A simplified and convenient laboratory-scale preparation of 14N or 15N high molecular weight poly(dichlorophosphazene) directly from PCl5

A simple and convenient onepot synthesis of THF solutions of high molecular weight poly(dichlorophosphazene) [NPCl2](n), or the N-15 isotopomer [(NPCl2)-N-15](n), starting directly from PCl5 and NH4Cl or (NH4Cl)-N-15 in a solution of 1,2,4-trichlorobenzene in the presence of sulfamic acid and calcium sulfate dihydrate, is described. The solutions of [NPCl2](n) in THF, which are obtained free of poly(tetrahydrofuran) by preparing them in the presence of K2CO3, can be reacted directly with phenols, biphenols, or even HO-CH2CF3 in the presence of K2CO3 Or Cs2CO3 to obtain, after a very simple workup, the corresponding polyphosphazene derivatives almost free of chlorine.