Significant Cation Effects in Carbon Dioxide–Ionic Liquid Systems

Hollóczki, Oldamur; Kelemen, Zsolt; Könczöl, László; Szieberth, Dénes; Nyulászi, László; Stark, Annegret; Kirchner, Barbara

doi:10.1002/cphc.201200970

Cited by 77 publications

(86 citation statements)

References 52 publications

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“…[32] Instead, it appears that, as in the case of LC-forming ILs and benzene, weaker cation-anion interactions allow the IL to act as ah ost network more easily and accommodate larger amountsoft he solute. While anions are correlatedw ith large changes in Henry's constants, it is the most weakly coordinating anion ([NTf 2 ] À ), whichg enerates the largests olubilities.…”

Section: Co 2 Solubilitymentioning

confidence: 99%

Understanding Carbon Dioxide Solubility in Ionic Liquids by Exploring the Link with Liquid Clathrate Formation

Kelley

Flores

Shannon

et al. 2017

Chemistry A European J

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The solubilities of the quadrupolar molecules benzene and CO in various ionic liquids (ILs) are compared in order to determine the connection between aromatic liquid clathrate formation and CO dissolution in ILs. It was found that both CO Henry's law constants and benzene solubility are remarkably well correlated with each other and with IL molar volume, suggesting both phenomena depend more on the strength of interionic interactions between the ions of an IL rather than the identity of either ion. However, IL ion-quadrupole interactions were found to have an effect for dicyanamide ([N(CN) ] ), where solubility of CO and benzene are affected by destabilizing and stabilizing interactions with [N(CN) ] , respectively. The results suggest both solubility phenomena are related to the incorporation of the solute into an IL host network. Aromatic liquid clathrate formation thus has potential as a facile experimental probe for predicting the relative ability of ILs to physisorb CO .

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Section: Co 2 Solubilitymentioning

confidence: 99%

Understanding Carbon Dioxide Solubility in Ionic Liquids by Exploring the Link with Liquid Clathrate Formation

Kelley

Flores

Shannon

et al. 2017

Chemistry A European J

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“…The second conformation is the on-top conformation, where the anion is above or below the ring center, see the ring and the side chain in gg or gt conformation of the same cation. 95,109,110,114,[118][119][120][121] To examine such coordination behavior, a combined distribution function containing the distance d CoR(+) − X(−) and the angle (r RN , r CoR(+) − X(−) ), where CoR(+) is the center of the imidazolium ring, RN is the ring normal of the same ring, and X(−) are the coordinating atoms of the anion, is employed. Representative CDFs are presented in Fig.…”

Section: E Cation-anion Interactionmentioning

confidence: 99%

Side chain fluorination and anion effect on the structure of 1-butyl-3-methylimidazolium ionic liquids

Weber

Hollóczki

Pensado

et al. 2013

The Journal of Chemical Physics

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112

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We present a comprehensive molecular dynamics simulation study on 1-butyl-3-methylimidazolium ionic liquids and their fluorinated analogs. The work focused on the effect of fluorination at varying anions. The main findings are that the fluorination of the cations side chain increases overall structuring, especially the aggregation of cation side chain. Furthermore, large and weakly coordinating anions tend to occupy on-top positions of the cation and decrease the aggregation of cation side chains, most likely due to enhanced alkyl-anion interaction.

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“…[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. 26 It was shown that the lack of strong hydrogen bonding between the hypovalent carbon atom of the carbene and the ring hydrogen atoms of the cation prevents the stabilization of this species explaining its high reactivity in acetate-based ILs.…”

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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Significant Cation Effects in Carbon Dioxide–Ionic Liquid Systems

Cited by 77 publications

References 52 publications

Understanding Carbon Dioxide Solubility in Ionic Liquids by Exploring the Link with Liquid Clathrate Formation

Understanding Carbon Dioxide Solubility in Ionic Liquids by Exploring the Link with Liquid Clathrate Formation

Side chain fluorination and anion effect on the structure of 1-butyl-3-methylimidazolium ionic liquids

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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