the present invention has the formula str3 preparation of tetrakis 4 bromophenoxy bis 4 carbomethoxyphenoxy cyclotriphosphazene str4 a solution of 30 8 g 0 2 m of methyl 4 hydroxybenzoate in 100 ml of tetrahydrofuran thf was added dropwise with stirring to a slurry of sodium hydride that had been obtained by rinsing 9 6 g 0 2 m of a 50 oil dispersion with benzene followed by the addition of 200 ml of thf when the entire ester solution had been added the mixture was stirred for an additional half hour a solution of 34 8 g 0 1 m of npcl 2 3 in 100 ml of thf was added rapidly with stirring the reaction mixture became warm this mixture was heated to reflux and was kept there for 23 hours a slurry of sodium 4 bromophenol prepared from 76 12 g 0 44 m of the phenol and 10 12 g 0 44 m of sodium metal in 400 ml of thf was added to the refluxing mixture this new mixture was refluxed for 115 hours upon cooling the insolubles were filtered from the reaction mixture leaving a clear filtrate removal of the solvent on a rotary evaporator left 115 7 g of a crude syrup this material was dissolved in 300 ml of benzene and was washed three times with 100 ml of 5 percent sodium hydroxide and then with 100 ml of water after.