Facile Shaping Mixed-valence Pd^0/IIO Nanoparticles in Al³⁺ Crosslinked Carboxymethylcellulose Microspheres for Catalytic Aminocarbonylations

A mixed-valence Pd^0/IIO nanocomposite microsphere (Pd^0/IIONPs@CMC–Al) was prepared by Al³⁺ ion crosslinked carboxymethylcellulose (CMC) procedure using PdO nanoparticles (NPs) and sodium carboxymethylcellulose in an Al(NO₃)₃ solution. As evidenced by X-ray photoelectron spectroscopy (XPS), the Pd⁰ was generated in situ on the surface of PdO NPs through the reduction of CMC in the formation of composite microspheres. The identity of the as-prepared Pd^0/IIONPs@CMC–Al microsphere was fully verified using various techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray analysis (EDX), elemental mappings, and thermogravimetric analysis (TGA). The composite microsphere was found to be effective in the aminocarbonylations of various iodobenzenes with different benzyl amines, resulting in moderate to good yields of the desirable products using phenyl formate as a simple and efficient CO surrogate. The microsphere can be easily recovered through simple filtration and can be recycled for up to five consecutive runs without losing its activity. The advantages include the ease of handling the catalyst, no additional reducing agent required, simple workup procedure, tolerance for a wide range of functional groups, and effective catalyst recyclability, all of which enhances its practical applicability.