Electrochemical Generation and Visible Spectrum of Nitrobenzene Free Radical Anion in Dimethylformamide

Abstract

POLAROGRAPHIC behaviour and electrolytic reduction of nitrobenzene in a solution of 0.2 N sodium nitrate in dimethylformamide show that free radical anions of nitrobenzene are formed^1,2. In this solution nitrobenzene is reduced in two polarographic waves, the first of which corresponds to the formation of the free radical anion C₆H₅–NO₂⁻. These anions can be generated, in a special electrolytic vessel containing the solution, by electrolysis at a mercury pool cathode at a potential corresponding to the diffusion current of the first polarographic wave of nitrobenzene in dimethylformamide. The nitrobenzene anions generated were relatively stable in the absence of oxygen and were of a yellow-brown colour in solution. The anions formed gave a polarographic oxidation current (Fig. 1) corresponding to the formation of nitrobenzene: C₆H₅–NO₂⁻ – e→C₆H₅–NO₂.