摘要
以3-氟-4-硝基甲苯为初始原料,先借助微波合成N-取代-2-硝基-4-甲基苯胺,其与不同的醛反应合成了1,2,6-三取代苯并咪唑。从反应温度、投料比两方面对第一步的取代反应进行了反应条件优化,确定了最佳反应条件:反应温度为83℃,投料比为n(3-氟-4-硝基甲苯)∶n(苯乙胺)∶n(K2CO3)=1.0∶1.5∶1.8,此时5-甲基-2-硝基-N-苯乙基苯胺(Ⅱa)产率为99.2%,5-甲基-2-硝基-N-(3-苯基丙基)苯胺(Ⅱb)产率为98.9%。从催化剂的用量、反应温度两方面对第二步反应进行了反应条件优化,确定了最佳反应条件:乙醇为溶剂、5-甲基-2-硝基-N-苯乙基苯胺(2 mmol)、醛(2 mmol)、1 mol/L的Na2S2O4水溶液18 m L,反应时间40-120 min,此时2-(4-氯苯基)-6-甲基-1-苯乙基-苯并咪唑(Ⅲb)收率为91.3%。与文献中报道的反应时间12 h相比,反应时间大大缩短。在该条件下合成10种1,2,6-三取代苯并咪唑,9种为新化合物,产物结构经IR、-1HNMR和-(13)CNMR进行了确证。
N-substituted 2-nitro-4-methyl-anilines were prepared from 3-fluoro-4-nitrotoluene under microwave irradiation,and then they reacted with different aldehydes to synthesize 1,2,6-substituted benzimidazole derivatives.The effect of reaction temperature and reactant feed ratio on the first step reaction was optimized.Under the optimum reaction conditions of temperature 83 ℃,n(3-fluoro-4-nitrotoluene) ∶ n(phenylethylamine) ∶ n(K2CO3) = 1.0 ∶ 1.5 ∶ 1.8,the yield of 5-methyl-2-nitro-Nphenylethylaniline(Ⅱa) and 5-methyl-2-nitro-N-(3-phenylpropyl) aniline(Ⅱ b) was 99.2% and98.9%,respectively.The reaction conditions were optimized for both amount of catalyst and reaction temperature in the second step reaction,and the optimum reaction conditions were determined as follows: the amount of aldehyde and N-substituted-2-nitro-4-methylaniline was 2 mmol,ethanol was used as solvent,18 m L Na2S2O4 aqueous solution(1 mol/L) was used as catalyst,and the reaction time was between 40 minutes and 2 hours,the yield of Ⅲb was 91.3%,which was shorter than that of the literature(12 hours).Ten kinds of 1,2,6-trisubstituted benzimidazole derivatives were synthesized,and nine of them were new compounds.All compounds were identified by IR,1 HNMR and13 CNMR.
出处
《精细化工》
EI
CAS
CSCD
北大核心
2018年第3期443-448,503,共7页
Fine Chemicals
基金
江苏前瞻性科研项目(BY2016066-02)
大学生创新项目(201410324014Z)~~