The electron spin resonance spectra of some hydroxylamine free radicals. Part IV. Radicals from alkylhydroximic acids and amidoximes

Abstract

Electron spin resonance spectra have been obtained, by the flow method, by the oxidation of two alkylhydroximic acids RC(:N·OH)·OEt in acid solution and from a number of amidoximes RC(:N·OH)·NH₂ in alkaline solution. With the radical-anions from amidoximes, the hydroxyimino-group ¹N–OH carries a larger electron spin density on nitrogen than does the imino-group ²N–H. Geometrical isomers appear to be formed by the oxidation of ²N-phenylbenzamidoxime, PhC(:¹N·OH)·²NHPh. The magnitudes of the splitting constants a_N–1 and a_N–2 on the nitrogen atoms of amidoxy-radical-anions, RC(:¹N–O·)·²NH, vary linearly, but in opposite directions, in accordance with the acid strength (pK_a) of the corresponding carboxylic acids RCO₂H.