Method for purifying cyclic dichlorophosphazene trimer of catalytic impurities
AssigneeThe Firestone Tire & Rubber Company
InventorsDaniel F. Graves, Dennis L. Snyder
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Abstract
Cyclic dichlorophosphazene trimer which is substantially pure except for catalytic impurities is purified by treating the trimer in the liquid phase with P.sub.2 O.sub.5 for 10-30 minutes at a temperature of 120.degree.-170.degree. C. and atmospheric pressure, then subjecting the reaction mix to a single further purification step by sublimation, melt filtration, or distillation. The purified trimer will not polymerize in the absence of added catalyst at 300.degree. C. or below.
Claims7
A process for purifying cyclic dichlorophosphazene trimer which is substantially pure except for catalytic impurities, said process comprising the steps of
- (a) contacting the trimer in the liquid phase with P.sub.2 O.sub.5 for about 10 to about 30 minutes at a temperature ranging from about 120.degree. C. to about 170.degree. C. at atmospheric pressure,
- (b) subjecting the product resulting from step (a) to a single further purification step by sublimation, melt filtration or distillation to recover trimer which is substantially free of catalytic impurities and which will not polymerize in the absence of added catalyst at 300.degree. C. or below.
Dependencies are inferred from the claim text.