Polycondensation of (NPCl₂)₃ with Bifunctional Reagents

Abstract

The reaction of hexachlorocyclotriphosphazene and hydroquinone in the two-phase solvent system tetrahydrofuran/aqueous NaCl-NaOH solution leads in the beginning of the polycondensation to a mixture of oligomers with formula N₃P₃Cl₅-[P-OC₆H₄O)-N₃P₃Cl₄]_n-(p-OC₆H₄)-N₃P₃Cl₅. The first compound (n=0) in this series could be isolated in a pure state. Two others have been identified by spectroscopic methods. As expected, the addition of a phase-transfer catalyst (Bu₄NBr) accelerates the polymerization reaction. In addition to the oligomers mentioned before two isomers with formula N₃P₃Cl₄-(p-OC₆H₄O)₂-N₃P₃Cl₄ were formed in the reaction mixture together with large amounts of polymeric material. One of these isomers was obtained as a pure compound in a very low yield. The X-ray crystal structures of N₃P₃Cl₅-(P-OC₆H₄O)-N₃P₃Cl₅ and N₃P₃Cl₄-(P-OC₆H₄O)₂-N₃P₃Cl₄ will be compared. The structural data in combination with ³¹P NMR data of various reaction mixtures provide some clues for the structure of the polymers, formed ultimately. The reaction pathway during the polycondensation will be discussed and compared with that of the polycondensation of (NPCl₂)₃ with p-phenylenediamine.