Nitroxide Radicals of some N-Phenyl Substituted 1,4- and 1,2-Phenylenediamines

Summary.  Several N-phenyl substituted 1,4- and 1,2-phenylenediamines were oxidized using radicals and 3-chloroperbenzoic acid. EPR spectroscopy confirmed the generation of nitroxide radicals originating from the oxidation of the bridging -NH-group. No radical products suggesting the simultaneous reaction with the NH₂-group were observed. Only in the case of 1,4-phenylenediamine, a low concentration of nitroxide radical H–NO–C₆H₄–NH₂ was obtained. In o-aminodiphenylnitroxide the steric effect of the NH₂-group causes a partially asymmetrical spin density distribution in both phenyl rings. Corresponding author. E-mail: omelka@fch.vutbr.cz Received September 30, 2002; accepted October 4, 2002