Ultrasonic treatment of CoFe2O4@B2O3-SiO2 as a new hybrid magnetic composite nanostructure and catalytic application in the synthesis of dihydroquinazolinones.

New hybrid magnetic composite nanostructure are prepared via ultrasonic treatment by glass-ceramic method, characterized by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), energy-dispersive X-ray (EDX), element distribution image (EDX mapping), thermal gravimetric analysis (TGA)/differential thermal analysis (DTA) and N2 adsorption-desorption by Brunauer-Emmett-Teller (BET) analyses. Then, the catalytic activity of the prepared CoFe2O4@B2O3-SiO2 nanoparticles was tested in the synthesis of 2-substituted-3-(phenylamino)-dihydroquinazolin-4(1H)-ones in deep eutectic solvent (DES) based on choline chloride as an eco-friendly and recyclable media. This novel protocol offers several advantages such as high yields (70-93%), short reaction times (10-20min), environmentally-friendly reaction media, easily isolation of the products, simple preparation and recoverability of the nanocatalysts (at least 5 times), recyclability of the solvents from the reaction mixture without use of hazardous volatile organic solvent. The catalyst was readily recycled by the use of an external magnetic field and could be reused several times without significant loss of activity or mass. The saturation magnetization of CoFe2O4@B2O3-SiO2 nanoparticles was 8.97emug-1. Their average size distribution was about 12.5nm. DES was a mixture of choline chloride and urea that was recovered from the filtrate by evaporating the water under vacuum.