Ionic Liquids In Aqueous Media Research Articles

An Efficient Procedure for Chloromethylation of Aromatic Hydrocarbons Catalyzed by PEG1000‐Dicationic Ionic Liquids in Aqueous Media

Chloromethylation of aromatic hydrocarbons is catalyzed by the recyclable and temperature-dependent phase-separation system composed of PEG1000-dicationic ionic liquid and methylcyclohexane in aqueous media.

ChemInform Abstract: One‐Pot Synthesis of Polyfunctionalized Pyrans Catalyzed by Basic Ionic Liquid in Aqueous Media.

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One-pot three-component Biginelli-type reaction catalyzed by ionic liquids in aqueous media

For the first time, 3,4-dihydropyrimidin-2(1H)-one and 3,4-dihydropyrimidin-2(1H)-thione derivatives have been synthesized in good yields by a modified Biginelli-type reaction with dicationic acidic ionic liquids as catalysts. The products could be separated simply from the catalyst–water system, and the catalysts could be reused at least six times without noticeably reducing catalytic activity.

Synthesis of 4H‐benzopyrans catalyzed by acyclic acidic ionic liquids in aqueous media

Abstract magnified imageSome halogen‐free acyclic task‐specific ionic liquids (TSILs) were synthesized as novel and recyclable catalysts for the synthesis of 5‐oxo‐5,6,7,8‐tetrahydro‐4H‐benzo[b]pyrans by one‐pot three‐component condensation of aromatic aldehyde, malononitrile (or ethyl cyanoacetate), and dimedone (or 1,3‐cyclohexanedione) in water. The condensation accomplished successfully with good yields ranged from 86 to 94%. After the reaction, the products could simply be separated from the catalyst/water, and the catalyst could be reused at least 10 times without noticeably decreasing the catalytic activity. J. Heterocyclic Chem., 2010.

One‐pot synthesis of polyfunctionalized pyrans catalyzed by basic ionic liquid in aqueous media

Abstract magnified image An efficient and convenient method for the synthesis of polyfunctionalized 4H‐pyrans has been achieved through the one‐pot condensation of aromatic aldehydes, malononitrile, and 4‐hydroxycoumarin, phenols or active methylene carbonyl compounds such as 1, 3‐cyclohexanedione and dimedone in the presence of 1‐butyl‐3‐methyl imidazolium hydroxide ([bmim]OH) as catalyst in aqueous media. This method offers several advantages short reaction time, high yields, and simple procedure. J. Heterocyclic Chem., (2009).

On the Interactions between Amino Acids and Ionic Liquids in Aqueous Media

The understanding of the molecular-level interactions between biomolecules and ionic liquids (ILs) in aqueous media is crucial for the optimization of a number of relevant biotechnological processes. In this work, the influence of a series of amino acids on the liquid-liquid equilibria between 1-butyl-3-methylimidazolium tricyanomethane and water was studied to evaluate the preferential interactions between these three compounds. The solubility effects observed are dependent on the polarity, size, and charge distribution of the amino acid side chains and are explained in terms of a refined version of the model proposed earlier (Freire et al. J. Phys. Chem. B 2009, 113, 202; Tome et al. J. Phys. Chem. B 2009, 113, 2815) for ion specific effects on aqueous solutions of imidazolium-based ILs. Although acting through different mechanisms, salting-in and salting-out phenomena possess a common basis which is the competition between water-amino acid side chain, IL-amino acid side chain, and water-IL interactions. The delicate balance between these interactions is dependent on the relative affinities of the biomolecules to water molecules or to IL cation and anion and determines the trend and magnitude of the solubility effect observed.

Synthesis of 1,8-Dioxo-octahydroxanthenes Catalyzed by Acidic Ionic Liquids in Aqueous Media

Some halogen-free acyclic task-specific ionic liquids (TSILs) were synthesized as cheap and recyclable catalysts for synthesis of 1,8-dioxo-octahydroxanthenes in water. This methodology offers several advantages, such as good yields, short reaction times, simple procedure, and mild conditions. The products could simply be separated from the catalyst/water, and the catalyst could be reused at least six times without noticeably decreasing the catalytic activity.

Self-aggregation of ionic liquids in aqueous media: A thermodynamic study

Aggregation process of the ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate [C4mim][BF4], 3-methyl-1-octylimidazolium tetrafluoroborate [C8mim][BF4], 3-methyl-1-octylimidazolium chloride [C8mim][Cl], and N-butyl-3-methylpyridinium chloride [C4mpy][Cl], in the aqueous solutions has been characterized by electrical conductivity, density, and speed of sound measurements at 298.15 K. The critical aggregation concentration (CAC), the standard Gibbs energy of aggregation ΔGagg.∘, isentropic compressibility κs and changes in the isentropic compressibility upon aggregation Δκs,agg for the ionic liquids were derived from the experimental data. The dependence of the CAC, ΔGagg.∘, and Δκs,agg on the nature of the cations and anions has been examined. The aggregation number n for various ILs was determined by applying the mass action theory to the concentration dependence of electrical conductivity and compressibility. Aggregation properties showed fairly good agreement with our previously reported results of 1H NMR and fluorescence spectroscopy.

Mannich reaction catalyzed by carboxyl-functionalized ionic liquid in aqueous media

Three-component Mannich reactions of aromatic aldehydes, anilines and acetophenone were efficiently catalyzed by a recyclable carboxyl-functionalized ionic liquid ([cmmim][BF4]) in aqueous [bmim][BF4] under mild conditions. Twelve β-aminoketones were successfully synthesized in high yields and the catalyst can be recycled at least 6 times without significant loss of activity.