Kinetic and product analysis study of the alkaline hydrolysis of the organophosphorus pesticide, phosmet

This research describes the abiotic degradation of the organophosphate pesticide, phosmet (O,O-dimethyl S-phthalimidomethyl phosphorodithioate) under controlled conditions in aqueous alkaline solutions.;The degradation products of phosmet hydrolysis under alkaline conditions were determined by 1H NMR and MS.;In the hydrolysis of NHPH, a fast degradation process under slightly acidic to slightly alkaline conditions (pH 6.0 to 8.0) was captured by a spectrophotometric method.;The product analysis results and kinetic data do not agree with a previously claimed multi-step pathway in which nucleophilic attack of hydroxide ion was proposed on methylene carbon. However, a new scheme is proposed involving nucleophilic attack of hydroxide ion on the carbonyl carbon; this scheme agrees well with the product analysis results and kinetic data. (Abstract shortened by UMI.).;Kinetic and product analyses of hydrolysis of phosmet were carried out in alkaline conditions by following spectrophotometrically the disappearance of phosmet reactant.