Friedlander Reaction Catalyzed by Supported Ionic Liquid: An Economical and Environmentally Friendly Method

First, 1-butyl-2,3-dimethylimidazolium imidazolium salt ionic liquid was prepared, and then it was combined with methyl orthosilicate to prepare silica gel supported ionic liquid catalyst by non-hydrolytic sol-gel method. Its chemical structure was characterized by Fourier infrared spectroscopy, and its thermal performance, apparent morphology, and pore structure were tested by high-temperature synchronous thermal analyzer, scanning electron microscope, and specific surface area analyzer. Then, the catalytic effect of the catalyst on the Friedlander reaction was investigated in a Schlenk reaction flask, and the effects of reaction temperature, reaction time, and reactant molar ratio on product yield were investigated. The experimental results show that the supported ionic liquid catalyst has the highest product yield (92%) at a reaction temperature of 110°C, reaction time of 9 h, catalyst dosage of 0.1 g, and a molar ratio of 2-amino-3-pyridine formaldehyde to diphenyl ketone reaction raw materials of 1 : 0.4. The catalyst is reused for 4 times without significant activity loss.