Electrochemical Reduction of 2,2-Dichlorovinyl Dimethyl Phosphate (Dichlorvos) at Carbon and Silver Cathodes

Abstract

Despite their negative ecological effects, halogenated organophosphates have been used as pesticides. For example, 2,2-dichlorovinyl dimethyl phosphate (or dichlorvos), found in many household and commercial insecticides, can lead to contamination of runoff and rinse water that is toxic to birds, bees, aquatic organisms, and mammals. Remediation of dichlorvos has focused either on electrochemical oxidation1 or on reductive cleavage of its carbon–chlorine bonds at mercury.2 In this study, we have examined the direct reduction of dichlorvos in dimethylformamide and acetonitrile at both carbon and silver cathodes. Shown in Figure 1 are cyclic voltammograms for reduction of dichlorvos at both carbon and silver electrodes. Whereas reduction of dichlorvos at carbon shows a single irreversible cathodic peak, reduction at a silver electrode results in two overlapping cathodic peaks. Controlled-potential (bulk) electrolyses at potentials corresponding to those of the voltammetric peaks indicate that dichlorvos undergoes carbon–chlorine bond cleavage. Catholytes have been analyzed by means of gas chromatography–mass spectrometry (GC–MS) to separate, identify, and quantitate the electrolysis products.