The electron spin resonance spectra of some hydroxylamine free radicals. Part III. Radicals formed by oxidations in alkaline solution

Abstract

The oxidation of hydroxamic acids by alkaline ferricyanide first yields radical-anions (R·CO·N·O·)^– which have e.s.r. spectra showing hyperfine splittings due both to the nitrogen atom and to α-C–H bonds in the group R. Further oxidation easily leads to the appearance of secondary radicals which, by their e.s.r. spectra, have been identified as those formed from carbamates of alkylhydroxylamines, –O·CO·NR·O·, a molecular rearrangement of the group R from CO to N having occurred. N-Methylhydroxamic acids give identical e.s.r. spectra on oxidation in acid or in alkaline solution. These show larger nitrogen splittings than those of their unmethylated analogues but no splitting due to α-C–H groups in their acyl substituents. The structural implications of these e.s.r. spectra are discussed.