Nano ordered polyacrylonitrile-grafted chitosan as a robust biopolymeric catalyst for efficient synthesis of highly substituted pyrrole derivatives

Abstract A novel heterogeneous nanocatalyst was developed using chitosan, as a natural polysaccharide derived from crustacean shells, and its in-situ grafting by polyacrylonitrile to afford nano ordered polyacrylonitrile-modified chitosan (CS-g-PAN). The obtained CS-g-PAN nanomaterial was thoroughly analyzed using several appropriate spectroscopic, microscopic or analytical techniques, including EDS and FTIR spectroscopy, EDS elemental mapping, FESEM imaging, XRD spectroscopy, TGA and DTA, and N2 adsorption-desorption isotherm. The catalytic activity of multifunctional CS-g-PAN nanomaterial, as an organocatalyst, was evaluated in the green synthesis of highly substituted pyrrole derivatives through multi-component reactions strategy from corresponding α-haloketones, β-dicarbonyl compounds, and primary amines. This method offers several advantages, including high efficiency, short reaction times, ease of catalyst separation and recovery as well as recyclability for at least five cycles without significant loss of its activity. The catalyst's eco-friendly nature, lack of toxic transition metals, and mild reaction conditions make it a promising sustainable alternative for the Hantzsch synthesis of different pyrrole derivatives.