Voltammetric characterisation of the radical anions of 4-nitrophenol, 2-cyanophenol and 4-cyanophenol in N,N-dimethylformamide electrogenerated at gold electrodes

The electrochemical reductions of 4-nitrophenol, 2-cyanophenol and 4-cyanophenol were studied in N,N-dimethylformamide (DMF) at gold macro- and microdisk electrodes. It was inferred at the gold macroelectrode that the reduction of the parent molecule to the corresponding radical anion is chemically irreversible due to a rapid protonation process in which the basic radical anion reacts with the acidic parent compound. The use of microdisk electrodes and fast scan cyclic voltammetry (144 kV s−1) for the reduction of each of the three compounds of interest failed to outrun the kinetics of the protonation reaction, suggesting a fast process with a second-order rate constant in excess of 1 × 107 M−1 s−1.