Reactivity of C-H and O-H bonds in reactions with aminyl and nitroxyl radicals and cyclic mechanisms of chain termination in oxidizable alcohols and olefins

The parabolic model of transition state has been used to analyze the problem of why aromatic amines and nitroxyl radicals cause the cyclic mechanism of chain termination in oxidizable alcohols and olefins (where HO₂· and >C(OH)0₂· radicals participate in chain propagation) and not in oxidizable hydrocarbons. The differences are caused by the existence of a weak triplet repulsion in transition states with the N...H...0 and 0...H...0 reaction centers, while the triplet repulsion is strong in transition states with reaction centers of the C...H...0 and C...H...N type in oxidizable hydrocarbons.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1972–1976, August, 1996.