Chlorocyclophosphazenes reagents

The reactions of chlorocyclophosphazenes with difunctional reagents such as diamines, diols, or amino alcohols can in principle lead to the formation of several products. These are shown in Fig. 19. The reactions of these reagents with the chlorocyclophosphazenes are discussed below. 

The reactions of the six-membered chlorocyclophosphazene were studied with a number of aliphatic diamines (169 175), aromatic diamines (176), aliphatic diols (177-179), aromatic diols (180,181) and compounds containing amino and hydroxyl functional groups (169,170,182). This subject has been reviewed (11,16,20). There are at least five different reaction products that are possible (Fig. 19). Replacement of two chlorine atoms from the same phosphorus atom produces a spirocyclic product. Replacement of two chlorine atoms from two different phosphorus atoms in the same molecule produces an ansa product. Reaction of only one end of the difunctional reagent, resulting in the substitution of only one chlorine atom, leads to an open-chain compound. Intermolecular bridged compounds are formed when the difunc-... 

Spirocyclic product is formed as a result of replacement of both the chlorines on the same phosphorus atom, while the ansa product is formed as a result of the replacement of chlorines from two distinct phosphorus atoms within the same molecule. In open chain product only one end of the difunctional reagent is involved in reaction with the chlorocyclophosphazene. Finally, intermolecular bridged products result from the reaction of two chlorocyclophosphazene molecules with a difunctional reagent. This last reaction also is a model reaction for condensation polymerization involving phosphazenes. 

The chlorocyclophosphazenes (NPCysor are found to be excellent reagents for the conversion of acyl halides into nitriles ... 

Chlorocyclophosphazenes are quite reactive towards nucleophiles such as amines, alcohols or phenols. Complete replacement of chlorines is readily possible with a number of reagents. For example, the reaction of N3P3CI6 or N4P4CI8 with dimethylamine can lead to the formation of N3P3(NMe2)e or N4P4G e2) (see Eqs. 3.12 and 3.13). These reactions also work quite well with primary, secondary and even aromatic amines although individual differences in reactivity are present. 

So far we have seen the reactions of chlorocyclophosphazenes with reagents that may be termed monofunctional. For example, a phenol in its reactions with chlorocyclophosphazenes will react as a nucleophile and form N3P3(OPh)6 containing P-0 linkages. If instead of a phenol we used a biphenol we will have two sites that can react with the phosphorus centers. In this manner there are several difunctional reagents such as diamines (ethylenediamine, 1,3-diaminopropane, phenylenediamine), diols (ethyleneglycol, 1,3-propanediol, catechol), and amino alcohols (ethanolamine, propanolamine, o-aminophenol) [2,15]. 

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