A LANTHANUM MACROCYCLE CATALYZED-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 effec tive catalyst for the hydrolysis of the water soluble phosphate triest er 2,4-dinitrophenyl diethyl phosphate. At pH 9, using a catalyst conc entration of 2.5 x 10(-3) mol dm(-3) at 25 degrees C, the rate enhance ment is ca 10(3) fold. The reaction is shown to be catalytic rather th an stoichiometric and possible mechanisms involving a metal-bound hydr oxide nucleophile are considered to account for the catalysis. The mac rocyclic complex is also shown to be an effective catalyst for the hyd rolysis of the anticholinesterase agent O-isopropyl methylfluorophosph onate (Sarin). (C) 1997 Elsevier Science Ltd.