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.

中文翻译：

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Knoevenagel缩合反应中的功能化磁铁矿/二氧化硅纳米结构

摘要

报道了一种简单的合成功能化磁性氧化铁负载的磺酸（Fe ₃ O ₄ @SiO ₂ -Pr-NH ₂ -SO ₂ CH ₃）的方法。使用傅里叶变换红外光谱（FT-IR），X射线衍射（XRD），扫描电子显微镜（SEM），振动样品磁力计（VSM），热重分析（TGA），透射电子显微镜（TEM）对产品进行表征X射线（EDAX）的能量分散分析。SEM分析显示球形纳米颗粒对Fe ₃ O ₄ @SiO ₂ –Pr–NH ₂ –SO ₂ CH _3的均匀分散。将所制得的催化剂在80°C无溶剂条件下用于苯甲醛衍生物与氰基乙酸乙酯的Knoevenagel缩合反应。在短时间内以高至优异的产量获得了产品。可以通过使用外部磁体将催化剂提取出来并在下一个反应周期中重新使用。

图形摘要

开发了非均相碱性磁性催化剂的合成方法，将其作为高效催化剂用于苯甲醛衍生物与氰基乙酸乙酯的Knoevenagel缩合反应。用二氧化硅涂覆Fe ₃ O ₄磁性纳米颗粒，然后用有机和无机化合物官能化是非常有效和有价值的过程。所制备的催化剂在无溶剂条件下表现出令人感兴趣的催化活性。