Voltammetric and in situ FTIRS study of the electrochemical oxidation of aniline from aqueous solutions buffered at pH 5

The electrochemical oxidation of aniline at low concentration was carried out in phosphate buffer solutions of pH 5. Both electrochemical and spectroscopic results indicate that during the initial stages of aniline oxidation, a dimerisation process takes place. The dimer has been identified as p-aminodiphenylamine (ADPA). No evidence supporting the formation of other dimerisation products, such as benzidine or hydrazobenzene has been found. The hydrolysis of ADPA seems to be a very slow and, consequently, the formation of hydroquinone/p-benzequinone has not been observed. ADPA is poorly soluble ill aqueous medium and a part of these species precipitates on the electrode surface when formed. This precipitated dimer could act as an active centre for the further growth of the polymeric chains. (C) 2001 Elsevier Science B.V. All rights reserved.