Fe3O4-decorated MWCNTs as an efficient and sustainable heterogeneous nanocatalyst for the synthesis of polyfunctionalised pyridines in water

Fe3O4-multiwalled carbon nanotube (MWCNT) nanoparticles were prepared by using Astragalus membranaceus root extract and characterised by all parameters. The synthesised Fe3O4-MWCNTs were used as a heterogeneous catalyst for the synthesis of diverse polyfunctionalised pyridines. Pyridines are important heterocyclic compounds in many natural products and pharmaceuticals with a wide range of biological and medicinal properties such as quinine, papaverine, emetine. TEM images showed that the Fe3O4 nanoparticles coated on the outer surface of the MWCNTs were arranged in consistent patterns. The mean diameters of Fe3O4 nanoparticles and MWCNTs were similar to 15 and similar to 25 nm, respectively. X-ray diffraction (XRD) analysis and Raman spectroscopic techniques revealed the degree of graphitisation. After preparation of pyridines in water with excellent yields, the nanocatalysts were recovered by an external magnet without filtration and reused for several runs without any significant loss of their activity. [GRAPHICS]