GENERATION OF N-TERT-BUTYL-ALPHA-PHENYLNITRONE RADICAL ADDUCTS IN IRON BREAKDOWN OF TERT-BUTYL-HYDROPEROXIDE

ESR spectroscopy coupled to the spin trapping technique was used to ev aluate the generation of radical species arising from the ferrous ion induced decomposition of tert-butyl hydroperoxide ('BuOOH) in methylen e chloride. We report here that N-tert-butyl-alpha-phenylnitrone (PEN) can trap peroxyl radicals generated in the ferrous ion induced breakd own of high concentration of 'BuOOH (1M) at room temperature, the radi cal adduct being stable under the light. The peroxyl radical formation was demonstrated by direct ESR measurements at 77K. In contrast, alko xyl and methyl radicals were trapped only in the presence of low hydro peroxide concentration (1mM). In order to measure the hyperfine splitt ing constants (hfsc) of the PEN-methyl adduct spectra were obtained in the presence of diphenylamine (DPA) or 2,6-di-tert-butyl-4-methylphen ol (BHT), which quenched the alkoxyl radical. For this latter radical, the hfsc were calculated by computer simulation. A mechanism for a di rect interaction between DPA and the alkoxyl radical is presented. DPA quenched the peroxyl radical in the reaction of high hydroperoxide co ncentrations, with the concomitant generation of a DPA nitrogen-based radical.