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A series of task-specific ionic liquids (TSILs) based on glycerylimidazolium cations have been prepared by reaction of 1-chloropropanediol, a compound obtainable from glycerol (a widely available and in-expensive waste product), with the appropriate base (1-H-imidazole, 1,2-dimethylimidazole and 1-methyl-1-H-imidazole). The reaction of 3-(1H-imidazol-1-yl)propane-1,2-diol with chloroalkanes, bromoalkanes and alkyl mesylates gave the corresponding salts which were characterized. The possibility to use these ILs in palladium catalyzed reactions was evaluated, evidencing good catalyst stability and a high recyclability. [ABSTRACT FROM AUTHOR]

A metal-free phosphazenium cation-catalyzed direct dehydrative condensation of phosphoric acid with alcohols has been developed for the environmentally benign synthesis of phosphoric acid monoesters. [ABSTRACT FROM AUTHOR]

The valorization of abundant agrowastes into chemicals and advanced materials is of key importance in the context of the circular bioeconomy and biorefinery. Herein, we report the ionothermal carbonization (ITC) of sugarcane bagasse, a fibrous residue made of lignocellulose, to engineer advanced carbonaceous materials, namely ionochars. We prepared a series of imidazolium tetrachloroferrate ionic liquids (IL) bearing modular substituents, e.g., alkyl chains with different lengths or benzyl groups. The effect of the cation on both textural and morphological properties is highlighted. Ionochars with high specific surface area (up to 800 m2 g−1), tuneable pore volume (up to 0.8 cm3 g−1), singular nanostructures and adjustable CO2 uptake/retention were obtained. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) including novel superbase-derived ILs and imidazolium-based ILs with the potential to be used as green solvents for biomass utilization should be deeply evaluated with respect to their corrosion ability towards metallic equipment in industrialization. Herein, the corrosion susceptibility of 304SS in [DBUH][CH3CH2OCH2COO] was investigated for the first time and compared with that in common [EMIM][Ac] and [AMIM][Cl] by electrochemical, surface, and theoretical analyses. [DBUH][CH3CH2OCH2COO] exhibited an unprecedentedly excellent corrosion inhibition for 304SS compared to imidazolium-based ILs. This may be due to the presence of electron-donating carboxylate anions and macrocyclic superbase cations, which reacted with metals to form a compact layer and protected metals from damage. [EMIM][Ac] showed a slightly unfavorable corrosion inhibition compared to [DBUH][CH3CH2OCH2COO]. However, the corrosion rate of 304SS was dramatically increased in [AMIM][Cl] by increasing the temperature and water contents, which was reflected by pitting corrosion with plenty of pits (5–10 μm in diameter) on the 304SS surface after a polarization test. By studying the corrosion behaviour of five common steels in [DBUH][CH3CH2OCH2COO] and taking economy into consideration, 304SS with high Rct (26.69 × 105 Ω cm2) and Rp values (1230.8 Ω cm2) was the top priority for industrial equipment materials. According to the possible corrosion mechanism of metals in ILs from the viewpoint of DFT calculations and complex physico-chemical interactions, carboxylate ILs displaying outstandingly low contributions to corrosion particularly involving superbase cations or imidazolium cations and carboxylate anions with electron-donating groups such as –OCH2CH3, –OCH3, and –HC＝CH2 should be designed to mitigate corrosion damage in industrialized operations. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) have been labeled as a promising green alternative to traditional materials; however, many ILs have been discovered to be toxic, especially hydrophobic ILs (HILs). HILs are limited in their structural diversity as most are composed of heteroaromatic cations with long alkyl chains and paired with [BF4], [PF6], or [NTf2] anions. This study aims to diversify HILs by synthesizing two sets of HILs with unique cations and anions. The first set of HILs contain cholinium- and dicholinium-based cations paired with the [NTf2] anion. The [DC-ether] cation is identified as a promising cation and is paired with an array of asymmetric bis(sulfonyl)amide anions to form the second set of HILs. In total, twenty HILs are synthesized. Each HIL is characterized using traditional physicochemical techniques and is evaluted for toxicity using in vitro and in vivo methods. [ABSTRACT FROM AUTHOR]

In the third issue of the then new journal Green Chemistry (2001, 3, 156-164), we published our first paper describing the physical properties of a few hydrophilic and hydrophobic ionic liquids (ILs) representing one of the first such studies to be published. To help celebrate the 15th anniversary of the Journal, we revisit the 'design' aspect of ILs by reviewing the growing area of what most are calling 'ionic liquid mixtures'. In 2001, designing IL properties meant essentially independent variation or synthesis of the cations and anions and determining what physical or chemical properties these liquid salts possessed. Recently, however, the mixing of ILs has been proposed and investigated as a way to add increased scope to the accessible properties of IL media. In this review, we question whether the same thinking and approach used for organic solvent mixtures should be applied to ILs simply because of the way they were made. Unlike organic solvent mixtures, IL compositions of varied ions, do not retain their individual nature, need not be made by simple mixing of two-ion salts, and preferential interactions of a given cation for a given anion are possible in these 3-ion, 4-ion, or higher order liquids. When two ILs are mixed together, one can't identify which ion is from which IL, and the chemistry is simply not based on the identity of the individual ILs, but on the ions comprising them and the interactions of each individual ion, independently of the counterion. Thus, we ask if it would not be better to consider these as unique ion combinations whose solvent properties are derived from the specific choice and abundance of each ion in the system. Through this review of the available literature, we support the concept of Double Salt Ionic Liquids (DSILs) and discuss the interactions involved in these systems, by examining their physicochemical properties and the novel applications they offer. [ABSTRACT FROM AUTHOR]

In this paper both the mechanistic and kinetic aspects of furfural formation from pentoses in aqueous acidic media have been reviewed. Based on the reviewed literature, a comprehensive reaction mechanism has been proposed consisting of more than one route, all starting from acyclic xylose, and involving alternately 1,2-enolization, β-elimination or isomerization via 1,2-hydride shift as key steps. Those studies that employ combined acid-base catalysts, soluble halide salts and trivalent cations in aqueous solutions appear to be most promising. Next, a detailed overview is presented of the results of kinetic studies on furfural formation from pentoses and furfural disappearance in aqueous acidic media. Although these results span over a very wide range of both experimental conditions and different kinetic models employed, an attempt has been made to present the published kinetic data in such a manner that it allows a global comparison. Since even in those cases where the reaction conditions seemed to be comparable, the reported kinetic constants often agree merely in the order of magnitude, thus, the validity of most of the data presented here is restricted to the specific conditions as used by each author. Additionally, a very concise overview is included of research on direct furfural production from lignocellulosic materials. In conclusion, the intricate set of reactions accompanying furfural formation from pentoses, although appearing well established in some aspects, is yet to be fully unraveled, especially with regard to the complex set of side and loss reactions seemingly involving largely unknown reaction intermediates. Such uncertainties are reflected in the contradictory kinetic models exploited and kinetic data presented in the literature, which still prevent a common and coherent interpretation. [ABSTRACT FROM AUTHOR]

Surface modification of colloidal lignin particles (CLPs), which are obtained from renewable resources, is a plausible route towards novel biomaterials. Here we show that adsorption of cationic lignin onto spherical CLPs produces positively charged particles with tailored properties for the stabilization of Pickering emulsions. The threshold dosing of cationic lignin needed to achieve colloidally stable cationic dispersions was 4% relative to the dry weight of CLPs. Compared to irregular kraft lignin particles or regular CLPs, cationic CLPs stabilized a broader array of durable Pickering emulsions. This all-lignin adsorption process to prepare cationic CLPs is advantageous because it minimizes the consumption of synthetic polymers, and opens new application opportunities for structurally defined nano- and microscale lignin particles. [ABSTRACT FROM AUTHOR]

Ion-adsorption rare earth element (REE) ores are strategic mineral resources, particularly for heavy REEs. To reduce the amount of nitrogen in the form of ammonia in waste waters and to increase the low recovery efficiency of the current extraction process for REEs, we developed a novel environmentally friendly stepwise solvent extraction method for the separation and enrichment of REEs. Based on their different extraction abilities and a cation-exchange mechanism, two acidic phosphorus extractants (HEH(EHP) and HDEHP) were selected to sequentially separate and enrich REEs. Using this novel technique, ammonia nitrogen emissions were completely avoided and the recovery efficiency of REEs was significantly improved. From the McCabe–Thiele plots, it was found that a three-stage HEH(EHP) extraction at VA/VO = 10/1 and two-stage HCl stripping at VA/VO = 1/16 were required to enrich heavy REEs, whereas a three-stage HDEHP extraction at VA/VO = 25/1 and three-stage HCl stripping at VA/VO = 1/20 were required to enrich light REEs. The total recovery efficiency realized for REEs was ＞99% and the heavy and light REE chloride concentrations in solution were up to 240 and 200 g L−1, respectively. These results suggest an efficient way of recovering REEs from a leaching solution with low concentrations. [ABSTRACT FROM AUTHOR]

In this work, neoteric and biodegradable ionic liquids (ILs) based on various hydroxyl ammonium cations and formic acid anions have been used as media for biocatalytic oxidoreductions catalyzed by different metalloproteins. The effect of these ILs on the biocatalytic behavior and structure of solubilized enzymes was investigated using cytochrome c (cyt c) as a model protein. The use of IL-based media enhances the tolerance of cyt c against the denaturing effect of H2O2 and increases (up to 20 fold) its catalytic efficiency compared to that observed in buffer. This beneficial effect strongly correlates with the concentration of ILs used, as well as the chaotropicity of their cations. UV–vis, circular dichroism and Fourier transform infrared (FT-IR) spectroscopic studies indicated that, the effect of ILs on the catalytic behavior of cyt c could be correlated with slight structural changes on the protein molecule and/or perturbations of the heme microenvironment. The use of hydroxyl ammonium-based ILs as reaction media increased (up to 4-fold) the decolorization activity of cyt c. All ILs used were recycled and successfully reused three times indicating the potential application of these novel ILs as environmentally friendly media for biocatalytic processes of industrial interest. [ABSTRACT FROM AUTHOR]

Hydrotropes are compounds able to enhance the solubility of hydrophobic substances in aqueous media and therefore are widely used in the formulation of drugs, cleaning and personal care products. In this work, it is shown that ionic liquids are a new class of powerful catanionic hydrotropes where both the cation and the anion synergistically contribute to increase the solubility of biomolecules in water. The effects of the ionic liquid chemical structures, their concentration and the temperature on the solubility of two model biomolecules, vanillin and gallic acid were evaluated and compared with the performance of conventional hydrotropes. The solubility of these two biomolecules was studied in the entire composition range, from pure water to pure ionic liquids, and an increase in the solubility of up to 40-fold was observed, confirming the potential of ionic liquids to act as hydrotropes. Using dynamic light scattering, NMR and molecular dynamics simulations, it was possible to infer that the enhanced solubility of the biomolecule in the IL aqueous solutions is related to the formation of ionic-liquid–biomolecules aggregates. Finally, it was demonstrated that hydrotropy induced by ionic liquids can be used to recover solutes from aqueous media by precipitation, simply by using water as an anti-solvent. The results reported here have a significant impact on the understanding of the role of ionic liquid aqueous solutions in the extraction of value-added compounds from biomass as well as in the design of novel processes for their recovery from aqueous media. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) are considered to be excellent alternatives to organic solvents, and are commonly used nowadays. However, introducing new classes of compounds always comes with the possibility of environmental threat and health issues they may induce. This work was aimed at examining which structural features of ILs are responsible for their toxicity. There are examples of structure-activity relationship models for ILs in the literature. However, in our approach, we have analysed this issue globally for a wide range of ionic liquids and their toxicity was measured by multiple toxicological tests (multiple endpoints). We have collected the experimentally measured available literature data on the toxicity of ILs for various organisms. Then, by employing Principle Component Analysis (PCA), we examined the structural similarity of 375 different ionic liquids having six different types of cations (namely imidazolium, ammonium, phosphinium, pyridinium, pyrolidinium and sulfonium). For expressing the structural features of studied ILs we used Weighted Holistic Invariant Molecular (WHIM) descriptors, calculated for cations and anions separately. The geometry of each structure was optimized at the level of the semi-empirical PM7 method. The toxicological response was thereafter analyzed in the space of the first and second principle components. We pointed out that for most of the tested cases there is a strong relationship between the variance in the observed toxicity and the cations' descriptors. We also proved the anions' influence on the IL toxicity to be less meaningful. After repeating PCA using only the cations' descriptors, we proved that the toxicity of ILs against selected targets depends mostly on the size and branching of the cation. On this basis, we have proposed a Toxicity Ranking Index based on the structural similarity of Cations (TRIC) for the initial toxicity screening studies of ILs. It should be mentioned however that the use of TRIC is limited to the prediction of toxicity endpoints used in its development. The use of TRIC as a preliminary toxicity indicator would provide a general view on ILs' toxicological potential and its predictions may provide valuable conclusions, which, taken under consideration, may help in simplifying the procedure of designing new greener and safer ionic liquids in future. [ABSTRACT FROM AUTHOR]

Biodegradable copolymers of L-lactic acid and ε-caprolactone [P(LLA-CL)s] were prepared in sulfonic acid-functionalized Brønsted acidic ionic liquids (SFBAILs) with very different anions and cations. SFBAILs work as both solvents and catalysts. The copolymerization process was proved to be a combination of polycondensation and simultaneous transesterification after a fast ring-opening polymerization of ε-caprolactone through a kinetic study. Copolymers with different monomer ratios were obtained. We found that the anions rather than the cations of SFBAILs have a great impact on the polymerizations. In addition, SFBAILs can be simply recovered by phase separation and recycled without decreasing the efficiency. [ABSTRACT FROM AUTHOR]

The chemical and thermal stability of ionic liquids (ILs) makes them interesting for a large variety of applications in nearly all areas of the chemical industry. However, this stability is often reflected in their recalcitrance towards biodegradation, which comes with the risk of persistence when they are released into the environment. In this study we carried out a systematic investigation of the biodegradability of pyrrolidinium, morpholinium, piperidinium, imidazolium and pyridinium-based IL cations substituted with different alkyl or functionalised side chains and using halide counterions. We examined their primary degradability by specific analysis and/or their ultimate biodegradability using biochemical oxygen demand tests according to OECD guideline 301F. Biological transformation products were investigated using mass spectrometry. A comparison of the biodegradation potential of these ILs shows that for all five head groups, representatives can be found that are readily or inherently biodegradable, thus permitting the structural design of ILs with a reduced environmental hazard. [ABSTRACT FROM AUTHOR]

As a kind of promising solvents, ionic liquids (ILs) have been used to dissolve cellulose and great progress has been made in recent years. However, the dissolution mechanism, especially the role of cations of ILs in the dissolution of cellulose, is still in debate. In this work, 13 kinds of ILs with a fixed anion [CH3COO]- but varied cationic backbones and alkyl chains have been prepared and characterized. The solubilities of cellulose in these ILs were measured at different temperatures. This allowed us to systematically study the effect of cationic structures on the cellulose dissolution at a given temperature. In order to investigate the dissolution mechanism, Kamlet-Taft parameters of these ILs in the temperature range from 25 to 65°C and 13C NMR spectra of 1-benzyl-3-methylimidazolium acetate ([phC1mim][CH3COO]) + cellulose systems at 90°C were also determined. It was found that acidic protons on the heterocyclic rings of the cations are essential for the dissolution of cellulose in the ILs, but the van der Waals interaction of cation with cellulose is not important. These protons may form C-H···O hydrogen bonds with hydroxyl and ether oxygen of cellulose to increase cellulose solubility. Cations of the ILs may also decrease cellulose solubility by strong interaction with anions or steric hindrance effect of large size group in their alkyl chains. These interactions together with strong O-H···O hydrogen bonds between the anion and hydroxyl protons of cellulose resulted in the disruption of the inter- and intra-molecular hydrogen bonds and thus effective dissolution of cellulose. [ABSTRACT FROM AUTHOR]

Polyvinylpyrrolidone-stabilized heteropolyacids (PVP-HPAs) are synthesized by self-assembling in alcohol. The structure of PVP-HPAs is determined by various characteristic techniques. HPAs can protonate PVP to form polymeric cations. In turn, the protonated PVP interacts strongly with the heteropolyanion by forming an ionic liquid (IL)-like structure. The self-assembling separation and recyclability characteristics are related to the PVP's IL-like structure. The catalyzing performance of PVP-HPAs varies with the species of HPA and the content of PVP. The optimized PVP-H4SiW12O40·5H2O (HSiW) (1/5 : 3/4) gives more than 60% conversion of cellulose and complete conversion of highly selective cellobiose into butylglucosides. The optimized PVP-HSiW is separated directly by centrifugation and retains the activity without any post-treatment during recycling. The deactivation of PVP-HPAs is related to the loss of the catalyst during recycling. The functional mechanism of the IL-like structure is explored in this control experiment. [ABSTRACT FROM AUTHOR]

Heteropolyanion-based ionic liquids with -SO3H functionalized cations and PMo11VO404- anions were synthesized and applied in the conversion of cellulose into formic acid (FA). It was demonstrated that the as-prepared ILs showed enhanced activity for catalysing cellulose conversion to FA in the presence of oxygen in water compared to H4PMo11VO40. A high FA yield over 50% accompanied by a FA concentration of ~10% in reaction solution was obtained at 180 °C and in an oxygen pressure of 1.0 MPa. The possible pathway of FA production from cellulose was investigated. It was indicated that the resulting ILs served as bifunctional catalysts with cations catalysing the cellulose hydrolysis to glucose and anions catalysing glucose oxidation to FA. These ILs may find more applications in cellulose conversion. [ABSTRACT FROM AUTHOR]

A series of room temperature ionic liquids (ILs), in which cholinium acts as the cation and amino acids as the anions, were prepared via a simple and green chemical route, and characterized. Most of the ILs dissolved lignin efficiently and selectively (with solubilities of 140–220 mg of lignin per g of IL). The solubility of xylan in these ILs (which ranged from ＜1 to 85 mg g−1) depended on the nature of the anion, while cellulose was scarcely soluble (＜5 mg g−1). In addition, enzymatic hydrolysis of microcrystalline cellulose and rice straw was enhanced significantly after pretreatment using the IL [Ch][Gly]. [ABSTRACT FROM AUTHOR]

Three feruloyl esterases, EC 3.1.1.73, (FAEs), namely FAE A from Aspergillus niger (AnFaeA), FAE C from Aspergillus nidulans (AndFaeC), and the FAE activity in a commercial β-glucanase mixture from Humicola insolens (Ultraflo L) were tested for their ability to catalyse esterification of sinapic acid with glycerol in four ionic liquid (IL) systems. The IL systems were systematically composed of two selected pairs of cations and anions, respectively: [BMIm][PF6], [C2OHMIm][PF6], [BMIm][BF4], and [C2OHMIm][BF4]. AnFaeA had activity in [PF6]−-based ILs, whereas the AndFaeC and the FAE in Ultraflo L had no appreciable activities and were generally unstable in the IL systems. FAE stability in the IL systems was apparently highly dependent on enzyme structure, and notably AnFaeA's similarity to IL-compatible lipases may explain its stability. The thermal stability of AnFaeA was higher in buffer than in the IL systems, but at 40 °C and below there was no significant difference in AnFaeA stability between the buffer and the [PF6]−-based systems: AnFaeA was stable in the [BMIm][PF6] and [C2OHMIm][PF6] systems for 2 h at 40 °C. However, the IL anion had a major effect on stability: [BF4]− caused rapid inactivation of AnFaeA, while [PF6]− did not. The cation did not have a similar effect. These observations could be explained in terms of the hydrogen bonding capacity of IL cations and anions via COSMO-RS simulations. [ABSTRACT FROM AUTHOR]

For the first time, the anodic behavior of platinum and titanium in ionic liquids (ILs) based on the imidazolium cation was investigated. ILs were established to possess a set of advantages compared with the traditional sulfuric acid electrolytes. It isn't necessary to maintain both a particular temperature and to use environmentally-harmful reagents, such as methanol or hydrofluoric acid, when electropolishing metals in IL media. The addition of propylene glycol to BMImCl (1 : 1) results in the formation of layers of titanium dioxide nanotubes on the metal surface. [ABSTRACT FROM AUTHOR]

The biodegradation of ionic liquids (ILs) was evaluated by an indirect impedance technique, through which carbon dioxide production was measured during bioassay time. The biodegradation study was focused on finding a microorganism able to efficiently degrade common IL compounds. For the first time, a bacteria strain of Sphingomonas paucimobilis was employed in biodegradability tests of ILs, carried out for 37 commercial imidazolium-, pyridinium-, pyrrolidinium-, ammonium- and phosphonium-based ILs, including in the sample 12 different anions and 14 different cations. Remarkably, more than half of ILs studied (54% of the sample) exhibited a biodegradation percentage ≥60% after a 28-day incubation period with S. paucimobilis at 45 °C; therefore, they behave as easily biodegradable compounds from the indirect impedance test. In summary, current results suggested the possibility of biotreatment for the rapid and ultimate mineralisation of widely used ILs, such as BmimNTf2, BmimPF6, etc., which were noted as recalcitrant to biodegradation in previous standard tests with other microorganisms. [ABSTRACT FROM AUTHOR]

This work aims at identifying, amongst extreme soil biotypes at locations of high salinity and high hydrocarbon load, microbial strains able to survive short or long-term exposure to the presence of selected ionic liquids. We have evaluated the impact of ionic liquids on the diversity of the soil microbiota to identify which microbial strains have higher survival rates towards ionic liquids, and consequently those which might possibly play a major role in their biotic fate. To the best of our knowledge, this is the first study of this kind. Soils, from a region in Portugal (Aveiro) were sampled and the bacterial and fungal strains able to survive after exposure to high concentrations of selected ionic liquids were isolated and further characterised. We have mainly focused on two types of cations: imidazolium – the most commonly used; and cholinium – generally perceived as benign. The surviving microbial strains were isolated and taxonomically identified, and the ionic liquid degradation was analysed during their cultivation. The continuing exposure of the microbial strains to petroleum hydrocarbons is likely to be the basis for their acquired resistance to some imidazolium salts; also, the higher capacity of fungi – compared to bacteria – to grow, even during their exposure to these liquid salts, became evident in this study. [ABSTRACT FROM AUTHOR]

Benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) are oxidized to their corresponding sulfones by an Anderson-type catalyst [(C18H37)2N(CH3)2]5IMo6O24using molecular oxygen as the oxidant under mild reaction conditions. These refractory sulfur-containing compounds can be oxidized completely in the absence of any sacrificial agent. Solvents such as acetonitrile and water play a negative effect on the oxidative desulfurization system. The catalytic activities of the amphiphilic Anderson catalysts depend on the quaternary ammonium cations. The reactivity of the sulfur-containing compounds follows the order 4,6-DMDBT > DBT > BT. [ABSTRACT FROM AUTHOR]

CdS quantum dot (QDs)-sensitized Zn1−xCdxS solid solutions were successfully prepared by a simple cation exchange using hydrothermally synthesized ZnS nanoparticles (NPs) and Cd(NO3)2as precursors. The prepared samples show especially high visible-light photocatalytic H2-production activity from aqueous solutions containing Na2SO3and Na2S as sacrificial reagents even without a Pt co-catalyst. It was found that this high visible-light photocatalytic H2-production activity is attributed to the quantum size effect of CdS; the presence of CdS QDs alters the energy levels of the conduction and valence bands in the coupled semiconductor system, which favors the electron transfer and enhances photoactivity. [ABSTRACT FROM AUTHOR]

Three types of copper-containing catalytic ionic liquids (CILs) have been synthesised and fully characterised by spectroscopy, elemental, thermal and, in most cases, XRD analyses. Whereas type IILs comprise copper exclusively in the cation (e.g.[Cu(Im12)4][PF6], Im12= 1-dodecylimidazole), type IIionic liquids contain Cu(i) in both the cation and the anion (e.g.[Cu(Im12)2][CuBr2]) and type IIIILs incorporate copper solely in form of halocuprate(i)/(ii) anions (e.g.[DMIM][CuBr2], DMIM = 1-dodecyl-3-methylimidazolium). A limitation concerning the preparation of a series of type IIionic liquids has been observed by the formation of the neutral compound [Cu(Im12)I]6instead of the expected IL [Cu(Im12)2][CuI2]. The novel ILs reveal a metallo-laminate structure in the crystalline state. The salts have a liquidus range of up to 300 °C before decomposition takes place. Their catalytic properties in the synthesis of dimethyl carbonate from MeOH, CO and O2have been studied. [ABSTRACT FROM AUTHOR]

The addition of small amount of different ionic liquids modified the activity and regioselectivity of different immobilized preparations of R. mieheilipase catalyzing the hydrolysis of hexa-O-acetyl lactal in aqueous media. ILs with [emim] as cation and different anions were first evaluated affecting in a different manner depending on the immobilized preparation used. The enzymatic activity of RML immobilized on octyl-agarose or CNBr-agarose decreased in the following order: NO3− BF4−> MeOSO3−> PF6−, whereas when RML was immobilized on Q-Sepharose, the enzymatic activity decreased in a different order: MeOSO3−> PF6−> BF4−> NO3−. Using [bdmim], the activity of octyl-RML and CNBr-RML preparations resulted higher in the presence of PF6−than BF4−, 6-fold for octyl-RML and 2-fold for CNBr-RML if compared with the enzyme activity without additive.In both preparations the enzyme was completely regioselective in the presence of the IL hydrolyzing at C-3 position in 99% yield. The modification of the cation in the IL did not affect to the activity of Q-RML with BF4−or decreased the activity with PF6−, although affected to the regioselectivity producing another undesired product, a bihydrolized product in 20–25% yield. In this case, the addition of [emim][MeOSO3] caused the best increment in the activity for this RML biocatalyst, 2-fold with only 8% of bihydrolized production. [ABSTRACT FROM AUTHOR]

Highly efficient dehydrochlorination of PVC is feasible using a readily available ionic liquid, 1-butyl-3-methylimidazolium chloride ([Bmim]Cl). The process does not require additional organic solvents, catalysts, or pressure, and the ionic liquid can be recycled (at least 6 time) without appreciable loss of catalytic efficiency. Both anions and cations of the ionic liquids influence upon dehydrochlorination. This ionic influence, combined with the concerted elimination of HCl in a single step, accounts for the faster dehydrochlorination rate. [ABSTRACT FROM AUTHOR]

Toxicological evaluation of a new group of ionic liquids was performed on human colon cancerous cells—CaCo-2. They belong to different classes of cations: imidazolium (IM), dimethyl-guanidinium (dmg) and tetramethyl-guanidinium (tmg), methyl-pyrrolidinium (MPyr), 2-methyl-1-ethyl-pyridinium (2-MEPy), quaternary ammonium (benzyltriethyl-ammonium–BzTEA; phenyltrimethyl-ammonium–PhTMA; tri-n-octyl-methylammonium-Aliquat) and tri-n-hexyl-tetra-n-decylphosphonium (P6,6,6,14). The new results were compared with data obtained in previous reported studies performed in our lab, and we clearly saw that toxicity can vary significantly with the type of anion. Dicyanoamide-[DCA] and bis(trifluoromethanesulfonyl)amide-[NTf2] were seen to visibly change the impact of some cations. Some were considerably less harmful for CaCo-2 monolayer when the anion was [DCA] or [NTf2], while others induced an abnormal increase of cellular metabolism when [NTf2] was present and therefore, they were considered toxic. However, some cations induced similar responses in the presence of a broad number of anions as (1-butyl-3-methylimidazolium)-[C4MIM] (with the exception of [FeCl4]), (1-(2-hydroxyethyl)-3-methylimidazolium)-[C2OHMIM] and [C4MPyr] and did not cause toxicity. Consequently, they are considered promising cations for building human friendlier solvents. But, a reasonable number of other combinations involving different classes of cations were also seen to not significantly affect viability of the CaCo-2 monolayer. [ABSTRACT FROM AUTHOR]

Heteropolyacids (H3PW12O40, H4SiW12O40) and salts of metal cations (Mn+) and PW12O403−(M3/nPW12O40) act as effective homogeneous catalysts for selective hydrolysis of cellobiose and cellulose to glucose and total reducing sugars (TRS), respectively, in an aqueous phase. For Brønsted acid catalysts, including mineral acid and heteropolyacids, the activity for both reactions increases with a decrease in the deprotonation enthalpies (DPE), indicating that stronger Brønsted acidity is more favorable. For M3/nPW12O40of 11 kinds of metal ions (Ag+, Ca2+, Co2+, Y3+, Sn4+, Sc3+, Ru3+, Fe3+, Hf4+, Ga3+and Al3+), the rate of cellulose hydrolysis increases with Lewis acidity of the cation, while the TRS selectivity was highest for cations with moderate Lewis acidity, such as Sn4+and Ru3+. For the hydrolysis of cellobiose, cellulose and lignocellulose, H3PW12O40and Sn0.75PW12O40showed higher TRS yield than H2SO4. [ABSTRACT FROM AUTHOR]

The biodegradability of a range of phosphonium ionic liquids (ILs) was assessed using the CO2headspace test (ISO 14593). Tetraalkylphosphonium cations in which one of the alkyl substituents contained ester, ether, alcohol or alkene functionality in order to promote biodegradation were targeted. These cations were paired with halide, triflimide and octylsulfate anions. In contrast to previously studied dialkylimidazolium and alkylpridinium ILs with incorporated ester moieties and octylsulfate anions, the phosphonium ILs showed relatively low levels of biodegradability. [ABSTRACT FROM AUTHOR]

Novel SO3H-functionalized ionic liquids bearing two alkyl sulfonic acid groups in the imidazolium cations were designed and successfully applied as catalysts for the one-pot Fischer indole synthesis in water medium. The sequence of the catalytic activity observed in the transformation was in good agreement with the Brønsted acidity order determined by the Hammett method. Various types of indoles from single-carbonyl ketones/aldehydes and cyclohexandiones were provided in 68–96% yields using the catalytic system of [(HSO3-p)2im][HSO4]/H2O. The indole products could be conveniently separated from the reaction mixture by filtration and the dissolved catalyst could be regenerated by treatment with a strongly acidic cation exchange resin, which meant the whole process was performed in water without using any organic solvents. [ABSTRACT FROM AUTHOR]

The stability and activity of hen's egg white lysozyme in the presence of four protic room temperature ionic liquids (ethylammonium formate (EAF), propylammonium formate (PAF), 2-methoxyethylammonium formate (MOEAF) and ethanolammonium formate (EtAF)) have been investigated. Near UV CD experiments have been used to determine protein structure in aqueous solutions of 25 wt%, 50 wt% and 75 wt% ionic liquid, and to assess the proteins ability to refold after heating to 90 °C. It was determined that EAF and MOEAF are similarly effective refolding additives, while PAF is more effective at promoting refolding at concentrations up to ∼62.5 wt%, but at higher PAF concentrations the protein spontaneously denatures. Both of these effects are attributed to the increased hydrophobicity of the cation. EtAF is shown to stabilise lysozyme against unfolding at high temperature, and renaturing appears to be near complete upon cooling. Studies of enzyme kinetics reveal increased protein activity in the presence of all ionic liquids examined, but the most significant increase is noted for EtAF, where rates are six times higher than those determined for lysozyme in buffered water. [ABSTRACT FROM AUTHOR]

In this study, an FeCl3·6H2O/cationic 2,2′-bipyridyl system was employed as a catalyst in the coupling of aryl iodides with thiols to form an aryl–sulfur bond in refluxed water under aerobic conditions. The residual aqueous solution after extraction could be reused for several cycles without a significant decrease in activity. [ABSTRACT FROM AUTHOR]