稻壳灰负载氯磺酸催化苯并咪唑化合物的合成研究

以绿色廉价的稻壳灰为载体,接着吸附氯磺酸作为固体酸催化剂,微波辅助、无溶剂条件下,利用邻苯二胺和醛分子间的缩合反应一步法制备得到2-取代苯并咪唑类化合物,其结构经IR、1HNMR和元素分析等加以确证。实验结果表明,600℃下煅烧的稻壳灰经氯磺酸处理后制备固体酸催化剂的用量为8 mol%,800 W功率下微波辐射反应5~10 min即可得目标化合物,且收率为87%~97%,该催化剂易于回收并多次使用。

Synthesis of Benzimidazoles Catalysized by Chlorosulfonic Acid Supported on Rice Husk Ash

Using rice husk ash as a green and cheap activated material to adsorb the chlorosulfonic acid as a powerful solid acid catalyst for the synthesis of 2-substituted benzimidazoles via the condensation reaction between o-aminothiophenol and aromatic or aliphatic aldehydes under microwave irradiation and solvent-free conditions was discussed.The structures of the corresponding products were confirmed by IR,1HNMR and elemental analysis.The results indicated that the rice husk ash burned at 600 ℃ and treated with sulfonation is efficient to catalyze the synthesis of a series of substituted benzimidazoles with good yields of 87％ ～97％ with the amount of 8 mol％ under irradiation at 5～ 10 min respectively.Meanwhile,this catalyst could be recovered and reused without any appreciable loss of efficiency.