Synthesis of Heterocyclic Compounds by Catalysts Supported on Nano-Magnetite (Fe3O4)-An Update

Fe3O4@gC3N4@Thiamine: a novel heterogeneous catalyst for the synthesis of heterocyclic compounds and microextraction of tebuconazole in food samples

Graphite carbon nitride (g-C3N4) is a two-dimensional nano-sheet with electronic properties, which shows unique characteristics with high chemical and thermal stability in its structure. The functionalization of these compounds through covalent bonding is an important step towards significantly improving their properties and capabilities. To achieve this goal, a novel strategy for the covalent functionalization of Fe3O4@g-C3N4 with thiamine hydrochloride (vitamin B1) via cyanuric chloride (TCT), which is a divalent covalent linker, was presented. The efficiency of Fe3O4@gC3N4@Thiamine as a heterogeneous organic catalyst in the synthesis of spirooxindole-pyran derivatives and 2-amino-4H-pyran under solvent-free conditions was evaluated and the yields of high-purity products were presented. In addition, easy recycling and reuse for seven consecutive cycles without significant reduction in catalytic activity are other features of this catalyst. Moreover, the performance of the prepared sorbent in the microextraction technique (herein, magnetic solid phase extraction) was studied. The tebuconazole was selected as the target analyte. The target analyte was extracted and determined by HPLC-UV. Under the optimum condition, the linear range of the method (LDR) was estimated in the range of 0.2-100 μg L-1 (the coefficient of determination of 0.9962 for tebuconazole). The detection limit (LOD) of the method for tebuconazole was calculated to be 0.05 µg L-1. The limit of quantification (LOQ) of the method was also estimated to be 0.16 µg L-1. In order to check the precision of the proposed method, the intra-day and inter-day relative standard deviations (RSD%) were calculated, which were in the range of 1.5- 2.8%. The method was used for the successful extraction and determination of tebuconazole in tomato, cucumber, and carrot samples.

Investigation of Fe3O4@boehmite NPs as efficient and magnetically recoverable nanocatalyst in the homoselective synthesis of tetrazoles

Magnetic boehmite nanoparticles (Fe3O4@boehmite NPs) were synthesized from a hybrid of boehmite and Fe3O4 nanoparticles. At first, boehmite nanoparticles (aluminum oxide hydroxide) were prepared via a simple procedure in water using commercially available materials such as sodium hydroxide and aluminum nitrate. Then, these nanoparticles were magnetized using Fe3O4 NPs in a basic solution of FeCl2·4H2O and FeCl3·6H2O. Fe3O4@boehmite NPs have advantages of both boehmite nanoparticles and Fe3O4 magnetic materials. Magnetic boehmite nanoparticles have been characterized by various techniques such as TEM, SEM, EDS, WDX, ICP, FT-IR, Raman, XRD and VSM. SEM and TEM images confirmed that particles size are less than 50 nm in diameter with a cubic orthorhombic structure. Then, Fe3O4@boehmite NPs were applied as a homoselective, highly efficient, cheap, biocompatibility, heterogeneous and magnetically recoverable nanocatalyst in the synthesis of 5-substituted 1H-tetrazole derivatives. Fe3O4@boehmite NPs can be recycled for several runs in the synthesis of tetrazoles. Also, all tetrazoles were isolated in high yields, which reveals high activity of Fe3O4@boehmite NPs in the synthesis of tetrazole derivatives. Fe3O4@boehmite NPs shows a good homoselectivity in synthesis of 5-substituted 1H-tetrazole derivatives.