Process for preparing cyclic phosphonitrilic chloride oligomers

Abstract

This invention provides a process for preparing cyclic phosphonitrilic chloride oligomers characterized by the combination of: (I) The first step of reacting phosphorus pentachloride with ammonium chloride in an inert organic solvent in the presence of a catalyst comprising at least one of (a) chlorides of bivalent metals and (b) organic acid salts of bivalent metals, and distilling off the solvent from the resulting reaction mixture to obtain a reaction product consisting essentially of cyclic phosphonitrilic chloride oligomers, and (II) the second step of contacting a solution of the reaction product in at least one solvent selected from the group consisting of aliphatic hydrocarbons and ethers with water at a temperature of about 40.degree. to about 100.degree. C., separating the resulting aqueous layer from the organic layer, and isolating from the organic layer a mixture of cyclic phosphonitrilic chloride oligomers having outstanding polymerization properties and consisting essentially of the trimer and tetramer of the phosphonitrilic chloride.

Dependencies are inferred from the claim text.