Mechanism of electropolymerization of 1-naphthylamine in aqueous acid media

The electrooxidation of 1-naphthylamine (ArNH2) in aqueous acid media was studied. The formation of a film adhered to the electrode surface is observed as principal product and for which a polymer structure through CN coupling is proposed. Another soluble product is detected in smaller proportion which has been characterized as the dimer 1,1′-naphthidine. On the other hand, from the analysis of the voltammetric and voltacoulometric experiments some aspects of the mechanism of electrooxidation of ArNH2 for the formation of both products is proposed. This mechanism allowed us to establish quantitative ratios between the charge and number of moles of ArNH2 consumed, with the redox process of the film. The electrochemical behaviour of the film is reported as a function of ArNH2 concentration and pH. The film behaves as a thin layer cell when it is obtained at low pH (ie pH = 1) and dilute solutions of ArNH2. Moreover the voltammetric response of the film seems to fit the “unusual quasi-reversibility” behaviour.