Immobilization of Zn(II) on Chitosan from Callinectes Sapidus Shells as an Efficient Heterogeneous Catalyst for the Synthesis of 4H-Pyran Derivatives

A new sustainable heterogeneous catalyst for the effective synthesis of 4H-pyran derivatives under mild reaction conditions was investigated. This heterogeneous catalyst was prepared through the complexation reaction between the naturally obtained chitosan from Callinectes sapidus shells and zinc(II) ions (Zn(II)/Chitosan), and characterized using a variety of techniques, including thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and infrared spectroscopy (IR). The corresponding 4H-pyran derivatives were obtained in good to excellent yields (58–96