| 摘要 |
Polymeric phosphonitrilic chlorides with a degree of polymerization of from 5 to 15 are prepared by heating polymeric phosphonitrilic chlorides with a degree of polymerization of less than five to a temperature of 250 DEG -350 DEG C. until a highly polymerized rubbery product is obtained, heating this rubbery product in water containing free chlorine at a temperature of at least 90 DEG C., and recovering the liquid polymeric phosphonitrilic chloride thus formed from the aqueous medium. The heating of the rubbery product in water may be carried out at any temperature from 90 DEG C. to the reflux temperature of the mixture, or higher in conjunction with superatmospheric pressures, the higher temperatures being preferred, until a partially depolymerized product is obtained, and the product then extracted with a water-immiscible organic solvent. The residue may be recycled, and the organic solvent is removed from the extract, e.g. by vacuum distillation, leaving a mixture of liquid and crystalline polymers of PNCl2 which are separated by filtration, for example. The required liquid product then has an average degree of polymerization of 7-8 and contains (PNCl2)n where n is 5-15. The quantity of free chlorine present in the water in which the rubbery product is heated is not critical, and it is therefore sufficient to pass chlorine gas through the water. The reaction time for this stage may be 10-70 minutes. The water-immiscible solvent may be a lower halogenated hydrocarbon containing up to 3 carbon atoms, for example carbon tetrachloride, chloroform, or sym-tetrachloroethane, or it may be diethyl ether, benzene, toluene, or xylene.
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