A lanthanum macrocycle catalysed hydrolysis of 2,4-dinitrophenyl diethyl phosphate and O-isopropyl methylfluorophosphonate (Sarin)

The lanthanum complex of a hexa-aza macrocycle is shown to be an effective catalyst for the hydrolysis of the water soluble phosphate triester 2,4-dinitrophenyl diethyl phosphate. At pH 9, using a catalyst concentration of 2.5 x 10(-3) mol dm(-3) at 25 degrees C, the rate enhancement is ca 10(3) fold. The reaction is shown to be catalytic rather than stoichiometric and possible mechanisms involving a metal-bound hydroxide nucleophile are considered to account for the catalysis. The macrocyclic complex is also shown to be an effective catalyst for the hydrolysis of the anticholinesterase agent O-isopropyl methylfluorophosphonate (Sarin). (C) 1997 Elsevier Science Ltd.