Efficient and Reusable Pb(II) Metal–Organic Framework for Knoevenagel Condensation
作者:Miroslav Almáši、Vladimír Zeleňák、Maksym V. Opanasenko、Jiří Čejka
DOI:10.1007/s10562-018-2471-8
日期:2018.8
980 m2 g−1. To obtain open framework with unsaturated Pb(II) sites needed for catalysis, the thermal activation of the solvent exchanged sample was performed (DMF was exchanged by EtOH). The activated compound was tested in Knoevenagel condensation of bulky aldehydes and active methylene compounds at different temperatures. Excellent catalytic conversion and selectivity in condensation of small-sized aldehydes
°C); no leaching of the active phase was evidenced. In contrast, zeolites were not active under such reaction conditions. We propose an activation of malonitrile on a pair of adjacent Cu ions to explain the high catalyticactivity of CuBTC with respect to conventional catalysts. Compared with CuBTC, zeolites exhibited usually lower selectivities, which is ascribed to a high acid strength of their active
A new non-interpenetrating 3D metalâorganic framework [Ni4(μ6-MTB)2(μ2-H2O)4(H2O)4]·10DMF·11H2O}n (DMF = N,Nâ²-dimethylformamide) built from nickel(II) ions as connectors and methanetetrabenzoate ligands (MTB4â) as linkers has been synthesized and characterized. The single crystal X-ray diffraction showed that complex exhibits CaF2-like fluorite structure topology and four types of 3D channels with sizes about 12.6 à 9.4 à 2, 9.4 à 8.0 à 2, 12.6 à 11.7 à 2 and 14.9 à 14.9 à 2, which are filled with guest molecules. Conditions of the activation of the compound have been studied and optimized by powder X-ray diffraction during in situ heating, thermogravimetric analysis and infrared spectroscopy. Nitrogen and carbon dioxide adsorption showed that the activated sample exhibits a BET specific surface area of 700 m2 gâ1 and a carbon dioxide uptake of 12.36 wt% at 0 °C, which are the highest values reported for the compounds of the MTB4â series. The complex was tested in Knoevenagel condensation of aldehydes and active methylene compounds. Straightforward dependence of the substrate conversion on the size of used aldehyde was established. A possible mechanism of Knoevenagel condensation over a MTB4â containing a metalâorganic framework was proposed.
一种新型的非穿插三维金属有机框架[Ni4(μ6-MTB)2(μ2-H2O)4(H2O)4]·10DMF·11H2O}n(DMF=N,N'-二甲基甲酰胺)已经合成并表征。该框架由镍(II)离子作为连接器和甲烷四苯甲酸配体(MTB4-)作为连接件构建而成。单晶X射线衍射显示,该复合物表现出类似CaF2的萤石结构拓扑,并具有四种尺寸约为12.6×9.4Ų、9.4×8.0Ų、12.6×11.7Ų和14.9×14.9Ų的三维通道,这些通道中填充有客体分子。通过粉末X射线衍射、热重分析和红外光谱在原位加热过程中研究并优化了化合物的活化条件。氮气和二氧化碳吸附实验表明,活化样品的BET比表面积为700 m² g-1,在0°C时二氧化碳吸附量为12.36 wt%,这是MTB4-系列化合物中报道的最高值。该复合物在醛和活性亚甲基化合物的Knoevenagel缩合反应中进行了测试。确定了底物转化率与使用的醛大小的直接依赖关系。提出了MTB4-型金属有机框架上的Knoevenagel缩合反应的可能机制。
Microporous Lead–Organic Framework for Selective CO<sub>2</sub> Adsorption and Heterogeneous Catalysis
作者:Miroslav Almáši、Vladimír Zeleňák、Róbert Gyepes、Sandrine Bourrelly、Maksym V. Opanasenko、Philip L. Llewellyn、Jiří Čejka
DOI:10.1021/acs.inorgchem.7b02491
日期:2018.2.19
denoted as 1′) was tested in gas adsorption and catalytic experiments. The studies of gas sorption revealed that 1′ exhibits a surface area (Brunauer–Emmett–Teller) of 980 m2·g–1. This value is the highest reported for any compound from the MTB group. Interactions of carbondioxide (CO2) molecules with the framework, confirmed by density functional theory calculations, resulted in high CO2 uptake and significant
Amine-Catalyzed Three-Component Cascade Reaction between Alcohols or Thiols, Activated Alkenes, and Enones: A Simple and Chemoselective Synthesis of Densely Functionalized Compounds
作者:Zhengjie He、Haiyun Sun、Bo Zhang、Xiangyu Chen
DOI:10.1055/s-0036-1588716
日期:——
three-component cascade reaction among alcohols or thiols, electron-deficient alkenes, and α,β-unsaturated ketones takes place under the catalysis of triethylamine, providing densely functionalized chain products in 44–99% yields. The transformation presumably proceeds through a sequential cascade of hetero-Michael/Michael reactions. A highly chemoselective three-component cascade reaction among alcohols or