AGRO 41 |
| The kinetics of diazinon (O,O-diethyl O-2-isopropyl-6-methylpyrimidin-4-yl phosphorothioate) and diazoxon (O,O-diethyl O-2-isopropyl-6-methylpyrimidin-4-yl phosphorate) reaction with reduced sulfur species, e.g., bisulfide, polysulfide, thiophenolate, and thiosulfate, were investigated in aqueous solution over a pH range of 5 to 9. The first-order rate constants for the reactions of diazinon or diazoxon with polysulfides and thiophenolate at concentrations commonly found in environment (approximate 0.3 millimolar for polysulfide) were significantly larger than their hydrolysis rate constants. Reactions of diazinon or diazoxon with hydrogen sulfide/bisulfide and thiophenol/thiophenolate were faster at low pH than that at high pH. The mechanistic investigation of reactions with thiophenol/thiophenolate indicated that the nucleophilic displacement occurs at the pyrimidyl carbon-6 (nucleophilic aromatic substitution) and the α-carbon of the ethoxyl group. |
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Agrochemical Education Awards For Graduate Student Travel
8:00 AM-11:00 AM, Monday, August 20, 2007 BCEC -- Exhibit Hall - B2, Poster
Division of Agrochemicals |