A new Schiff‐base complex of palladium nanoparticles on modified boehmite with di(pyridin‐2‐yl)methanone as a robust, reusable, and selective nanocatalyst in the C‐C coupling reaction

Abstract

Boehmite is one of the stable phases of alumina that is easily available, and it also has a variety of applications. Therefore in this work, for preparation of AlOOH, Sodium hydroxide (NaOH) solutions was added to aluminum nitrate nonahydrate (Al(NO3)3.9H2O) solution. Then, the surface of AlOOH was modified with (3‐aminopropyl)triethoxysilane (APTES), due to high condensation of hydroxyl groups on its surface. Then, di(pyridin‐2‐yl)methanone (di(PM)) was immobilized on the surface of modified AlOOH toward synthesis of immobilized Schiff‐base on AlOOH (di(PM)@AlOOH) as a heterogeneous Schiff‐base ligand. Finally, a palladium complex was immobilized on its surface (Pd‐di(PM)@AlOOH) as a reusable, practical, and novel nanocatalyst. Pd‐di(PM)@AlOOH was characterized by thermogravimetric analysis (TGA) analysis, Fourier‐transform infrared spectroscopy (FT‐IR), transmission electron microscopy (TEM), scanning electron microscope (SEM) imaging, energy‐dispersive X‐ray spectroscopy (EDS) analysis, wavelength‐dispersive X‐ray spectroscopy (WDX) analysis, and inductively coupled plasma (ICP) analysis. After the characterization of Pd‐di(PM)@AlOOH, its performance was used as a highly practical, stable, retrievable, and hybrid organic–inorganic catalyst in the C‐C coupling of the Suzuki reaction. The hot filtration study of Pd‐di(PM)@AlOOH revealed that it acts heterogeneously in the Suzuki reaction. We found that this catalyst can be recycled for five runs without palladium leaching, as studied by hot filtration test and ICP analysis.