Para-Aminobenzoic acid grafted on silica-coated magnetic nanoparticles: a highly efficient and synergistic organocatalyst for on-water synthesis of 2,3-dihydroquinazolin-4(1H)-ones

In the present study, new para-aminobenzoic acid (PABA) grafted on the silica-coated magnetic nanoparticles -(Fe3O4@SiO2@Pr-PABA) was prepared and its structure was properly confirmed using Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD), vibrating sample magnetometer (VSM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray detector (EDS), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), N-2 adsorption-desorption technique (BET) and atomic force microscopy (AFM). The Fe3O4@SiO2@Pr-PABA nanocomposite was used as a novel, highly efficient and synergistic recoverable organocatalyst for the synthesis of biologically active 2,3-disubstituted-2,3-dihydroquinazolin-4(1H)-one derivatives via on-water and one-pot three-component condensation of isatoic anhydride, aromatic aldehydes and aromatic or aliphatic amines under reflux conditions. Transition metal-free process, the use of a naturally occurring component and environmental-friendly properties of the catalyst as well as solvent, cost-effectiveness, low catalyst loading, convenient work-up and reusability of the catalyst are some of the remarkable advantages of this green protocol.