Synthesis and reactivity of 4-aryl substituted phosphazenes and their precursors: synthesis of poly(phenylenephosphazenes)

Abstract

Polyphosphazenes can display a wide variety of chemical and physical properties depending on the substituents on phosphorus. Polymers obtained from condensation polymerization of N -silylphosphoranimines can have organic groups attached to the polymer skeleton through direct P-C bonding. Deprotonation-substitution reactions of the P -Me groups of both monomers and polymers have led to a rich derivative chemistry. However, relatively little derivative chemistry of the phenyl groups of such polymers has been investigated. In this study, 4-aryl substituted phosphazenes and their precursors, (silylamino)phosphines and N -silylphosphoranimines, have been synthesized.* Deprotonation-substitution reactions, metal-halogen exchange reactions, and substitution at phosphorus have been observed for the N -silylphosphoranimines. The metal-halogen exchange reaction has been observed for the polymers as well. The electronic effect of the functional groups on the phenyl rings of the N -silylphosphoranimines appears to influence the course of substitution reactions at phosphorus. Some polyphosphazene analogs that contain skeletal hetero-elements in the polymer backbone have attracted great interest recently. Attempts to synthesize polyphenylenephosphazenes, a polymer system with phosphorus, nitrogen, and benzene rings in the backbone, have led to the synthesis of some N -silylanilino-phosphines. Oxidative bromination of the N -silylanilino-phosphines appears to afford polymeric products that are under further investigation.* *Please refer to dissertation for diagrams.