Functionalized Magnetite/Silica Nanostructures in Knoevenagel Condensation
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RESEARCH PAPER
Functionalized Magnetite/Silica Nanostructures in Knoevenagel Condensation Fatemeh Lashkari1,2 • Rashid Badri2 • Elham Tahanpesar2 Received: 27 December 2019 / Accepted: 2 June 2020 Ó Shiraz University 2020
Abstract A simple procedure for the synthesis of functionalized magnetic iron oxide supported sulfonic acid (Fe3O4@SiO2–Pr– NH2–SO2CH3) is reported. The product was characterized using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and energy-dispersive analysis of X-ray (EDAX). SEM analysis exhibits homogeneous dispersion of spherical nanoparticles for Fe3O4@SiO2–Pr–NH2–SO2CH3. The as-prepared catalyst was applied in Knoevenagel condensation of benzaldehyde derivatives with ethyl cyanoacetate in solvent-free condition at 80 °C. The products were obtained in high-to-excellent yields at short times. The catalyst can be extracted and reused in the next reaction cycle by using an external magnet. Graphic abstract The synthesis of heterogeneous basic magnetic catalyst is developed which is applied as efficient catalyst in Knoevenagel condensation of benzaldehyde derivatives with ethyl cyanoacetate. The coating of Fe3O4 magnetic NPs with silica followed by functionalization with organic and inorganic compounds is very effective and valuable process. The as-prepared catalyst exhibited interesting catalytic activity in solvent-free conditions.
Keywords Magnetite/silica nanostructure Solvent-free Knoevenagel condensation Benzaldehyde derivatives Electronic supplementary material The online version of this article (https://doi.org/10.1007/s40995-020-00903-6) contains supplementary material, which is available to authorized users. & Rashid Badri [email protected]; [email protected] 1
Department of Chemistry, Khouzestan Science and Research Branch, Islamic Azad University, Ahvaz, Iran
2
Department of Chemistry, Ahvaz Branch, Islamic Azad University, Ahvaz, Iran
1 Introduction Heterogeneous catalysts attracted considerable attention in a wide area of science and technology due to their advantages such as simple recovery and reusability from reaction medium (Tashiro 2016; Hoseini 2017; Sebti 1996). Nowadays, application of the solid acidic and basic catalysts is considerable for chemical processes (Lima 2016). There are few reports in development of polymer-
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Iran J Sci Technol Trans Sci
Scheme 1 Schematic illustration for the synthesis of Fe3O4 NPs
supported catalysts on inorganic surfaces that leads to the easy workup and reusability of the catalyst with less environmental hazards (Benaglia 2003; Toy 2000). High cost, harsh reaction conditions and time-consuming processes are some of the disadvantages of applying these kinds of catalysts (Tarpada 2016). Metal oxides are the other group of effective catalysts with the unique properties such as hardness, thermal and
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