Modification of boehmite nanoparticles with Adenine for the immobilization of Cu(II) as organic–inorganic hybrid nanocatalyst in organic reactions

Abstract

Boehmite nanoparticles are aluminum oxide hydroxide (γ‐AlOOH) particles, which has large specific surface area (>120 m2 g−1) and can be prepared using an inexpensive procedure in water. Herein, we present an economical, simple, and environmentally friendly route for the preparation of a copper catalyst on Adenine coated boehmite nanoparticles (Cu–Adenine@boehmite). This catalyst has been characterized by several techniques such as SEM, XRD, AAS, ICP and TGA analysis. Cu–Adenine@boehmite was applied as highly efficient and reusable nanocatalyst in carbon–carbon coupling reactions between various aryl halides and sodium tetraphenyl borate, phenylboronic acid, or 3,4-diflorophenylboronic acid under aerobic conditions, palladium-free and phosphine-free ligand. Also this catalyst was applied for the synthesis of polyhydroquinoline derivatives. In continuation, selective oxidation of sulfides to sulfoxides using hydrogen peroxide (H2O2) was studied in the presence of Cu–Adenine@boehmite as catalyst. The synthesis of sulfoxides using H2O2 in the presence of Cu–Adenine@boehmite does not generate waste and any byproducts. This catalyst was reused for several times in CC coupling reaction without loss of its catalytic activity. Reused catalyst was characterized by SEM, XRD and ICP techniques. Heterogeneity and stability of Cu–Adenine@boehmite were studied by hot filtration test, poisoning test and ICP analysis.