Introducing rGO@Fe3O4@Ni as an efficient magnetic nanocatalyst for the synthesis of tetrahydrobenzopyranes via multicomponent coupling reactions of dimedone, malononitrile, and aromatic aldehydes

In this study, the synthesis and characterization of the modified GO and rGO@Fe3O4@Ni composite systems were investigated. Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive x-ray spectroscopy (EDX), x-ray powder diffraction (XRD), vibrating sample magnetometer (VSM), Brunauer-Emmett-Teller (BET) analysis, thermogravimetric analysis (TGA), and inductively coupled plasma optical emission spectroscopy (ICP-OES) were employed to characterize the prepared nanomaterials. Also, catalytic activities of GO, rGO@Fe3O4, rGO@Ni, and rGO@Fe3O4@Ni were compared, and rGO@Fe3O4@Ni as the efficient magnetic nanocatalyst was applied to expedite the multicomponent coupling reactions (MCRs) of dimedone, malononitrile, and structurally diverse aromatic aldehydes to prepare tetrahydrobenzopyranes. All reactions were fulfilled efficiently in deionized water under reflux conditions. In addition, sustainability of the nanocatalyst was examined for five consecutive reaction cycles without the significant loss of its catalytic activity.

Automated summary

The study investigated the synthesis and characterization of modified GO and rGO@Fe3O4@Ni composite systems. Various analytical techniques were employed to characterize the prepared nanomaterials, and the catalytic activities of different materials were compared in multicomponent coupling reactions. The efficient magnetic nanocatalyst rGO@Fe3O4@Ni was successfully applied to facilitate the reactions, showing sustainable catalytic activity over multiple reaction cycles.