- Cycloaddition of carbon dioxide and epoxides catalyzed by rare earth metal complexes bearing a Trost ligand
-
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
-
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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- Heterobimetallic rare earth metal-zinc catalysts for reactions of epoxides and CO2under ambient conditions
-
Four homodinuclear rare earth metal (RE) complexes1-4bearing a multidentate diglycolamine-bridged bis(phenolate) ligand were synthesized. In addition, seven heterobimetallic RE-Zn complexes5-11were prepared through a one-pot strategy. In these heterobimetallic complexes, two RE centers are bridged by either Zn(OAc)2or Zn(OBn)2moieties. All complexes were characterized by single crystal X-ray diffraction, elemental analysis, IR spectroscopy, and multinuclear NMR spectroscopy (in the case of diamagnetic complexes1,4,7and11). Moreover, the multi-nuclear structures of complexes4and11in solution were also studied by1H DOSY spectroscopy. These complexes were applied in catalyzing the coupling reaction of carbon dioxide (CO2) with epoxides. Zn(OAc)2- and Zn(OBn)2-bridged heterobimetallic complexes showed comparable catalytic activities under ambient conditions and were more active than monometallic RE complexes. Significant synergistic effect in heterobimetallic complexes is observed. Mono-substituted epoxides were converted into cyclic carbonates under 1 atm CO2at 25 °C in 88-96% yields, whereas di-substituted epoxides reacted under 1 atm CO2at higher temperatures in 40-80% yields.
- Yin, Kuan,Hua, Linyan,Qu, Liye,Yao, Quanyou,Wang, Yaorong,Yuan, Dan,You, Hongpeng,Yao, Yingming
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p. 1453 - 1464
(2021/02/09)
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- A Strained Ion Pair Permits Carbon Dioxide Fixation at Atmospheric Pressure by C-H H-Bonding Organocatalysis
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The cycloadditions of carbon dioxide into epoxides to afford cyclic carbonates by H-bond donor (HBD) and onium halide (X) cocatalysis have emerged as a key strategy for CO2 fixation. However, if the HBD is also a halide receptor, the two will quench each other, decreasing the catalytic activity. Here, we propose a strained ion pair tris(alkylamino)cyclopropenium halide (TAC·X), in which TAC repels X. TAC possesses a positively charged cyclopropenium core that makes the vicinal C-H or N-H a nonclassical HBD. The interionic strain within TAC·X makes TAC a more electrophilic HBD, allowing it to activate the oxygen of the epoxide and making X more nucleophilic and better able to attack the methylene carbon of the epoxide. NMR titration spectra and computational studies were employed to probe the mechanism of the cycloaddition of CO2 to epoxides reactions under the catalysis of TAC·X. The 1H and 13C{1H}NMR titration spectra of the catalyst with the epoxide substrate unambiguously confirmed H-bonding between TAC and the epoxide. DFT computational studies identified the transition states in the ring-opening of the epoxide (TS1) and in the ring-closure of the cyclic carbonate (TS2).
- Xu, Jiaxi,Xian, Anmei,Li, Zhenjiang,Liu, Jingjing,Zhang, Zhihao,Yan, Rui,Gao, Luoyu,Liu, Bo,Zhao, Lili,Guo, Kai
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p. 3422 - 3432
(2021/02/27)
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- The catalytic system ‘Rhodamine B/additive’ for the chemical fixation of CO2
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The catalytic system ‘Rhodamine B/additive’ was introduced to promote the CO2 reactions. We synthesized various cyclic carbonates in good to excellent yields under the catalysis of rhodamine B and TBAB. A variety of 2-oxazolidinone derivatives were obtained in the presence of rhodamine B and DBU.
- Wu, Feng-tian,Wu, Ling,Cui, Chun-na
-
-
- Fixation of CO2 into Cyclic Carbonates by Halogen-Bonding Catalysis
-
Halogen bonding, parallel to hydrogen bonding, was introduced into the catalytic cycloaddition of carbon dioxide into epoxide (CCE) reactions. A series of halogen-bond donor (XBD) catalysts of N-iodopyridinium halide featured with N?I bond were synthesized and evaluated in CCE reactions. The optimal XBD catalyst, 4-(dimethylamino)-N-iodopyridinium bromide ([DMAPI]Br), under screened conditions at 100 °C, ambient pressure, and 1 mol % catalyst loading, realized 93 % conversion of styrene oxide into cyclic carbonate in 6 h. The substrate scope was successfully extended with excellent yields (mostly ≥93 %) and quantitative selectivity (more than 99 %). 1H NMR spectroscopy of the catalyst [DMAPI]Br on substrate epoxide certified that the N?I bond directly coordinated with the epoxide oxygen. A plausible mechanism of halogen-bonding catalysis was proposed, in which the DMAPI cation functioned as halogen-bond donor to activate the epoxide, and the counter anion bromide attacked the methylene carbon to initiate the ring-opening of the epoxide. CCE reactions promoted by N-iodopyridinium halide, exemplify a first case of halogen-bonding catalysis in epoxide activation and CO2 transformation.
- Yan, Rui,Chen, Kai,Li, Zhenjiang,Qu, Yuanyuan,Gao, Luoyu,Tong, Haoying,Li, Yongqiang,Li, Jie,Hu, Yongzhu,Guo, Kai
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p. 738 - 744
(2020/11/30)
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- Conversion of dilute CO2to cyclic carbonates at sub-atmospheric pressures by a simple indium catalyst
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The transformation of CO2to value added commodity chemicals presents an impactful strategy to obtain products that are less dependent on fossil fuels. In this study, indium tribromide (InBr3) mixed with tetrabutylammonium bromide (NBu4Br) co-catalyst has been identified as a simple, highly efficient catalyst for the synthesis of cyclic carbonates from epoxides and CO2at sub-atmospheric pressures, room temperature, and under solvent-free conditions. The InBr3/NBu4Br catalytic system is tolerant toward different functional groups with high conversions and >99% selectivity for cyclic carbonate without resorting to high pressures and temperatures. Moreover, a combination ofin situIR, NMR spectroscopy, and substrate labelling experiments enabled the proof of key catalytic steps and detection of reaction intermediates to elucidate the reaction mechanism. This technology represents a potential scalable system for the utilization of waste CO2
- Baalbaki, Hassan A.,Roshandel, Hootan,Hein, Jason E.,Mehrkhodavandi, Parisa
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p. 2119 - 2129
(2021/04/09)
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- Synthesis method of cyclic carbonate
-
The invention discloses a preparation method of cyclic carbonate, and belongs to the technical field of green catalytic synthesis. According to the invention, epoxide and carbon dioxide are catalyzed by the catalyst to obtain cyclic carbonate, the synthesis method is simple and low in cost, the catalyst has the characteristics of no metal and no halogen, and the reaction condition is mild.
- -
-
Paragraph 0074-0075
(2021/05/19)
-
- A Porous Copper-Organic Framework Assembled by [Cu12] Nanocages: Highly Efficient CO2Capture and Chemical Fixation and Theoretical DFT Calculations
-
A new porous copper-organic framework assembled from 12-nuclear [Cu12] nanocages {[Cu2(L4-)(H2O)2]·4DMA·2H2O}n (1) (H4L = 5,5′-(butane-1,4-diyl)-bis(oxy)-diisophthalic acid) was successfully prepared and structurally characterized. Compound 1 feathering of a 3D framework with two types of 1D nanotubular channels and a large specific surface area can effectively enrich various harmful dyes. Additionally, due to the carbon dioxide (CO2) interactions with open Cu(II) sites and the electron-rich ether oxygen atoms of ligand in 1, it exhibits a highly selective CO2 uptake. Interestingly, 1 can effectively catalyze the cycloaddition reaction of CO2 with various epoxides under mild conditions, which is ascribed to the Lewis acid Cu(II) sites in the framework of 1. Importantly, 1 acting as a heterogeneous catalyst can be recycled at least 10 times without an obvious loss of catalytic activity, and the CO2 cycloaddition mechanism was further uncovered by density functional theory (DFT) calculations. This study can greatly enrich the MOF catalysts system of CO2 conversion and also provide a valuable guidance for the design of efficient MOFs catalysts.
- Wang, Wen-Min,Wang, Wan-Ting,Wang, Mei-Ying,Gu, Ai-Ling,Hu, Tian-Ding,Zhang, Ya-Xin,Wu, Zhi-Lei
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p. 9122 - 9131
(2021/06/27)
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- Self-assembled bimetallic aluminum-salen catalyst for the cyclic carbonates synthesis
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Bimetallic bis-urea functionalized salen-aluminum catalysts have been developed for cyclic carbonate synthesis from epoxides and CO2. The urea moiety provides a bimetallic scaffold through hydrogen bonding, which expedites the cyclic carbonate formation reaction under mild reaction conditions. The turnover frequency (TOF) of the bis-urea salen Al catalyst is three times higher than that of a μ-oxo-bridged catalyst, and 13 times higher than that of a monomeric salen aluminum catalyst. The bimetallic reaction pathway is suggested based on urea additive studies and kinetic studies. Additionally, the X-ray crystal structure of a bis-urea salen Ni complex supports the self-assembly of the bis-urea salen metal complex through hydrogen bonding.
- Abboud, Khalil A.,Hahm, Hyungwoo,Hong, Sukwon,Kim, Seyong,Park, Jongwoo,Seong, Wooyong
-
supporting information
(2021/07/21)
-
- Preparation method of cyclic carbonate
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The invention discloses a preparation method of cyclic carbonate, and belongs to the technical field of organic catalytic synthesis. An organic strong base and squaramide react to prepare a squaramide anion catalyst, and the squaramide anion catalyst catalyzes a cycloaddition reaction of epoxide and carbon dioxide to obtain the cyclic carbonate. The catalyst used in the method does not contain metal and halogen, is easy to obtain, and has good chemical stability and higher catalytic efficiency.
- -
-
Paragraph 0136-0137
(2021/08/06)
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- Plasma-Assisted Immobilization of a Phosphonium Salt and Its Use as a Catalyst in the Valorization of CO2
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The first plasma-assisted immobilization of an organocatalyst, namely a bifunctional phosphonium salt in an amorphous hydrogenated carbon coating, is reported. This method makes the requirement for prefunctionalized supports redundant. The immobilized catalyst was characterized by solid-state 13C and 31P NMR spectroscopy, SEM, and energy-dispersive X-ray spectroscopy. The immobilized catalyst (1 mol %) was employed in the synthesis of cyclic carbonates from epoxides and CO2. Notably, the efficiency of the plasma-treated catalyst on SiO2 was higher than those of the SiO2 support impregnated with the catalyst and even the homogeneous counterpart. After optimization of the reaction conditions, 13 terminal and four internal epoxides were converted with CO2 to the respective cyclic carbonates in yields of up to 99 %. Furthermore, the possibility to recycle the immobilized catalyst was evaluated. Even though the catalyst could be reused, the yields gradually decreased from the third run. However, this is the first example of the recycling of a plasma-immobilized catalyst, which opens new possibilities in the recovery and reuse of catalysts.
- Brüser, Volker,Epping, Jan Dirk,Frank, Marcus,Hu, Yuya,Longwitz, Lars,Peglow, Sandra,Werner, Thomas
-
-
- Iron Coordination to Hollow Microporous Metal-Free Disalphen Networks: Heterogeneous Iron Catalysts for CO2 Fixation to Cyclic Carbonates
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This work shows that a hollow and microporous metal-free N,N′-phenylenebis(salicylideneimine) (salphen) network (H-MSN) can be engineered by Sonogashira coupling of [tetraiodo{di(Zn-salphen)}] building blocks with 1,4-diethynylbenzene in the presence of silica templates and by successive Zn and silica etching. Iron(III) ions could be incorporated into the H-MSN to form hollow and microporous Fe–disalphen networks (H-MFeSN) with enhanced microporosity and surface area. The H-MFeSN showed efficient catalytic performance and recyclability in the CO2 conversion to cyclic carbonates.
- Cho, Kyoungil,Lee, Sang Moon,Kim, Hae Jin,Ko, Yoon-Joo,Kang, Eun Joo,Son, Seung Uk
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p. 788 - 794
(2019/12/24)
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- Cobalt-based catalytic system for the chemical fixation of CO2 under solvent-free conditions
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We have described a novel and efficient method for synthesizing cyclic carbonates with ‘Co (NO3)2 .6H2O/L6’-catalyzed coupling of epoxides and CO2 under solvent-free conditions. We proposed a possible reaction mechanism based on some control experiments. Phenylpropiolic acid could be provided by using the same method.
- Wu, Fengtian,Lin, Yu
-
-
- Preparation method of cyclic carbonate
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The invention belongs to the technical field of green catalytic synthesis, and particularly relates to a preparation method of cyclic carbonate. Epoxide and carbon dioxide are catalyzed by using a catalyst provided by the invention to obtain the cyclic carbonate. According to the invention, the synthesis method is simple, cost is low, the catalyst has high activity and high selectivity, a reactioncondition is mild, and good reusability is realized.
- -
-
Paragraph 0094; 0099
(2020/07/02)
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- Method for fixing carbon dioxide (by machine translation)
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Under 60 - 120 °C conditions, the epoxide and carbon dioxide represented by the formula II are adopted to generate cyclic carbonate compounds under the catalysis of the catalyst shown in the formula I. The method has the advantages of high carbon dioxide conversion rate, no metal residue reaction, mild reaction conditions, and easier preparation of the catalyst, and can be widely applied to industrial production. (by machine translation)
- -
-
Paragraph 0085-0086
(2020/07/13)
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- Benzotriazolium ionic liquid immobilized on periodic mesoporous organosilica as an effective reusable catalyst for chemical fixation of CO2into cyclic carbonates
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A type of dichloro(dimethoxyethane)nickel anionic benzotriazolium ionic liquid-functionalized periodic mesoporous organosilicas were synthesized and tested as effective and practical heterogeneous catalysts in the cycloaddition of CO2 with epoxides. The catalyst PMO?ILC4H10O2NiCl3(1.0) showed brilliant catalytic activity for the synthesis of cyclic carbonates with high yields and selectivities under solvent- and cocatalyst-free conditions. We also found that the catalytic activity could be significantly influenced by the hydroxyl groups sites of periodic mesoporous organosilica and the active sites (hydroxyl groups/ dichloro(dimethoxyethane)nickel anion) of the benzotriazoliumcation ionic liquid, probably due to an intensification of intramolecular synergistic effect. The catalytic process displayed ease of recovery, excellent stability and recyclability for at least five runs without significant loss of its catalytic activity.
- Hu, Yu Lin,Li, Jing Rui
-
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- Novel and effective strategy of dual bis(trifluoromethylsulfonyl)imide imidazolium ionic liquid immobilized on periodic mesoporous organosilica for greener cycloaddition of carbon dioxide to epoxides
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Novel periodic mesoporous organosilica supported nanocatalysts with different loading levels of a bis(trifluoromethylsulfonyl)imide anion-based dual imidazolium ionic liquid have been prepared and evaluated as efficient catalysts for the cycloaddition of CO2 to epoxides. The as-fabricated PMO@IL-NTf2(1.0) exhibited the best catalytic performance with excellent conversions (98-100%) and yields (96-99%) at 90 °C and 0.6 MPa for 0.5-1 h, based on a synergistic effect between the dual nucleophilic anion sites of the imidazolium ionic liquid and the hydroxyl group sites of periodic mesoporous organosilica. The excellent recyclability and operational simplicity make this protocol economic and environment-friendly.
- Jin, Tan,Dong, Fang,Liu, Yang,Hu, Yu Lin
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p. 2583 - 2590
(2019/02/12)
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- Synthesis of Homo- And Heteronuclear Rare-Earth Metal Complexes Stabilized by Ethanolamine-Bridged Bis(phenolato) Ligands and Their Application in Catalyzing Reactions of CO2 and Epoxides
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A series of homonuclear rare-earth (RE) metal complexes (1Y, 2Yb, 3Nd, and 4La) and heteronuclear RE-Zn complexes (1Y-Zn, 3Nd-Zn, and 5Sm-Zn) stabilized by ethanolamine-bridged bis(phenolato) ligands was prepared and structurally characterized. Heteronuclear complexes are assembled through bridging acetate ligands, and their formation and characterization add to the diversity of 3d-4f complexes. Their activities in mediating reactions of CO2 and epoxides were evaluated and compared. Heteronuclear RE-Zn complexes found application in the copolymerization of cyclohexene oxide and CO2, giving rise to acetate-group-capped copolymers. Homonuclear complexes showed good activity in catalyzing the cycloaddition of variously monosubstituted epoxides and CO2 (1 bar), generating cyclic carbonates in 65-96% yield. For sterically hindered disubstituted epoxides, good yields of 60-91% were achieved in the presence of 10 bar CO2
- Hua, Linyan,Li, Baoxia,Han, Cuiting,Gao, Pengfei,Wang, Yaorong,Yuan, Dan,Yao, Yingming
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p. 8775 - 8786
(2019/07/03)
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- Efficient Aluminum Catalysts for the Chemical Conversion of CO2 into Cyclic Carbonates at Room Temperature and Atmospheric CO2 Pressure
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A series of dimeric aluminum compounds [Al(OCMe2CH2N(R)CH2X)]2 [X=pyridin-2-yl, R=H (PyrH); X= pyridin-2-yl, R=Me (PyrMe); X=furan-2-yl, R=H (FurH); X= furan-2-yl, R=Me (FurMe); X=thiophen-2-yl, R=H (ThioH); X= thiophen-2-yl, R=Me (ThioMe)] containing heterocyclic pendant group attached to the nitrogen catalyze the coupling of CO2 with epoxides under ambient conditions. In a comparison of their catalytic activities with those of aluminum complexes without pendant groups at N [X=H, R=H (HH); X=H, R=Me (HMe)] or with non-heterocyclic pendant groups [X=CH2CH2OMe, R=H (OMeH); X=CH2CH2NMe2, R=H (NMe2H); X=CH2CH2NMe2, R=Me (NMe2Me)], complexes containing heterocycles, in conjunction with (nBu)4NBr as a cocatalyst, show higher catalytic activities for the synthesis of cyclic carbonates under the same ambient conditions. The best catalyst system for this reaction is PyrH/(nBu)4NBr system, which gives a turnover number of 99 and a turnover frequency of 4.1 h?1, making it 14- and 20-times more effective than HH/(nBu)4NBr and HMe/(nBu)4NBr, respectively. Although there are no direct interactions between the aluminum and the heteroatoms in the heterocyclic pendants, electronic effects combined with the increased local concentration of CO2 around the active centers influences the catalytic activity in the coupling of CO2 with epoxides. In addition, PyrH/(nBu)4NBr shows broad epoxide substrate scope and seven terminal epoxides and two internal epoxides undergo the designed reaction.
- Kim, Yoseph,Hyun, Kyunglim,Ahn, Duseong,Kim, Ran,Park, Myung Hwan,Kim, Youngjo
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p. 4211 - 4220
(2019/08/12)
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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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- Influence of Mesoporous Silica Properties on Cyclic Carbonate Synthesis Catalysed by Supported Aluminium(Salen) Complexes
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By modification of pore size and morphology, pore-expanded variants of SBA-15 and KIT-6 have been utilised as mesoporous silica supports for the immobilisation of a bimetallic aluminium-salen complex. The performance of the resulting heterogeneous catalysts in the synthesis of cyclic carbonates from carbon dioxide and terminal epoxides was assessed. Support materials which retained higher pore volume and surface areas after catalyst immobilisation demonstrated enhanced conversions to the desired cyclic carbonates. This was rationalised to be a consequence of the promotion of reactant mass transport through a less-inhibited pore structure. (Figure presented.).
- Carvalho, Patricia A.,Comerford, James W.,Lamb, Katie J.,North, Michael,Reiss, Paul S.
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supporting information
p. 345 - 354
(2018/12/04)
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- [OSSO]-Type Fe(III) Metallate as Single-Component Catalyst for the CO2 Cycloaddition to Epoxides
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A new [OSSO]-Fe(III) metallate complex was prepared and characterized. We demonstrated that such metallate is the real catalytic active species for the cycloaddition of CO2 to the epoxides, formed from the in situ reaction of the related [OSSO]-Fe(III) neutral complexes and tetrabutylammonium bromide. The metallate complex was used as a single component catalyst for the formation of cyclic organic carbonates from ten epoxides and CO2 at 1 bar pressure with good activity. (Figure presented.).
- Della Monica, Francesco,Buonerba, Antonio,Paradiso, Veronica,Milione, Stefano,Grassi, Alfonso,Capacchione, Carmine
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p. 283 - 288
(2018/11/02)
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- Halide-Free and Bifunctional One-Component Catalysts for the Coupling of Carbon Dioxide and Epoxides
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In this paper, we first report a new class of halide-free and bifunctional one-component catalysts for the coupling of CO2 with epoxides. The catalysts do not need halide-based additives or tethered salts attached to the ligand when used for this coupling reaction. As the halide-free and bifunctional one-component catalysts, we chose nonionic and monomeric tetracarbonylchromium(0), tetracarbonylmolybdenum(0), and tetracarbonyltungsten(0) complexes chelated by modified ethylenediamines, namely N,N-dimethylethylenediamine, N,N′-dimethylethylenediamine, N,N,N′-trimethylethylenediamine, and N,N,N′,N′-tetramethylethylenediamine. A simple mixture of M(CO)6 (M = Cr, Mo, and W) with the modified ethylenediamines shows only one-third of the activity achieved with the tetracarbonyl metal complexes precoordinated to the corresponding modified ethylenediamines. Increasing the number of methyl substituents on the nitrogen atoms of the ethylenediamine derivatives as well as the chromium metal center in the metal carbonyl complex significantly enhanced the catalytic activity. Thus, among the 12 catalysts tested, tetracarbonyl(tetramethylethylenediamine)chromium(0) exhibited the best catalytic activity under the same reaction conditions. Various terminal and internal epoxides were easily converted into the corresponding cyclic carbonates using this chromium system. Calculations based on density functional theory were also carried out to elucidate the mechanism of the coupling reaction.
- Kim, Yoseph,Ryu, Seol,Cho, Woolee,Kim, Min,Park, Myung Hwan,Kim, Youngjo
-
supporting information
p. 5922 - 5931
(2019/05/08)
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- Heteronuclear metal complex and preparation method of cyclic carbonate catalyzed by heteronuclear metal complex
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The invention discloses a method for preparing cyclic carbonate by converting carbon dioxide and an epoxide compound under the effect of a catalyst, and belongs to the technical field of organic compound preparation. According to the method disclosed by the invention, the catalyst is easy to prepare, the yield is high, reaction conditions are mild, and high-selectivity conversion of the carbon dioxide and the epoxide compound can be realized at ambient temperature and under normal pressure, so that the cyclic carbonate compound is synthesized, and universality of a substrate is wide. The technical scheme is as the follows that a diethylene glycol amino bridged diaryloxy rare earth-benzyloxy magnesium heteronuclear metal complex and a quaternary ammonium salt are used as a catalytic system,and the carbon dioxide and the epoxide compound are used as reactants to synthesize the cyclic carbonate compound.
- -
-
Paragraph 0117; 0118; 0119; 0120
(2019/05/15)
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- Highly regio- And stereoselective synthesis of cyclic carbonates from biomass-derived polyols: Via organocatalytic cascade reaction
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The cascade reaction of CO2, vicinal diols, and propargylic alcohol, was firstly achieved by dual Lewis base (LB) organocatalytic systems involving LB-CO2 adducts and commercially available organic amines. This methodology could overcome the chemical inertness of CO2, providing an alternative route to various functionalized five-membered cyclic carbonates in moderate to high yields under mild reaction conditions (25 °C, 1.0 atm of CO2). More importantly, this method could also be applied for facile and efficient synthesis of chiral polycyclic carbonates from biomass-derived polyols with complete configuration retention of chiral centers. This study provides an environment-friendly, scalable and cost effective protocol to construct value-added cyclic carbonates with multi-functional groups and chiral centers.
- Zhou, Hui,Zhang, Hui,Mu, Sen,Zhang, Wen-Zhen,Ren, Wei-Min,Lu, Xiao-Bing
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supporting information
p. 6335 - 6341
(2019/12/03)
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- Versatile and scalable synthesis of cyclic organic carbonates under organocatalytic continuous flow conditions
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The benchmark route for the preparation of cyclic organic carbonates starts from toxic, volatile and unstable epoxides. In this work, cyclic organic carbonates are prepared according to alternative sustainable and intensified continuous flow conditions from the corresponding 1,2-diols. The process utilizes dimethyl carbonate (DMC) as a low toxicity carbonation reagent and relies on the organocatalytic activity of widely available and cheap organic ammonium and phosphonium salts. Glycerol is selected as a model substrate for preliminary optimization with a library of homogeneous ammonium and phosphonium salts. The nature of the anion dramatically influences the catalytic activity, while the nature of the cation does not impact the reaction. Upon optimization, glycerol carbonate is obtained in 95% conversion and 79% selectivity within 3 min residence time at 180 °C (11 bar) with 3.5 mol% of tetrabutylammonium bromide as the organocatalyst. A straightforward liquid-liquid extraction procedure enables both the purification of glycerol carbonate and the recycling of the homogeneous catalyst. The conditions are amenable to refined and crude bio-based glycerol, although conversions are lower in the latter case. Control experiments suggest that water present in the crude samples induces significant hydrolysis of glycerol carbonate. The reaction conditions are then successfully applied on a wide variety of substrates, affording the corresponding cyclic carbonates in overall good to excellent yields (20 examples, 45-95%). The substrate scope notably encompasses bio-based starting materials such as glycerol ethers and erythritol-derived diols. In-line NMR is featured as a qualitative analytical tool for real-time reaction monitoring. The scalability of this carbonation procedure on glycerol is assessed in a commercial pilot-scale silicon carbide continuous flow reactor of 60 mL internal volume. Glycerol carbonate is obtained in 76% yield, corresponding to a productivity of 13.6 kg per day.
- Gérardy, Romaric,Estager, Julien,Luis, Patricia,Debecker, Damien P.,Monbaliu, Jean-Christophe M.
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p. 6841 - 6851
(2019/12/24)
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- Scorpionate Catalysts for Coupling CO2 and Epoxides to Cyclic Carbonates: A Rational Design Approach for Organocatalysts
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Novel scorpionate-type organocatalysts capable of effectively coupling carbon dioxide and epoxides under mild conditions to afford cyclic propylene carbonates were developed. On the basis of a combined experimental and computational study, a precise mechanistic proposal was developed and rational optimization strategies were identified. The epoxide ring-opening, which requires an iodide as a nucleophile, was enhanced by utilizing an immonium functionality that can form an ion pair with iodide, making the ring-opening process intramolecular. The CO2 activation and cyclic carbonate formation were catalyzed by the concerted action of two hydrogen bonds originating from two phenolic groups placed at the claw positions of the scorpionate scaffold. Electronic tuning of the hydrogen bond donors allowed to identify a new catalyst that can deliver >90% yield for a variety of epoxide substrates within 7 h at room temperature under a CO2 pressure of only 10 bar, and is highly recyclable.
- Hong, Mannkyu,Kim, Yoseph,Kim, Hyejin,Cho, Hee Jin,Baik, Mu-Hyun,Kim, Youngjo
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p. 9370 - 9380
(2018/06/29)
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- Zinc–Azatrane Complexes as Efficient Catalysts for the Conversion of Carbon Dioxide into Cyclic Carbonates
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Three Zn complexes based on the N4-tris(2-aminoethyl)amine (tren) chelating ligand and presenting a C3-symmetrical axis were synthesized and successfully applied in the coupling of CO2 with terminal and internal epoxides. These complexes proved to be efficient catalysts if associated with tetrabutylammonium iodide, even at a low catalyst loading (0.005 mol %) or at room temperature, and allowed the production of cyclic carbonates in good to high yields. Variation of the substitution pattern on the tren ligand was shown to impact the catalyst performance greatly, and the highest turnover number (TON) (up to 11 200) was achieved with the less sterically hindered methyl-substituted ZnII–azatrane complex. These binary Zn–azatrane/NBu4I catalytic systems could be applied to a wide range of epoxide substrates, including the more challenging internal epoxides. Moreover, although soluble in the reaction medium, Zn–azatrane catalysts could be easily recovered and reused up to three times without any substantial loss in activity, proving their robustness under the reaction conditions.
- Bousquet, Benjamin,Martinez, Alexandre,Dufaud, Véronique
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p. 843 - 848
(2018/01/27)
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- Catalytic annulation of epoxides with heterocumulenes by the indium-tin system
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In the synthesis of five-membered heterocycles by the annulation of epoxides with heterocumulenes such as carbon dioxide and isocyanates, we developed the indium-tin catalytic system and synthesized various cyclic adducts including novel types products under mild reaction conditions.
- Suzuki, Itaru,Imakuni, Akira,Baba, Akio,Shibata, Ikuya
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- Novel hydrazine-bridged covalent triazine polymer for CO2 capture and catalytic conversion
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Carbon dioxide (CO2) capture and catalytic conversion has become an attractive and challenging strategy for CO2 utilization since it is an abundant, inexpensive, and renewable C1 resource and a main greenhouse gas. Herein, a novel hydrazine-bridged covalent triazine polymer (HB-CTP) was first designed and synthesized through simple polymerization of cyanuric chloride with 2,4,6-trihydrazinyl-1,3,5-triazine. The resultant HB-CTP exhibited good CO2 capture capacity (8.2 wt%, 0 °C, and 0.1 MPa) as well as satisfactory recyclability after five consecutive adsorption-desorption cycles. Such a polymer was subsequently employed as a metal-free heterogeneous catalyst for the cyclo-addition of CO2 with various epoxides under mild and solvent-free conditions, affording cyclic carbonates with good to excellent yields (67%–99%) and high functional-group tolerance. The incorporation of hydrazine linkages into HB-CTP's architecture was suggested to play the key role in activating epoxides through hydrogen bonding. Moreover, HB-CTP can be reused at least five times without significant loss of its catalytic activity.
- Liu, Anhua,Zhang, Jinju,Lv, Xiaobing
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p. 1320 - 1328
(2018/07/13)
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- Catalytic synthesis of glycerol carbonate from biomass-based glycerol and dimethyl carbonate over Li-La2O3 catalysts
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The trans-esterification of glycerol and dimethyl carbonate (DMC) for the synthesis of glycerol carbonate was investigated over a series of Li-La2O3 catalysts with different Li contents under mild reaction conditions. Li-La2O3 catalysts were prepared by simple precipitation and impregnation methods, and characterized using ICP, XRD, BET, XPS, CO2-TPD and TEM techniques. It was found that the basicity of La2O3 was obviously changed and the interaction between Li and La2O3 occurred after doping Li component, and the catalytic activity of Li-La2O3 was highly relevant to the strength and content of basic sites on the catalysts. Li doping influenced the crystal phase growth of La2O3, and also changed the exposed crystal planes of the Li-La2O3 catalysts. The highest catalytic performance was obtained over 3.50Li-La2O3 catalyst calcined at 600 °C for 5 h. The glycerol conversion of 94.4% and glycerol carbonate selectivity of 92.1% were obtained over this catalyst under the proper reaction conditions of 85 °C, 3 h, and the molar ratio of glycerol and DMC being 1/3 with using 0.1 g 3.50Li-La2O3 catalyst.
- Li, Yajin,Liu, Jiaxiong,He, Dehua
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p. 234 - 242
(2018/08/04)
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- Aluminum complexes derived from a hexadentate salen-type Schiff base: Synthesis, structure, and catalysis for cyclic carbonate synthesis
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Different aluminum complexes were synthesized by the reaction of aluminum alkyls with a hexadentate salen-type Schiff base. The reaction of N,N′-bis(3,5-di-tert-butylsalicylidene)-2,2′-(ethylenedioxy)dianiline (LH2) with one equiv. of AlMe3 in toluene at 100 °C proceeded by methane elimination to produce the intermediate methyl complex [AlMeL] (1), and then subsequent intramolecular methyl migration to give the aluminum complex [AlL′] (2) [L′ = (2-O-3,5-tBu2C6H2)CHNC6H4OCH2CH2OC6H4NCH(Me)(2′-O-3′,5′-tBu2C6H2)]. The reaction of the same ligand with AlEt3 under the same experimental conditions involved ethane elimination, ethylene elimination and intramolecular hydrogen migration, and led to the complex [AlL′′] (3) [L′′ = (2-O-3,5-tBu2C6H2)CHNC6H4OCH2CH2OC6H4NCH2(2′-O-3′,5′-tBu2C6H2)]. However, the interaction of two equivalents of AlMe3 and AlEt3 afforded the corresponding binuclear complexes [(AlMe2)2L] (4) and [(AlEt2)2L] (5), respectively, and no methyl or hydrogen migration was found. The solid-state structures of aluminum complexes 1-3 were determined by single-crystal X-ray diffraction. It was found that complexes 2-5 show a very effective catalytic activity for the cycloaddition of epoxides and CO2 in the presence of NBu4Br as a cocatalyst at atmospheric pressure.
- Xu, Ya,Yuan, Dan,Wang, Yaorong,Yao, Yingming
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p. 5848 - 5855
(2017/07/10)
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- Hollow and microporous catalysts bearing Cr(III)-F porphyrins for room temperature CO2 fixation to cyclic carbonates
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Hollow and microporous metal free/Cr-porphyrin networks were prepared via the Sonogashira coupling of metal-free or Cr-tetra(4-ethynylphenyl) porphyrins and 1,4-diiodobenzene on the surface of silica templates followed by silica etching. Zinc was introduced into a hollow and microporous metal free porphyrin network (H-MPN) through post-synthetic modification to form a H-MZnPN. Hollow and microporous Cr(iii)-F porphyrin networks (H-MCrPNs) showed the best catalytic activities in room temperature CO2 fixation with epoxides to cyclic carbonates. In addition, the H-MCrPN could be reused at least for five runs, maintaining the original catalytic activity. The good performance of the H-MCrPN is attributed to its microporosity, the shortened diffusion pathways for substrates due to the hollow structure, and the efficient Lewis acidic activity of Cr(iii)-F moieties.
- Kim, Myung Hyun,Song, Taemoon,Seo, Ue Ryung,Park, Ji Eun,Cho, Kyoungil,Lee, Sang Moon,Kim, Hae Jin,Ko, Yoon-Joo,Chung, Young Keun,Son, Seung Uk
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p. 23612 - 23619
(2017/11/30)
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- Polystyrene-supported bifunctional resorcinarenes as cheap, metal-free and recyclable catalysts for epoxide/CO2 coupling reactions
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We here report the synthesis of bifunctional catalysts that can be assembled using simple, cheap and accessible building blocks based on resorcinarenes, and their application as efficient, one-component homogeneous catalysts in the coupling of both terminal and internal epoxides with carbon dioxide affording their cyclic carbonate products. Furthermore, a heterogeneous version was also prepared that combines the activity of these bifunctional systems with excellent stability and recycling potential, allowing for a turnover of >1250. This newly prepared organocatalyst obviates the use of any metal, solvent or additives marking it as an attractive catalyst for CO2 valorization.
- Jose,Ca?ellas,Pericàs,Kleij
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supporting information
p. 5488 - 5493
(2017/11/22)
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- Recyclable Single-Component Rare-Earth Metal Catalysts for Cycloaddition of CO2 and Epoxides at Atmospheric Pressure
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Ionic rare-earth metal complexes 1-4 bearing an imidazolium cation were synthesized, which, as single-component catalysts, showed good activity in catalyzing cyclic carbonate synthesis from epoxides and CO2. In the presence of 0.2 mol % catalyst, monosubstituted epoxides bearing different functional groups were converted into cyclic carbonates in 60-97% yields under atmospheric pressure. In addition, bulky/internal epoxides with low reactivity yielded cyclic carbonates in 40-95% yields. More importantly, the readily available samarium complex 2 was reused for six successive cycles without any significant loss in its catalytic activity. This is the first recyclable rare-earth metal-based catalyst in cyclic carbonate synthesis.
- Zhao, Zhiwen,Qin, Jie,Zhang, Chen,Wang, Yaorong,Yuan, Dan,Yao, Yingming
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p. 4568 - 4575
(2017/04/26)
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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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- Highly Active Salen-Based Aluminum Catalyst for the Coupling of Carbon Dioxide with Epoxides at Ambient Temperature
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Aluminum complex [(naph)salen]AlMe [(naph)salen = N,N′-(2,3-naphthalene)bis(3,5-dimethylsalicylideneiminato)] was synthesized and fully characterized by NMR spectroscopy, high-resolution mass spectrometry, elemental analysis, and single-crystal XRD. The complex exhibits square-pyramidal geometry around the aluminum center in the solid-state structure, and it has a trigonality parameter τ of 0.13. Comparison of the catalytic activity of [(naph)salen]AlMe with that of four related aluminum complexes containing tetradentate salen ligands with different bridging groups revealed that the naphthyl-bridged salen-based aluminum complex, in conjunction with nBu4NI as cocatalyst, showed higher catalytic activity than the other complexes for the coupling of CO2 with epoxides under the mild conditions of room temperature and 5 bar of CO2 in 12 h. In addition, [(naph)salen]AlMe showed favorable features, such as requiring low catalyst loading (0.5 mol-%) and broad epoxide substrate scope, including six terminal epoxides and three internal epoxides.
- Woo, Won Hee,Hyun, Kyunglim,Kim, Yoseph,Ryu, Ji Yeon,Lee, Junseong,Kim, Min,Park, Myung Hwan,Kim, Youngjo
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p. 5372 - 5378
(2017/12/08)
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- Continuous-Flow O-Alkylation of Biobased Derivatives with Dialkyl Carbonates in the Presence of Magnesium–Aluminium Hydrotalcites as Catalyst Precursors
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The base-catalysed reactions of OH-bearing biobased derivatives (BBDs) including glycerol formal, solketal, glycerol carbonate, furfuryl alcohol and tetrahydrofurfuryl alcohol with non-toxic dialkyl carbonates (dimethyl and diethyl carbonate) were explored under continuous-flow (CF) conditions in the presence of three Na-exchanged Y- and X-faujasites (FAUs) and four Mg–Al hydrotalcites (HTs). Compared to previous etherification protocols mediated by dialkyl carbonates, the reported procedure offers substantial improvements not only in terms of (chemo)selectivity but also for the recyclability of the catalysts, workup, ease of product purification and, importantly, process intensification. Characterisation studies proved that both HT30 and KW2000 hydrotalcites acted as catalyst precursors: during the thermal activation pre-treatments, the typical lamellar structure of the hydrotalcite was broken down gradually into a MgO-like phase (periclase) or rather a magnesia–alumina solid solution, which was the genuine catalytic phase.
- Cattelan, Lisa,Perosa, Alvise,Riello, Piero,Maschmeyer, Thomas,Selva, Maurizio
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p. 1571 - 1583
(2017/04/14)
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- Transformation of Carbon Dioxide into Oxazolidinones and Cyclic Carbonates Catalyzed by Rare-Earth-Metal Phenolates
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Rare-earth-metal complexes stabilized by amine-bridged tri(phenolato) ligands were developed, and their activities in catalyzing transformations of CO2 were studied. A series of terminal epoxides and challenging disubstituted epoxides were converted into the respective cyclic carbonates in the presence of CO2 in yields of 58 to 96 %. In addition, these rare-earth-metal complexes also showed good activities in catalyzing three-component reactions of anilines, epoxides, and CO2, which generated 5-substituted-3-aryl-2-oxazolidines in yields of 48 to 96 %, as a useful strategy to construct oxazolidinones.
- Xu, Bin,Wang, Peng,Lv, Min,Yuan, Dan,Yao, Yingming
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p. 2466 - 2471
(2016/08/24)
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- Dinuclear Aluminum Poly(phenolate) Complexes as Efficient Catalysts for Cyclic Carbonate Synthesis
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A series of dinuclear aluminum complexes 1-4 stabilized by amine-bridged poly(phenolato) ligands have been synthesized, which are highly active in catalyzing the cycloaddition of epoxides and CO2. In the presence of 0.3 mol % complex 3 and 0.9 mol % NBu4Br at 1 bar CO2 pressure, terminal epoxides bearing different functional groups were converted to cyclic carbonates in 60-97% yields. Complex 3 is one of the rare examples of Al-based catalysts capable of promoting the cycloaddition at 1 bar pressure of CO2. Moreover, reactions of more challenging disubstituted epoxides also proceeded at an elevated pressure of 10 bar and afforded cyclic carbonates in 52-90% yields.
- Gao, Pengfei,Zhao, Zhiwen,Chen, Lijuan,Yuan, Dan,Yao, Yingming
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p. 1707 - 1712
(2016/07/06)
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- Cavitand-Based Polyphenols as Highly Reactive Organocatalysts for the Coupling of Carbon Dioxide and Oxiranes
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A variety of cavitand-based polyphenols was prepared from cheap and accessible aldehyde and resorcinol/pyrogallol reagents to give the respective resorcin[4]- or pyrogallol[4]arenes. The preorganization of the phenolic units allows intra- and intermolecular hydrogen bond (HB) networks that affect both the reactivity and stability of these HB-donor catalysts. Unexpectedly, we found that the resorcin[4]arenes show cooperative catalysis behavior compared to the parent resorcinol in the catalytic coupling of epoxides and CO2 with a significantly higher turnover. At elevated reaction temperatures, the resorcin[4]arene-based catalyst 3 d displays the best catalytic performance with very high turnover numbers and frequencies, combining increased reactivity and stability compared to pyrogallol, and an ample substrate scope. This type of polyphenol structure thus illustrates the importance of a new, highly competitive organocatalyst design to devise sustainable CO2 conversion processes.
- Martínez-Rodríguez, Luis,Otalora Garmilla, Javier,Kleij, Arjan W.
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p. 749 - 755
(2016/05/09)
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- Lewis acid-base bifunctional aluminum-salen catalysts: synthesis of cyclic carbonates from carbon dioxide and epoxides
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Two Lewis acid-base bifunctional monometallic aluminum-salen complexes were prepared based on a new type of salen ligand with two N-methylhomopiperazine moieties at the 3,3′-position. The Al(salen) complexes proved to be efficient and recyclable homogeneous catalysts towards the organic solvent-free synthesis of cyclic carbonates from epoxides and CO2 in the absence of a co-catalyst, in which >90% yield of cyclic carbonate could be obtained under relatively mild conditions. The catalysts can be easily recovered and reused five times without significant loss of activity and selectivity. Furthermore, the Lewis acid-base cooperative activation mechanism by the bifunctional Al(salen) complexes was proposed according to experimental data.
- Ren, Yanwei,Jiang, Ou,Zeng, Hang,Mao, Qiuping,Jiang, Huanfeng
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p. 3243 - 3249
(2016/01/16)
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- Facile synthesis of a dimeric titanium(iv) complex with terminal TiO moieties and its application as a catalyst for the cycloaddition reaction of CO2 to epoxides
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In this report, facile and exclusive synthesis of dimeric titanium(iv) complex with a terminal TiO moiety from the reaction between novel pyridine-based tridentate ligand (LH2) and Ti(O-i-Pr)4 under the bubbling of wet air is presented. Alternatively, the same dimeric Ti complex was obtained via wet air bubbling of monomeric LTi(O-i-Pr)2 or addition of the same equiv. of H2O into LTi(O-i-Pr)2. All compounds including LH2 and two titanium complexes were characterized by single crystal X-ray analyses. Newly synthesized terminal oxo-titanium compound is the first example of structurally characterized dimeric terminal oxo-titanium compound having no TiO→Ti bonds. Two titanium complexes were used as effective catalysts for the cycloaddition of CO2 to propylene oxide in the presence of various kinds of cocatalysts such as n-Bu4PBr, n-Bu4NI, n-Bu4NBr, n-Bu4NCl, PPNCl, and DMAP.
- Kim, Hyejin,Choi, Sung Ho,Ahn, Duseong,Kim, Yoseph,Ryu, Ji Yeon,Lee, Junseong,Kim, Youngjo
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p. 97800 - 97807
(2016/10/31)
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- Highly efficient synthesis of cyclic carbonates from carbon dioxide and epoxides catalyzed by ionic liquid [Heemim][ZrCl5]
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A facile and efficient synthesis of cyclic carbonates by cycloaddition reaction is described. Treatment of epoxides with carbon dioxide in the presence of [Heemim][ZrCl5] under solvent- and additive-free conditions gives the corresponding cyclic carbonates in good to high yields and selectivity. Furthermore, the catalyst can be recycled or reused without any significant loss of catalytic activity. Additionally, the possible mechanism of cycloaddition in the catalytic system is also proposed.
- Hu, Yu-Lin,Lu, Ming,Yang, Xue-Lin
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p. 67886 - 67891
(2015/08/24)
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- Highly Efficient Organocatalyzed Conversion of Oxiranes and CO2 into Organic Carbonates
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A binary catalyst system based on tannic acid/NBu4X (X=Br, I) is presented as a highly efficient organocatalyst at very low catalyst loading for the coupling of carbon dioxide and functional oxiranes to afford organic carbonates in good yields. The presence of multiple polyphenol fragments within the tannic acid structure is considered to be beneficial for synergistic effects that lead to higher stabilization of the catalyst structure during catalysis. The observed turnover frequencies (TOFs) exceed 200 h-1 and are among the highest reported to date for organocatalysts in this area of CO2 conversion. This organocatalyst system presents a useful, readily available, inexpensive, and, above all, reactive alternative for most of the metal-based catalyst systems reported to date.
- Sope?a, Sergio,Fiorani, Giulia,Martín, Carmen,Kleij, Arjan W.
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p. 3248 - 3254
(2015/10/19)
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- Quaternary ammonium hydroxide as a metal-free and halogen-free catalyst for the synthesis of cyclic carbonates from epoxides and carbon dioxide
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Tetrabutylammonium hydroxide (TBAH) and other quaternary ammonium hydroxides catalyzed the cycloaddition of CO2 to epoxides under solvent-free conditions to give cyclic carbonates. When TBAH was exposed to CO2, TBAH was converted into tetrabutylammonium bicarbonate (TBABC), which was a catalytically active species. A D-labeled epoxide and an optically active epoxide were used to study the reaction mechanism, which invoked three plausible pathways. Among them, path A seemed to be predominant; the bicarbonate ion of TBABC attacks the less hindered C atom of the epoxide to generate a ring-opened alkoxide intermediate, which adds to CO2 to give a carbonate ion, and the subsequent cyclization yields a cyclic carbonate. Density functional theory (DFT) calculations successfully delineated the potential energy profile for each reaction pathway, among which path A was the lowest-energy pathway in accordance with the experimental results. The tetrabutylammonium (TBA) cation carries the positive charges on the H atoms, but not on the central N atom, and the positively charged H atoms close to the central N atom form an anion-binding site capable of stabilizing various anionic transition states and intermediates.
- Ema, Tadashi,Fukuhara, Kazuki,Sakai, Takashi,Ohbo, Masaki,Bai, Fu-Quan,Hasegawa, Jun-Ya
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p. 2314 - 2321
(2015/04/14)
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- A new type of lewis acid-base bifunctional M(salphen) (M=Zn, Cu and Ni) catalysts for CO2 fixation
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A new type of Lewis acid-base bifunctional M(salphen) complexes (M=ZnII, CuII, and NiII) pending two N-methylhomo- piperazine groups as nucleophiles were prepared by a one-pot method. The Zn(salphen) complexes proved to be efficient and recyclable homogeneous catalysts towards the solvent-free synthesis of cyclic carbonates from epoxides and CO2 in the absence of a co-catalyst. The catalysts can be easily recovered and five times reused without significant loss of activity and selectivity. Bifunctional catalysts: A new type of Lewis acid-base bifunctional Zn(salphen) catalysts with an organic base, N-methylhomopiperazine, as a nucleophile were prepared by a one-pot method and successfully applied in the production of cyclic carbonates from CO2 and epoxides. The catalysts used in this catalytic system are extremely stable and can be recycled at least five times and their activity is almost unchanged.
- Ren, Yanwei,Chen, Jungui,Qi, Chaorong,Jiang, Huanfeng
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p. 1535 - 1538
(2015/05/27)
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- Method for the synthesis of alpha/alpha-prime-alcoxylated glycerol linear carbonic esters
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A method for the synthesis of α/α′-alcoxylated glycerol linear carbonic esters, wherein the following are brought into contact at a reaction temperature lower than 220° C.: a quantity of at least one precursor selected from the group consisting of α/α′-alcoxylated glycerol cyclo-carbonates; a quantity of at least one catalyst selected from the group consisting of metal oxides, Lewis acids, organometallic catalysts and mineral bases; and a quantity of at least one organic primer. A composition containing at least one novel α/α′-alkoxylated glycerol linear carbonic ester.
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Paragraph 0165; 0166
(2016/01/15)
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- Catalytic production of cyclic carbonates mediated by lanthanide phenolates under mild conditions
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Readily available lanthanide complexes stabilized by a bridged poly(phenolate) ligand have been used for the first time as efficient catalysts for the insertion of CO2 into epoxides to generate cyclic carbonates with high activity, high selectivity, and a wide substrate scope under mild conditions. This journal is the Partner Organisations 2014.
- Qin, Jie,Wang, Peng,Li, Qingyan,Zhang, Yong,Yuan, Dan,Yao, Yingming
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supporting information
p. 10952 - 10955
(2014/09/30)
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