Improvements relating to the preparation of phosphonitrilic chloride polymers

摘要

Phosphonitrilic chloride polymers are produced by bringing into contact gaseous elemental chlorine, phosphorus trichloride and ammonium chloride in an inert solvent at reflux temperature, the ammonium chloride being present at any time during the reaction in a proportion at least equimolecular with the phosphorus trichloride. Reaction may be effected by adding Cl2 to a mixture of phosphorus trichloride and ammonium chloride in an inert solvent, by adding Cl2 and phosphorus trichloride simultaneously to an ammonium chloride solution or by continuously adding all 3 reactants to the refluxing solvent. Solvents specified are phosphorus oxychloride, tetrachloroethane, chlorobenzene, o-dichlorobenzene and benzyl chloride. The addition may extend over a period of at least 50% of the total reaction time, but in Example 3 occupies less than 50% of the reaction time. It should be at such a rate that the rate of evolution of HCl is 40-100% that predicted by the equation PCl3+Cl2+NH4Cl--PNCl2+4HCl. Anhydrous metal chlorides capable of complexing with NH3, e.g. cobaltous, aluminium, cupric and zinc chlorides, act as catalysts and the reaction can also be accelerated by using finely divided ammonium chloride and using it in excess, e.g. at least 10% excess of ammonium chloride of a specified surface area of at least 1000 sq. cm./g. Specification 905,315 also is referred to.