Sodium X-type faujasite zeolite decomposition of dimethyl methylphosphonate (DMMP) to methylphosphonate: Nucleophilic zeolite reactions I

Abstract

Dimethyl methylphosphonate (DMMP), used extensively as a nerve agent simulant, strongly adsorbs in X-type faujasite zeolite and undergoes nucleophilic substitution by the supercage oxygens. Solid state magic angle spinning (MAS) 31P and cross polarization (CP) MAS 13C NMR studies of the zeolite were performed after adsorption of DMMP into it. Methylphosphonate ions and possibly a framework methyl species are formed at low levels of water. The greater reactivity of NaX than the reactivity of NaY toward VX (phosphonothioic acid, methyl-, S-[2-[bis(1-methylethyl)amino]ethyl] O-ethyl ester) and one of its simulants [G.W. Wagner, P.W. Bartram, Langmuir 15 (1999) 8113], may be attributable to the smaller Si:Al ratio of NaX. Consequently, the NaX framework oxygen atoms are more nucelophilic and supercage Na ions are present to attract the methylphosphonate ion leaving groups.