Simultaneous electrochemical and e.s.r. studies on the reduction of aliphatic nitrocompounds

Abstract

The electrochemical reduction of 2-nitropropane and 2-nitro-2-methylpropane at an amalgamated silver electrode in aqueous alkaline solution was studied. Current potential curves were measured, and simultaneously the amount of the radical intermediates (CH₃)₂CHNO^–₂· and (CH₃)₃CNO^–₂· present in the diffusion layer was determined by e.s.r. From decay curves of the e.s.r. signal recorded upon interrupting the current, the rate constants for the chemical reaction of the radical intermediates were deduced. The dependence on potential of the current yield of the radical intermediates detectable in solution was measured at pH values of 9.6, 10.7, and 11.9 in the absence and in the presence of different concentrations of the inhibitor triphenylphosphine oxide. The result is discussed in terms of a proposed mechanism of the electroreduction. A provisional model of desorption from the electrode and reaction in solution of the radical intermediate (CH₃)₃CNO^–₂· is suggested to account for the decay curves observed at the pH of 11.9.