Abstract
A tungstate/pertungstate redox mediator combined with cathodically generated hydrogen peroxide from dioxygen was developed for a new cathodic indirect oxidation system. The system involves the cathodic reduction of dioxygen to hydrogen peroxide and the oxidation of tungstate to pertungstate with the hydrogen peroxide. A starting substrate is oxidized by the pertungstate to the corresponding product in high current efficiency and product selectivity. Influences of current density, pH, temperature, and charge passed, etc., on the current efficiencies for the reduction of dioxygen and for the oxidation of dimethyl sulfoxide (DMSO) with the tungstate/pertungstate redox mediator were examined. Under conditions thus optimized, cathodic oxidations of some sulfides, sulfoxides, and N‐hydroxy secondary amines were carried out to give high efficiencies and selectivities. Anodic indirect oxidations of sulfides and N‐hydroxy secondary amines with Os(VIII)/Os(VI) and redox mediators, respectively, were also developed to realize the paired electrosynthesis of the corresponding sulfones and nitrones by pairing the above indirect cathodic oxidation. The current efficiencies for the paired electrosynthesis of sulfones and nitrones reached 166 and 185% in maxima, respectively. © 1999 The Electrochemical Society. All rights reserved.
Published Version
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