Green synthesis of zinc ferrite magnetic nanoparticles using Arabic gum and its catalytic activity in the synthesis of polyhydroquinoline derivatives

Arabic gum-assisted sol-gel method was employed for the preparation of magnetic zinc ferrite nanoparticles (MNPs) using zinc nitrate and iron nitrate as the metal source by the novel sol–gel method without adding external surfactant. The sample calcined at 600 °C. The green synthesized ZnFe2O4 MNPs are characterized by powder X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), vibrating sample magnetometer (VSM) and scanning electron microscopy (SEM). XRD analysis revealed the formation of cubic phase ferrite MNPs with average crystallite size of 38 nm. The ZnFe2O4 nanoparticles have high catalytic activity and gave the desired products in good to high yields. The catalyst can be easily recovered by filtration and was used at least three times with only a slight reduction in its catalytic activity [1,2]. A four-component reaction of aldehydes, dimedone, ammonium acetate and ethyl acetoacetate was achieved in the presence of ZnFe2O4 MNPs as a heterogeneous catalyst to produce polyhydroquinoline derivatives (scheme 1). Synthesis of polyhydroquinoline has been reported using ZnFe2O4 nanoparticles at 100 °C under reflux condition in ethanol. However, some of the reported methods have disadvantages including long reaction times, harsh reaction conditions, and use of toxic and non-reusable catalysts. Therefore, to avoid these limitations, the exploration of an efficient and reusable catalyst with high catalytic activity for the preparation of polyhydroquinoline is still favored. Atom economy, excellent yields in short times, high catalytic activity, recycling of catalyst, and environmental benignity are some of the important features of this protocol [3].