高纯度2-(4-氨基苯基)-1H-苯并咪唑-5-胺的合成

Synthesis of high-purity 2-(4-aminophenyl)-1H-benzimidazol-5-amine

以廉价的2,4-二硝基苯胺(DNBA)和对硝基苯甲酰氯(NBC)为原料,通过缩合、还原和环合反应制备了2-(4-氨基苯基)-1H-苯并咪唑-5-胺(ABIA)。研究结果表明:170～180℃下的熔融缩合是制备三硝基中间体N-(4'-硝基苯甲酰基)-2,4-二硝基苯胺(NDBA)的优选工艺,提纯后可获得纯度97%以上的NDBA,收率68.40%;NDBA在HCl-H2O溶液中先Pd/C催化加氢还原成N-(4'-氨基苯甲酰基)-2,4-二氨基苯胺(ADBA),再碱性环合反应,经乙醇-H2O重结晶后获得纯度99.5%以上的聚合级单体,收率为64.87%;经FT-IR、1H-NMR和13C-NMR定性为ABIA,以NBC计聚合级ABIA的总收率为44.37%。

2-（4-aminophenyl）-1H-benzimidazol-5-amine （ABIA） was synthesized through condensation, reduction and cyclization reaction from 2,4-dinitrobenzenamine （DNBA） and 4-nitrobenzoyl chloride （NBC）. The results showed that the optimum procedure of preparing the important intermediate N-（4＇-nitrobenzoyl）-2,4-dinitro benzenamine （NDBA） by melt condensation at 170-180℃ could obtain NDBA with purity of 97% min. and yield of 68.40%. NDBA was reduced in HCl-aqueous solution by hydrogenation with catalyst of Pd/C to form N-（4＇-aminobenzoyl）-2,4-diaminobenzenamine, and the product ABIA was obtained through the cyclization of ABTA under alkaline condition. Its purity can reach 99.5% min. （polymer monomer grade） by purification with yield of 64.87%. The structure of ABIA was identified by means of FT-1R, ^1HNMR and^13CNMR. The total yield was 44.37% based on NBC.