Synthesis and characterization of nano acid catalyst derived from rice husk silica and its application for the synthesis of 3,4-dihydropyrimidinones/thiones compounds

Abstract

In the present work, the extraction of silica nanoparticles from the rice husk followed by the modification using an acidic ionic liquid containing imidazolium butyl sulfonic acid through a sol-gel method (RH@[SiPrImBuSO3H]Cl) has been investigated. The composition, morphology and structural properties of the synthesized solid acid were analyzed by fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal gravimetric analysis-derivative thermogravimetric (TGA-DTG), and nitrogen adsorption-desorption. The catalytic activity of the nanocomposite was examined through the one-pot condensation of aromatic aldehyde, β-diketone, urea or thiourea under reflux condition. Diverse 3,4-dihydropyrimidinones/thiones derivatives were produced up to excellent yields in a short period of time. This nanocatalyst could be easily recovered, and reused without considerable loss of catalytic activity. This method seems to be a promising method for synthesizing organic chemicals. In addition to the conducted experiments, the 1H and 13C chemical shift and X-ray spectra values together with the structural parameters of 3,4-dihydropyrimidinones/thiones were computed and compared to the corresponding experimental values. As a result, the calculated 1H and 13C chemical shift and X-ray spectra show a good agreement with the experimental results.