- Biomass-derived metal-organic hybrids for CO2 transformation under ambient conditions
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The fabrication of catalysts that can activate CO2 under ambient conditions is very interesting but challenging. Metal-organic hybrids (MOHs) have promising applications in catalysis, and their fabrication from renewable resources is very attractive. Herein, we report a simple protocol to fabricate metal-organic hybrids (MOHs) from chitosan, phytic acid and ZnCl2, obtaining mesoporous MOH-Zn possessing-OH,-NH2, and-PO4 groups. The resulting MOH-Zn shows excellent activity for CO2 activation and enables the cyclization of epoxides with CO2 to proceed under ambient conditions, affording a high turnover frequency of 7.8 h-1. The high performance of MOH-Zn originates from the synergistic effects among multi-functional sites in the catalysts.
- Guo, Shien,Han, Buxing,Li, Dongyang,Liu, Zhimin,Wang, Huan,Wu, Yunyan,Zhang, Jing,Zhao, Yanfei,Zhao, Zhijuan,Zuo, Shouwei
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- N-Heterocyclic carbene-nitrogen molybdenum catalysts for utilization of CO2
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Three new N-heterocyclic carbene-nitrogen molybdenum complex was synthesized, and its catalytic activity was evaluated in the cycloaddition of epoxides with CO2. The molybdenum complex combined with tetrabutyl ammonium iodide (TBAI) resulted in a catalytic system for efficient conversion of a wide range of terminal and internal epoxides under 80 °C and 5–7 bar pressure for CO2. The cooperative catalysis mechanism between molybdenum complex and TBAI was elucidated, in which molybdenum complex was used as Lewis acid, and TBAI was employed as nucleophilic reagent. In addition, the NHC-Mo catalytic system was also successfully applied for the direct carboxylation of terminal alkynes with CO2.
- Chen, Fei,Tao, Sheng,Liu, Ning,Dai, Bin
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- Cycloaddition of carbon dioxide and epoxides catalyzed by rare earth metal complexes bearing a Trost ligand
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A series of rare earth metal complexes (Sm (1), Eu (2), Y (3), Yb (4), and Lu (5)) based on Trost ligands were synthesized and well characterized, and catalyzed the cycloaddition of carbon dioxide and epoxides successfully. The combination of 1 mol% Sm-based complex1with 2 mol% tetrabutylammonium bromide (TBAB) was proved to be the optimal catalyst system for the formation of the monosubstituted cyclic carbonate at 70 °C under the atmospheric pressure. While for the more challenging disubstituted epoxides, the adduct cyclic carbonates were successfully obtained when the pressure of CO2was elevated to 0.7 MPa.
- Cheng, Jun,Lu, Chengrong,Zhao, Bei
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p. 13096 - 13103
(2021/08/04)
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- Catalytic, Kinetic, and Mechanistic Insights into the Fixation of CO2 with Epoxides Catalyzed by Phenol-Functionalized Phosphonium Salts
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A series of hydroxy-functionalized phosphonium salts were studied as bifunctional catalysts for the conversion of CO2 with epoxides under mild and solvent-free conditions. The reaction in the presence of a phenol-based phosphonium iodide proceeded via a first order rection kinetic with respect to the substrate. Notably, in contrast to the aliphatic analogue, the phenol-based catalyst showed no product inhibition. The temperature dependence of the reaction rate was investigated, and the activation energy for the model reaction was determined from an Arrhenius-plot (Ea=39.6 kJ mol?1). The substrate scope was also evaluated. Under the optimized reaction conditions, 20 terminal epoxides were converted at room temperature to the corresponding cyclic carbonates, which were isolated in yields up to 99 %. The reaction is easily scalable and was performed on a scale up to 50 g substrate. Moreover, this method was applied in the synthesis of the antitussive agent dropropizine starting from epichlorohydrin and phenylpiperazine. Furthermore, DFT calculations were performed to rationalize the mechanism and the high efficiency of the phenol-based phosphonium iodide catalyst. The calculation confirmed the activation of the epoxide via hydrogen bonding for the iodide salt, which facilitates the ring-opening step. Notably, the effective Gibbs energy barrier regarding this step is 97 kJ mol?1 for the bromide and 72 kJ mol?1 for the iodide salt, which explains the difference in activity.
- Hu, Yuya,Wei, Zhihong,Frey, Anna,Kubis, Christoph,Ren, Chang-Yue,Spannenberg, Anke,Jiao, Haijun,Werner, Thomas
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p. 363 - 372
(2020/11/30)
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- Synthesis of carbonates from CO2 and epoxides catalyzed by the system of N-heterocyclic carbene, hydrogen bond donor, CrCl2, and tetrabutylammonium bromide
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A three-component catalytic system including pyridine-bridged benzimidazolium salts, CrCl2, and tetrabutylammonium bromide (TBAB) was developed. Based on the control experiments and spectroscopic measurements, the role of the three components in the catalytic process was clarified, in which benzimidazolium salts were used as N-heterocyclic carbene precursor, a new Cr complex generating from the coordination of CrCl2 with pyridine nitrogen and pyrazole nitrogen bearing benzimidazolium salts was employed as hydrogen bond donor, TBAB was used as nucleophilic reagent, respectively. Under mild conditions (50°C and 1?bar CO2), the terminal epoxides displayed high reactivity in the three-component catalytic system. The catalytic system showed also high catalytic activity for the internal epoxides by increasing the temperature and CO2 pressure and/or prolonging the reaction time.
- Zhang, Kuikui,Liu, Zhenbang,Liu, Ning
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- Method for preparing cyclic carbonate by immobilizing CO2 under catalysis of organic boric acid
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The invention discloses a synthesis method for synergistically catalyzing carbon dioxide immobilization through weak Lewis acid phenylboronic acid and tetrabutylammonium bromide. According to the method, CO2 is immobilized by epoxide, and a cyclic carbonate product is generated. The method comprises the following step: under the concerted catalysis of phenylboronic acid and tetrabutylammonium bromide, performing reaction on epoxide as shown in a formula IV, a formula V or a formula VI and carbon dioxide to respectively obtain a cyclic carbonate product as shown in a formula I, a formula II or a formula III. According to the method, raw materials are convenient and easy to obtain, reaction conditions are mild, operation is easy and convenient, and the yield can reach 97%.
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Paragraph 0197-0202
(2021/06/22)
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- Microwave-Assisted Synthesis of Tris-Anderson Polyoxometalates for Facile CO2Cycloaddition
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Four new tris-Anderson polyoxometalates (POMs), (NH4)4[ZnMo6O18(C4H8NO3)(OH)3]·4H2O (1), (NH4)4[CuMo6O18(C4H8NO3)(OH)3]·4H2O (2), (TBA)3(NH4)[ZnMo6O17(C5H9O3)2(OH)]·10H2O (3) (TBA = n-C16H36N), and (NH4)4[CuMo6O18(C5H9O3)2]·16H2O (4), were synthesized by a microwave-assisted method. Single-crystal X-ray diffraction revealed that 1 and 2 contained a tris (trihydroxyl organic compounds) ligand grafted on one side, while two tris ligands were grafted on two sides to form χ/δand δ/δisomers in 3 and 4, respectively. 1H and 13C NMR spectra of the χ/δisomer 3 were obtained for the first time, with six methylenes showing six peaks in the 1H NMR spectrum and only four peaks in the 13C NMR spectrum. Mass spectrometry monitoring revealed that during the microwave-assistant process the tris ligand can graft onto POMs to form 1, while tris directly coordinates with metallic heteroatoms to form isopolymolybdates during the conventional reflux synthesis process. In addition, 1-4 can catalyze CO2 with epoxides into cyclic carbonates with high selectivity and yields at an atmospheric pressure of CO2, which is lower than the pressure of CO2 in other catalysis using POMs as catalysts. Furthermore, 1-4 showed good catalytic stability and cycling properties. Mechanism studies substantiated POMs cocatalyzed with Br- to improve the catalytic yields.
- Yu, Wei-Dong,Zhang, Yin,Han, Yu-Yang,Li, Bin,Shao, Sai,Zhang, Le-Ping,Xie, Hong-Ke,Yan, Jun
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supporting information
p. 3980 - 3987
(2021/04/07)
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- Catalytic Formation of Cyclic Carbonates using Gallium Aminotrisphenolate Compounds and Comparison to their Aluminium Congeners: A Combined Experimental and Computational Study
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This work reports on the use of gallium aminotrisphenolate compounds as catalysts for the synthesis of cyclic carbonates from epoxides and CO2. The results show that they are highly active, and more so than the corresponding aluminium congeners. The catalyst system is applicable at low and elevated temperatures across a wide substrate scope including terminal, internal, multiple and fully deuterated epoxides. Applying low catalyst loadings has allowed for a TON of 344,000 to be obtained, highlighting their stability. A DFT investigation has confirmed that the gallium catalysts have lower energetic profiles compared to the aluminium congeners. Measurement of the Lewis acidity of both the gallium and aluminium aminotrisphenolate compounds using the Gutmann-Beckett method provides the experimental proof that the gallium compounds are more Lewis acidic than their aluminium congeners. Finally, Ab-Initio Molecular Dynamic (AIMD) simulations have investigated and quantified the dynamic behaviour of the catalytic systems, highlighting an important increase in fluxionality in some cases which helps to explain the increase in catalytic activity.
- álvarez-Miguel, Lucía,Burgoa, Jesús Damián,Mosquera, Marta E. G.,Hamilton, Alex,Whiteoak, Christopher J.
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p. 4099 - 4110
(2021/08/23)
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- Efficient conversion of CO2into cyclic carbonates at room temperature catalyzed by Al-salen and imidazolium hydrogen carbonate ionic liquids
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A novel process for the efficient synthesis of cyclic carbonates from CO2 and epoxides at room temperature in the absence of a solvent has been achieved by using Al-salen complexes as catalysts and imidazolium hydrogen carbonate ionic liquids ([CnCmIm][HCO3]) as cocatalysts. As a halide ion-free cocatalyst, [CnCmIm][HCO3] showed higher catalytic reactivity compared to traditional halogen-containing quaternary ammonium salts (such as (nBu)4NBr) and organic bases. The catalytic system can be used for the cycloaddition of a series of substrates with good to excellent yields at room temperature in the absence of a solvent. Besides, the catalytic system can be easily recycled at least four times without significant loss of catalytic activity. A possible mechanism was proposed, in which Al-salen and carbene activate the epoxides and CO2 respectively.
- Hu, Xingbang,Liu, Jia,Liu, Ying,Yang, Guoqiang,Zhang, Dejin,Zhang, Zhibing
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supporting information
p. 4509 - 4515
(2020/08/10)
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- A Phosphonium Ylide as a Ligand for [3 + 2] Coupling Reactions of Epoxides with Heterocumulenes under Mild Conditions
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The potential of carbonyl-stabilized phosphonium ylides as ligands for novel catalysis was explored. We found that the combination of phosphonium ylides and metal halide salts efficiently catalyzed the reaction of epoxides with carbon dioxide under mild c
- Hashimoto, Kousuke,Mori, Yoko,Suga, Hiroyuki,Toda, Yasunori
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p. 10980 - 10987
(2020/09/23)
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- Pyridine-bridged bifunctional organocatalysts for the synthesis of cyclic carbonates from carbon dioxide
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Hydroxyl- and carboxyl-functionalized imidazolium halides are used as efficient bifunctional organocatalysts for the synthesis of cyclic carbonates from CO2 and epoxides under mild reaction conditions. Control experiments suggest that the cycloaddition reaction is realized by the combination of the nucleophilic halide anions with hydroxyl and carboxyl groups as hydrogen bond donors. Moreover, the bifunctional organocatalysts can be easily recycled five times by simple filtration; however, a loss of activity was observed.
- Liu, Quan-Yao,Shi, Lei,Liu, Ning
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p. 248 - 256
(2019/07/15)
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- Zinc single atoms on N-doped carbon: An efficient and stable catalyst for CO2 fixation and conversion
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The cycloaddition of epoxides and carbon dioxide represents a straightforward and atom-efficient method for synthesis of cyclic carbonates and utilization of CO2. So far, homogeneous metal complexes have been mainly applied for such transformations. Here, we describe the synthesis of novel heterogeneous Zn-based catalysts, which were conveniently prepared by pyrolysis of an active-carbon-supported phenanthroline-ligated Zn(OAc)2 complex. Detail structural characterizations proved the existence of single zinc sites in the active material. Compared to a Zn-based nanoparticle (Zn-NP) catalyst, the resulting single metal atom catalyst (SAC) displayed improved activity and stability for the cycloaddition of epoxides. By applying the optimal catalyst, a variety of carbonates were successfully obtained in high yields with good functional group tolerance.
- Cui, Xinjiang,Dai, Xingchao,Surkus, Annette-Enrica,Junge, Kathrin,Kreyenschulte, Carsten,Agostini, Giovanni,Rockstroh, Nils,Beller, Matthias
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p. 1679 - 1685
(2019/11/11)
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- Methoxy Groups Increase Reactivity of Bifunctional Tetraarylphosphonium Salt Catalysts for Carbon Dioxide Fixation: A Mechanistic Study
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The development of carbon dioxide fixation under mild conditions is a central theme in organic synthesis. Despite the tremendous progress in the field of organocatalysis in the past two decades, the coupling reactions of epoxides with carbon dioxide that proceed at atmospheric pressure at temperatures of less than 100 °C have remained challenging. In our aspirational studies of tetraarylphosphonium salts (TAPS) catalysis, we report here the bifunctional TAPS-catalyzed synthesis of five-membered cyclic carbonates by chemical fixation using 1 atm of carbon dioxide at 60 °C. Intriguing substituent effects of TAPS were observed, in which electron-donating groups enhanced their reactivity. In addition, the mechanism was thoroughly investigated by undertaking both experimental and theoretical studies, suggesting that the electronic properties of TAPS affect carbon dioxide insertion into halohydrin intermediates. The results provided fruitful information to understand the origin of the TAPS behavior, which would contribute to the design of novel catalysts for carbon dioxide capture.
- Toda, Yasunori,Komiyama, Yutaka,Esaki, Hiroyoshi,Fukushima, Kazuaki,Suga, Hiroyuki
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supporting information
p. 15578 - 15589
(2019/11/21)
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- Efficient transformation of CO2 to cyclic carbonates using bifunctional protic ionic liquids under mild conditions
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A series of 1,8-diazabicyclo-[5.4.0]undec-7-ene (DBU) based bifunctional protic ionic liquids (DBPILs) were easily prepared by acid-base reactions at room temperature. They were used to catalyze the cycloaddition reaction of CO2 with epoxides u
- Meng, Xianglei,Ju, Zhaoyang,Zhang, Suojiang,Liang, Xiaodong,Von Solms, Nicolas,Zhang, Xiaochun,Zhang, Xiangping
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p. 3456 - 3463
(2019/06/24)
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- Cooperative Multifunctional Organocatalysts for Ambient Conversion of Carbon Dioxide into Cyclic Carbonates
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A series of pincer-type compounds possessing an N-heterocyclic carbene precursor and a carboxyl group as proton transfer agent were synthesized and used as organocatalysts for the cycloaddition of epoxides with CO2. In this context, we have demonstrated the high activity of these one-component organocatalysts in the CO2 transformation to cyclic carbonates under ambient conditions (room temperature, 1 bar of CO2). The catalytic potential of these multifunctional organocatalysts on challenging internal epoxides is particularly deserving of mention because organocatalysts that are able to mediate the cycloaddition reaction of internal epoxides with CO2 under mild conditions remain scarce. The intramolecular synergistic activation mechanism was elucidated by control experiments and DFT calculations.
- Liu, Ning,Xie, Ya-Fei,Wang, Chuan,Li, Shi-Jun,Wei, Donghui,Li, Min,Dai, Bin
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p. 9945 - 9957
(2018/10/15)
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- An in situ formed Ca2+-crown ether complex and its use in CO2-fixation reactions with terminal and internal epoxides
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Herein we report an efficient catalytic system based on readily available calcium iodide and 18-crown-6 ether for the atom economical addition of CO2 to epoxides. 1H NMR experiments revealed the selective in situ formation of a crown ether complex. This catalyst allows the conversion of various terminal epoxides under 1 atm CO2 pressure even at room temperature. Remarkably, a broad range of internal epoxides with various substitution patterns and substituents were smoothly converted which confirms the high efficiency and capability of the protocol. Notably, most of the internal carbonates were synthesized in high yields and diastereoselectivities of up to ≥99%. Furthermore, this system operates under solvent-free conditions without any co-catalysts e.g. onium salts.
- Steinbauer,Spannenberg,Werner
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supporting information
p. 3769 - 3779
(2017/08/26)
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- Immobilized bifunctional phosphonium salts as recyclable organocatalysts in the cycloaddition of CO2 and epoxides
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Several bifunctional phosphonium salt catalysts were prepared and immobilized on silica and polystyrene supports. The immobilized systems were compared with their homogeneous analogs in cyclic carbonate synthesis. Interestingly, in some cases, higher acti
- Steinbauer,Longwitz,Frank,Epping,Kragl,Werner
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p. 4435 - 4445
(2017/09/29)
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- Design of bifunctional quaternary phosphonium salt catalysts for CO2 fixation reaction with epoxides under mild conditions
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An efficient synthesis of cyclic carbonates from epoxides and CO2 under mild reaction conditions was achieved via the use of a newly designed bifunctional quaternary phosphonium iodide catalyst. The importance of the bifunctional design of the
- Liu, Shiyao,Suematsu, Naoki,Maruoka, Keiji,Shirakawa, Seiji
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p. 4611 - 4615
(2016/09/04)
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- Cyclic Carbonates from Carbon Dioxide and Oxiranes
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The synthesis of cyclic carbonates 2 by reaction of carbon dioxide with oxiranes 1 in the presence of alkali metal salt-phase-transfer agent catalysts is reported.A reaction mechanism is proposed. - Keywords: Crown ether; Phasetransfer catalyst
- Rokicki, Gabriel,Kuran, Witold,Pogorzelska-Marciniak, Barbara
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p. 205 - 214
(2007/10/02)
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