Highly efficient and recyclable basic ionic liquids supported on SBA-15 for the synthesis of substituted styrenes, carbinolamides, and naphthopyrans

Abstract

In this study, highly stable mesoporous silica, SBA-15, was prepared and used as a support to functionalize ionic liquids. Triazole and N,N-dimethylaminopyridine were functionalized on the surface of SBA-15 through surface silanol groups of SBA-15 to obtain basic ionic liquids. In order to obtain high basicity, −OH containing basic ionic liquids, based on triazole and N,N-dimethylaminopyridine, were prepared. Catalysts were characterized by the complementary combination of low angle powder X-ray diffraction, N2-adsorption, electron microscopes, Fourier-transform infrared spectroscopy, thermal gravimetric analysis, elemental analysis, and temperature programme desorption techniques. Systematic assessment of the catalytic activity was made using Knoevenagel condensation reaction for the synthesis of substituted styrenes. Application of these catalysts was also evaluated in the synthesis of carbinolamides. Recycling study shows that no significant decrease in the catalytic activity was observed after five recycles. Finally, application of the highly active basic ionic liquid was evaluated in one-pot, two-step tandem reaction for the synthesis naphthopyrans.