Catalysis In Ionic Liquids Research Articles

Supported ionic liquid catalysts—From batch to continuous operation in preparation of fine chemicals

The use of ionic liquids in catalysis is attracting ever more attention in chemical engineering. In line with this research we have studied supported ionic liquid catalysts (SILCAs) which consist of immobilized catalytic species, e.g., transition metal particles residing in an ionic liquid layer immobilized on a solid support, in batch mode operations. In this study the same concept was successfully applied in continuous mode applying a three-phase structured reactor in the hydrogenation of citral.

Supported hydrogensulfate ionic liquid catalysis in Baeyer–Villiger reaction

We report here the method of synthesis and characterisation of ionic liquid: 1-methyl-3-(triethoxysilylpropyl)imidazolium hydrogensulfate, anchored onto solid support via cation–anion stays unbounded to the surface. As a support, we used a silica material with the extensive system of meso- and macropores. The structure of the support was not destroyed after the immobilisation of the ionic liquid. The new material was tested as acidic catalyst with the Baeyer–Villiger reaction. Cyclic ketones were readily oxidised with 68% hydrogen peroxide in dry dichloromethane to their corresponding lactones in high yields (60–91%) at 50 °C within a short time (5–20 h). The use of hydrogen peroxide and a heterogeneous catalyst allows a clean oxidation and the possibility of easy catalyst removal by simple filtration and reuse three times in another oxidation process without lost of catalyst activity.

Ionic Liquid-Supported Bis-(salicylaldimine) Nickel Complexes: Robust and Recyclable Catalysts for Ethylene Oligomerization in Biphasic Solvent System

Two new ionic liquid-supported bis-(salicylaldimine) Ni(II) complexes Ni[2-(O)C6H4CH=N(CH2)3(methylimidazole)Br]2 (1) and Ni[3, 5-tBu2-2-(O)C6H2CH=N(CH2)3(methylimidazole)Br]2 (2) have been synthesized and characterized. Ethylene oligomerizations were carried out with these two complexes in biphasic solvent systems consisting of chloroaluminate ionic liquid and n-heptane or toluene under mild reaction conditions. In the presence of diethylaluminum chloride, both complexes 1 and 2 are highly active for ethylene oligomerization. The olefinic products can be easily separated from the catalytic ionic liquid phase by simple decantation, and the nickel catalysts can be reused in successive ethylene oligomerization cycles. GC-MS analyzes showed that the obtained oligomers contained mainly C4, C6, and C8 olefins.

Towards one-pot synthesis of menthols from citral: Modifying Supported Ionic Liquid Catalysts (SILCAs) with Lewis and Brønsted acids

The use of ionic liquids in catalysis is attracting ever more attention in chemical engineering. In line with this research we have studied Supported Ionic Liquid Catalysts (SILCAs) which consist of immobilized catalytic species, e.g. transition metal particles residing in an ionic liquid layer immobilized on a solid support. We found out that dissolution of Lewis or Brønsted acids into the ionic liquid layer of SILCA has major effects to the activity as well as the product distribution of the catalyst in citral transformation reactions. In fact, one-pot synthesis of menthols from citral was accomplished. The effects of different amounts of added Lewis and/or Brønsted acids to SILCA (one of them or both) were studied in this work.

Homogeneous epoxidation of lipophilic alkenes by aqueous hydrogen peroxide: catalysis of a Keggin-type phosphotungstate-functionalized ionic liquid in amphipathic ionic liquid solution

The ionic liquid compositions (ILC) composed of the Keggin-type phosphotungstate-functionalized ionic liquid of [Dopy]3[PW12O40] (1) and the amphipathic IL mixture of [Bpy]BF4 and [Dopy]BF4, were constructed as an effective catalytic system and ideal reaction medium for alkene epoxidation by aqueous H2O2, in which the real homogeneous catalysis was fulfilled with advantages of high activity, simplified work-up and available recyclability. The designing concept of the ILC and the IL effect on the activity/stability were discussed herein.

Synthesis, properties and catalysis of novel methyl- or ethyl- sulfate-anion-based acidic ionic liquids

In this paper, two kinds of novel acidic ionic liquids containing methyl- or ethyl-sulfate anions can be easily and efficiently prepared. The density, viscosity, thermal property of these ILs, and temperature dependency of ionic conductivity were measured and investigated in detail. The catalysis of ionic liquids to the Fisher esterifications was also studied.

Infrared Spectroscopy of a Wilkinson Catalyst in a Room‐Temperature Ionic Liquid

Homogeneous catalysis in room-temperature ionic liquids (ILs) constitutes a most interesting field of research with high potential in technical applications. As concerns the hydrogenation of unsaturated hydrocarbons, Wilkinson's compound RhCl(PPh(3))(3) represents a catalyst that provides high selectivity and activity. Herein, we demonstrate the application of infrared spectroscopy to the quantitative analysis of the Wilkinson catalyst in the IL 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]). Our study demonstrates for the first time the quantitative, accurate and reproducible determination of the concentration of a rhodium catalyst by means of IR spectroscopy and, moreover, allows the investigation of intermolecular interactions. Spectral features, located mainly in the fingerprint region of the IR spectrum, are identified revealing the influence of the dissolved catalyst on the IL's vibrational structure. In particular, the ring-bending mode of the imidazolium ring shows a frequency shift as a function of catalyst concentration, probably due to hydrogen-bond formation between the IL cation and the Rh complex. The results show the potential of IR spectroscopy both for application as a quick process control technology in catalytic processes and as a tool for better understanding of IL-catalyst interactions.

A one-pot multicomponent reaction for the synthesis of 2-amino-2-chromenes promoted by N,N-dimethylamino-functionalized basic ionic liquid catalysis under solvent-free condition

A simple, clean, and environmentally benign three-component process to the synthesis of 2-amino-4H-chromenes using N,N-dimethylaminoethylbenzyldimethylammonium chloride, [PhCH2Me2N+CH2CH2NMe2]Cl−, as an efficient catalyst under solvent-free condition is described. A wide range of aromatic aldehydes easily undergo condensations with α-naphthol and malononitrile under solvent-free condition to afford the desired products of good purity in excellent yields. Taking into account environmental and economical considerations, the protocol presented here has the merits of environmentally benign, simple operation, convenient work-up and good yields. Furthermore, the catalyst can be easily recovered and reused for at least five cycles without losing its activities.

Heterogeneous catalysis in ionic liquids: The heck reaction of bromobenzene with styrene over palladium supported on mesoporous carbon

Tributylhexylammonium bistriflamide [(C4H9)(C6H13)N][(CF3SO2)2N], an ionic liquid, was used as a solvent for the Heck reaction of bromobenzene with styrene in the presence of Pd deposited onto a mesoporous carbon support. It was found that dibutylamine used as a basic reagent to scavenge hydrogen bromide results in higher conversions of the reactants and higher yields of stilbene than sodium acetate. It was shown that the IL is fully recoverable after use in the catalytic reaction.

Molecular Electrochemistry and Redox Catalysis in Ionic Liquids

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ChemInform Abstract: Asymmetric Catalysis in Ionic Liquids

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ChemInform Abstract: Functionalized Chiral Ionic Liquid Catalyzed Enantioselective Desymmetrizations of Prochiral Ketones via Asymmetric Michael Addition Reaction.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Basic Functionalized Ionic Liquid Catalyzed One‐Pot Mannich‐Type Reaction: Three‐ Component Synthesis of β‐Amino Carbonyl Compounds.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Is catalysis in ionic liquids a potentially green technology?

Is catalysis in ionic liquids a potentially green technology?

Synthesis of β-enaminones by ionic liquid catalysis: A one-pot condensation under solvent-free conditions

The synthesis of a series of 12 β-dimethylaminovinylketones [RC(O)CH CHN(Me) 2 , where X = Ph, Me-4-Ph, F-4-Ph, Cl-4-Ph, Br-4-Ph, NO 2 -4-Ph, fur-2-yl, thien-2-yl, pirrol-2-yl, pyrid-2-yl, CH(OMe) 2 and hexyl] from the condensation reaction of methyl ketones with dimethylformamide dimethylacetal in the presence of equimolar amounts of imidazolium based ionic liquids [BMIM] · BF 4 and [OMIM] · BF 4 is reported. The reaction time and the yields were investigated and this method showed advantages over the methods described in the literature.

Kinetics of Citral Hydrogenation by Supported Ionic Liquid Catalysts (SILCA) for Fine Chemicals

The use of ionic liquids in catalysis is attracting interesting attention in chemical engineering. Supported ionic liquid catalyst (SILCA) compounds consist of immobilized catalytic species (e.g., transition metal particles residing in an ionic liquid layer immobilized on a solid support). In this work, the kinetics of SILCA compounds has been studied in detail and a mechanistic kinetic model, which describes the differences in selectivity and activity of the catalysts that contain different ionic liquids, has been developed.

Asymmetric Catalysis in Ionic Liquids

Asymmetric Catalysis in Ionic Liquids

Functionalized Chiral Ionic Liquid Catalyzed Enantioselective Desymmetrizations of Prochiral Ketones via Asymmetric Michael Addition Reaction

Functionalized chiral ionic liquids were found to be highly effective and reusable organocatalysts for asymmetric Michael additions of 4-substituted cyclohexanones. The desymmetrization reaction afforded the desired Michael adducts bearing three carbon stereocenters with up to 99% ee.

Catalysis in Ionic Liquids

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Ionic liquids as solvent for regioselective arylation of α-substituted allylic alcohols by aryl bromides

Regioselective Heck arylation of α-substituted allylic alcohols by aryl bromides was achieved by Pd-DPPP catalysis in ionic liquids, affording a β/γ ratio of up to 78/22 in the case of the coupling of 1-bromonaphthalene with but-1-en-3-ol. In addition to the effects of both ligands and reaction media, the regiocontrol toward the formation of branched products was significantly affected by the steric properties of allylic alcohols; with the increasing bulkiness of the substituent on allylic alcohol, the β/γ regioselectivity decreased. For comparison, arylation by aryl triflates in a molecular solvent was also demonstrated, which showed the same trend in regioselectivity.