Electrochemical behaviour of 2-(4′-hydroxybenzeneazo)benzoic-acid at pyrolytic graphite electrodes

The electrochemical reduction of 2-(4′-hydroxybenzeneazo)benzoic acid (I) has been studied at pyrolytic graphite electrodes in the pH range 2.0–10.4. The cyclic voltammetric behaviour clearly indicated an ECE mechanism in acidic medium in which the two-electron two-proton reduction of I gives the hydrazo derivative. The acid catalysed disproportionation of the hydrazo intermediate was also studied in the pH range 2.0–6.0 and the value of k′/[H⁺] was found to be 1.4 × 10^?2 1 mol^?1 s^?1 The products of the reduction have been isolated and characterized using IR, melting point, mass and related techniques.