TETRAVALENT METAL CATALYZED HYDROLYSIS OF CYANOFENPHOS: A DELAYED NEUROTOXIC ORGANOPHOSPHORUS COMPOUND

Hydrolysis of O-ethyl O-p-cyanophenyl, phenyl phosphonothionate (Cyanofenphos) has been studied in the acidicmedium with catalyst such as Zr4+, Ce4+, Hf4+ and Th4+ cations, and the rate maxima observed were at around pH 2.0. Sincethe metal aquo complex are known to exist in equilibrium with deprotonated species, and therefore metal bound OHnucleophilemight be available abundantly even in acidic aqueous solutions. Thus an interaction of sulphur of P=S groupwith metal cation followed by an intramolecular nucleophilic attack of hydroxy anion at the ester phosphorus atom wouldresults in the cleavage of P-O bond.