PROCESS FOR PREPARING LOW MOLECULAR WEIGHT LINEAR PHOSPHONITRILIC CHLORIDE OLIGOMERS

摘要

A two-stage process for the production of linear phosphonitrilic chloride oligomers is provided. In the first step, phosphorus trichloride (PCl3) and chlorine are reacted in a suitable liquid reaction medium. In the second step PCl3, Cl2 and NH3 are concurrently fed into the medium while maintaining a temperature at 100 DEG C to 140 DEG C. The feeds of the reactants are controlled so that until the first half of the NH3 has been reacted the molar ratio of PCl3:NH3 (including the PCl3 of the first step) is kept above two. Thereafter, the feeds are adjusted so that with respect to the total amount of ammonia, said molar ratio is between 1.2 and 1.5. Linear phosphonitrilic chloride oligomers having a number average degree of polymerization from 2 to 9 are produced in high yield.