ELECTRODIMERIZATION OF AN AROMATIC AMINE IN A 2-PHASE SOLVENT SYSTEM

A comparative study of the electrochemical oxidation of N,N-dimethyl-1-naphthylamine (DMN) in emulsified water-nitrobenzene mixtures with different electrolytes and conditions was performed by quasi-stationary current-potential curves, cyclic voltammetry, controlled potential electrolysis and rotating disk electrode experiments, combined with conventional analytical techniques. The anodic oxidation mechanism of DMN in the two-phase system is similar to that in non-aqueous solvents. However due to the ionic migration across the liquid-liquid interface, the product N,N,N′,N′-tetramethyl-1,1′-naphthidine dication (TMN2+) remains in the organic phase while the protons migrate to the aqueous phase. This results in an appreciable increase in the yield of the organic product compared with the one obtained in one-phase non-aqueous electrolysis. The nature of the anions of the supporting electrolyte used in the aqueous phase of the emulsified systems exerts a direct influence in the rate of DMN oxidation which correlates with their Gibbs transfer energy. The effect of the addition of surfuctants such as sodium dodecylsulphate (SDS) and Brij 35 to this systems was also investigated. SDS practically inhibit the reaction. However Brij 35 exerts a catalytic effect by a micellar mechanism in combination with the liquid-liquid interface and no supporting electrolyte is needed in the oil phase. © 1990.