HINDERED AMINE MECHANISMS .3. INVESTIGATIONS USING ISOTOPIC LABELING

The literature 'peroxide' mechanism and our proposed mechanism for the regeneration of hindered amine nitroxyls have been tested with isotopically labelled reactants. Both mechanisms deal with the reaction of alkylperoxy radicals with N-alkyloxy hindered amines, which are products of the reaction of nitroxyl radicals with alkyl radicals. The 'peroxide' mechanism predicts the regeneration of nitroxyl and formation of dialkyl peroxide. Our mechanism predicts the regeneration of nitroxyl and formation of ketones, alcohols and carboxylic acids, depending on the oxidizing substrate. The results of this work confirm the new proposed regeneration mechanism but not the previous 'peroxide' mechanism. The features of the confirmed mechanism are {A figure is presented}. This basic mechanism is also proposed for acylperoxy radicals {A figure is presented}. © 1989.