Cyclophosphazenes chlorine replacement reactions

Fig. 8. Mechanistic pathways involved in the chlorine replacement reaction of chloro-cyclophosphazenes (A) = S 2 (non-polar) (B) = S 2 (concerted) (C) = S l (D) = SnI(CB).

The replacement of fluorine, chlorine or bromine from the corresponding halogenocyclophosphazenes by another substituent (a nucleophile) is an important aspect of the chemistry of these ring systems [2, 7, 12]. First, this route provides a way of preparing cyclophosphazenes with substituents involving exocyclic P-N, P-0, P-S, P-C, P-H and P-M linkages. Thus, in a way it may be said that the halogen replacement reactions are the most... 

Nucleophilic substitution reactions involving the replacement of chlorine (or bromine or fluorine) atoms on the phosphorus have been among the most well studied reactions of cyclophosphazenes... 

Other inorganic metathetical exchange reactions studied include the replacement of bromine by fluorine and chlorine in N3P3Br6 and the preparation of azido-, cyano-, and isothiocyanatocyclophospha-zenes (21, 22, 249). In the reactions of N3P3C16 with KF and KSCN, addition of [18-Crown-6]ether considerably enhances the yields of substituted cyclophosphazenes, N3P3R6 (R = F, NCS) (449). 

A more elaborate synthesis involving the preparation of a methacryloyl containing cyclophosphazene is shown in Fig. 4.7. Thus, the reaction of N3P3CI6 with the sodium salt of p-hydroxybenzaldehyde affords N3P3Cl5(0-C6H4-p-CH0). Replacement of all the chlorine atoms from this... 

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