Elucidation of the reaction of phosphorus pentachloride and ammonium chloride by phosphorus-31 nuclear magnetic resonance spectroscopy

Abstract

The reaction of PCl₅ and NH₄Cl in 1,1,2,2-tetrachloroethane has been studied by ³¹P n.m.r. analysis of samples withdrawn from the reaction mixture at regular intervals. Other reaction variables such as the rate of evolution of HCl and changes in conductivity of the solution have also been recorded. Consequently the course of the reaction is now seen to go in two main phases; the first is the production of Cl₃PNPCl₃⁺PCl₆^– in over 80% yield from PCl₅ and NH₄Cl, and the second is the reaction of this with more NH₄Cl to give the linear phosphonitrilic chlorides which can then undergo cyclization, the mechanism of which is discussed. The ³¹P chemical shifts of some of the intermediate compounds are reported.