Ultrasonic Effects on Electroorganic Processes. XVIII. A Limiting Current Study on Indirect Electrooxidation of n-Butylamine with a Triarylamine Redox Mediator

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Ultrasonic effects on indirect electrolytic oxidation of n-butylamine with a tris (p-bromophenyl)amine redox mediator were investigated in comparison with mechanical stirring effects. The cyclic voltammogram of a mixture of the n-butylamine substrate and the mediator exhibited a typical catalytic anodic peak current for the indirect oxidation in silence without the stirring, while limiting currents were observed in silence and under irradiation with and without the stirring, respectively. The current was significantly increased under the irradiation. Influence of ultrasonic power, stirring speed and concentrations of the substrate and mediator on the current were experimentally and theoretically examined, and consequently it was suggested that (a) diffusion layer thickness of anode interface is significantly decreased by ultrasonic irradiation, (b) reaction rate constant of the mediator with the substrate is not affected, and (c) distance from the electrode surface to region of the reaction is also not influenced.