Abstract

The alkylation of indole with benzaldehyde and derivatives catalyzed by 1-(4- sulfobutyl)-3-methylimidazolium hydrogene sulfate ion gel has been developed. The reaction was taken place under solvent-free ultrasonic irradiation afforded the corresponding product in high yield. Ion gel catalysis was formed by sol-gel method. The recovered ionic liquid gel in each reaction which is quite simply achieved by filtration could be reused up to 5 times without any detectable loss of catalytic performance.