Investigation of the Nucleophilic Attack of Dichlorvos by Reduced Sulfur Species Using 1H NMR.

The mechanism of the reaction of dichlorvos through hydrolysis reactions and through the reaction with polysulfide (Sn2-) and thiophenolate (PhS-) was investigated by proton nuclear magnetic resonance (1H NMR). The study confirmed product identities of an organophosphorus insecticide reacting with reduced sulfur species using 1H NMR in oxygen sensitive solutions. The experiments of dichlorvos with polysulfide led to the detection of a previously undetected product. The thiophenolate experiments were further advanced to investigate second-order rate kinetics using an internal standard. The experiments provide new evidence for a nucleophilic attack by the reduced sulfur species at the methoxy carbon of dichlorvos. In addition, the observation of in situ reaction dynamics illustrates the applicability of 1H NMR spectroscopy toward kinetic investigations in environmental science.