Kaolin-SO3H nanoparticles: A new efficient and reusable catalyst for synthesis of 2-substituted benzimidazoles at room temperature

Kaolinite clay found its application in medicine, in toothpaste, in cosmetic and as a food additive. Recently, a specially formulated spray is used in fruit and vegetable production to repel the insects and prevent sunburn. Kaolin-SO3H nanoparticles were prepared via reaction of kaolin and chlorosulfonic acid and characterized by FT-IR, XRD, FESEM, TEM, XRF, EDS, BET and TGA. 2-Substituted benzimidazoles have been used as selective neuro-peptides YY, receptor antagonists, antitumor, antivirus, antimicrobial, antioxidant, antiparasitic, antihelmintics, antiproliferative, anti-HIV, anticonvulsant, anti-inflammatory, antihypertensive, antineoplastic, analgesicand antitrichinellosis, topoisomerase IV inhibitors, potent inhibitors of TiE-2 and VEGFER-2 tyrosine kinase receptor, and 5-HT3 antagonists. 2-Substituted benzimidazoles are prepared via condensation of o-phenylenediamines and aldehydes. In this article, we have used Kaolin-SO3H nanoparticles for the synthesis of 2-substituted benzimidazoles under mild reaction conditions. The structure of products were identified by FT-IR, 1H-NMR and 13C-NMR. This method has the advantages of high yields, short reaction times and easy work-up.