2025-40-3Relevant articles and documents
Highly active hybrid mesoporous silica-supported base organocatalysts for C–C bond formation
Erigoni,Hernández-Soto,Rey,Segarra,Díaz
, p. 227 - 236 (2020)
New base hybrid catalysts, based on silyl-derivatives of molecules carrying amino, diamino, pyrrolidine, pyrazolium and imidazolium functionalities have been successfully achieved through post synthetic grafting onto M41S-type support. Different character
H3PW12O40/mpg-C3N4 as an efficient and reusable bifunctional catalyst in one-pot oxidation-Knoevenagel condensation tandem reaction
Wang, Hefang,Wang, Cunyue,Yang, Yongfang,Zhao, Meng,Wang, Yanji
, p. 405 - 417 (2017)
A single-site bifunctional catalyst for the oxidation-Knoevenagel condensation tandem reaction was prepared by the immobilization of phosphotungstic acid (HPW) on mesoporous graphitic carbon nitride (mpg-C3N4) via electrostatic interaction (HPW/mpg-C3N4). The results of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), solid-state 31P nuclear magnetic resonance (solid-state 31P NMR), zeta potentials, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) demonstrated that HPW was successfully immobilized on the protonated mpg-C3N4 by electrostatic interaction. The acid amounts of the catalysts were determined by NH3 temperature programmed desorption (NH3-TPD). The textural properties and morphology of HPW/mpg-C3N4 were characterized by N2 adsorption-desorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). 30% HPW/mpg-C3N4 shows the best catalytic performance in the tandem reaction with 98.4% benzyl alcohol conversion and 96.2% selectivity to benzylidene malononitrile. The excellent catalytic performance of 30% HPW/mpg-C3N4 in the tandem reaction is due to the good catalytic performance of HPW in the oxidation and Knoevenagel condensation, respectively. Furthermore, protonated mpg-C3N4 not only acts as a support to facilitate good dispersion of HPW but also promotes the Knoevenagel condensation reaction effectively. Moreover, the HPW/mpg-C3N4 catalyst could be recycled easily without significant loss of catalytic activity.
Knoevenagel condensation catalysed by new montmorillonitesilylpropylethylenediamine
Subba Rao,Choudary
, p. 1163 - 1166 (1991)
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Polystyrene Nanometer-Sized Particles Supported Alkaline Imidazolium Ionic Liquids as Reusable and Efficient Catalysts for the Knoevenagel Condensation in Aqueous Phase
Ma, Min,Li, Hansheng,Yang, Wang,Wu, Qin,Shi, Daxin,Zhao, Yun,Feng, Caihong,Jiao, Qingze
, p. 134 - 143 (2018)
Abstract: Polystyrene nanometer-sized particles supported alkaline 1-propyl imidazolium ionic liquids catalysts (nano-PS-CH2-[pIM][B]) were prepared and characterized by FT-IR, SEM, TG/DTA, BET and particle size distribution analysis. The resul
Efficient bifunctional reactivity of K-doped CrO(OH) nanosheets: Exploiting the combined role of Cr(iii) and surface -OH groups in tandem catalysis
Vernekar, Dnyanesh,Ratha, Satyajit,Rode, Chandrashekhar,Jagadeesan, Dinesh
, p. 1154 - 1164 (2019)
This work reports the bifunctional catalytic activity of layered K-doped α-CrO(OH). The combined action of the redox active Cr(iii) and the surface hydroxyl groups was efficiently used to carry out 2-3 oxidation reactions in tandem followed by condensation/coupling reactions in one pot. Oxidation of benzyl alcohol followed by Knoevenagel condensation or coupling reactions forming C-C and C-N linkages in one pot is demonstrated. The catalyst has been characterized using XRD, IR, TGA, CO2-TPD, cyclic voltammetry, XPS and microscopic techniques to gain insight into the nature of active sites. The role of O- and O2- on the CrO(OH) catalyst in the bifunctional activity was studied using analytical techniques. Recyclability and leaching tests confirmed that K-α-CrO(OH) is a stable and environmentally safe catalyst.
Synthesis of cyclopropane-1,1,2,2-tetracarboxylic acid derivatives from aldehydes and CH-acids in the K2CO3/Bun 4NPF6/toluene heterogeneous system
Kryshtal, G. V.,Zhdankina, G. M.,Zlotin, S. G.
, p. 2286 - 2290,5 (2011)
A one-pot method for the synthesis of cyclopropane-1,1,2,2-tetracarboxylic derivatives was developed starting from aldehydes and cyanoacetic and 2-bromomalonic esters under heterogeneous conditions (K2CO 3/PhMe) in the presence of re
Highly active zinc oxide-supported lithium oxide catalyst for solvent-free Knoevenagel condensation
Basude, Manohar,Bhongiri, Yadagiri,Masula, Keshavulu,Pasala, Vijay Kumar,Puppala, Veerasomaiah,Sunkara, Prasad
, (2021/07/09)
Li2O/ZnO catalyst was prepared by wet impregnation method and characterized by XRD, SEM, EDX, FTIR, BET surface area and UV-Vis diffuse reflectance spectroscopy. This study revealed a decrease in average particle size and change in the shape of
Synthesis of lithium/cesium-Zagronas from zagrosian natural asphalt and study of their activity as novel, green, heterogeneous and homogeneous nanocatalysts in the Claisen–Schmidt and Knoevenagel condensations
Soleiman-Beigi, Mohammad,Ghalavand, Saba,Venovel, Hadis Gholami,Kohzadi, Homa
, p. 3267 - 3279 (2021/06/17)
A novel, heterogeneous and homogeneous basic nanocatalysts were synthesized by grafting of lithium and cesium on zagrosian natural asphalt sulfonate (Li/Cs-Zagronas). The activity of these catalysts was examined in the Claisen–Schmidt and Knoevenagel condensations under mild reaction conditions. Li/Cs-Zagronas were characterized by FT-IR spectroscopy, scanning electron microscopy, X-ray diffraction, energy-dispersive spectroscopy, inductively coupled plasma and thermogravimetric analysis techniques. These nanocatalysts were removed by simple filtration and reused several times without any deterioration of activity.
MOFs assembled from C 3symmetric ligands: Structure, iodine capture and role as bifunctional catalysts towards the oxidation-Knoevenagel cascade reaction
Zhang, Ying-Ying,Liu, Qing,Zhang, Lin-Yan,Bao, Yu-Mei,Tan, Jing-Yi,Zhang, Na,Zhang, Jian-Yong,Liu, Zhen-Jiang
, p. 647 - 659 (2021/01/28)
Three new NiII/CoII-metal organic frameworks were self-assembled by the reaction of C3 symmetric 1,3,5-tribenzoic acid (H3BTC) and 2,4,6-tris(4-pyridyl)-1,3,5-triazine (4-TPT) ligands and NiII/CoII salts under solvothermal conditions. Isomorphous MOF1 and MOF2 exhibit a 3D pillar-layer framework based on binuclear M2(OH)(COO)2 units connected by tritopic BTC3- and 4-TPT ligands with a novel (3,5)-connected topology net. MOF3 displays a 3-fold interpenetrated 3D network exhibiting a (3,4)-connected topology net. The porous MOF3 can reversibly take up I2. The activated MOFs contain both Lewis acid (NiII center) and basic (uncoordinated pyridyl or carboxylic groups) sites, and act as bifunctional acid-base catalysts. The catalytic measurements demonstrate that the activated MOF3 exhibits good activities for benzyl alcohol oxidation and the Knoevenagel reaction and can be recycled and reused for at least four cycles without losing its structural integrity and high catalytic activity. Thus, the catalytic properties for the oxidation-Knoevenagel cascade reaction have also been studied.
