In situ radiolysis electron spin resonance study of the radical-anions of substituted nitroimidazoles and nitroaromatic compounds

Abstract

Reaction of e^–_aq, (CH₃)₂ĊOH, (CH₃)₂CO^{[graphic omitted]} or CO^{[graphic omitted]}₂ with a number of substituted nitroimidazoles and nitrobenzenes results in the formation of their radical-anions and in no case were radical-adducts detected. Changes in the e.s.r. spectra of the product species with pH are interpreted in terms of either the protonation of the radical-anion (metronidazole) or the loss of a proton from the radical anion (2-methyl-5-nitroimidazole, 4-nitroimidazole and nitrophenols) and pK values of some of these processes are evaluated. In several cases the dynamics of these acid–base reactions influence the linewidths of the e.s.r. spectra.