APPLIED CATALYSIS A-GENERAL
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2013
·
IF 3.41
Jin Zhao,Jun Xie,Chak-Tong Au,Shuang-Feng Yin
We report a new strategy for one-pot synthesis of potassium-loaded MgAl oxides using KOH to adjust the pH value of the reaction system. The as-prepared solid superbases were studied by N 2 physisorption method, energy-dispersive X-ray spectroscopy, powder X-ray diffraction, and Fourier transform infrared. The superbasic sites were characterized by the use of Hammett indicators and CO 2 temperature-programmed desorption. We found that with a base strength ( H – ) above 26.5, the potassium-loaded MgAl oxides showed high catalytic activity for Knoevenagel condensation at room temperature. Furthermore, the higher the superbasicity and/or the more the amount of superbasic sites, the better is the catalytic activity. The findings open up a new route for the synthesis of new functional superbases using composite oxides as supports.
研究领域:
催化化学
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材料科学
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产品关联
DOI
高影响因子
FIBERS AND POLYMERS
·
2018
·Vol. 19
·期 8
·1611-1617
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IF 1.353
Wang Cuie,Wang Ning,Liu Xinhua,Wan Peng,He Xinwei,Shang Yongjia
We propose a green synthesis of benzopyran compound based on immobilized lipase. Firstly, by using a combined electrospun membrane and biocompatible chitosan, we show that the chitosan-functionalized electrospun PMA-co-PAA fibrous membrane can provide effective anchoring sites for immobilization of the Candida antarctica lipase B (CALB), and a maximum loading amount of CALB (152 mg/g) can be achieved. Then, the resulting membrane displays enhanced stability in catalyzing Knoevenagel condensation reaction of salicylaldehyde with active methylene compound in mixed aqueousorganic media. The catalytic activity and stability of the CALB on chitosan-modified fiber is better than its non-immobilized counterpart. Furthermore, this immobilize CALB catalyst still retained about 45 % of the initial activity after 5 cycles, which potentially had implications for the design of “green” enzyme catalyst for sustainable organic synthesis.
研究领域:
生物化学
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绿色化学
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材料科学
✓ 已验证
DOI
高影响因子
DALTON TRANSACTIONS
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2023
·Vol. 52
·期 21
·7119-7128
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IF 4
Zhengguo Zhang,Hongxiao Lv,Kun Yang,Xiutang Zhang
Developing materials with excellent properties has become the norm in the field of basic research, prompting us to explore highly robust hybrid materials based on electron-rich POMs and electron-deficient MOFs. Herein, a θ-[Mo8O26]4−-based hybrid material of [Cu2(BPPP)2]{θ-[Mo8O26]} (NUC-62) with excellent physicochemical stability was self-assembled under acidic solvothermal conditions from Na2MoO4 and CuCl2 in the presence of a designed chelated ligand of 1,3-bis(3-(2-pyridyl)pyrazol-1-yl)propane (BPPP), which has sufficient coordination sites, spatial self-regulation and great deformation ability. In NUC-62, each of two tetra-coordinated CuII ions and two BPPP are unified into one dinuclear unit serving as the cation, which is interactively linked to θ-[Mo8O26]4− anions via rich hydrogen bonds of C–H⋯O. Because of the unsaturated Lewis acidic CuII sites, NUC-62 exhibits high catalytic performance on the cycloaddition reactions of CO2 with epoxides under mild conditions with a high turnover number and turnover frequency. Furthermore, NUC-62, as a recyclable heterogeneous catalyst, shows high catalytic activity for the esterification of aromatic acid under refluxing, which is much better than the inorganic acid catalyst of H2SO4 in terms of turnover number and turnover frequency. Moreover, because of open metal sites and rich terminal oxygen atoms, NUC-62 shows high catalytic activity for Knoevenagel condensation reactions of aldehydes and malononitrile. Hence, this study lays the groundwork for constructing heterometallic cluster-based microporous MOFs with excellent Lewis acidic catalysis and chemical stability. Therefore, this study lays a foundation for the construction of functional polyoxometalate complexes.
研究领域:
材料科学
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催化化学
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产品关联
DOI
PubMed
高影响因子
CATALYSIS LETTERS
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2021
·Vol. 152
·期 4
·1215-1223
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IF 3.186
Wang Yun,Cheng Hong,He Jia-Rui,Yao Qiao-Xia,Li Li-Ling,Liang Zhi-Hui,Li Xiang
The Knoevenagel condensation of acetylacetone and aromatic aldehyde catalyzed by lipase from porcine pancreas(PPL) and α-amylase from hog pancreas in ionic liquids and deep eutectic solvents was achieved for the first time. The highest yields is up to 96.1%. Mild reaction conditions, enhanced rates, improved yields and reagents’ reactivity which is different from that in standard organic solvents are the remarkable features observed in ionic liquids and deep eutectic solvents. Graphical Abstract
研究领域:
生物化学
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有机化学
✓ 已验证
DOI
高影响因子
Biomass Conversion and Biorefinery
·
2022
·
IF 4.05
Chen Lulu,Liu Shima,Pan Hu,Song Ke,Zhou Xianwu,Guo Jie,Zhuo Ou,He Jian
Exploitation of natural biopolymers as heterogeneous catalysts for biomass valorization is highly attractive as it renders the production processes to be sustainable and increases the economic competitiveness of bio-refinery. Herein, sodium alginate was for the first time developed as heterogeneous base catalyst for Knoevenagel condensation of furfural and acetylacetone to produce high-quality fuel precursor. A furfural conversion rate as high as 89.58% along with 86.47% yield of 3-(furan-2-ylmethylene)pentane-2,4-dione was obtained in ethanol at 140 °C with 10 h. The excellent catalytic performance of sodium alginate in Knoevenagel condensation of furfural with acetylacetone was confirmed by the low value (10.8 kJ/mol) of as-obtained activation energy. In addition, a plausible reaction mechanism for Knoevenagel condensation of furfural with acetylacetone over sodium alginate was proposed. Moreover, sodium alginate almost sustained its original activity in consecutive six reuse experiments and the durability of sodium alginate was characterized by several techniques. Furthermore, other bio-based aldehydes such as 5-hydroxymethylfurfural and 5-methylfurfural were also applicable in the as-established system with producing the corresponding fuel precursor in excellent yields.
研究领域:
生物化学
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可再生资源与环境科学
✓ 已验证
产品关联
DOI
高影响因子
AUSTRALIAN JOURNAL OF CHEMISTRY
·
2014
·Vol. 68
·期 6
·919-925
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IF 1.644
Jianping Wei,Fangmei Li,Junhui Xu,Xinhua Peng
New polynitrostilbenes were directly synthesised by the Knoevenagel condensation of aromatic aldehydes with nitrotoluenes. The differential scanning calorimetry results demonstrated that the introduction of an amino group and C=C double bonds could improve the thermal stability.
研究领域:
有机化学
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材料科学
✓ 已验证
DOI
高影响因子
ChemistrySelect
·
2024
·Vol. 9
·期 4
·e202304217
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IF 1.9
Jinfa Yu,Zhaoqin Luo,Xiangying Sun
Graphical NCDs-1, which is the first carbon dot by the microwave method using ethylenediamine and L-arginine, can serve as an efficient heterogeneous catalyst for the synthesis of cyclic carbonates from epoxides with CO 2 and Knoevenagel condensation under mild and solvent-free condition. A simple and convenient method for catalytic reactions with amine-terminated carbon dots was developed. Carbon dots (CDs) as new efficient catalysts have been developed for the Knoevenagel condensation reaction and the synthesis of cyclic carbonates under solvent-free conditions. Six kinds of carbon dots with different numbers of amino groups were synthesized. The amine-terminated carbon dot (NCDs-1) was synthesized using arginine and ethylenediamine by a microwave technique, and its catalytic action was studied. NCDs-1 with the highest numbers of amino groups was used as new metal-free and effective heterogeneous catalysts to perform essential Knoevenagel condensation and cycloaddition reactions in solvent-free conditions. 1 H NMR was used to demonstrate the Knoevenagel condensation mechanism, in situ Fourier infrared spectroscopy was used to investigate CO 2 cycloaddition and a catalytic mechanism was postulated. NCDs-1 showed a yield of 96.3±1.5 % for Knoevenagel condensation of benzaldehyde and malononitrile. In addition, NCDs-1/TBAB showed a yield of (97.0±1.0 %) of 4-phenyl-1,3-dioxolan-2-one for styrene oxide at 100 °C and 0.1 MPa in 1.5 h. A simple and convenient method for catalytic reactions with amine-terminated carbon dots was developed.
研究领域:
化学
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材料科学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2018
·Vol. 8
·期 5
·2357-2364
·
IF 2.936
Jianyun Yu,Xinxin Chen,Min Jiang,Anming Wang,Linlin Yang,Xiaolin Pei,Pengfei Zhang,Stephen Gang Wu
To develop an efficient and green immobilized biocatalyst for promiscuous catalysis which has a broad scope of applications, hybrid nanoflower (hNF) confined papain as a biocatalyst has been proposed and characterized in this study. hNFs were firstly prepared through mixing CuSO4 aqueous solution with papain in phosphate saline (PBS) at room temperature. The resulting hNFs were characterized by SEM and verified through a hydrolysis reaction with N-benzoyl-DL-arginine amide as substrate. Under optimal conditions, this nano-biocatalyst demonstrated a 15-fold hydrolytic activity compared with papain of free form, along with better thermal stability. A series of reaction factors (reaction temperature, time, and solvent) have been investigated for Knoevenagel condensation reactions with hNFs as catalyst. At optimal conditions, product yield of the hNFs catalyzed reaction was 1.3 fold higher than that of the free enzyme with benzaldehyde and acetylacetone as substrates. A few aldehydes and methylene compounds have also been used to test the generality and scope of this new enzymatic promiscuity. To sum up, the obtained hNFs demonstrate better catalytic properties than free papain and the inorganic metal-salt crystal can function as both support and promotor in biocatalysis.
研究领域:
生物化学
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材料科学
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酶工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Flow Chemistry
·
2018
·Vol. 8
·期 1
·29-34
·
IF 1.658
Yu Jiangang,Xu Jianguo,Li Jie,Jin Yi,Xu Wanghui,Yu Zhiqun,Lv Yanwen
A two-step flow reactor has been set up for an expeditious synthesis of 4-benzylidene-pyrazol-5-one derivatives. This procedure involved cyclization of aromatic hydrazine/ β -keto ester and subsequent Knoevenagel condensation reaction with aromatic aldehydes in tandem without isolation of intermediates. Residence time was reduced to less than 2 min in total through conducting this reaction at a relatively high temperature. Accordingly, 15 samples were achieved and isolated in moderate to excellent yields.
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研究领域:
有机化学
·
药物化学
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DOI
高影响因子
DYES AND PIGMENTS
·
2020
·
IF 4.613
Yan Gong,Xinjie Guo,Baohui Teng,Qian Zhang,Peng Zhang,Caifeng Ding
Malononitrile is a versatile dinitrile compound with high reactivity, which has wide prospect in application for multisynthetic organic medical chemistry and industrial manufacture. Considering of the transformation to HCN in animal tissue metabolism, malononitrile has potential environmental pollution and health risks. Here, a ratiometric fluorescent probe 4-(benzothiazol-2-yl)-2-hydroxy benzaldehyde (HBTA) for detection of malononitrile in organic and aqueous phase is developed on the basis of reaction-triggered fluorophore for the first time. The ratiometric assay with malononitrile-responsive fluorescence signal was contributed by Knoevenagel condensation and intramolecular cyclization , which was confirmed by HR-MS analysis and NMR titration spectra. In addition, this ratiometric probe provided a fancy strategy for detection of malononitrile with fast response, high sensitivity and selectivity, declaring excellent imaging performance in vivo capable of semi-quantification for malononitrile level.
研究领域:
有机化学
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分析化学
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环境科学
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生物医学
✓ 已验证
DOI
高影响因子
CRYSTENGCOMM
·
2020
·Vol. 22
·期 24
·4147-4153
·
IF 3.117
Ming-Yu Dou,Dan-Dan Zhong,Xian-Qiang Huang,Guo-Yu Yang
Polyoxometalate (POM) cluster organic frameworks (POMCOFs) are an emerging class of catalytic materials, providing an opportunity to develop fascinating catalysts with well-defined, tunable, active sites for a range of chemical transformations. Although remarkable progress on numerous POMCOF materials has been reported, the synthesis of polyoxovanadate (POV) cluster organic frameworks (POVCOFs) has seldom been reported. Thus, the exploration of novel POVCOFs still attracts considerable research interest. Additionally, Knoevenagel condensation as a versatile tool for the construction of CC bonds still continues to be a challenge at room-temperature and under solvent-free conditions. Herein, three POV-based clusters, [Ni(1-bIm)4]2(V4O12)·H2O (1), [Ni(1-eIm)(H2O)4]2(V10O28)(1-eImH)2·2H2O (2) and [Ni(H2O)5]2(V10O28)(1-pImH)2·4H2O (3) (1-bIm = 1-butylimidazole; 1-eIm = 1-ethylimidazole and 1-pIm = 1-propylimidazole), have been made. 1 was controllably achieved by an imidazole-induced self-assembly strategy and exhibited a 2D POVCOF in which circular [V4O12]4− clusters are bridged by four six-coordinated Ni(II) atoms (NiN4O2 model). 2 and 3 are obtained at lower pH values. Notably, among the three POV-based clusters, POVCOF 1 displays highly efficient heterogeneous solvent-free catalytic activity (yields of up to 99%) and excellent recyclability in Knoevenagel condensation at room temperature.
研究领域:
材料化学
·
催化化学
✓ 已验证
DOI
高影响因子
Biomass Conversion and Biorefinery
·
2022
·
IF 4.05
Wang Yun,Dong Kai-hui,Zhen Miao-lan,He Jia-Rui,Yao Qiao-xia
The Knoevenagel condensation of aromatic aldehydes and ethyl acetoacetate catalyzed by L-proline in water, ionic liquid, and deep eutectic solvents (DESs), respectively, was studied. The mild reaction conditions, enhanced rates, improved yields, and reagents’ reactivity are observed in deep eutectic solvents. The highest yields are up to 94.4%. The Z/E selectivity of products is up to 3.21. In addition, the influencing factors of product configuration were studied by calculation and experiment.
研究领域:
有机化学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）