Facile immobilization of copper(I) acetate on silica: A recyclable and reusable heterogeneous catalyst for azide-alkyne clickable cycloaddition reactions

The structurally well-defined copper(I) acetate was immobilized on silica gel via electrostatic interactions. The catalytic activity of the immobilized catalyst Cu(l)-SiO2 was examined in the click synthesis of 1,2,3-triazoles in water/ethanol at room temperature. The catalyst showed high catalytic activity and regioselectivity for the Huisgen [3+2] cycloaddition reaction between terminal alkynes and azides. The catalyst was recovered by simple filtration and reused for up to five times. The analysis of the local electrophilicity/nucleophilicity has been performed on the dinuclear copper-acetylide complex intermediate. Conceptual DFT (CDFT) analysis enabled the explanation of the formation of 1,2,3-triazole in a regioselective manner. FT-IR, XRPD, SEM and ICP techniques were used to characterize the immobilized catalyst. (C) 2019 Elsevier Ltd. All rights reserved.