A simple, safe, eco-friendly, and unique synthesis of hexahydro-quinolines employing Fe3O4-MWCNT@MnO2 as a reusable catalyst

Abstract

This work aims to explore the catalytic potential of manganese oxide (MnO2) supported on (Fe3O4-MWCNT) nano-composite, which is composed of iron oxide and multi-walled carbon nanotubes. The nano-composite was synthesized using a simple impregnation technique. The catalyst material was extensively characterized using a variety of possible analytical methods, including X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). Then, utilizing a multi-component condensation protocol comprising substituted aldehydes, cyclohexadione, ethylacetoacetate, and NH4OAc, the catalytic efficacy of the Fe3O4-MWCNT@MnO2 nano-composite was assessed for synthesizing novel hexahydro-quinoline analogues. The catalyst was found to be effective because of its huge specific surface area, stability, porosity, and distinctive exposed surfaces. The catalyst's surface exhibited an exceptionally active nature, as seen by the notably high turnover frequency. Herein, we present a reusable and effective catalytic method that produces outstanding product yields (93%–97%) under mild reaction conditions, using ethanol as a green solvent. Cost-effectiveness, environmental safety, and high atom efficiency are achieved using the nano-composite.