Metals cause fast breakdown of pesticides

Processes for decomposing pesticides and chemical warfare agents are being unravelled by Canadian scientists.

Phosphate triesters and phosphorothioate esters are close relatives of pesticides and chemical warfare agents. Stan Brown and his team at Queen’s University have looked at how two metal-ion containing systems catalyse their methanolysis reactions.

During methanolysis a methoxide group coordinated to either La³⁺ or Zn²⁺ displaces part of the phosphorus-containing molecules making them break down. These reactions are fast and in alcohol solvents the metals promote phosphate triester decomposition by up to a billion-fold.

This research sheds light on an unusual class of metalloenzymes, the phosphotriesterases, and how they catalyse the breakdown of pesticides like paraoxon, an organophosphate cholinesterase inhibitor.

Providing ’practical and simple ways of applying catalytic alcoholysis reactions to decontaminate pesticide laden sites and objects contaminated by chemical warfare agents,’ is the ultimate goal of this work, said Brown.

Kathryn Sear