ELECTROREDUCTION OF 1-NAPHTHYLHYDRAZONODIMEDONE AND 2-NAPHTHYLHYDRAZONODIMEDONE IN DMSO

A detailed investigation on the reduction of 2-(1-naphthylhydrazono)dimedone (1-NHD) and 2-(2-naphthylhydrazone)dimedone (2-NHD) in 0.1 M TEAI-DMSO was made using various electroanalytical techniques. Each of the two compounds gave two well-defined polarographic waves/cyclic voltammetric (CV) peaks. The first one-electron diffusion-limited wave/peak arises out of the formation of the corresponding anion radical and has been characterised to be of oxy type from in-situ EPR studies. However, the second wave/peak is attributed to an EC reaction involving a fast reverse disproportionation reaction by which the anion radical is regenerated, as confirmed from CV studies and also from the non-integral n value obtained for the second wave from microcoulometry. Macroscale CPE experiments carried out at the limiting regions of the first and second polarographic waves of 1-NHD and 2-NHD afforded the corresponding naphthylamines as the major product. Based on these results, a plausible mechanism for the electroreduction of 1-NHD and 2-NHD in DMSO has been proposed.