Spin trapping by use of nitroso-compounds. Part IV. Electron spin resonance studies on oxidation with nickel peroxide

The oxidation reactions of nickel peroxide were studied by use of nitrosobenzene and 2-methyl-2-nitrosopropane as spin traps. We have demonstrated by spin trapping with nitrosobenzene that nickel peroxide suspended in benzene oxidises aromatic hydrocarbons ArCHR2 or Ar2CHR to benzylic radicals, that radicals can similarly be formed from many compounds containing active methylene groups, and that nitroxide radicals can also be obtained from many phenols and amines. A molecule-induced homolysis occurs in the reaction of a nitroso-compound with a hydroperoxide which may be contained as an impurity in a substrate. Relationships between spectral data and structures of nitroxides formed are also discussed.