Abstract

In the present investigation, magnetic ferrite nanoparticles (ferrite NPs) were synthesized and coated with silica (ferrite@SiO₂NPs) by using the sol-gel method. After that, silica propylmethylimidazolium chloride ionic liquid [Sipmim]Cl was prepared and linked with the above-prepared ferrite@SiO₂NPs to synthesize ferrite silica propylmethylimidazolium chloride [Fesipmim]Cl catalyst. The formation of [Fesipmim]Cl catalyst was confirmed by Fourier-transform infrared (FT-IR) spectroscopy analysis. X-ray diffraction (XRD) analysis confirmed the structure of ferrite NPs and ferrite@SiO₂ NPs. Transmission electron microscopy (TEM) evidenced the successful formation of ferrite NPs and ferrite@SiO₂ NPs. Scanning electron microscopy (SEM) results revealed the change in morphology of ferrite NPs, ferrite@SiO₂NPs and [Fesipmim]Cl. The magnetic properties of [Fesipmim]Cl catalyst were measured by vibrating sample magnetometer (VSM). The efficiency of the [Fesipmim]Cl catalyst was checked by using it for the synthesis of different derivatives of dihydropyridine through Hantzsch reaction via a three-component coupling reaction of substituted benzaldehydes, ethyl/ methyl acetoacetate and ammonium acetate. The formation and structures of all the synthesized compounds were confirmed by FT-IR, ¹HNMR, ¹³C NMR spectral analyses. The reusability of the catalyst [Fesipmim]Cl was checked up to seven cycles and found to have excellent activity up to five cycles.

Graphic abstract

中文翻译：

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[Fesipmim] Cl是高效且可重复使用的催化剂，用于通过Hantzsch反应无溶剂合成二氢吡啶衍生物

摘要

在本研究中，合成了磁性铁氧体纳米粒子（铁氧体NPs）并通过溶胶-凝胶法用二氧化硅（ferrite @ SiO ₂ NPs）进行了包覆。然后，制备二氧化硅丙基甲基咪唑氯化物离子液体[Sipmim] Cl，并与上述制备的铁氧体@SiO ₂ NPs连接，以合成铁氧体二氧化硅丙基甲基咪唑氯化物[Fesipmim] Cl催化剂。[Fesipmim] Cl催化剂的形成通过傅立叶变换红外（FT-IR）光谱分析确认。X射线衍射（XRD）分析证实了铁氧体NPs和铁氧体@SiO ₂ NPs的结构。透射电子显微镜（TEM）证明成功形成了铁素体NP和铁素体@SiO ₂NP。扫描电子显微镜（SEM）结果表明，铁氧体NPs，铁素体@SiO ₂ NPs和[Fesipmim] Cl的形态发生了变化。通过振动样品磁力计（VSM）测量[Fesipmim] Cl催化剂的磁性。[Fesipmim] Cl催化剂的效率通过使用Hantzsch反应，通过取代的苯甲醛，乙酰乙酸乙酯/乙酰乙酸甲酯/乙酸铵的三组分偶联反应，用于合成二氢吡啶的不同衍生物来检查其效率。FT-IR，¹ HNMR，¹³证实了所有合成化合物的形成和结构。1 H NMR光谱分析。对催化剂[Fesipmim] Cl的可重复使用性进行了多达七个循环的检查，发现其具有出色的活性（长达五个循环）。

图形摘要