Diethyl phosphite production from phosphorothioate degradation with molybdenum peroxides and hydrogen peroxide in ethanol

The first case of degrading phosphorothioate pesticides of the form (EtO)2P(=S)Ar by a supported molybdenum complex reveals both oxon ((EtO)2P(=O)Ar) and diethyl phosphite formation. In terms of the diethyl phosphite product, this transformation converts a known neurotoxin into a commodity chemical. Specifically, the pesticide diazinon produces only diethyl phosphite by polystyrene-supported Mo(OO)n peroxide complex in EtOH with the addition of H2O2(aq). [Display omitted] •A supported molybdate material degrades live phosphorothioate pesticides.•Diazinon degradation produces the commodity organophosphate diethyl phosphite.•A solution compound is presented that models the supported molybdate material. A polystyrene-supported molybdate-peroxide polymer (Mo-Y(s)) destroys phosphorothioate pesticides of the form (ArO)P(=S)(OEt)2 in EtOH under mild oxidative (H2O2) conditions and produces a commodity organophosphate. This is the first report of a metal-based system that successfully degrades the “live” pesticides parathion, diazinon and coumaphos. In addition to the operational advantages of heterogeneous reaction chemistry, the Mo-Y(s) support degrades multiple equivalents of the pesticide in H2O2(aq). Of particular importance is the predominant production of diethyl phosphite, a commodity chemical, from diazinon degradation over Mo-Y(s) in EtOH; no toxic oxon is found. Coumaphos and parathion produce the corresponding oxon which have ΔHǂ (kcal/mol) of 15.4 (0.5) and 21.7 (0.8), respectively; these activation parameters are consistent with key observations found in the relative amount of coumoxon and paraoxon produced. Finally, a discrete molybdate-peroxide complex is presented as a possible solution model for this heterogeneous reaction.