title: Rate constants for one-electron oxidation by the CF3O2., CCl3O2., and CBr3O2. radicals in aqueous solutions.
abstract: The peroxyl radicals CF3O2., CCl3O2. and CBr3O2. were produced by radiolysis of aerated aqueous-alcohol solutions of CF3Br, CF3Cl, CCl4 or CBr4. Kinetic spectrophotometric pulse radiolysis experiments were carried out in the presence of various substrates: urate, ascorbate, xanthine, hydroquinone, p-methoxyphenol, phenol and chlorpromazine. Absolute rate constants for one-electron oxidation of these substrates by the alkylperoxyl radicals were found to vary from less than 10(5) to greater than 10(9) M-1 s-1, depending to some extent on the redox potential of the substrate. For all substrates the order of reactivity was CF3O2. greater than CBr3O2. greater than CCl3O2. . Because of its high reactivity, CF3O2., may have deleterious effects on biological systems. Its likely environmental precursor, CF3Br, which is used as a fire extinguisher and a refrigerant, was found to be reduced by a ferrous porphyrin model for cytochrome P-450 only very slowly and thus is not expected to have a major toxic effect if inhaled.
mesh_terms: D005609:Free Radicals; D006846:Hydrocarbons, Halogenated / Q000633:toxicity; D010084:Oxidation-Reduction; D011675:Pulse Radiolysis; D012996:Solutions
chemical_list: D005609:Free Radicals; D006846:Hydrocarbons, Halogenated; D012996:Solutions