RSC Adv. 2023 May 2;13(20):13374-13383. doi: 10.1039/d3ra00804e. eCollection 2023 May 2.
In this study, tungstic acid immobilized on polycalixresorcinarene, PC4RA@SiPr-OWO3H, as a mesoporous acidic solid catalyst was synthesized and investigated for its catalytic activity. Polycalixresorcinarene was prepared via a reaction between formaldehyde and calixresorcinarene, and then the resulting polycalixresorcinarene was modified using (3-chloropropyl)trimethoxysilane (CPTMS) to obtain polycalixresorcinarene@(CH2)3Cl that was finally functionalized with tungstic acid. The designed acidic catalyst was characterized by various methods including FT-IR spectroscopy, energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), elemental mapping analysis and transmission electron microscopy (TEM). The catalyst efficiency was evaluated via the preparation of 4H-pyran derivatives using dimethyl/diethyl acetylenedicarboxylate, malononitrile, and beta-carbonyl compounds, confirmed by FT-IR spectroscopy and 1H and 13C NMR spectroscopy. The synthetic catalyst was introduced as a suitable catalyst with high recycling power in 4H-pyran synthesis.
PMID:37143914 | PMC:PMC10152327 | DOI:10.1039/d3ra00804e