Aqueous Liquid Media Research Articles

Hydrolysis kinetics of inulin by imidazole-based acidic ionic liquid in aqueous media and bioethanol fermentation

This article focused on the inulin-containing energy biomass, Jerusalem artichoke, to explore environment-friendly processes for bioethanol production. An imidazole-based acidic ionic liquid (VImaILs) was prepared as the catalyst of inulin hydrolysis in aqueous media. The hydrolysis kinetics was studied under different conditions. The kinetic parameters of hydrolysis by VImaILs and dilute sulfuric acid were estimated and compared. This work demonstrated that the hydrolysis rate of inulin into reducing sugars by VImaILs was obviously faster than that by the latter. The proposed kinetic model successfully predicted the inulin hydrolysis in wider ranges of experimental conditions. The hydrolysate was fermented into ethanol by Saccharomyces cerevisiae which activity was not inhibited by the VImaILs. The conversion efficiency of inulin-type sugars to ethanol was greater than 92.5% of the theoretical yield. And the ethanol production capacity reached 123.76g/(L). This system integrated the chemical and biological processes to prepare ethanol in an environment-friendly way.

Thermodynamic investigations of protein's behaviour with ionic liquids in aqueous medium studied by isothermal titration calorimetry

BackgroundWhile a number of reports appear on ionic liquids–proteins interactions, their thermodynamic behaviour using suitable technique like isothermal titration calorimetry is not systematically presented. MethodsIsothermal titration calorimetry (ITC) is a key technique which can directly measure the thermodynamic contribution of IL binding to protein, particularly the enthalpy, heat capacities and binding stoichiometry. Scope of reviewIonic liquids (ILs), owing to their unique and tunable physicochemical properties have been the central area of scientific research besides graphene in the last decade, and growing unabated. Their encounter with proteins in the biological system is inevitable considering their environmental discharge though most of them are recyclable for a number of cycles. In this article we will cover the thermodynamics of proteins upon interaction with ILs as osmolyte and surfactant. The up to date literature survey of IL–protein interactions using isothermal titration calorimetry will be discussed and parallel comparison with the results obtained for such studies with other techniques will be highlighted to demonstrate the accuracy of ITC technique. Major conclusions and general significanceNet stability of proteins can be obtained from the difference in the free energy (ΔG) of the native (folded) and denatured (unfolded) state using the Gibbs–Helmholtz equation (ΔG=ΔH−TΔS). Isothermal titration calorimetry can directly measure the heat changes upon IL–protein interactions. Calculation of other thermodynamic parameters such as entropy, binding constant and free energy depends upon the proper fitting of the binding isotherms using various fitting models. This article is part of a Special Issue entitled Microcalorimetry in the BioSciences — Principles and Applications, edited by Fadi Bou-Abdallah.

Synthesis, modeling and optimization of cyanide antidote (3-methylbutyl) nitrite using response surface methodology

In this research, synthesis of cyanide antidote (3-methylbutyl) nitrite has been designed and performed by response surface methodology. The antidote was prepared by the reaction of 3-methyl-1-butanol with sodium nitrite, which is the nitrosonium (NO ? ) source, in the presence of sulfonic acid-functionalized Fe3O4 (Fe3O4@SO3H) as a nanomagnetic solid acid catalyst and triethylammonium hydrogen sulfate as ionic liquid in aqueous media. Optimization of the reaction conditions was investigated using the response surface method (central composite design). In accordance with analysis of variance, a quadratic polynomial model was able to predict the response. Predicted response values by the obtained model was in good agreement with the experimental results. A clean reaction, easy workup procedure, reusability of the catalyst and a high yield are some advantages of this method.

One-pot three-component synthesis of tetrahydrobenzo[b]pyrans catalyzed by cost-effective ionic liquid in aqueous medium

A simple and efficient method is proposed for the synthesis of tetrahydrobenzo[b]pyrans with aromatic aldehydes, active methylene compounds, and dimedone using basic ionic liquid catalyst in water. The procedure offers several advantages including short reaction time, good yield, easy procedure, and good recyclability of catalysts, which may be a practical alternative to conventional processes for preparation of 4-hpyrans.

Aggregation behavior of non-cytotoxic ester functionalized morpholinium based ionic liquids in aqueous media

Ester functionalized surface active ionic liquids (SAILs), [CnEMorph][Br], where n=8, 12 and 16, comprising of long hydrophobic chain appended with ester functionality connected to N-methylmorpholine group have been synthesized and investigated for their aggregation behavior and cytotoxicity. A variety of state of art techniques viz. tensiometry, conductometry, isothermal titration calorimetry (ITC), spectrofluorometry, dynamic light scattering (DLS) and atomic force microscopy (AFM) have been employed to get insight into the various aspects of aggregation behavior. The investigated SAILs have been found to possess lower critical aggregation concentration (cac) and greater adsorption efficacy at air–solution interface as compared to earlier reported non-functionalized SAILs or conventional ionic surfactants. Further, the thermal stability of these morpholinium cationics has been evaluated by thermal gravimetric analysis (TGA). These SAILs have been found to be non-cytotoxic in the concentration range generally required for different biological applications as judged by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on the C6 glioma cell line. The dependence of characteristic properties of aggregation on alkyl chain length has been established.

Study the effect of substituent position in aromatic counterion to self-aggregation of cationic surface active ionic liquid in aqueous medium

Specific effects of m- and p-hydroxybenzoate anions (m-HB and p-HB) as counterion on the aggregation process of surface active ionic liquids based on 1-dodecyl-3-methylimidazolium were investigated by surface tension, conductivity and steady state fluorescence measurements. Compared to that for 1-dodecyl-3-methylimidazolium bromide (C12mimBr), lower critical micelle concentration (cmc) and larger Πcmc and pC20 values for these SAILs indicate that the introduction of aromatous counterions favors micellization and reduction of surface tension. The most incorporated salicylate anion can effectively screen electrostatic repulsion, promoting a closer arrangement of C12mimSal at air–solution interface. Thus m- and p-C12mimHB have smaller Γmax and larger Amin values than C12mimSal. From the results of conductivity measurements, the cmc values of these SAILs increase slightly with increasing temperature, which has similar trend with cationic SAIL, 1-alkyl-3-methylimidazolium bromide, [Cnmim]Br. The negative ΔGmθ values, mainly result from more negative-T ΔSmθ, reveal that the micellization process is spontaneous and entropy-driven in the whole studied temperature range. The data also show that ΔHmθ values of all systems are negative, which implies that the micellization process is exothermic. This work suggests that small changes, such as position of the substitute on aromatic ring of counterion, can considerably influence the micellization behavior of SAILs.

Complexation of triblock reverse copolymer 10R5 with surface active ionic liquids in aqueous medium: a physico-chemical study

A comprehensive study on the interactions of surface active ionic liquids (SAILs) [Cnmim][Cl], where n = 8, 10, and 12, with a triblock reverse copolymer, 10R5, [(PPO)8–(PEO)22–(PPO)8] has been performed using various physico-chemical techniques.

Correction to “Micellization Behavior of Morpholinium Based Amide Functionalized Ionic Liquids in Aqueous Media”

Correction to “Micellization Behavior of Morpholinium Based Amide Functionalized Ionic Liquids in Aqueous Media”

ChemInform Abstract: Activation of 1,3‐Dioxolane by a Protic Ionic Liquid in Aqueous Media: A Green Strategy for the Selective Hydrolytic Cleavage of Acetals and Ketals.

A convenient method for the deprotection of acetals and ketals was achieved using an imidazolium based protic ionic liquid as a catalyst in aqueous medium via the dual activation of dioxolane. The protocol is highly efficient towards the deprotection of acyclic and cyclic acetals, ketals, benzylidene acetals and tetrahydropyranyl (THP) ethers, giving excellent yields. Functional groups such as tert-butyl ester, tert-butyl dimethyl silyl (TBDMS), N-tert-butyloxycarbonyl (N-Boc), and double bond, mesyl, nitro, and glycosidic linkage were tolerated under the benign reaction conditions. Selective deprotection of the 5,6-isopropylidene moiety in 1,2:5,6-di-O-isopropylidene hexose and 3,5-cyclohexylidene moiety in pentose derivatives proceeded smoothly without affecting the 1,2-protected group. The attractive features of this new protocol are the use of mild reaction conditions, tolerance of a wide range of functional groups, use of relatively non-toxic solvent systems and recyclability of the ionic liquid catalyst.

Micellization behavior of morpholinium-based amide-functionalized ionic liquids in aqueous media.

Morpholinium-based amide-functionalized ionic liquids (ILs) [C(n)AMorph][Br], where n = 8, 12, and 16, have been synthesized and characterized for their micellization behavior in aqueous medium using a variety of state of the art techniques. The adsorption and micellization behavior of [CnAMorph][Br] ILs at the air-solution interface and in the bulk, respectively, has been found to be much better compared to that observed for nonfunctionalized homologous ILs and conventional cationic surfactants, as shown by the comparatively higher adsorption efficiency, lower surface tension at the critical micelle concentraiton (γ(cmc)), and much lower critical micelle concentration (cmc) for [C(n)AMorph][Br] ILs. Conductivity measurements have been performed to obtain the cmc, degree of counterion binding (β), and standard free energy of micellization (ΔG(m)°). Isothermal titration calorimetry has provided information specifically about the thermodynamics of micellization, whereas steady-state fluorescence has been used to obtain the cmc, micropolarity of the cybotactic region, and aggregation number (N(agg)) of the micelles. Both dynamic light scattering and atomic force microscopy have provided insights into the size and shape of the micelles. 2D (1)H-(1)H nuclear Overhauser effect spectroscopy experiments have provided insights into the structure of the micelle, where [C16AMorph][Br] has shown distinct micellization behavior as compared to [C8AMorph][Br] and [C12AMorph][Br] in corroboration with observations made from other techniques.

Activation of 1,3-dioxolane by a protic ionic liquid in aqueous media: a green strategy for the selective hydrolytic cleavage of acetals and ketals

A convenient method for the deprotection of acetals and ketals was achieved using an imidazolium based protic ionic liquid as a catalyst in aqueous medium via the dual activation of dioxolane. The protocol is highly efficient towards the deprotection of acyclic and cyclic acetals, ketals, benzylidene acetals and tetrahydropyranyl (THP) ethers, giving excellent yields. Functional groups such as tert-butyl ester, tert-butyl dimethyl silyl (TBDMS), N-tert-butyloxycarbonyl (N-Boc), and double bond, mesyl, nitro, and glycosidic linkage were tolerated under the benign reaction conditions. Selective deprotection of the 5,6-isopropylidene moiety in 1,2:5,6-di-O-isopropylidene hexose and 3,5-cyclohexylidene moiety in pentose derivatives proceeded smoothly without affecting the 1,2-protected group. The attractive features of this new protocol are the use of mild reaction conditions, tolerance of a wide range of functional groups, use of relatively non-toxic solvent systems and recyclability of the ionic liquid catalyst.

Green synthesis of 5-arylidene-2,4-thiazolidinedione, 5-benzylidene rhodanine and dihydrothiophene derivatives catalyzed by hydrated ionic liquid tetrabutylammonium hydroxide in aqueous medium

An efficient synthesis of 5-arylidene-2,4-thiazolidinediones and 5-benzylidene rhodanines by the Knoevenagel condensation of 2,4-thiazolidinedione or rhodanine with aromatic aldehydes was studied. It proceeded smoothly in the presence of tetrabutylammonium hydroxide/H 2O-EtOH to afford the corresponding products in high yields at 50°C. Also, a series of dihydrothiophene derivatives were synthesized via the four-component reaction of aldehyde, malonitrile, 2,4-thiazolidinedione, and piperidine in the presence of Bu4NOH as a basic ionic liquid in aqueous medium. This new method offers several advantages, such as excellent yields, short reaction times, and simple procedure.

Encapsulation of silica nano-spheres with polymerized ionic liquid for selective isolation of acidic proteins

A nanocomposite is prepared by encapsulating silica nano-spheres with polymerized ionic liquid in aqueous medium without use of any organic solvents. Vinyl groups are covalently introduced on to the surface of silica nano-spheres, which are then encapsulated by copolymerization of 1-vinyl-3-ethylimidazolium bromide (monomer) and 1,4-butanediyl-3,3'-bis-l-vinylimidazolium dibromide (cross-linker) at room temperature. The derived nanocomposite, PIL@SiO2, provides a green adsorbent for protein sorption. PIL@SiO2 is selective toward acidic proteins, and its selectivity can be controlled via varying the amount of monomer used in the copolymerization process. At pH 6.0, use of 5 mg PIL@SiO2 nanocomposite results in a sorption efficiency of up to 95 % for 200 mg L(-1) ovalbumin in 1 mL sample solution. Electrostatic and hydrophobic interactions between PIL@SiO2 and protein species dominate the adsorption process. The ovalbumin adsorption behavior is consistent with the Langmuir model, giving a sorption capacity of 333.3 mg g(-1). The retained ovalbumin is recovered by elution with 0.2 % SDS solution. Circular dichroism spectra reveal virtually no change to the α-helix content of ovalbumin after elimination of SDS by use of dialysis. In summary, high-purity ovalbumin is isolated from chicken egg-white by use of the PIL@SiO2 nanocomposite as adsorbent.

Characteristics and durability of fluoropolymer thin films

The use of plasma-polymerised fluoropolymer (CFxOy) thin films in the manufacture of microelectromechanical systems (MEMS) devices is well-established, being employed in the passivation step of the deep reactive ion etching (DRIE) process, for example. This paper presents an investigation of the effect of exposure to organic and aqueous liquid media on plasma-polymerised CFxOy thin films. Atomic force microscopy (AFM), scanning electron microscopy (SEM), ellipsometry, X-ray photoelectron spectroscopy (XPS) and dynamic wetting measurements were all employed as characterisation techniques. Highly basic aqueous solutions, including known silicon etchants, were found to cause delamination via degradation of the countersurface below the CFxOy thin film. Films were found to be stable in organic solvents, acidic aqueous solutions and slightly basic aqueous solutions.

Eco‐friendly synthesis of 1,8‐dioxo‐octahydroxanthenes catalyzed by ionic liquid in aqueous media

Abstract A biodegradable functionalized ionic liquid 3‐(N,N‐dimethyldodecylammonium)propanesulfonic acid hydrogen sulfate ([DDPA][HSO4]) was prepared and used as a Brønsted acid–surfactant‐combined catalyst for the eco‐friendly one‐pot synthesis of 1,8‐dioxo‐octahydroxanthenes at 100°C in water. Under these conditions, the reaction of various aromatic aldehydes with dimedone generated 1,8‐dioxo‐octahydroxanthenes in good yields with a simple postreaction procedure. The products could simply be separated from the catalyst/water system, and the catalyst could be reused at least six times without noticeably decreasing the catalytic activity. J. Heterocyclic Chem., (2011).

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

AbstractChloromethylation 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.

Ultrasound promoted synthesis of quinolines using basic ionic liquids in aqueous media as a green procedure

The basic ionic liquid (BIL) based on imidazolum cation efficiently catalyzes the condensation reaction of isatin with ketones by ultrasonic irradiation in aqueous media for quinoline synthesis. When two different α-protons are available in a ketone, a mixture of two quinolines is obtained. In this method, one of the quinolines with high selectivity is produced. Another significant advantage of this method is omission of subsidiary reactions, such as aldol condensation. Compared with conventional methods, the main advantages of the present procedure are its being a green method, its milder conditions, necessary shorter reaction time, and its higher yields and selectivity without the need for a transition metal catalyst. The use of BILs and ultrasound promoted this protocol under room temperature. By changing the type of BILs, ultrasonic irradiation time, and ultrasonic frequency, synthesis of quinolines is manageable.

ChemInform Abstract: Synthesis of 4H‐Benzopyrans Catalyzed by Acyclic Acidic Ionic Liquids in Aqueous Media.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 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.

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.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 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.