The reactions of cyclophosphazenes with Diols

Abstract

Cyclophosphazene derivatives have been of considerable interest for many years because of their versatile and complex chemistry. It is possible to use them to design materials with special properties such as thermal stability, catalytic properties, electrical conductivity, liquid crystallinity and biomedical activity. The reactions of the cyclophosphazenes (cyclotriphosphazene and cyclotetraphosphazene) were studied with numerous diols, leading to formation of regioisomers; open chain, spiro, ansa, bridged-structures and their mixtures. The investigation of reactions of cyclophosphazenes with diols has many advantages in terms of obtaining products with high yield, ease of isolation, high reactivity potential, determination of exact structure with crystallization and environmentally friendless. The large separation between nucleophilic sites (in diol, diamine, dithiol etc.) allows for considerable structural diversity with often small variations in preparation conditions. The selectivity of the nucleophilic substitution patterns and formation of the structures are highly dependent on various factors such as ring size of the cyclophosphazene, temperature, solvent, base and the type of the nucleophilic reagent used in the synthetic procedure. The important factors are ring size of cyclophosphazene and carbon chain length of nucleophile in which adjust the competition between the intra- (spiro, ansa) and intermolecular (bridged compounds) mechanisms for the reaction of diol with cyclophosphazene. This chapter deals with reactions of chlorocyclophosphazenes and their derivatives with diols and the investigation of their reaction mechanisms. © 2020 Elsevier B.V., All rights reserved.