Rate constants for the reactions of halogenated organic radicals

Absolute rate constants have been measured by means of pulse radiolysis for the reactions of various halogenated aliphatic compounds (ethane derivatives, including the anaesthetics halothane, enflurane, isoflurane and methoxyflurane) with hydrated electrons and OH anion radicals, the reactions of halogenated carbon-centred radicals, derived thereby, with molecular oxygen, and the reactions of halogenated peroxyl radicals with various antioxidants (ascorbate, chlorpromazine promethazine, propyl gallate, ABTS) in aqueous solutions. All oxygen addition reactions occur essentially diffusion-controlled. This finding is correlated with the stereoelectronic properties of the primary carbon-centred radicals. The oxidative power of the halogenated peroxyl radicals reflects the inductive-l effect of the halogens and accordingly increases with the degree of halogen substitution, with fluorine substituents being particularly effective. The peroxyl radicals derived from freon 113, namely CClF2CClFOO radical and CCl2FCF2OO radical, have been identified as the best oxidants among these species. (author)