Heterogeneous Organophosphate Ethanolysis: Degradation of Phosphonothioate Neurotoxin by a Supported Molybdenum Peroxo Polymer.

Autor: Kuo LY; Department of Chemistry, Lewis & Clark College , Portland, Oregon 97219, United States., Bennett A; Department of Chemistry, Lewis & Clark College , Portland, Oregon 97219, United States., Miao Q; Department of Chemistry, Lewis & Clark College , Portland, Oregon 97219, United States.
Jazyk: angličtina
Zdroj: Inorganic chemistry [Inorg Chem] 2017 Aug 21; Vol. 56 (16), pp. 10013-10020. Date of Electronic Publication: 2017 Aug 02.
DOI: 10.1021/acs.inorgchem.7b01545
Abstrakt: A polystyrene-supported molybdenum peroxo material [Mo-Y(s)] was applied toward the oxidative degradation of the organophosphate neurotoxin O,S-diethylphenyl phosphonothioate (1) through ethanolysis. In addition to the operational advantages of the heterogeneous reactivity, oxidative ethanolysis with a 10-fold excess of hydrogen peroxide yields only P-S bond scission to produce diethylphenyl phosphonate and ethyl sulfate. This is the first report of a molybdenum solid support that promotes the degradation of sulfur-containing organophosphate with the turnover benefits of heterogeneous catalysis. The activation parameters of 1 ethanolysis by Mo-Y(s) (E a = 57 ± 6 kJ/mol and ΔS ⧧ = -124 ± 21 J/mol·K) and by the model compound oxodiperoxo(pyridine-2-carboxylato)molybdate(VI) bis(pyridine-2-carboxylic acid) monohydrate (3; E a = 55 ± 5 kJ/mol and ΔS ⧧ = -154 ± 15 J/mol·K) are almost identical for the oxidation of thioanisole by 3. This suggests that the rate-determining step for 1 ethanolysis is sulfur oxidation to form an intermediate phosphonothioate S-oxide, which subsequently undergoes nucleophilic attack by the ethanol solvent to form diethylphenyl phosphonate and ethyl sulfate. Evidence for the formation of this S-oxide intermediate and the postulated ethanolysis mechanism is provided.
Databáze: MEDLINE
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