Preparation of core/shell nanostructure Fe3O4@PEG400-SO3H as heterogeneous and magnetically recyclable nanocatalyst for one-pot synthesis of substituted pyrroles by Paal-Knorr reaction at room temperature

An efficient procedure has been proposed for the loading of sulfonic acid groups on the surface of polyethylene glycol 400 (PEG400)-encapsulated Fe3O4 nanoparticles to synthesize a core-shell Fe3O4@PEG400-SO3H nano catalyst. Surface functionalization of magnetic particles in such a way is a refined method of bridging the gap amongst heterogeneous and homogeneous catalysis. The procured nano catalyst was classified through Fourier transformed infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), wavelength-dispersive X-ray spectroscopy (WDX), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS), BET, and back titration. The nanoparticles have been utilized as a convenient catalyst for synthesizing a variety of N-substituted pyrroles via Paal-Knorr reactions of gamma-diketones with amines, diamines or triamines at room temperature under solvent-free conditions. Notably, the newly produced catalyst was recoverable and recyclable (9 times) without any noticeable decrease in its activity.