Synthesis Of 1,3,5-Triazine-Phosphazene Catalyst And Its Application For Ring-Opening Alternating Copolymerization Of Epoxides And Anhydride

Polyesters are a kind of important material that have been widely used as plastics,fibers and films.Various functional polyesters are prepared by alternating copolymerization.Compared with the traditional polycondensation and ring-opening polymerization,the alternating copolymerization of epoxides and cyclic anhydride to prepare polyester has the following advantages:atom economy,controllable,abundant monomer types and mild reactions etc.As an organic catalyst for the synthesis of polyester,phosphazene has developed into a powerful type of catalyst whose catalytic performances highly depend on the basicity and molecular structure（molecular size and shape）.Therefore,designing phosphazenes with adjustable basicity and molecular structure is an important way to develop organic catalysts with higher activity and selectivity.In this thesis,a new type of 1,3,5-triazine-phosphazene catalyst was designed and synthesized.The new catalyst was applied to the alternating copolymerization of epoxides and cyclic anhydrides,and achieved a series of meaningful results:1)First,cyanuric chloride and sodium azide were used as raw materials to synthesize1,3,5-triazine azide compound according to the method in the literature;using phosphorus trichloride and pyrrolidine as raw materials,synthesized Tripyrrolidine phosphoru;Finally,we synthesized the C₃N₃-Me-P₃ and C₃N₃-Py-P₃ by reacting 1,3,5-triazine azide compound with tripyrrolidinophos and tris（dimethylamino）phosphorus respectively.The structures of C₃N₃-Me-P₃ and C₃N₃-Py-P₃were confirmed by NMR spectrum analysis,single crystal X-ray diffraction and ESI mass spectrometry,and then the bases of C₃N₃-Me-P₃ and C₃N₃-Py-P₃ were obtained by the p Ka test method.In addition,the synthesis steps of the new phosphazene catalysts C₃N₃-Me-P₃ and C₃N₃-Py-P₃ are simple and the raw materials are cheap.2)The performance of two new phosphazene catalyst to catalyze the alternating ring-opening copolymerization of epoxides and cyclic anhydrides was investigated.In the condition of BDM as the initiator,these two phosphazene catalysts can catalyze the alternating copolymerization of epoxides and cyclic anhydrides with high activity and high controllability,but catalytic activity of C₃N₃-Me-P₃ is slightly lower than that of C₃N₃-Py-P₃.The polyesters obtained are completely alternating,and the molecular weight of the polymer is basically in line with the designed molecular weight and the molecular weight distribution is very narrow（less than 1.15）.Compared with traditional t-Bu P₁,the degree of polymerization is 50 at 60°C,and the catalytic activity of C₃N₃-Py-P₃is significantly higher than t-Bu P1,and its controllability is comparable.