Acidic Ionic Liquids

Amarasekara, Ananda S.

doi:10.1021/acs.chemrev.5b00763

Cited by 719 publications

(382 citation statements)

References 707 publications

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“…Furthermore, ILs have received growing interest due to their various uses as media in chemical, biochemical, and/or electrochemical systems. [1][2][3][4][5][6] Common anions of ILs such as BF 4 -, PF 6 -, and AlCl 4 -are produced by neutralization, i.e. the adducts of a Lewis acid (BF 3 , PF 5 , or AlCl 3 ) and a Lewis base (F -or Cl -).…”

mentioning

confidence: 99%

A Hydronium Solvate Ionic Liquid: Facile Synthesis of Air-Stable Ionic Liquid with Strong Brønsted Acidity

Kitada

Takeoka

Kintsu

et al. 2018

J. Electrochem. Soc.

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A new kind of ionic liquid (IL) with strong Brønsted acidity, i.e., a hydronium (H 3 O + ) solvate ionic liquid, is reported. The IL can be described as [H 3 When two or more kinds of substances are mixed, the properties of the mixture can differ from those of the pure substances. Depending on the interactions between the components, some components undergo ionization, e.g. dissociation, protonation, solvation and complexation, due to the neutralization of Brønsted or Lewis acids and bases. Sometimes, the acid-base mixtures can be categorized as ionic liquids (ILs) with melting points below 100• C, which consist only of cations and anions. ILs are regarded as "the third liquid" and some ILs have fascinating physicochemical properties, such as low volatility, low flammability, high chemical, and thermal stability. Furthermore, ILs have received growing interest due to their various uses as media in chemical, biochemical, and/or electrochemical systems. [1][2][3][4][5][6] Common anions of ILs such as BF 4 -, PF 6 -, and AlCl 4 -are produced by neutralization, i.e. the adducts of a Lewis acid (BF 3 , PF 5 , or AlCl 3 ) and a Lewis base (F -or Cl -). Examples of ILs prepared through neutralization include solvate ILs.7-13 Solvate ILs often consist of equimolar molten mixtures of polyethers (linear or cyclic ones, i.e. glymes or crown ethers) and certain metal salts, where the Lewis acidic metal cations are solvated by equimolar amounts of Lewis basic glymes to give complex cations. Besides, neutralization of Brønsted acids and bases produces so-called protic ILs, which are preferred as acid-catalyzed reaction media due to the presence of an acidic proton.3-6 Since proton transfer is a common chemical transformation, Brønsted acidic ILs receive research attention especially for acid catalysts, fuel cells, biomass processing, polymerization, CO 2 fixation, etc.6,14-19 The design of stronger Brønsted acidic ILs and evaluation of the acidity in ILs are important for exploring their possible applications as media for acid-base reactions.Although 21-24 However, there is an exception. In solid, anhydrous HTf 2 N, the proton is bonded to the anion nitrogen and two oxygens of a neighboring HTf 2 N molecule. 25 Likewise, in the case of monohydrate, the imide superacid HTf 2 N remains associated and does not protonate water, as suggested experimentally and theoretically. In the infrared measurements for an H 2 O and HTf 2 N mixture in CCl 4 , strong Fermi resonance for N-H vibrations serves as evidence that HTf 2 N remains * Electrochemical Society Member.z E-mail: kitada.atsushi.3r@kyoto-u.ac.jp intact, and from the ab initio calculations, spontaneous proton dissociation was not observed for the Fig. 1a

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mentioning

confidence: 99%

A Hydronium Solvate Ionic Liquid: Facile Synthesis of Air-Stable Ionic Liquid with Strong Brønsted Acidity

Kitada

Takeoka

Kintsu

et al. 2018

J. Electrochem. Soc.

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“…[15] Most of the Brønsted acidic ionic liquids are environmentally friendly, efficient, and simple acid catalysts, and have been used in various organic transformations. [16][17][18] Now, in continuation of our works on the synthesis of heterocyclic compounds, [19][20][21] we wish to report the use of the naturally-based ionic liquid 3-sulfonic acid-1-imidazolopyridinium hydrogen sulfate, [Simp]HSO4, as a catalyst in the eco-friendly and practical synthesis of 3,4-dihydropyrimidin-2(1H)-ones (thiones) via a one-pot, three-component condensation of aromatic aldehydes, α,β-dicarbonyl compound and urea or thiourea under the solvent-free conditions (Scheme 1).…”

Section: Introduction and Resultsmentioning

confidence: 99%

A Highly Efficient and Green Catalytic Synthesis of 3,4-dihydro-pyrimidin-2-(1H)-ones (Thiones) Using 3-sulfonic Acid-1-imidazolopyridinium Hydrogen Sulfate under Solvent-free Conditions

Bakherad¹,

Javanmardi²,

Doosti³

et al. 2017

Croat. Chem. Acta

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Abstract:The ionic liquid catalyst 3-sulfonic acid-1-imidazolopyridinium hydrogen sulfate, [Simp]HSO4 was found to be a highly active and green catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones (thiones) under the solvent-free conditions. Avoiding organic solvents during the chemical reactions leading to an economic approach is effective. The reactions are characterized by high efficiency, short reaction time, high product yield, simple experimental procedure, availability of catalyst, and environmentally-friendly reaction conditions.

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“…However, Figure 1 also demonstrates that these promotions of glycerol conversion and acetal yield are insignificant at the continuously increased catalyst dosage. Generally, for a homogeneous catalyst, a higher catalyst dosage indicates a more catalytic active center, resulting in a higher catalytic performance [20], and thereby an intensified acetalization is shown at a relatively higher catalyst amount. However, it is well known that the catalyst can merely improve the dynamic property but not the thermodynamic equilibrium of a reversible reaction.…”

Section: Effect Of Catalyst Dosagementioning

confidence: 99%

Catalytic Acetalization: An Efficient Strategy for High-Value Utilization of Biodiesel-Derived Glycerol

Sun

Dai

et al. 2017

Catalysts

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Abstract:In this study, an efficient process for high value utilization of biodiesel-derived glycerol was proposed via a simple reaction of acetalization catalyzed by novel catalysts of ester sulfate-functionalized ionic liquids (ILs). The relationship between the IL structure and its catalytic activity was investigated. The effects of reaction conditions, and the substrate adaptability, were also carefully studied. The results demonstrate that ester sulfate-functionalized IL shows excellent catalytic activity on the acetalization of glycerol with aldehyde (ketone). Under the optimized condition, 87% glycerol conversion was obtained with 99% acetal selectivity when glycerol was condensed with cyclohexanone. In particular, 29% of product consists of six-membered compound, an important fine chemical and an excellent precursor in organic chemistry, because of the significant steric-hindrance effect of IL catalyst. Furthermore, the IL catalyst shows good recyclability where insignificant activity loss was exhibited even after six runs.

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Acidic Ionic Liquids

Cited by 719 publications

References 707 publications

A Hydronium Solvate Ionic Liquid: Facile Synthesis of Air-Stable Ionic Liquid with Strong Brønsted Acidity

A Hydronium Solvate Ionic Liquid: Facile Synthesis of Air-Stable Ionic Liquid with Strong Brønsted Acidity

A Highly Efficient and Green Catalytic Synthesis of 3,4-dihydro-pyrimidin-2-(1H)-ones (Thiones) Using 3-sulfonic Acid-1-imidazolopyridinium Hydrogen Sulfate under Solvent-free Conditions

Catalytic Acetalization: An Efficient Strategy for High-Value Utilization of Biodiesel-Derived Glycerol

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