The nucleophilic chemical reactions of NaX Faujasite zeolite with diisopropyl phosphorofluoridate (diisopropyl fluorophosphate, DFP)

Abstract

Diisopropyl phosphorofluoridate (commonly known as diisopropyl fluorophosphate and commonly abbreviated DFP) was adsorbed in dry NaX zeolite with and without adsorption of a stoichiometric amount of water. The chemical products from the reaction of zeolite and water with DFP, in relation to residual DFP, were identified and quantified from the quantitative NMR chemical shift values and intensities of solid-state 13C and 31P NMR and solution 13C, 31P, 17O and 1H NMR. In dry zeolite, DFP undergoes an elimination reaction to form propene and a framework bound isopropyl phosphorofluoridate ion. In NaX loaded with a stoichiometric amount of water, DFP undergoes hydrolysis to form isopropanol and isopropyl hydrogen phosphate. Upon addition of water to the DFP exposed zeolite, residual DFP undergoes hydrolysis to form isopropanol and isopropyl hydrogen phosphorofluoridate. Evidently upon addition of water to the dry DFP exposed NaX, the previously formed framework bound isopropyl phosphorofluoridate ion is also hydrolyzed to isopropyl hydrogen phosphate. Addition of water to the zeolite after DFP adsorption increased the hydrolysis reaction from 6.5% to 44.5%. Unlike other reported catalyzed hydrolyses, where hydrolysis of DFP involves water attack on the phosphorous, in NaX zeolite the ester carbon is attacked.