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

A simple and convenient one-pot synthesis of THF solutions of high molecular weight poly(dichlorophosphazene) [NPCl2]n, or the 15N isotopomer [15NPCl2]n, starting directly from PCl5 and NH4Cl or 15NH4Cl 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.