A lanthanum macrocycle catalysed hydrolysis of 2,4-dinitrophenyl diethyl phosphate and O-isopropyl methylfluorophosphote (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 × 10⁻³ mol dm⁻³ at 25°C, the rate enhancement is ca 10³ 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 alswn to be an effective catalyst for the hydrolysis of the anticholinesterase agent O-isopropyl methylfluorophosphate (Sarin).