peroxyl radicals; radiolysis; reactiom mechanism

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