Ionic liquid immobilized on Fe3O4 nanoparticles: a magnetically recyclable heterogeneous catalyst for one-pot three-component synthesis of 1,8-dioxodecahydroacridines
作者:Heshmatollah Alinezhad、Mahmood Tajbakhsh、Neda Ghobadi
DOI:10.1007/s11164-015-2003-8
日期:2015.12
A magnetically recoverable nanocatalyst based on 1-methylimidazolium hydrogen sulfate ionic liquid has been synthesized by reaction of 1-methylimidazole with 3-(trimethoxysilyl)propyl chloride group, leading to formation of 1-methyl-3-(triethoxysilyl)propyl imidazolium chloride ([pmim]Cl). The ionic liquid was anchored onto silica-coated magnetic Fe3O4 particles, and Cl− anion exchange by treatment with H2SO4 afforded the corresponding immobilized ionic liquid MNP-[pmim]HSO4. The synthesized catalyst was characterized by various techniques such as Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), (differential) thermogravimetry (TG/DTG), CHN analysis, and vibrating-sample magnetometry (VSM), revealing the superparamagnetic nature of the particles. From electron microscopy (SEM and TEM) studies it can be inferred that the particles were mostly spherical in shape with average size of 20 nm. The loading amount of ionic liquid supported on the magnetic particles was indicated to be 0.98 mmol/g by the results of elemental and thermogravimetric analyses (CHN and TG). The catalytic activity of the supported ionic liquid was examined in synthesis of 1,8-dioxodecahydroacridines by condensation reaction of cyclic diketones with aromatic aldehydes and ammonium acetate or primary amines under solvent-free conditions. The catalyst could be easily recovered by applying an external magnetic field and reused for at least nine runs without deterioration in catalytic activity.
一种基于1-甲基咪唑硫酸氢盐离子液体的磁性可回收纳米催化剂已通过1-甲基咪唑与3-(三甲氧基硅基)丙基氯反应合成,导致形成1-甲基-3-(三乙氧基硅基)丙基咪唑氯([pmim]Cl)。将该离子液体固定在涂有二氧化硅的磁性Fe3O4粒子上,并通过用H2SO4处理置换Cl−阴离子,得到了相应的固定化离子液体MNP-[pmim]HSO4。该合成的催化剂通过傅里叶变换红外(FT-IR)光谱、X射线衍射(XRD)分析、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、(差示)热重分析(TG/DTG)、CHN元素分析和振动样品磁力计(VSM)等多种技术进行表征,显示了粒子的超顺磁性质。从电子显微镜(SEM和TEM)研究可以推断,粒子大多呈球形,平均尺寸为20 nm。根据元素和热重分析(CHN和TG)的结果,固定在磁性粒子上的离子液体的负载量为0.98 mmol/g。在无溶剂条件下,通过环状二酮与芳香醛和乙酸铵或伯胺的缩合反应,研究了该固定化离子液体的催化活性,用于合成1,8-二氧十氢吖啶。该催化剂可通过施加外部磁场轻松回收,并可重复使用至少九次而不会降低催化活性。