Ionic liquid-functional MCM-41 as a high effective catalyst for the synthesis of isatylidene malononitrile via Knoevenagel condensation

Ionic liquid functional MCM-41 was synthesized, characterized and used as heterogeneous catalyst for the Knoevenagel condensation of isatins with malononitrile. A series of corresponding isatylidene malononitrile were obtained in high isolated yield (96–99%) at room temperature in a short time. The heterogeneous catalyst can be easily recovered by centrifugation and showed almost no loss of activity over 10 recycle experiments. At the same time, the gram-scale experiments showed excellent yields and provided a highly effective method for scale up applications.     

MCM-41 anchored sulfonic acid (MCM-41-R-SO3H): A mild, reusable and highly efficient heterogeneous catalyst for the Biginelli reaction

An efficient three-component synthesis of 3A-dihydropyrimidinones using MCM-41 anchored sulfonic acid (MCM-41-R-SO3H) as a mild, heterogeneous catalyst for Biginelli reaction in CH3CN under reflux condition is described.     

Polycarbosilane‐supported titanium(IV) catalyst for Knoevenagel condensation reaction

Polycarbosilane (PCS) was synthesized by the polycondensation of trichloromethylsilane and trimethoxyvinylsilane in the presence of sodium metal. PCS has a highly crosslinked structure, high ceramic yield and high surface area. Titanium metal ion was attached to the polycarbosilane and its catalytic activity was investigated. The Knoevenagel condensation reaction catalysed by titanium‐incorporated polycarbosilane is reported. The titanium‐incorporated PCS catalysed the reaction well and with a diverse set of substrates the reaction proceeded with good yield. PCS‐supported transition metal catalysts have been prepared for the first time and used successfully in the Knoevenagel condensation reaction. Copyright © 2012 John Wiley & Sons, Ltd.     

Mn-MOF@Pi composite: synthesis,characterisation and an efficient catalyst for the Knoevenagel condensation reaction

We have synthesised new Mn-MOF@Pi composite by encapsulation of piperidine in desolvated Mn-MOF and investigated its catalytic performance in Knoevenagel condensation reaction. The newly developed composite is compatible with various aromatic aldehydes and converting them to the desired Knoevenagel condensation products in good yields and selectivity. Furthermore, composite Mn-MOF@Pi is reusable and shows good catalytic activity than native MOF.     

MCM-41 anchored sulfonic acid （MCM-41-R-SO3H）： A mild,reusable and highly efficient heterogeneous catalyst for the Biginelli reaction

An efficient three-component synthesis of 3,4-dihydropyrimidinones using MCM-41 anchored sulfonic acid （MCM-41-R-SO3H） as a mild, heterogeneous catalyst for Biginelli reaction in CH3CN under reflux condition is described.     

Magnetic nanoparticle supported amine: An efficient and environmental benign catalyst for versatile Knoevenagel condensation under ultrasound irradiation

Amine functionalized silica coated Fe₃O₄ nanoparticles (SiO₂@MNP-A) were successfully prepared as a novel heterogeneous amine. The catalyst was characterized by XRD, FT-IR, TEM, magnetic measurement, elemental analysis and was found to be a magnetically separable and highly active catalyst for ambient Knoevenagel condensation of aromatic aldehydes and α-aromatic (heteroaromatic or polyaromatic)-substituted methylene compounds in water under ultrasonic irradiation to afford the corresponding products in good to excellent yields. Very interestingly, SiO₂@MNP-A successfully catalyze the reaction of the non-cyano substituted compound with benzaldehyde to achieve a key intermediate for the preparation of Atorvastatin calcium in green and atom-economic manner. In addition, the catalyst SiO₂@MNP-A can be reused for 8 times without any obvious loss of its activity. The role of ultrasonication in the Knoevenagel condensation was also discussed with the assistance of UV–vis spectrometry.     

中孔MCM-41锚合Zr（IV）-salen催化剂制备及用于硫化物氧化制亚砜和Knoevenagel缩合反应

通过NH2-MCM-41与水杨醛反应得到席夫碱配体,然后加入八水氧氯化锆形成络合物,制得Zr(IV)-salen-MCM-41催化剂。采用X射线衍射、N2吸附-脱附、热重、红外光谱、电感耦合等离子体发射光谱和能量散射谱等分析手段对催化剂结构进行了表征。在含有该催化剂的体系中进行了硫化物选择氧化为亚砜以及醛与丙二腈和氰乙酸乙酯的Knoveonagel缩合反应,并考察了催化剂的循环使用性能。     

Dicalcium phosphate dehydrate DCPD as a highly efficient and reusable catalyst for Knoevenagel condensation

We have described the catalytic activities of dicalcium phosphate dihydrate (DCPD) in the condensation reaction of various substituted benzaldehydes with active methylene compound malononitrile. The influences of reaction conditions on the corresponding catalytic behavior have been investigated. The results showed that the DCPD exhibited high catalytic activity and versatility and that it can be recycled without significant loss of its activity for the condensation reactions, which shows the material is a promising new type of heterogeneous catalyst for the condensation reactions. Meanwhile, the catalytic results of DCPD compared favorably with those of other materials for Knoevenagel reactions reported previously.     

中孔MCM-41负载Ru纳米粒子催化剂用于超声辐射下芳烃选择氧化反应

以中孔MCM-41为载体制得均一分散的粒径约5nm的Ru纳米粒子催化剂MCM-41-Ru,采用电感耦合等离子体、透射电镜、能量散射谱、X射线衍射和N2吸附-脱附法对其进行了表征,并将其作为可重复使用高效催化剂用于超声辅助芳烃选择氧化反应.结果表明,在超声辐射和KBrO3为氧化剂条件下,MCM-41-Ru催化剂加速了氧化反应,并以较高产率得到目的产物.回收的催化剂用于下次反应时活性保持不变,但其活性中心性质发生变化.     

Hydrotalcite catalysis in ionic liquid medium: a recyclable reaction system for heterogeneous Knoevenagel and nitroaldol condensation

Knoevenagel condensation proceeds efficiently in recyclable [bmim]PF₆ and [bmim]BF₄ without any catalyst, and hydrotalcites in ionic liquid serve as a safe and recyclable reaction system for both Knoevenagel as well as nitroaldol condensations.     

Lithium hydroxide: A simple and an efficient catalyst for Knoevenagel condensation under solvent-free Grindstone method

Synthesis of arylmethylidenes from araldehydes and active methylene compounds catalyzed by catalytic amount of lithium hydroxide (LiOH·H₂O) in the absence of a solvent under Grindstone method is reported. The reactions go to completion within 1–5 min and give products in excellent yields at 26 °C.     

Sevelamer as an efficient and reusable heterogeneous catalyst for the Knoevenagel reaction in water

A catalyst system of Sevelamer, a phosphate-binding drug, has been prepared and used in the Knoevenagel reaction of aromatic aldehydes in water to produce substituted electrophilic alkenes. The products were obtained in excellent yields. Several novel, related catalytic systems showed promising catalytic properties for aromatic and heterocyclic aldehydes. The Sevelamer catalyst can be recovered using simple filtration and reused numerous times（up to 15 times） in the aqueous Knoevenagel reaction without any significant lowering of activity.     

高氮含量MCM-41的制备及其对Knoevenagal缩合反应的催化性能

 采用二次合成法制备了含氮MCM-41分子筛,系统考察了氨气流速、氮化温度和氮化时间等因素对分子筛氮含量的影响,并通过X射线衍射、 N2吸附、透射电镜、 X射线光电子能谱和 29Si MAS NMR等方法探测了氮化后分子筛的物理化学特性. 结果表明,氨气流速和氮化温度是影响分子筛氮含量的主要因素. 氨气流速为400 ml/min时, 950 ℃下经12 h氮化后的MCM-41分子筛氮含量(质量分数)可达26.0%, 并较好地保持了原有分子筛的骨架结构. 由于氮化温度相对较低,对分子筛的结构破坏较小,而氮含量高、氮化后的MCM-41分子筛对Knoevenagal缩合反应具有很高的碱催化活性.     

MCM-41-supported bidentate phosphine palladium(0) complex: a highly active and recyclable catalyst for the Sonogashira reaction of aryl iodides

The first MCM-41-supported bidentate phosphine palladium(0) complex has been prepared. This complex is a highly efficient catalyst for Sonogashira reaction and can be reused at least 10 times without any decrease in activity.     

A novel MCM-41-supported sulfur palladium(0) complex catalyst for Sonogashira coupling reaction

A novel MCM-41-supported sulfur palladium(0) complex was conveniently prepared from commercially available and cheap γ-mercaptopropyltriethoxysilane via immobilization on MCM-41, followed by reacting with palladium chloride and then the reduction with hydrazine hydrate. This complex exhibited excellent performance in Sonogashira coupling reaction.     

有机胺修饰稀土金属有机骨架：用于Knoevenagel缩合反应的三种固体碱催化剂

稀土金属有机骨架(Ln-MOFs)是利用有机配体和稀土离子之间配位自组装形成的具有超分子多孔网络结构的类沸石材料,其优点是稳定性好,一般不溶于常规的有机和无机溶剂,并且孔径、孔形及孔表面性质可通过其构建分子的选择或修饰进行灵活设计和制备.稀土离子性能独特,有机配体种类繁多,将稀土离子与有机配体可控组装可获得许多结构多样、性能优异的Ln-MOFs材料.这些功能材料已在气体吸附与分离、发光器件、化学传感以及磁性材料等多方面显示出潜在应用价值.特别是Ln-MOFs材料作为非均相催化剂具有热稳定性高、比表面积大以及稀土离子配位环境多样等优点,近年来受到国内外研究者关注和重视.后合成修饰法(PSM)是利用MOFs骨架中不饱和配位的金属离子或潜在的有机反应基团,通过配位键或共价键方式引入有机或无机分子,制备具有新功能的骨架材料.本文采用PSM策略,将三种不同的有机二胺后合成修饰到具有配位不饱和位点的稀土金属有机骨架[Er(btc)]的孔道中,得到三种固体碱催化剂：Er(btc)(ED)0.75(H2O)0.25(2), Er(btc)(PP)0.55(H2O)0.45(3)和Er(btc)(DABCO)0.15(H2O)0.85(4).其中, btc为1,3,5-均苯三甲酸, ED为乙二胺, PP为哌嗪, DABCO位为三乙烯二胺.单晶结构分析表明,在[Er(btc)(H2O)]·DMF0.7(1)中,铒离子与六个btc配体的六个羧酸氧原子和一个水分子配位,形成变形的五角双锥几何构型.每个btc配体连接六个铒离子构成具有一维开放孔道(0.7 nm′0.7 nm)的三维立体结构.重要的是,孔道中的配位水分子和游离DMF分子可通过真空加热除去而不影响其骨架结构(热稳定性达500 oC),这将有利于对其进行后合成修饰.热重分析(TGA)表明,催化剂2在25–300 oC失去孔道中配位的乙二胺和水分子;催化剂3在250 oC之前失去孔道中的哌嗪和水分子;催化剂4则在100 oC之前失去孔道中配位的三乙烯二胺和水分子.粉末X射线衍射(PXRD)结果显示,后合成修饰过程并没有改变催化剂骨架的稳定性,其稳定性在空气中超过30 d.氮气吸附实验表明, Ln-MOF 1的比表面积和孔体积分别为2000 m2/g和0.75 cm3/g,平均孔尺寸为0.65 nm,与晶体结构分析结果基本一致.相比之下,后合成修饰的催化剂2的比表面积明显降低,为650 m2/g,而催化剂3和4由于后修饰较大体积的二胺分子(哌嗪和三乙烯二胺),表现出可忽略的氮气吸附能力.上述结果表明,催化剂2具有较高的有机胺负载量、较高的热稳定性和多孔性.采用苯甲醛和丙二腈的Knoevenagel缩合反应研究了三种固体碱的非均相催化能力.结果表明,在相同反应条件下,催化剂2具有很好的首次催化能力(99%),优于催化剂3(93%)和4(63%).并且,催化剂2循环使用三次后,催化能力几乎没有改变,而催化剂3和4的催化能力则逐渐降低,催化剂4在第三次使用时已无催化能力.滤出实验显示,催化剂2在反应过程中无活性物种离去进入液相体系中,即无乙二胺分子从催化剂骨架孔道中离去,证明其为非均相催化本质.而催化剂3和4则在反应过程中有二胺分子离去,进入反应液相中,从而导致其循环使用催化能力降低.催化剂2的底物择形催化反应结果显示,先是丙二腈分子进入催化剂孔道中,形成碳负离子,然后亲核进攻醛分子生成产物.因此,体积较大的腈衍生物因不能进入孔道而不能发生反应,而体积较大的醛分子则不受影响,能顺利地发生反应.     

MCM-41-anchored sulfonic acid (MCM-41-SO3H): An efficient heterogeneous catalyst for green organic synthesis

MCM-41-anchored sulfonic acid (MCM-41-SO₃H) used as a solid acid catalyst has been reported in recent years for various synthetic protocols. The superior advantage of MCM-41-SO₃H is that it can be recovered and reused several times without loss of its efficiency. In this tutorial review, we attempt to give an overview of the use of MCM-41-SO₃H as a solid and heterogeneous catalyst in the synthesis of various organic compounds that have industrial and pharmaceutical applications.     

Synthesis of MCM-41 supported amino-palladium complex and its catalytic performance for heck reaction

Using MCM-41 as the supporter, a series of MCM-41 supported amino-palladium complexes has been prepared and characterized by XRD (X-ray diffraction) and XPS (X-ray photoelectron spectroscopy), etc. The XRD and XPS results indicate that the Pd coordinates with the -NH₂ groups on the MCM-41 surface, and the structure of MCM-41 has been not damaged. Its catalytic performance for Heck arylation of alkene with aryl iodide shows that the catalysts have high activity and stereoselectivity in 70–90°C. The product of Heck reaction is in E form. And the effect of the preparation condition of catalyst on the catalytic performance was examined. Translated form Chinese Journal of Organic Chemistry, 2008, 28(5) (in Chinese)     

Synthesis of WO2pyprMCM-41 as selective and reusable catalyst for the epoxidation of alkenes

The sythesis, characterization and catalytic activity of WO₂pypr [N,N′-bis (2-pyrrolmethlidenaminopropyl) amine] complexed to MCM-41 surface in the epoxidation of some alkenes with excellent selectivity toward the corresponding epoxides is described in this presentation.     

MCM-41-supported bidentate phosphine palladium(0) complex as an efficient catalyst for the heterogeneous Stille reaction

A Stille coupling reaction of organostannanes with organic halides has been developed in the presence of a catalytic amount of MCM-41-supported bidentate phosphine palladium(0) complex (0.5 mol %) in DMF/H₂O (9:1) under air atmosphere in high yields. This polymeric palladium catalyst exhibits higher activity than Pd(PPh₃)₄ and can be reused at least 10 times without any decrease in activity.