One-Pot Preparation of Various 2-Pyrazoles using Functionalized Fe Oxide Magnetic Nanoparticles with Sulfonated Tris(Hydroxymethyl)Aminomethane/Copper(II) Nitrate by in Situ Oxidation Method

In this research, first, functionalized Fe oxide magnetic nanoparticles based on sulfonated tris(hydroxymethyl)aminomethane/copper (II) nitrate were synthesized as a new, effective and recyclable magnetic catalyst, and then, was used in the reaction of preparing of Various 2-pyrazolines. Finally, the  prepared 2-pyrazolines were  oxidized to  the corresponding 2-pyrazoles under in situ and one-pot conditions, in such a way that, under optimal conditions, a wide and different range of unsaturated α, β-unsaturated  ketones (trans-chalcones) that had various functional groups including electron-donating and electron-withdrawing groups, were successfully transformed into the corresponding final products under easy and mild conditions. All products were obtained in good to excellent yields and no by-product was observed. The new synthesized magnetic nanocatalyst was characterized by various methods including infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray (EDAX), X-ray diffraction (XRD), elemental analysis (CHN) and analysis Thermogravimetry (TGA). The catalyst was easily recycled by the external magnetic field and was used for several times without observing a significant and effective decrease in its catalytic activity. Also, the structure of various synthesized 2-pyrazoles were confirmed by comparing their physical characteristics including melting point with the reported samples and also by infrared spectroscopy (FT-IR), proton nuclear magnetic resonance spectrum (1H-NMR), carbon nuclear magnetic resonance spectrum (13C-NMR) and elemental analysis. Finally, no using of harsh reaction conditions, the no by-product formation, as well as the ability to recycle and reuse the catalyst, made this method an environmentally friendly method.