Electrochemical Properties of Three Dicarboximide-Type Pesticides : Vinclozoline, Iprodione and Procymidone

The reduction mechanism of vinclozoline, 3-(3,5-dichlorophenyl)-5-methyl-5-vinyl-1,3-oxazolidine-2,4-dione, iprodione, 3-(3,5- dichlorophenyl)-N-(1-methylethyl)-2,4-dioxo-1-imidazolidinecarboxamide, and procymidone, 3-(3,5-dichlorophenyl)-1,5-dimethyl- 3-azabicyclo[3.1.0]hexane-2,4-dione, was studied in acetonitrile by electrochemical methods combined with GC:MS identification of products. Irreversible reduction was observed at about 2.2 V. The electron transfer reaction was coupled with subsequent chemical reactions yielding several final products. The main decomposition pathways included the elimination of the hetero-ring (producing chloroanilines and most likely diketones) and the cleavage of one or both chlorine atoms. Vinclozoline also yielded compounds that derive from the reductive elimination of the OCO fragment (carbon dioxide) from the heterocyclic ring.