Electrosynthesis of Imidazolium Carboxylates

Robillard, Guillaume de; Devillers, Charles H.; Kunz, Doris; Cattey, Hélène; Digard, Eric; Andrieu, Jacques

doi:10.1021/ol401949f

Cited by 34 publications

(23 citation statements)

References 43 publications

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“…[1,2,[9][10][11][12][13][14][15][16] It depends of course on the ionic species [1,2,10,12,13,16] but also on the material of the working electrode [2,[10][11][12][13][14] and on the presence of impuritiesincluding water. They mainly rely on quantum chemical calculations [15,21] or experimental investigations by NMR, [21,24,25,32] mass spectrometry [24,25,29] or in situ infrared spectroscopy. They mainly rely on quantum chemical calculations [15,21] or experimental investigations by NMR, [21,24,25,32] mass spectrometry [24,25,29] or in situ infrared spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

NMR Study of the Reductive Decomposition of [BMIm][NTf₂] at Gold Electrodes and Indirect Electrochemical Conversion of CO₂

et al. 2017

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Potential controlled electrolyses of [BMIm][NTf ] ionic liquid were performed at a gold cathode under nitrogen atmosphere. The structures of the major conversion products of the BMIm cation were elucidated on the basis of 1D and 2D nuclear magnetic resonance (NMR) analyses and gas chromatography (GC) analysis of the volatile compounds. Recombination of the imidazol-2-yl radicals, generated at the electrode by single electron transfer, leads to neutral diastereomeric dimers in equal proportions, with a faradaic efficiency of 80 %, while disproportionation of these radicals and/or reaction with hydrogen atoms adsorbed at the electrode generates a neutral monomer with 20 % faradaic efficiency. Both pathways also yield the N-heterocyclic carbene imidazolin-2-ylidene, which is involved in fast proton exchange with the parent BMIm cation. The reductive decomposition products of the BMIm cation are no longer detected if the pre-electrolysed sample is reacted with CO , which undergoes an indirect reduction and generates the carboxylate adduct.

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Section: Introductionmentioning

confidence: 99%

NMR Study of the Reductive Decomposition of [BMIm][NTf₂] at Gold Electrodes and Indirect Electrochemical Conversion of CO₂

et al. 2017

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“…Besides the various applications in organic chemistry, electrochemistry or material chemistry, ionic liquids gained popularity in the field of carbon dioxide capture and storage (CCS, e.g., in CO 2 absorption from industrial waste gases), as carbon dioxide catch and release reagents (de Robillard et al, 2013; Feroci et al, 2013b). Physisorption is the mechanism for such a CO 2 capture in ILs, but chemisorption was invoked for some functionalized ILs.…”

Section: The Presence Of Co2mentioning

confidence: 99%

NHC in Imidazolium Acetate Ionic Liquids: Actual or Potential Presence?

et al. 2018

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Ionic liquids (ILs) are considered in the majority of cases green solvents, due to their virtually null vapor pressure and to the easiness in recycling them. In particular, imidazolium ILs are widely used in many fields of Chemistry, as solvents or precursors of N-heterocyclic carbenes (NHCs). The latter are easily obtained by deprotonation of the C2-H, usually using strong bases or cathodic reduction. Nevertheless, it is known that weaker bases (e.g., triethylamine) are able to promote C2-H/D exchange. From this perspective, the possibility of deprotonating C2-H group of an imidazolium cation by means of a basic counter-ion was seriously considered and led to the synthesis of imidazolium ILs spontaneously containing NHCs. The most famous of this class of ILs are N,N'-disubstituted imidazolium acetates. Due to the particular reactivity of this kind of ILs, they were appointed as “organocatalytic ionic liquids” or “proto-carbenes.” Many papers report the use of these imidazolium acetates in organocatalytic reactions (i. e., catalyzed by NHC) or in stoichiometric NHC reactions (e.g., with elemental sulfur to yield the corresponding imidazole-2-thiones). Nevertheless, the actual presence of NHC in N,N'-disubstituted imidazolium acetate is still controversial. Moreover, theoretical studies seem to rule out the presence of NHC in such a polar environment as an IL. Aim of this Mini Review is to give the reader an up-to-date overview on the actual or potential presence of NHC in such an “organocatalytic ionic liquid,” both from the experimental and theoretical point of view, without the intent to be exhaustive on N,N'-disubstituted imidazolium acetate applications.

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“…More recently, the voltammetric behavior of neat azolium salts (imidazolium-, triazolium-, and thiazolium-based) or of their solutions (N,N-dimethylformamide (DMF), and MeCN as solvents) was reconsidered [28][29][30][31][32]. The NHCH + reduction and NHC oxidation potentials are obviously dependent on structure of the azolium cation, of the counter-ion, the presence and the nature of the solvent, and the electrode material ( Figure 5).…”

Section: Electrodic Activity Of the System Nhch + /Nhcmentioning

confidence: 99%

“…Recently, papers described the electrochemical synthesis of NHC-CO 2 adducts for the CO 2 catch and release [29,31,39]. A simple electrolysis of neat liquid imidazolium salts (e.g., 1-butyl-3-methyl-1H-imidazolium tetrafluoroborate) generated NHC in the catholyte and, after carbon dioxide bubbling, the NHC-CO 2 adduct.…”

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confidence: 99%

Advances in the Knowledge of N-Heterocyclic Carbenes Properties. The Backing of the Electrochemical Investigation

2016

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In the last twenty years, N-heterocyclic carbenes (NHCs) have acquired considerable popularity as ligands for transition metals, organocatalysts and in metal-free polymer synthesis. NHCs are generally derived from azolium based salts NHCH+X− by deprotonation or reduction (chemical or electrochemical) of NHCH+. The extensive knowledge of the physicochemical properties of NHCH+/NHC system could help to select the conditions (scaffold of NHC, nature of the counter-ion X−, solvent, etc.) to enhance the catalytic power of NHC in a synthesis. The electrochemical behavior of NHCH+/NHC system, in the absence and in the presence of solvent, was extensively discussed. The cathodic reduction of NHCH+ to NHC and the anodic oxidation of NHC, and the related effect of the scaffold, solvent, and electrodic material were emphasized. The electrochemical investigations allow acquiring further knowledge as regards the stability of NHC, the acidic and nucleophilic properties of NHCH+/NHC system, the reactivity of NHC versus carbon dioxide and the effect of the hydrogen bond on the catalytic efficiency of NHC. The question of the spontaneous or induced formation of NHC from particular ionic liquids was reconsidered via voltammetric analysis. The results suggested by the classical and the electrochemical methodologies were compared and discussed.

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Electrosynthesis of Imidazolium Carboxylates

Abstract: Synthesis of imidazolium carboxylate compounds was efficiently achieved by electrochemical reduction of imidazolium precursors under very mild conditions.

Cited by 34 publications

References 43 publications

NMR Study of the Reductive Decomposition of [BMIm][NTf₂] at Gold Electrodes and Indirect Electrochemical Conversion of CO₂

NMR Study of the Reductive Decomposition of [BMIm][NTf₂] at Gold Electrodes and Indirect Electrochemical Conversion of CO₂

NHC in Imidazolium Acetate Ionic Liquids: Actual or Potential Presence?

Advances in the Knowledge of N-Heterocyclic Carbenes Properties. The Backing of the Electrochemical Investigation

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Electrosynthesis of Imidazolium Carboxylates

Abstract: Synthesis of imidazolium carboxylate compounds was efficiently achieved by electrochemical reduction of imidazolium precursors under very mild conditions.

Cited by 34 publications

References 43 publications

NMR Study of the Reductive Decomposition of [BMIm][NTf2] at Gold Electrodes and Indirect Electrochemical Conversion of CO2

NMR Study of the Reductive Decomposition of [BMIm][NTf2] at Gold Electrodes and Indirect Electrochemical Conversion of CO2

NHC in Imidazolium Acetate Ionic Liquids: Actual or Potential Presence?

Advances in the Knowledge of N-Heterocyclic Carbenes Properties. The Backing of the Electrochemical Investigation

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NMR Study of the Reductive Decomposition of [BMIm][NTf₂] at Gold Electrodes and Indirect Electrochemical Conversion of CO₂

NMR Study of the Reductive Decomposition of [BMIm][NTf₂] at Gold Electrodes and Indirect Electrochemical Conversion of CO₂