Magnetic nanoparticles-supported tungstosilicic acid: as an efficient magnetically separable solid acid for the synthesis of benzoazoles in water

摘要

The magnetic nanoparticles-supported tungstosilicic acid (TSAMNP) was found to be a highly efficient solid acid for the synthesis of benzoazoles in water. TSAMNP catalyst was achieved by the immobilization of tungstosilicic acid [H_4(W_(12)SiO_(40))] species on the silica core-shell magnetic nanoparticles (Fe_3O_4@SiO_2). A variety of aldehydes were successfully condensed with 1,2- diaminobenzene, 2-aminophenol and 2-aminothiophenol in water as a green solvent to synthesize benzoazoles in goodto- excellent yields. TSAMNP catalyst was easily separated from the reaction mixture and reused several times without any loss of efficiency.