| Polyimide is currently an essential class of fine chemical products,widely used in high-tech fields such as medicine,new materials and so on.Diamine monomer is the key to polyimide.At present,the introduction of heterocyclic to polyimide monomers is a major aspect.In this paper,we have synthesized four heterocyclic compounds,which are3,5-diamino-N-(furan-2-ylmethyl)benzamide,3,5-diamino-N-(thiophen-2-ylmethyl)benzamide,2-(4-aminophenyl)-1,3-benzoxazol-5-amine and 2-(4-aminophenyl)-3Hbenzimidazol-5-amine.And we also studied their conditions.Additionally,we determined the structure of its raw materials,intermediates and products through GC-MS,HPLC-MS,NMR and FTIR.In the process of 3,5-diamino-N-(furan-2-ylmethyl)benzamide and3,5-diamino-N-(thiophen-2-ylmethyl)benzamide,the Ni-Mo catalyst was made by ourselves and characterized by XRD,XPS and BET.And at the same time,the catalyst was applied to the the synthesis of raw materials: furfurylamine and2-Thiophenemethylamine.The influences of the amount of catalyst,reaction pressure,reaction time and reaction temperature were studied in the raw materials synthesis.The results show that when the amount of catalyst is 10%,reaction pressure is 0.5MPa,reaction time is 2.5h and reaction temperature is 100℃,the yield of furfurylamine could reach 95.6%;when the amount of catalyst is 15%,reaction pressure is 0.5 MPa,reaction time is 2h and reaction temperature is 90℃,the yield of2-Thiophenemethylamine could reach 71.3%.During the reduction of the nitro intermediate,the effects of the amount of Pd/C catalyst,the amount of hydrazine hydrate,and the reaction time were also investigated.The results show that when the amount of Pd/C is 3%,the molar ratio of hydrazine hydrate to the nitro intermediate is5:1,and the reaction time is 5h,the yield of 3,5-diamino-N-(furan-2-ylmethyl)benzamide is 73.2%;When the amount of Pd/C is 5%,the molar ratio of hydrazine hydrate to the nitro intermediate is 6:1,and the reaction time is 6h,the yield of3,5-diamino-N-(thiophen-2-ylmethyl)benzamide is 67.7%;In the synthesis of 2-(4-aminophenyl)-1,3-benzoxazol-5-amine and2-(4-aminophenyl)-3H-benzimidazol-5-amine,the raw material 2-amino-4-nitrophenol was obtained by 2,4-dinitrophenol through partially reduced.we studied the conditions of the amount of Pd/C,the dosage of hydrazine hydrate and the reaction time.The results show that on the conditions of 3% catalyst,the molar ratio of hydrazine hydrate is 5:1,and the reaction time is 4.5h,the yield could reach 80.9%;Afterwards,the synthesis of nitro intermediates by "one-pot " method was studied.The influences of the amount of polyphosphoric acid(PPA),cyclization temperature and time wasdiscussed.The results show that when the amount of PPA is about 1.8 times to twice to the raw material,the yield of the nitro compound intermediates is above85%,The yield of diamine monomers after reduction is also above 72%. |
