Halogen Replacement Reactions of Cyclophosphazenes

Halogenocyclophosphazenes react with ammonia and primary and secondary amines to form an ammono- or amino-substituted cyclo-phosphazene  

Two equivalents of amine or ammonia are needed to replace one halogen atom the amine also functions as the hydrogen halide acceptor. In some cases the aminophosphazene formed in the reaction has a base strength comparable to that of the parent amine, and it is subsequently isolated as a hydrohalide adduct (see Section IV, A,2). A tertiary base, such as triethylamine or pyridine, can also be employed as a hydrogen halide acceptor. 

The wealth of data available on the aminolysis reactions of N3P3C16 (1) presents a complex picture (Table I). A comprehensive mechanistic theory explaining all the observations has not yet emerged. Some of the variations in the aminolysis patterns are undoubtedly due to a lack of awareness on the part of earlier investigators of the importance of reaction variables, such as temperature, solvent, and stoichiometry of reagents in determining the relative proportions of isomers formed. 

Products of the Reactions of N3P3C16 with Various Amines 1  

Most secondary amines react predominantly by the nongeminal mode of replacement. Assumption of an SN2(P) mechanism (228) would be consistent with this observation. The phosphorus atom carrying the amino substituent acquires a partial negative charge because of 

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