Inorganic-organic hybrid nanomaterial (Fe3O4@SiO2-AQ): A retrievable heterogeneous catalyst for the green synthesis of 4H-chromenes

Preparation of 4aminiquinaldine grafted on silicacoated nanoFe3O4 particles (Fe3O4@SiO2AQ) as a novel retrievable heterogeneous nanocatalyst is described. This novel hybrid nanomaterial was applicated for the green synthesis of substituted 2amino4Hchromenes via the onepot condensation reaction of an aldehyde, malononitrile and αnaphthol/βnaphthol/phenol under solventfree condition. Ecofriendly method, high yield and purity of the desired products, short reaction time along with the ease of the workup procedure outlines the advantages of these new methodologies over the earlier ones. Surface and magnetic properties of the core/shell hybrid nanoparticles were characterized via transmission electron microscopy (TEM), scanning electron microscope (SEM), Xray powder diffraction (XRD), energydispersive Xray spectroscopy (EDS), thermogravimetric analysis (TGA/DTA), and Fouriertransform infrared spectroscopy (FTIR) techniques. This nanocatalyst can be reused at least six times without considerable loss of its performance.