The use of spin traps to characterize sulphur- and phosphorus-containing radicals from OO-dialkyl hydrogen phosphorodithioates, zinc bis-(OO-di-isopropyl phosphorodithioate), and related compounds

Abstract

A spin-trapping method, in conjunction with e.s.r. spectroscopy, has been employed to demonstrate that thiyl radicals are formed in the reactions of the hydroxyl radical with a variety of sulphur-containing compounds: radicals trapped with the nitromethane aci-anion have been characterised on the basis of the g values and β-proton splittings of the resulting adducts. The approach has been extended to the detection of radicals formed in the oxidation of some dialkyl phosphonates and in the photolytic decomposition of sulphur- and phosphorus-containing substrates; the magnitude of a(³¹P) in the resulting adducts is particularly informative. Complicating features which arise from nucleophilic attack by substrates on the traps have been noted. Finally the spin trapping–e.s.r. technique has been applied to the detection of radicals formed from the antioxidant zinc bis-(OO-di-isopropyl phosphorodithioate) by electrochemical oxidation and by reaction with t-butyl hydroperoxide.