On the spontaneous carboxylation of 1-butyl-3-methylimidazolium acetate by carbon dioxide

Besnard, M.; Cabaço, M. Isabel; Chávez, Fabián Vaca; Pinaud, Noël; Sebastião, Pedro J.; Coutinho, João A. P.; Danten, Y.

doi:10.1039/c1cc16702b

Cited by 93 publications

(100 citation statements)

References 22 publications

(29 reference statements)

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“…[37] This is owed to the fact that the presence of water does not compete with the CO 2 -sorption sites present in these ILs. [18,22,[29][30][31][40][41][42] The 13 C-{ 1 H} HP-NMR of BMIm·OAc containing water (3:1) at 80 bar CO 2 and 313 K( Figure S20) shows the characteristic peaks of the CO 2 -imidazolium adduct (C2carboxylated), in particular,t he signals at 155.0 and 141.4 ppm correspond to the carbon of carboxylate and C2-carboxylated moieties, [22] and the signal at 124.2 ppm is owed to noncovalently IL-dissolved CO 2 . [38,39] The solubility of CO 2 in imidazolium-based ILs associated with acetate anion was already investigated in detail.…”

Section: Resultsmentioning

confidence: 99%

Carbon Dioxide Capture by Aqueous Ionic Liquid Solutions

et al. 2017

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Confined water in aqueous solutions of imidazolium-based ionic liquids (ILs) associated with acetate and imidazolate anions react reversibly with CO to yield bicarbonate. Three types of CO sorption in these "IL aqueous solutions" were observed: physical, CO -imidazolium adduct generation, and bicarbonate formation (up to 1.9 mol mol of IL), resulting in a 10:1 (molar ratio) total absorption of CO relative to imidazolate anions in the presence of water 1:1000 (IL/water). These sorption values are higher than the classical alkanol amines or even alkaline aqueous solutions under similar experimental conditions.

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Section: Resultsmentioning

confidence: 99%

Carbon Dioxide Capture by Aqueous Ionic Liquid Solutions

et al. 2017

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“…In addition, FTIR and Raman spectroscopy have been utilized. [40][41][42] This paper focuses specifically on certain ionic liquids that are capable of acting as chemisorbents for CO 2 in cyclic carbon capture separation processes in which the CO 2 can be easily desorbed from the ionic liquid which is then recycled to the absorption step. Specific ionic liquids have been found to be effective at low pressures by a process of chemisorption in the liquid thus facilitating exceptionally high overall system CO 2 uptake efficiency.…”

Section: Introductionmentioning

confidence: 99%

“…27,40,41,43,44,45 The cation of such ionic liquids contains a relatively acidic hydrogen atom bonded to a potentially nucleophilic carbon atom at the C-2 position.…”

Section: Introductionmentioning

confidence: 99%

Pathways of the Chemical Reaction of Carbon Dioxide with Ionic Liquids and Amines in Ionic Liquid Solution

2015

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This paper focuses specifically on certain ionic liquids which are capable of acting as chemisorbents for CO2 at ambient pressure and temperature. This low pressure approach based on chemical reactivity is more effective than traditional physical absorption / solubility approaches for CO2 capture in ionic liquids for higher pressure carbon capture. We describe a class of imidazolium ionic liquids bearing a relatively acidic hydrogen atom at C-2 which upon initial abstraction develops a nucleophilic carbon atom that is carboxylated by CO2. Basicity of the anion plays role in the ability to remove the acidic hydrogen to generate the nucleophilic carbon. The yield of carboxylated ionic liquid is not affected by non-aqueous co-solvents, but changes as a function of CO2 partial pressure, solution temperature, and presence of H2O in solution. CO2 chemisorption by ionic liquids is particularly efficient in the presence of a non-nucleophilic nitrogenous base that serves to promote ionic liquid carboxylation and stabilize the carboxylic acid product as a salt. Selected ionic liquids are able to stabilize the formation of amine carbamic acids in the ionic liquid solution. In this case, each amine captures up to 1 CO2 molecule which is beneficial for the overall CO2 capacity in the solution. Carboxylation of the ionic liquids themselves is lower because the basic anion of the ionic liquid also stabilizes N-carboxylated products. In-situ 13C and 1H NMR spectroscopy using a built-in micro reactor was used to provide real time insights on CO2 -ionic liquid and CO2 -amine reaction pathways and product speciation under various conditions.

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“…[14][15][16][17][18][19][20][21][22][23] A reactive mechanism has been proposed in which the proton bounded to carbon atom 2 of the imidazolium cation is released leading to the generation of a carbene intermediate, whereas the proton interacts with the acetate anion to form acetic acid (Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

“…Other works, although considering the formation of carbene and acetic acid, differ slightly from this initial interpretation, arguing that the reactions are triggered by the introduction of carbon dioxide itself in the IL and that the carbene and carboxylate formation results from a concerted cooperative process between the cation, the anion, and the CO 2 molecule. [20][21][22] More recently, it was theoretically inferred that it is the introduction of neutral molecules like CO 2 in the IL charged network which cancels partially the charge-stabilizing effect existing in the neat IL and that this so-called inverse ionic liquid effect facilitates the carbene formation and, thus, the chemical absorption. 24,25 Very recently, new insights in the understanding of solute-solvent interactions within IL were provided from a theoretical study on the solvation of a carbene 1-ethyl-3-methylimidazole-2-ylidene in 1-ethyl-3-methylimidazolium acetate.…”

Section: Introductionmentioning

confidence: 99%

Understanding chemical reactions of CO2 and its isoelectronic molecules with 1-butyl-3-methylimidazolium acetate by changing the nature of the cation: The case of CS2 in 1-butyl-1-methylpyrrolidinium acetate studied by NMR spectroscopy and density functional theory calculations

Cabaço¹,

Besnard

Chávez

et al. 2014

The Journal of Chemical Physics

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NMR spectroscopy ( 1 H, 13 C, 15 N) shows that carbon disulfide reacts spontaneously with 1-butyl-1-methylpyrrolidinium acetate ([BmPyrro][Ac]) in the liquid phase. It is found that the acetate anions play an important role in conditioning chemical reactions with CS 2 leading, via coupled complex reactions, to the degradation of this molecule to form thioacetate anion (CH 3 COS − ), CO 2 , OCS, and trithiocarbonate (CS 3 2− ). In marked contrast, the cation does not lead to the formation of any adducts allowing to conclude that, at most, its role consists in assisting indirectly these reactions. The choice of the [BmPyrro] + cation in the present study allows disentangling the role of the anion and the cation in the reactions. As a consequence, the ensemble of results already reported on (2), and CO 2 - [Bmim][Ac] (3) systems can be consistently rationalized. It is argued that in system (1) both anion and cation play a role. The CS 2 reacts with the acetate anion leading to the formation of CH 3 COS − , CO 2 , and OCS. After these reactions have proceeded the nascent CO 2 and OCS interact with the cation to form imidazolium-carboxylate ([Bmim] CO 2 ) and imidazoliumthiocarboxylate ([Bmim] COS). The same scenario also applies to system (2). In contrast, in the CO 2 - [Bmim] [Ac] system a concerted cooperative process between the cation, the anion, and the CO 2 molecule takes place. A carbene issued from the cation reacts to form the [Bmim] CO 2 , whereas the proton released by the ring interacts with the anion to produce acetic acid. In all these systems, the formation of adduct resulting from the reaction between the solute molecule and the carbene species originating from the cation is expected. However, this species was only observed in systems (2) and (3). The absence of such an adduct in system (1) has been theoretically investigated using DFT calculations. The values of the energetic barrier of the reactions show that the formation of [Bmim] CS 2 is unfavoured and that the anion offers a competitive reactive channel via an oxygensulphur exchange mechanism with the solute in systems (1) and (2). © 2014 AIP Publishing LLC.

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On the spontaneous carboxylation of 1-butyl-3-methylimidazolium acetate by carbon dioxide

Cited by 93 publications

References 22 publications

Carbon Dioxide Capture by Aqueous Ionic Liquid Solutions

Carbon Dioxide Capture by Aqueous Ionic Liquid Solutions

Pathways of the Chemical Reaction of Carbon Dioxide with Ionic Liquids and Amines in Ionic Liquid Solution

Understanding chemical reactions of CO2 and its isoelectronic molecules with 1-butyl-3-methylimidazolium acetate by changing the nature of the cation: The case of CS2 in 1-butyl-1-methylpyrrolidinium acetate studied by NMR spectroscopy and density functional theory calculations

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