Palladium nanoparticles immobilized on a magnetic chitosan-anchored Schiff base: applications in Suzuki-Miyaura and Heck-Mizoroki coupling reactions

A palladium nanocatalyst Fe3O4@CS-SB-Pd has been synthesized and characterized by FT-IR, XRD, XPS, FESEM, EDX, TEM, TGA, and ICP-AES analysis. The nanocatalyst has been found to be an efficient and magnetically separable heterogeneous catalyst for Suzuki-Miyaura and Heck-Mizoroki coupling reactions at a low concentration (0.02 mol% of Pd). The nanocatalyst afforded arylated products with high TON (4950) and TOF (9900 h(-1)) in the Suzuki-Miyaura coupling reactions. However, for the Heck-Mizoroki coupling reaction, the values of TON and TOF were found to be 4900 and 7350 h(-1), respectively. The nanocatalyst could be easily recovered from the reaction mixture by using an external magnet and recycled up to five times without significant decrease in its catalytic activity. All isolated products were obtained as white to off-white crystalline solids and brown oils and fully characterized by H-1 and C-13 NMR spectroscopy.