Anomalies in Faradaic rectification polarography of aromatic compounds in non-aqueous solvents

Abstract

The electrode reaction of p-dicyanobenzene O/− in N, N-dimethylformamide is studied with the aid of the galvanostatic double pulse (GDP) method and faradaic rectification (FR) polarography. The results of the GDP measurements obey the theoretical requirements in all aspects. Conversely, the FR polarogram can be fitted with the theoretical polarograms only in the potential range ∔-50 mV vs. the reversible half-wave potential of this electrode. Furthermore, the most suitable k 0 values used in this curve-fit analysis depends on the frequency of ac input and differ greatly from the value determined by the GDP method. Attention is called to the fact that the p-dicyanobenzene 0/− system is just one of the 16 redox systems of aromatic compounds which show this type of behaviour in FR and GDP experiments. Their kinetic parameters are also tabulated, with some comments on the anomalies in FR polarography.