Zn-B_(2)O_(3)催化合成2-(3,4-二氯苯甲基)苯并咪唑

Synthesis of 2-(3,4-dichlorobenzyl)-1H-benzimidazole Catalyzed by Zn-B_(2)O_(3)

创新性引入Zn-B_(2)O_(3)复合型催化剂,实现3,4-二氯苯乙酸和邻苯二胺环化反应合成2-(3,4-二氯苯甲基)苯并咪唑。利用FTIR、1HNMR、13CNMR和ESI-MS对产物结构进行详细表征,并对反应条件进行了优化,结果表明Zn-B2O3复合型催化剂能显著提高产物的收率,最佳合成条件为:复合型催化剂用量为邻苯二胺质量的9.1%,反应温度140℃,反应时间8 h,甲醇为重结晶溶剂。在该条件下产物总收率达78.5%,纯度99.0%以上。该合成方法具有操作简单、反应时间短、成本低廉、收率高、纯度高、避免柱层析分离纯化等优点,更适合工业化生产。

2-(3,4-dichlorobenzyl)-1H-benzimidazole was obtained via condensation reaction between 3,4-dichlorophenylacetic acid and o-phenylenediamine in the presence of composite catalyst Zn-B_(2)O_(3) novelly.The structure of the target compound was characterized by FTIR,1HNMR,13CNMR and ESI-MS.The reaction conditions were optimized,the result indicated that by using of Zn-B_(2)O_(3) as composite catalyst,the yield could increase dramatically compared to previous catalyst.The optimum process conditions were determined as follows:catalyst being 9.1 % of the mass of o-phenylenediamine,reaction temperature 140 ℃,reaction time 8h,methanol as recrystallizaion solvent.Under these conditions,the total yield of 2-(3,4-dichlorobenzyl)-1H-benzimidazole could achieve 78.5 %,and purity was more than 99.0 % respectively.The novel synthetic method take the advantages of simple operation,short reaction time,low costs,excellent yield and high purity,avoiding column chromatography separation,which is suitable for industrial production.