- Chemisorption of carbon dioxide in carboxylate-functionalized ionic liquids: A mechanistic study
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Spectroscopic investigations on the CO2 chemisorption by tetra-n-butylphosphonium formate as an example of carboxylate- functionalized ionic liquids reveal that the formation of hydrogen-bond complexes such as diformate anion supplies the driving force of the chemisorption.
- Yasaka, Yoshiro,Ueno, Masakatsu,Kimura, Yoshifumi
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- Thermal Phase Transition of Cesium Formate
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The phase transition of cesium formate observed at around 36°C was found to be a reversible first-order transition by means of thermal analyses. The results of the Rietveld analysis of powder X-ray diffraction data showed that an orthorhombic phase (Pbcm, Z = 8; a = 4.785(1), b =9.553(9), and c = 15.927(2) ?) transformed to a cubic phase (Pm3m, Z = 1; a = 4.500(5) ?). The large values of enthalpy and entropy change for the transition (ΔHtr = 6.87 .+-. 0.28 kJ mol**-1 and ΔStr = 22.2 .+-. 0.9 J K**-1 mol**-1) were discussed on the basis of the change of the orientation freedom of the formate ion.
- Masuda, Yoshio,Yahata, Akihiko,Ogawa, Hiroshi
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- Visible-light photoredox-catalyzed selective carboxylation of C(sp3)?F bonds with CO2
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It is highly attractive and challenging to utilize carbon dioxide (CO2), because of its inertness, as a nontoxic and sustainable C1 source in the synthesis of valuable compounds. Here, we report a novel selective carboxylation of C(sp3)?F bonds with CO2 via visible-light photoredox catalysis. A variety of mono-, di-, and trifluoroalkylarenes as well as α,α-difluorocarboxylic esters and amides undergo such reactions to give important aryl acetic acids and α-fluorocarboxylic acids, including several drugs and analogs, under mild conditions. Notably, mechanistic studies and DFT calculations demonstrate the dual role of CO2 as an electron carrier and electrophile during this transformation. The fluorinated substrates would undergo single-electron reduction by electron-rich CO2 radical anions, which are generated in situ from CO2 via sequential hydride-transfer reduction and hydrogen-atom-transfer processes. We anticipate our finding to be a starting point for more challenging CO2 utilization with inert substrates, including lignin and other biomass.
- Bo, Zhi-Yu,Chen, Lin,Gao, Tian-Yu,Jing, Ke,Lan, Yu,Liu, Shi-Han,Luo, Shu-Ping,Yan, Si-Shun,Yu, Bo,Yu, Da-Gang
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supporting information
p. 3099 - 3113
(2021/11/16)
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- A Carbon-Neutral CO2 Capture, Conversion, and Utilization Cycle with Low-Temperature Regeneration of Sodium Hydroxide
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A highly efficient recyclable system for capture and subsequent conversion of CO2 to formate salts is reported that utilizes aqueous inorganic hydroxide solutions for CO2 capture along with homogeneous pincer catalysts for hydrogenation. The produced aqueous solutions of formate salts are directly utilized, without any purification, in a direct formate fuel cell to produce electricity and regenerate the hydroxide base, achieving an overall carbon-neutral cycle. The catalysts and organic solvent are recycled by employing a biphasic solvent system (2-MTHF/H2O) with no significant decrease in turnover frequency (TOF) over five cycles. Among different hydroxides, NaOH and KOH performed best in tandem CO2 capture and conversion due to their rapid rate of capture, high formate conversion yield, and high catalytic TOF to their corresponding formate salts. Among various catalysts, Ru- and Fe-based PNP complexes were the most active for hydrogenation. The extremely low vapor pressure, nontoxic nature, easy regenerability, and high reactivity of NaOH/KOH toward CO2 make them ideal for scrubbing CO2 even from low-concentration sources - such as ambient air - and converting it to value-added products.
- Kar, Sayan,Goeppert, Alain,Galvan, Vicente,Chowdhury, Ryan,Olah, Justin,Prakash, G. K. Surya
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supporting information
p. 16873 - 16876
(2018/11/06)
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- Synthesis of zero-valent iron nanoparticles via laser ablation in a formate ionic liquid under atmospheric conditions
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Transition metal nanoparticles (NPs) are promising materials for use as catalysts in many processes, although they are easily oxidized under ambient conditions. In this communication, a novel synthetic method is proposed for producing zero-valent iron (Fe) NPs by laser ablation under atmospheric conditions using the reducing properties of a formate-based ionic liquid solvent. The valence state of Fe was confirmed using X-ray absorption near edge structure (XANES) spectroscopy. The Fe NPs adopt a face centered cubic structure after synthesis, which gradually transforms to a body centered cubic structure after one month. The method can be extended to the synthesis of other transition metal NPs that are easily oxidized.
- Okazoe, Shinya,Yasaka, Yoshiro,Kudo, Masaki,Maeno, Hiroshi,Murakami, Yasukazu,Kimura, Yoshifumi
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supporting information
p. 7834 - 7837
(2018/07/25)
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- PRODUCTION OF CESIUM OXALATE FROM CESIUM CARBONATE
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Processes for producing cesium oxalate are disclosed. The process includes contacting cesium carbonate, cesium hydrogenbicarbonate or a mixture thereof with carbon dioxide and carbon monoxide, carbon dioxide and hydrogen or carbon monoxide and oxygen at elevenated temperatures and pressures.
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Paragraph 0060; 0061; 0062
(2018/08/20)
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- CONVERSION OF CESIUM CARBONATE TO CESIUM OXALATE
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Processes for producing a disubstituted oxalate are disclosed. The process includes contacting a cesium salt with one or more alcohols and carbon dioxide (CO2) under reaction conditions sufficient to produce a composition comprising a disubstituted oxalate.
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Paragraph 0089
(2018/08/20)
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- Carbon dioxide utilization via carbonate-promoted C-H carboxylation
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Using carbon dioxide (CO2) as a feedstock for commodity synthesis is an attractive means of reducing greenhouse gas emissions and a possible stepping-stone towards renewable synthetic fuels. A major impediment to synthesizing compounds from CO2 is the difficulty of forming carbon-carbon (C-C) bonds efficiently: although CO2 reacts readily with carbon-centred nucleophiles, generating these intermediates requires high-energy reagents (such as highly reducing metals or strong organic bases), carbon-heteroatom bonds or relatively acidic carbon-hydrogen (C-H) bonds. These requirements negate the environmental benefit of using CO2 as a substrate and limit the chemistry to low-volume targets. Here we show that intermediate-temperature (200 to 350 degrees Celsius) molten salts containing caesium or potassium cations enable carbonate ions (CO32-) to deprotonate very weakly acidic C-H bonds (pKa > 40), generating carbon-centred nucleophiles that react with CO2 to form carboxylates. To illustrate a potential application, we use C-H carboxylation followed by protonation to convert 2-furoic acid into furan-2,5-dicarboxylic acid (FDCA) - a highly desirable bio-based feedstock with numerous applications, including the synthesis of polyethylene furandicarboxylate (PEF), which is a potential large-scale substitute for petroleum-derived polyethylene terephthalate (PET). Since 2-furoic acid can readily be made from lignocellulose, CO32--promoted C-H carboxylation thus reveals a way to transform inedible biomass and CO2 into a valuable feedstock chemical. Our results provide a new strategy for using CO2 in the synthesis of multi-carbon compounds.
- Banerjee, Aanindeeta,Dick, Graham R.,Yoshino, Tatsuhiko,Kanan, Matthew W.
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p. 215 - 219
(2016/03/22)
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- A Viable Hydrogen Storage and Release System Based on Cesium Formate and Bicarbonate Salts: Mechanistic Insights into the Hydrogen Release Step
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Aqueous solutions of cesium formate and bicarbonate represent an effective hydrogen storage-delivery couple that undergoes either release or take up of hydrogen in the presence of {RuCl2(mTPPTS)2}2 (TPPTS=triphenylphosphine trisulfonate) and excess mTPPTS ligand, with no other additives required. Cesium salt solutions offer the advantage of improved volumetric and gravimetric H2 density compared to their sodium and potassium analogs, owing to their high water solubility. Details of the equilibrium between formate and bicarbonate, which constitutes an important parameter for the applicability of this H2 storage/release cycle, were determined. H2 production is readily tunable by controlling the operating pressure. This behavior was also rationalized through the identification of catalytic intermediates under various conditions. High concentration formate and bicarbonate solutions were used during the tests and the bidirectional catalytic system could be recycled without loss of activity or replacement of solvent. A tentative mechanism is proposed for the formate dehydrogenation step. Among the identified hydride species, the pentacoordinated [RuH(H2O)(TPPTS)3] complex was indispensable for promoting the formate dehydrogenation reaction. Cesium cycling: In the presence of a ruthenium catalytic precursor and a stabilizing phosphine ligand, cesium formate and bicarbonate in aqueous solution perform as a stable hydrogen storage-release couple. An intermediate pentacoordinated 16-electron ruthenium hydride complex is crucial in the promotion of the formate dehydrogenation.
- Sordakis, Katerina,Dalebrook, Andrew F.,Laurenczy, Gbor
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p. 2332 - 2339
(2015/08/11)
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- Homogeneous hydrogenation of CO2 to methyl formate utilizing switchable ionic liquids
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Combined capture of CO2 and subsequent hydrogenation allows for base/methanol-promoted homogeneous hydrogenation of CO2 to methyl formate. The CO2, captured as an amidinium methyl carbonate, reacts with H2 with no applied pressure of CO2 in the presence of a catalyst to produce sequentially amidinium formate, then methyl formate. The production of methyl formate releases the base back into the system, thereby reducing one of the flaws of catalytic hydrogenations of CO2: the notable consumption of one mole of base per mole of formate produced. The reaction proceeds under 20 atm of H2 with selectivity to formate favored by the presence of excess base and lower temperatures (110 °C), while excess alcohol and higher temperatures (140 °C) favor methyl formate. Known CO2 hydrogenation catalysts are active in the ionic liquid medium with turnover numbers as high as 5000. It is unclear as to whether the alkyl carbonate or CO2 is hydrogenated, as we show they are in equilibrium in this system. The availability of both CO2 and the alkyl carbonate as reactive species may result in new catalyst designs and free energy pathways for CO2 that may entail different selectivity or kinetic activity.
- Yadav, Mahendra,Linehan, John C.,Karkamkar, Abhijeet J.,Van Der Eide, Edwin,Heldebrant, David J.
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supporting information
p. 9849 - 9854
(2015/02/19)
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- Thermal Stability of σ Complexes of Aromatic Dinitro Compounds with Alkali Metal Methylates
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Thermal stability of σ complexes of 2,4-dinitroanisole, 2-methoxy-3,5-dinitrobenzamide, 2,4-dinitro-5- and 2,4-dinitro-6-methoxyanisole, and 1-methoxy-2,4-dinitronaphthalene with alkali metal methylates was studied by differential thermal analysis in combination with differential thermogravimetry. The temperature and heat of decomposition of these compounds depend on the nature of substituent in the anion of the σ complex and on the radius of the alkali metal cation. In the first step of the thermolysis the corresponding dinitrophenolates and dinitronaphtholates are formed. The final products of the thermolysis are alkali metal formates.
- Kartashova,Gitis,Atroshchenko,Alifanova,Soldatova,Shakhkel'dyan
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p. 1925 - 1928
(2007/10/03)
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- Novel Synthesis of Oxalate from Carbon Dioxide and Carbon Monoxide in the Presence of Caesium Carbonate
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In the presence of caesium carbonate 1, the direct reaction of CO2 (110 atm) with CO (20 atm) results in reductive capture of CO2 to give caesium oxalate 2 in good yield at elevated temperature (380 deg C).
- Kudo, Kiyoshi,Ikoma, Futoshi,Mori, Sadayuki,Komatsu, Koichi,Sugita, Nobuyuki
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p. 633 - 634
(2007/10/02)
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- Photolysis of Alkali Hexa(formato)ferrates(III) in Solution
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Photolysis of alkali hexa(formato)ferrates(III) in solution and solid phase has been investigated.The formation of iron(II) species has been detected by UV spectroscopy.Solid state photopysis does not show the formation of Fe(II) species.
- Brar, A. S.,Brar, S.,Sandhu, S.
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