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 kVs) 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 × 10 M s.