Sulfur-containing organophosphates called phosphonothioates are used as chemical warfare agents and potent pesticides. Their ability to readily inhibit acetylcholinesterase, coupled with their wide abundance in food and water supplies, presents an enormous public health concern for the U.S. and abroad. Molybdenum (VI) oxides and Amberlite free base IRA 743 ion exchange resin have proven effective in phosphonothioate degradation under mild aqueous conditions, yielding the desired P-S specific bond scission product, which is relatively non-toxic. The purpose of this research is to identify conditions that will increase the rate of phosphothioate hydrolysis and methanolysis. Specifically, this research will focus on two separate mechanisms for phosphonothioate degradation. The first will use tetramethyl and tetrabutyl ammonium molybdate with surfactants, cetrimonium bromide (CTAB) and polyoxyethanyl-α-tocopheryl sebacate (PTS), in order to sequester these more hydrophobic molybdates in micellar cores with the hydrophobic pesticide. Previous research has attempted to sequester the molybdate dimer, hexamer, and octomer in the micelles, however each of these was not hydrophobic enough to enter the micellar core. The pesticide analog, O-S-diethyl phenylphosphonothioate, has been shown to enter the micelles, which motivates this research to find a more hydrophobic candidate for phosphonothioate degradation. The second mechanism uses Amberlite free base IRA 743 ion exchange resin, which was only recently discovered to degrade phosphonothioates. Previous research has shown that upon removing glucamine, which is the active species of the resin, phosphonothioate degradation continues to occur. More research must be done in order to determine the mechanism behind the resin’s degradation of phosphonothioates.

Degradation of organophosphate pesticides using molybdenum (VI) oxides and ion exchange resin

251st National Meeting (2016)

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