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Uwe Bayer Adrian Jenner Jonas Riedmaier Ccilia Maichle-Mssmer Reiner Anwander 《Molecules (Basel, Switzerland)》2021,26(7)
Homoleptic ceric pyrazolates (pz) Ce(RR’pz)4 (R = R’ = tBu; R = R’ = Ph; R = tBu, R’ = Me) were synthesized by the protonolysis reaction of Ce[N(SiHMe2)2]4 with the corresponding pyrazole derivative. The resulting complexes were investigated in their reactivity toward CO2, revealing a significant influence of the bulkiness of the substituents on the pyrazolato ligands. The efficiency of the CO2 insertion was found to increase in the order of tBu2pz < Ph2pz < tBuMepz < Me2pz. For comparison, the pyrrole-based ate complexes [Ce2(pyr)6(µ-pyr)2(thf)2][Li(thf)4]2 (pyr = pyrrolato) and [Ce(cbz)4(thf)2][Li(thf)4] (cbz = carbazolato) were obtained via protonolysis of the cerous ate complex Ce[N(SiHMe2)2]4Li(thf) with pyrrole and carbazole, respectively. Treatment of the pyrrolate/carbazolate complexes with CO2 seemed promising, but any reversibility could not be observed. 相似文献
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Temperature‐Responsive Microgel Films as Reversible Carbon Dioxide Absorbents in Wet Environment 下载免费PDF全文
Mengchen Yue Prof. Yu Hoshino Yukinori Ohshiro Kazushi Imamura Prof. Yoshiko Miura 《Angewandte Chemie (International ed. in English)》2014,53(10):2654-2657
Hydrogel films composed of temperature‐responsive microgel particles (GPs) containing amine groups work as stimuli‐responsive carbon dioxide absorbent with a high capacity of approximately 1.7 mmol g?1. Although the dried films did not show significant absorption, the reversible absorption capacity dramatically increased by adding a small amount of water (1 mL g?1). The absorption capacity was independent of the amount of added water beyond 1 mL g?1, demonstrating that the GP films can readily be used under wet conditions. The amount of CO2 absorbed by the GP films was proportional to their thickness up to 200–300 μm (maximum capacity of about 2 L m?2). Furthermore, the films consisting of GPs showed faster and greater absorption and desorption of CO2 than that of monolithic hydrogel films. These results indicated the importance of a fast stimulus response rate of the films that are composed of GPs in order to achieve long‐range and fast diffusion of bicarbonate ions. Our study revealed the potential of stimuli‐responsive GP films as energy‐efficient absorbents to sequester CO2 from high‐humidity exhaust gases. 相似文献
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Organocatalyzed Domino [3+2] Cycloaddition/Payne‐Type Rearrangement using Carbon Dioxide and Epoxy Alcohols 下载免费PDF全文
Sergio Sopeña Mariachiara Cozzolino Cristina Maquilón Dr. Eduardo C. Escudero‐Adán Dr. Marta Martínez Belmonte Prof. Dr. Arjan W. Kleij 《Angewandte Chemie (International ed. in English)》2018,57(35):11203-11207
An unprecedented organocatalytic approach towards highly substituted cyclic carbonates from tri‐ and tetrasubstituted oxiranes and carbon dioxide has been developed. The protocol involves the use of a simple and cheap superbase under mild, additive‐ and metal‐free conditions towards the initial formation of a less substituted carbonate product that equilibrates to a tri‐ or even tetrasubstituted cyclic carbonate under thermodynamic control. The latter are conveniently trapped in situ, providing overall a new domino process for synthetically elusive heterocyclic scaffolds. Control experiments provide a rationale for the observed cascade reactions, which demonstrate similarity to the well‐known Payne rearrangement of epoxy alcohols. 相似文献
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Lehenmeier MW Bruckmeier C Klaus S Dengler JE Deglmann P Ott AK Rieger B 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(32):8858-8869
The homogeneous dinuclear zinc catalyst going back to the work of Williams et al. is to date the most active catalyst for the copolymerisation of cyclohexene oxide and CO2 at one atmosphere of carbon dioxide. However, this catalyst shows no copolymer formation in the copolymerisation reaction of propylene oxide and carbon dioxide, instead only cyclic carbonate is found. This behaviour is known for many zinc‐based catalysts, although the reasons are still unidentified. Within our studies, we focus on the parameters that are responsible for this typical behaviour. A deactivation of the catalyst due to a reaction with propylene oxide turns out to be negligible. Furthermore, the catalyst still shows poly(cyclohexene carbonate) formation in the presence of cyclic propylene carbonate, but the catalyst activity is dramatically reduced. In terpolymerisation reactions of CO2 with different ratios of cyclohexene oxide to propylene oxide, no incorporation of propylene oxide can be detected, which can only be explained by a very fast back‐biting reaction. Kinetic investigations indicate a complex reaction network, which can be manifested by theoretical investigations. DFT calculations show that the ring strains of both epoxides are comparable and the kinetic barriers for the chain propagation even favour the poly(propylene carbonate) over the poly(cyclohexene carbonate) formation. Therefore, the crucial step in the copolymerisation of propylene oxide and carbon dioxide is the back‐biting reaction in the case of the studied zinc catalyst. The depolymerisation is several orders of magnitude faster for poly(propylene carbonate) than for poly(cyclohexene carbonate). 相似文献
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Il Kim Min Ju Yi Seung Hoon Byun Dae Won Park Bu Ung Kim Chang Sik Ha 《Macromolecular Symposia》2005,224(1):181-192
As a means for the chemical fixation of carbon dioxide and the synthesis of biodegradable polycarbonates, copolymerizations of carbon dioxide with various epoxides such as cyclohexene oxide (CHO), cyclopetene oxide, 4-vinyl-1-cyclohexene-1,2epoxide, phenyl glycidyl ether, allyl glycidyl ether, propylene oxide, butene oxide, hexene oxide, octene oxide, and 1-chloro-2,3-epoxypropane were investigated in the presence of a double metal cyanide catalyst (DMC). The DMC catalyst was prepared by reacting K3Co(CN)6 with ZnCl2, together with tertiary butyl alcohol and poly(tetramethylene ether glycol) as complexing reagents and was characterized by various spectroscopic methods. The DMC catalyst showed high activity (526.2 g-polymer/g-Zn atom) for CHO/CO2 (PCO2 = 140 psi) copolymerization at 80 °C, to yield biodegradable aliphatic polycarbonates of narrow polydispersity (Mw/Mn = 1.67) and moderate molecular weight (Mn = 8900). The DMC catalyst also showed high activities with different CO2 reactivities for other epoxides to yield various aliphatic polycarbonates with narrow polydispersity. 相似文献
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Seung Hyo Kim Kwang Hee Kim Prof. Dr. Soon Hyeok Hong 《Angewandte Chemie (International ed. in English)》2014,53(3):771-774
A carbon capture and use (CCU) strategy was applied to organic synthesis. Carbon dioxide (CO2) captured directly from exhaust gas was used for organic transformations as efficiently as hyper‐pure CO2 gas from a commercial source, even for highly air‐ and moisture‐sensitive reactions. The CO2 capturing aqueous ethanolamine solution could be recycled continuously without any diminished reaction efficiency. 相似文献
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《中国化学》2018,36(4):299-305
The selective synthesis of polypropylene carbonate (PPC) and cyclic propylene carbonate (CPC) from coupling reaction of CO2 and propylene oxide (PO) is a long term pursuing target. Here we report that a temperature controllable porphyrin aluminum catalyst using 5,10,15,20‐tetra(1,2,3,4,5,6, 7,8‐octahydro‐1,4:5,8‐dimethanoanthracen‐9‐yl)porphyrin as ligand, once in conjunction with suitable onium salt, achieved single cycloaddition or copolymerization reaction. Only cycloaddition reaction happened at temperature above 75 °C to produce 100% CPC, whereas copolymerization became dominant to afford PPC with selectivity over 99% at 25 °C, and the obtained PPC showed over 99% carbonate linkage and 92% head‐to‐tail structure. Based on systematic analysis of the electronic and steric feature in the porphyrin ligand, it was found that the electronic feature of the substituent in porphyrin ligand was decisive for PPC selectivity, porphyrin ligand bearing strong electron‐donating substituents displayed a significantly reduced tolerance towards increased temperature with respect to PPC formation. Therefore, temperature‐responsive catalyst could be designed by suitable modification in porphyrin ligand, and such accurate synthesis of target product by one catalyst may create a useful and facile platform for selective PPC or CPC production. 相似文献
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Catalytic Formation of Propylene Carbonate from Supercritical Carbon Dioxide/Propylene Oxide Mixture
TheuseofsupercriticalcarbondioxideasasubstitUtesolventforchemicalsynthesisisaveryattractiveareainviewofresourceutiIizationandenvironmentalproblems"'.SinceCO2,whichhasaneasilyaccessibIecriticalpointwithaTcof3l.l'CandaPcof7.3MPa,isnontoxic,nonflammableandinexpensive,itcanreplacehazardousorganicsolventandtherebyprovideavaluablepollutionpreventiontool.Assimilartoothersupercriticalfluids,SC-CO,hasgaslikediffusitivityandliquidIikedensity,andchangingpressureandtemperaturecanvaryitsphysicalpro… 相似文献
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Dr. Chihiro Maeda Junta Shimonishi Ray Miyazaki Prof. Jun‐ya Hasegawa Prof. Tadashi Ema 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(19):6556-6563
Bifunctional metalloporphyrins with quaternary ammonium bromides (nucleophiles) at the meta, para, or ortho positions of meso‐phenyl groups were synthesized as catalysts for the formation of cyclic carbonates from epoxides and carbon dioxide under solvent‐free conditions. The meta‐substituted catalysts exhibited high catalytic performance, whereas the para‐ and ortho‐substituted catalysts showed moderate and low activity, respectively. DFT calculations revealed the origin of the advantage of the meta‐substituted catalyst, which could use the flexible quaternary ammonium cation at the meta position to stabilize various anionic species generated during catalysis. A zinc(II) porphyrin with eight nucleophiles at the meta positions showed very high catalytic activity (turnover number (TON)=240 000 at 120 °C, turnover frequency (TOF)=31 500 h?1 at 170 °C) at an initial CO2 pressure of 1.7 MPa; catalyzed the reaction even at atmospheric CO2 pressure (balloon) at ambient temperature (20 °C); and was applicable to a broad range of substrates, including terminal and internal epoxides. 相似文献
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Milad Abolhasani Prof. Axel Günther Prof. Eugenia Kumacheva 《Angewandte Chemie (International ed. in English)》2014,53(31):7992-8002
Carbon dioxide (CO2) sequestration, storage and recycling will greatly benefit from comprehensive studies of physical and chemical gas–liquid processes involving CO2. Over the past five years, microfluidics emerged as a valuable tool in CO2‐related research, due to superior mass and heat transfer, reduced axial dispersion, well‐defined gas–liquid interfacial areas and the ability to vary reagent concentrations in a high‐throughput manner. This Minireview highlights recent progress in microfluidic studies of CO2‐related processes, including dissolution of CO2 in physical solvents, CO2 reactions, the utilization of CO2 in materials science, and the use of supercritical CO2 as a “green” solvent. 相似文献
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Rhodium‐Catalyzed [2+2+2] Cycloaddition of Diynes with Carbodiimides and Carbon Dioxide under Ambient Conditions 下载免费PDF全文
Masahiro Ishii Fumiya Mori Prof. Dr. Ken Tanaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(8):2169-2174
It has been established that a cationic rhodium(I)/H8‐binap complex is able to catalyze the [2+2+2] cycloaddition of diynes with carbodiimides and carbon dioxide under ambient conditions. Enantio‐ and/or regioselective variants of these reactions are also disclosed. 相似文献
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Dr. Fawang Chen Dr. Xiaofang Li Prof. Dr. Bo Wang Dr. Tiegang Xu Dr. Shi‐Lu Chen Dr. Peng Liu Prof. Dr. Changwen Hu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(32):9870-9876
CoII‐substituted α‐Keggin‐type 12‐tungstenphosphate [(n‐ C4H9)4N]4H[PW11Co(H2O)O39]‐ (PW11Co) is synthesized and used as a single‐component, solvent‐free catalyst in the cycloaddition reaction of CO2 and epoxides to form cyclic carbonates. The mechanism of the cycloaddition reaction is investigated using DFT calculations, which provides the first computational study of the catalytic cycle of polyoxometalate‐catalyzed CO2 coupling reactions. The reaction occurs through a single‐electron transfer from the doublet CoII catalyst to the epoxide and forms a doublet CoIII–carbon radical intermediate. Subsequent CO2 addition forms the cyclic carbonate product. The existence of radical intermediates is supported by free‐radical termination experiments. Finally, it is exhilarating to observe that the calculated overall reaction barrier (30.5 kcal mol?1) is in good agreement with the real reaction rate (83 h?1) determined in the present experiments (at 150 °C). 相似文献
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Jinhua Ji Hao Liu Zewei Chen Yajun Fu Prof. Weijun Yang Prof. Shuang-Feng Yin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(43):11102-11109
Metal-organic framework (MOF) is an ideal precursor/template for porous carbon, and its active components are uniformly doped, which can be used in energy storage and catalytic conversion fields. Metal-organic framework PCN-224 with carboxylporphyrin as the ligand was synthesized, and then Zn2+ and Co2+ ions were coordinated in the center of the porphyrin ring by post-modification. Here, PCN-224−ZnCo with different ratios of bimetallic Zn2+/Co2+ ions were used as the precursor, and the metal-nitrogen-carbon(M−N−C) material of PCN-224−ZnCo-950 was obtained by pyrolyzing the precursor at 950 °C in Ar. Because Zn is easy to volatilize at 950 °C, the formed M−N−C materials can reflect different Co contents and different basic site concentrations. The formed material still maintains the original basic framework. With the increase of Zn2+/Co2+ ratio in precursor, the concentration of N-containing alkaline sites in pyrolysis products gradually increase. Compared with the precursor, PCN-224−ZnCo1-950 with Zn2+/Co2+=1 : 1 has greatly improved basicity and suitable acidic/ alkaline site concentration. It can be efficiently used to carbon dioxide absorption and catalyze the cycloaddition of CO2 with epoxide. More importantly, the current method of adjusting the acidic/basic sites in M−N−C materials through volatilization of volatile metals can provide an effective strategy for adjusting the catalysis of MOF derivatives with porphyrin structure. 相似文献