Synthesis And Property Of Hexachlorocyclotriphosphazene And Its Derivatives

The chloride atoms on hexachlorocyclotriphosphazene show high reactivity and can be substituted by many useful groups. Because hexachlorocyclotriphosphazene contains high phosphorus and nitrogen portion, most derivatives containing hexachlorocyclotriphos- phazene unit have excellent fire-retardant property.Hexachlorocyclotriphosphazene was prepared by the reaction of ammonium chloride with phosphorus chloride in chlorobenzene, using metal oxide and pyridine as catalyst system. The optimal reaction condition was reached by changing the proportion of the reactants , increasing addition time of phosphorus pentachloride to the system, carefully choosing the kinds of catalyst and dosage of the catalyst, reducing the particle diameter of ammonium chloride and changing the addition method of ammonium chloride. The optimal reaction condition is as follows: the molar ration of n(NH4Cl):n(PCl5): n(ZnO):n(pyridine)=1.30:1:0.026:0.24, PCl5 was added dropwise to the system within 3h, then the reaction mixture was stirred for another 2h. The reaction mechanism was discussed and the product was characterized by melting point, FT-IR and 31PNMR. Hexachlorocyclotriphosphazene was manufactured in large-scale according to the optimal reaction conditions obtaining in the laboratory.A photosensitive cyclophosphazene compound with unsaturated side group was designed and synthesized. The compound was characterized by FT-IR and 1H NMR. The experimental results were consistent to chemical structure.The photosensitive cyclotriphosphazene was hardened by UV radiation. The cured film was tested by DSC and TGA. It could be noted that the cured film has exhibited high char yield (48% in the Air condition at 750℃). The results indicated that the cured film had excellent thermo-stability. In addition, limiting oxygen index (LOI) was calculated as 35.4 via the char yield data by semi-empirical method. The result demonstrated that the cured film has good flame retardant property.The Witting Reactions between Hexakis(4-formylpheoxy)cyclophosphazene and two phosphors ylides-(cyanomethylene)triphenylphosphine and O,O-Diethyl(cyanomethyl) phosphonate were studied respectively. Though further purification was needed to obtain pure double bond-containing cyclotriphosphazene, all the characterization data obtained from the synthesized compounds indicated that the double bond-containing cyclotri- phosphazene was successfully synthesized.