One of the principles of green chemistry is the use of catalysts to prevent and eliminate hazardous chemicals. Recently, remarkable developments have been made in the field of green catalysis, the design of safer chemicals, and green solvents. In this paper, novel magnetic choline chloride-based deep eutectic solvent immobilized on Fe3O4 magnetic nanoparticles (Fe3O4@SiO2@THAM@ChCl = D) was obtained from the sequential synthesis of Fe3O4 (A), Fe3O4@SiO2 (B), and Fe3O4@SiO2@THAM (C), and characterized with various techniques such as Fourier transform–infrared spectroscopy (FT–IR), energy–dispersive X-ray spectroscopy (EDX), elemental map- ping, vibrating sample magnetometer (VSM), field emission scanning electron microscopy (FE–SEM), trans- mission electron microscopy (TEM), thermo–gravimetric–differential thermal analysis (TGA–DTA) and X-ray diffraction analysis (XRD). TEM images confirm that the nanoparticles are core–shell. Then, the novel D was used as a capable heterogeneous catalyst for the one-pot three-component condensation reaction of 3-amino-1,2,4-tri- azole, aromatic aldehydes, and malononitrile for the synthesis of 1,2,4-triazolo[4,3-a]pyrimidines under solvent- free conditions with high yields and short reaction times. Some advantages of using this catalyst are the novelty, easy separation from the reaction medium, reusability, high thermal stability, excellent yield, and short reaction times.
