Hydrolytic cleavage of paraoxon and parathion by oximate and functionalized oximate ions: A comparative study

Abstract

<span style="font-size:11.0pt;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-bidi-font-family:="" mangal;letter-spacing:-.1pt;mso-ansi-language:en-gb;mso-fareast-language:en-us;="" mso-bidi-language:hi"="" lang="EN-GB">Bimolecular reactions of O,O-diethyl-O-<i>p</i>-nitrophenylphosphate (paraoxon) and O,O-diethyl-O-<i>p</i>-nitrophenyl phosphorothioate (parathion) with oximate (pyridinealdoxime 2-PyOx^- and 4-PyOx^-) <span style="font-size:11.0pt;font-family:" times="" new="" roman";mso-fareast-font-family:="" "times="" roman";mso-bidi-font-family:mangal;mso-ansi-language:en-gb;="" mso-fareast-language:en-us;mso-bidi-language:hi"="" lang="EN-GB">and its functionalized oximate, 4-(hydroxyimino)methyl)-1-alkylpyridinium bromide ions (alkyl = C₁₀H₂₁ (4-C₁₀PyOx^-); alkyl = C₁₂H₂₅ (4-C₁₂PyOx^-)) have been investigated in aqueous and cationic micellar media of cetylpyridinium bromide, cetyltrimethyl-ammonium bromide and cetyltetradecyltrimethylammonium bromide at <i>p</i>H 9.5 and 27 ^oC. Under the micellized condition, a 1.2×10³ fold and 9.0×10⁶ fold rate enhancement over the aqueous reaction of paraoxon (<i style="mso-bidi-font-style:normal">k</i>_o = 7.5×10^-8 s^-1) and parathion (<i style="mso-bidi-font-style:normal">k</i>_o = 9.5×10^-11) is observed.</span></span>