The role of phosphotungstic acid in enhancing the catalytic performance of UiO-66 (Zr) and its applications as an efficient solid acid catalyst for coumarins and dihydropyrimidinones synthesis

Abstract

In recent study, we report a facile and easy technique for the synthesis phosphotungstic acid (PTA) with different weight contents (10, 25, 50 and 75 wt%) loaded on UiO-66 (Zr) as efficient and reusable catalysts for the preparation of coumarin and dihydropyrimidinones derivatives. The structural and textural properties of the prepared catalysts were characterized through XRD, FT-IR, TGA, BET, TEM, SEM, non-aqueous potentiometric titration and FT-IR of chemisorbed pyridine. 50.0 wt% of PTA/UiO-66 (Zr) catalyst showed the highest surface acidity (Ei = 578.5 mV) and highest catalytic performance toward the preparation of 7-hydroxy-4-methyl coumarin (97.8%) and 3, 4-dihydropyrimidinones (94.7%).