With chlorophosphazenes products

The modification of lignins with chlorophosphazenes allows the manufacture of products characterized by flame resistance and thermal stability. This can be attributed to the aromatic structure of the lignin-phosphazene polymer as well as to the presence of such flame inhibiting elements as phosphorous, nitrogen and sulfur. Other useful properties may also result from this combination. It has previously been reported (8-13) that the modification provides crosslinked products with suitably low chlorine content. This is a consequence of incomplete substitution of the phosphazenes cycles. Additional modification of the reaction products by chemical compounds with reactive hydroxyl or amine groups reduces the unreacted chlorine content and improves product properties (8-13). Some properties of the derivatives obtained are presented in Table I. 

The factors affecting the preparation of the cyclic chlorophosphazenes from phosphorus pentachloride and ammonium chloride continue to receive attention. For example, the yields and reaction times for the preparation of the series, (NPCla) ( — 3—7), varied with the fineness of the ammonium chloride, the nature and volume of the solvent, and added catalysts such as phosphoryl chloride. A procedure, giving due consideration to these factors, was described for the preparation of N3P3CI6 in good yield (88% of cyclic products) and in a relatively short time (2J h). The cyclic chlorophosphazenes can be obtained in even shorter times ca. 10 min) by addition of four moles of pyridine to remove the hydrogen chloride formed ... 

The lignin modifications in solid (C) were carried out using lignins (1.0 g) mixed with corresponding amounts of hydrogen chloride acceptor and chlorophosphazenes. The reaction was carried out by heating at a temperature of 100°C, i.e., above the melting point of chlorophosphazene. The reaction mixture was poured into ice water, and then the solid product was purified as described before (9). 

Phosphoryl chloride (phosphorus oxychloride), POCI3, can be obtained from the pentachloride by several reactions (4.256 through 4.259). Phosphorus pentachloride reacts with ammonium chloride to give chlorophosphazenes (7.320). If the pentachloride is reacted with excess liquid ammonia and the ammonium chloride removed by sublimation, the products include P(NH2)4C1 (7.392). Reactions with various other nitrogen compounds are known (Chapter 7). 

Hydrazinium di-chlorophosphazene, Cl3P=N-N=PCl3, can be made by the Kirsanov reaction (7.498). It is a colourless very hygroscopic solid which is slightly soluble in POCI3, but insoluble in other common solvents. Controlled hydrolysis at low temperature leads to unstable hydrazido-N,N-bis(phosphoryl dichloride) (7.499), but with excess water the products are HCl, H3PO4 and N2H4 (7.500). 

---