Synthesis of pyrazole derivatives in the presence of a dioxomolybdenum complex supported on silica-coated magnetite nanoparticles as an efficient and easily recyclable catalyst

Abstract

Efficient synthesis of pyrazole derivatives catalyzed by a dioxomolybdenum complex supported on functionalized Fe₃O₄ magnetite nanoparticles containing a Schiff base ligand is reported. The synthesized catalyst was characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), vibrating sample magnetometry (VSM), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and Fourier transform infrared spectroscopy (FT-IR). This heterogeneous catalyst can be reused several times without significant loss of its catalytic activity. The described metal-complex immobilized on MNPs catalyst was efficiently tested in the synthesis of pyrazole derivatives via three-component condensation of aromatic aldehydes, malononitrile and phenylhydrazine with short reaction times and good yields and also ease of separation, recycling and reusability of catalyst. Besides, the catalyst could be recovered in a facile manner from the reaction mixture and recycled eight times without loss in activity. Also, a mechanistic approach was proposed for the final step of the synthesis of pyrazole derivatives which was supported by theoretical studies.