Parathion was once a commonly used pesticide before it was banned due to toxicity. While Parathion is quite toxic, it metabolizes in the human body to create the much more dangerous chemical of paraoxon. Given the molecule’s history of application to crops it is imperative that its detailed degradation mechanism is determined. Such mechanistic analysis will allow for further remediation as well as technical analysis of water and soil sites. Several experimental investigations were executed in the 1970s in order to determine the kinetics of parathion degradation to paraoxon and 4-nitrophenol in different chemical environments. These works hypothesize that for the degradation mechanism to proceed, an oxygen attack occurs at the phosphate-sulfur double bond, allowing for removal of sulfur. In order to elucidate the intricacies driving the reaction, and determine if this proposed mechanism actually occurs, we have performed several DFT calculations of Parathion degradation by a hydroxide molecule with several explicit water molecules. This work, illustrating the effect of the solvation environment and several internal movements around the phosphorus center, will be presented.

DFT investigations into the degradation pathways of parathion

ACS Spring Meeting 2021

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