Research on Chemical Intermediates, 2019, vol 45, 4, pp. 1863-1881
DOI:10.1007/s11164-018-3707-3
Abstract
Propylsulfonic acid functionalized Santa Barbara Amorphous-15 (SBA-15PrSO3H) catalyst has been synthesized using a surface modification of mesoporous SBA-15 via the one-pot co-condensation method. The synthesized SBA-15PrSO3H has been characterized by peculiar characterization techniques such as small- and wide-angle XRD, SEMEDX, TEM, TGDTA, acidity, FT-IR, Py-FT-IR and BET surface area analysis. The catalytic activity of synthesized catalyst has been studied towards solvent-free MW irradiation for the green and rapid synthesis of multi-substituted imidazoles, [2,4,5-triphenyl-1(H)-imidazole (tri-imidazole) and 1-benzyl-2,4,5-triphenyl-1H-imidazole (tetra-imidazole)]. The SBA-15PrSO3H catalyst was found to be an efficient and recyclable solid acid catalyst and this solvent-free MW protocol afforded products in good to excellent yields of both, tri and tetra imidazoles (> 95%) within shorter reaction time (3 min) at 600 W as compared to the SBA-15 and other existing protocols. The applicability of this protocol was further explored by conducting the experiments in the presence of varied solvents and substituted aldehydes to generate a library of both, tri- and tetra-imidazole scaffolds. The catalyst was found to be reusable up to several runs without loss of its catalytic activity. This report allows the rapid and scalable access to a variety of multi-substituted imidazoles using SBA-15PrSO3H, as heterogeneous catalyst.Graphical abstractSBA-15PrSO3H catalyzed solvent-free MW assisted green synthesis of multi-substituted imidazoles via MCRs. Open image in new window
