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Continuous-flow rhodium-catalysed hydroformylation of long chain alkenes has been achieved with selectivities to the desired linear aldehyde of 92% and minimum rhodium loss, using a xantphos-derived ligand attached to an imidazolium salt in a supercritical fluid–ionic liquid system. The effect of oxygen in the system can be ameliorated to some extent by adding a simple sulfonated triphenylphosphine to the catalytic solution. [ABSTRACT FROM AUTHOR]

Both softwood (southern yellow pine) and hardwood (red oak) can be completely dissolved in the ionic liquid 1-ethyl-3-methylimidazolium acetate ([C2mim]OAc) after mild grinding. Complete dissolution was achieved by heating the sample in an oil bath, although wood dissolution can be accelerated by microwave pulses or ultrasound irradiation. It has been shown that [C2mim]OAc is a better solvent for wood than 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) and that variables such as type of wood, initial wood load, particle size, etc.affect dissolution and dissolution rates; for example, red oak dissolves better and faster than southern yellow pine. Carbohydrate-free lignin and cellulose-rich materials can be obtained by using the proper reconstitution solvents (e.g., acetone/water 1 : 1 v/v) and approximately 26.1% and 34.9% reductions of lignin content in the reconstituted cellulose-rich materials (from pine and oak, respectively) have been achieved in one dissolution/reconstitution cycle. The regenerated cellulose-rich materials and lignin fractions were characterized and compared with the original wood samples and biopolymer standards. For pine, 59% of the holocellulose (i.e., the sum of cellulose and hemicellulose) in the original wood can be recovered in the cellulose-rich reconstituted material; whereas 31% and 38% of the original lignin is recovered, respectively, as carbohydrate-free lignin and as carbohydrate-bonded lignin in the cellulose-rich material. [ABSTRACT FROM AUTHOR]

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]

The simultaneous achievement of large surface areas and high IL contents in porous materials are highly beneficial for efficient carbon dioxide (CO2) capture and atmospheric fixation. Herein, a series of porous hypercrosslinked poly(ionic liquid)s (HPILs) are successfully developed through a two-step synthetic strategy, including free radical self-polymerization of a specific benzyl bromide-tethered imidazole ionic liquid (IL) to fabricate a linear PIL as a precursor, and a subsequent Friedel–Crafts alkylation between the precursor and the crosslinker for hypercrosslinking. The HPILs featured large surface areas of up to 855 m2 g−1 along with a hierarchically nanoporous structure, high IL contents (2.19–2.91 mmol g−1) and satisfactory CO2-philic properties. By virtue of the combined advantages, HPILs served as metal-free heterogeneous catalysts for solvent-additive-free CO2 cycloaddition with epichlorohydrin at 80 °C and 0.1 MPa CO2 for 24 h, presenting high catalytic activity and stable reusability. A high yield of 99.0% coupled with a turnover frequency (TOF) of 6.0 h−1 was achieved, much higher than most of the reported metal-free heterogeneous catalysts, even superior to homogeneous analogues. Furthermore, various epoxides, including large-sized epoxides, were effectively converted into carbonates with high yields, affording good substrate applicability. This work reports a facile and universal approach for the construction of porous HPILs with both great porosities and high IL contents towards efficient chemical fixation of CO2 under mild conditions. [ABSTRACT FROM AUTHOR]

Alcoholysis is a potential method for the degradation of polyesters to their precursor building blocks, which can then be polymerized again to form new qualified polyester materials. This method therefore makes recycling possible in a permanent polymer–monomer–polymer loop. In this study, a series of metal-free tetrabutylphosphonium-based ionic liquids (ILs) were prepared as catalysts for the methanolysis of poly(ethylene 2,5-furandicarboxylate) (PEF), which is well known as an ideal alternative to the petroleum-based plastic poly(ethylene terephthalate) (PET). It was found that anions with stronger electronegativity were more efficient for the methanolysis of PEF. By adjusting the structures of the anions and cations of ILs, 1-butyl-3-methylimidazole acetate ([BMIm][OAc]) exhibited excellent catalytic activity in the methanolysis of PEF. The optimization of reaction parameters enabled the [BMIm][OAc]-catalyzed methanolysis of PEF with nearly 100% PEF degradation and a 77.6% dimethyl furan-2,5-dicarboxylate (DMFD) yield at 130 °C for 30 min. Furthermore, [BMIm][OAc] could keep high-activity after using for six times under the optimum conditions. Assisting with 1H NMR, FT-IR and density functional theory (DFT) calculations, an in-depth study was performed on the feasible synergetic catalytic mechanism of [BMIm][OAc] for the methanolysis of PEF, induced by hydrogen bonds formed between reactants and [BMIm][OAc]. Finally, on the basis of experimental results and scanning electron microscopy (SEM), it was confirmed that PEF with the spiral motif could be degraded under milder conditions than PET. Therefore, this strategy of using adjustable cation and anion structures in ILs provides an opportunity to develop other more efficient ILs for the alcoholysis of furan-based polymers via a green and mild pathway. [ABSTRACT FROM AUTHOR]

In this study, a series of high-activity imidazole-based dicationic ionic liquids (DILs) were designed and prepared as efficient catalysts for balancing the reactivity between the endo-hydroxyl group (endo-OH) and the exo-hydroxyl group (exo-OH) of isosorbide (ISO) to synthesize high molecular weight poly(isosorbide carbonate) (PIC). Meanwhile, the thermal performance of PIC was precisely optimized by regulating the chain configuration. The results showed that when the trace amounts (4.5 × 10−5 based on the ISO molar amount) of bis-(3-methyl-1-imidazole)-ethylene dibromide ([C2(Min)2][Br]2) were used, the weight average molecular weight (Mw) of PIC reached 98 700 g mol−1. It could be concluded from the results of the experiment and the stimulation that the high catalytic activity of DILs was attributed to the strong electrostatic interaction between the cation and the substrate and the effective balance of the reactivity of the endo-OH and the exo-OH. Furthermore, we found that the reduction of hydroxyl groups in the terminal groups and the increase of endo–endo (a1) structure in the repeating unit improved the thermal properties of PIC. Finally, 1H NMR, Fourier infrared spectroscopy, and density functional theory (DFT) calculations were used to verify the reaction process through anion and cation multi-site synergistic effect and a possible electrophilic–nucleophilic reaction mechanism was successfully obtained. [ABSTRACT FROM AUTHOR]

This paper reports on an investigation into the toxicity of 1-alkyl-3-methylimidazolium ionic liquids (ILs) towards two green algae (Chlorella vulgarisand Oocystis submarina) characteristic of freshwater and brackish environments, as well as two brackish and marine diatoms (Cyclotella meneghinianaand Skeletonema marinoi). The test kit of IL compounds consisted of five 1-alkyl-3-methylimidazolium chlorides (from -ethyl to -decyl) for evaluating the expected alkyl chain length effect, together with 1-butyl-3-methylimidazolium tetrafluoroborate, dicyanamide, trifluoromethanesulfonate, methyl sulfate an α-methyl[poly(oxy-1,2-ethanediyl)]sulfate for investigating the influence of the anion on IL toxicity towards various algal species. A pronounced alkyl chain effect was confirmed with all the organisms studied. EC50values were linearly very well correlated with the number of carbon atoms in the IL alkyl chains. The results indicate that diatoms are far more sensitive than green algae to ILs. Cell size also plays an important part in the intoxication process: a tenfold difference in cell size results in a 100% more sensitive reaction to ionic liquids in both the green algae and diatoms. No significant differences were observed between alkylimidazolium salts and an alkylpyridinium compound of similar lipophilicity. It was also found that the use of tetrafluoroborate and trifluoromethanesulfonate as counteranions in the IL structure gave rise to the most pronounced toxic effects in comparison with the other anions tested. In the case of tetrafluoroborate this is probably caused by the potential hydrolysis of this entity, which leads to the formation of fluoride and a further increase in toxicity. Whereas in the case of trifluoromethanesulfonate it is likely caused by relatively high lipophilicity of this anion, additionally known to be strongly associated with alkylimidazolium cations, that in turn may enhance cell wall penetration. [ABSTRACT FROM AUTHOR]

The separation of aromatics from aliphatics is challenging and energy-consuming because of the very close boiling points among these compounds and the possibility of forming azeotropes. In this work, we designed two imidazolium-based dicationic ionic liquids, [C5(MIM)2][NTf2]2 (DIL1) and [C6(MIM)2][NTf2]2 (DIL2), and found that they could highly efficiently extract aromatics from aliphatics. Three different aromatic and aliphatic mixtures, toluene/n-heptane, benzene/n-hexane and benzene/cyclohexane, were used to investigate the universality of DILs. The extractive performance of both DILs was compared with those of other promising ILs and sulfolane. The mixtures of toluene and aliphatics with different chain lengths were also investigated. The results showed that the two DILs had relatively high selectivity and distribution coefficients for different aromatic and aliphatic mixtures. At 30 °C, the highest values of selectivity and distribution coefficient for toluene/n-heptane, benzene/n-hexane and benzene/cyclohexane systems were 50.4, 64.8, and 24.9 and 1.44, 2.44, and 2.25, respectively. The performance of DILs at 30 °C was better than that at 40 °C. Besides, a higher selectivity could be obtained when toluene is used with a longer chain aliphatic, such as a selectivity of 61.4 could be obtained when the aliphatic was n-nonane. The study of the physicochemical properties of DILs showed that they were more stable than the previous ones. In a word, the two DILs were evaluated as potential solvents for the separation of aromatics from aliphatics. [ABSTRACT FROM AUTHOR]

Fluoroquinolones (FQs) and Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) are two classes of Active Pharmaceutical Ingredients (APIs) in widespread use in human healthcare and as veterinary drugs, and that have been found throughout the water cycle in the past years. These two classes of APIs are commonly present in aqueous streams in concentrations ranging from ng L−1 to μg L−1. Despite such low concentrations, these contaminants tend to bioaccumulate, leading to serious environmental and health issues after chronic exposure. The low concentrations of FQs and NSAIDs in aqueous media also render difficult identification and quantification, which may result in an inefficient evaluation of their environmental impact and persistence. Therefore, the development of alternative pre-treatment techniques for their extraction and preconcentration from aqueous samples is a crucial requirement. In this work, liquid–liquid systems, namely ionic-liquid-based aqueous biphasic systems (IL-based ABS), were tested as simultaneous extraction and preconcentration platforms for FQs and NSAIDs. ABS composed of imidazolium-, ammonium- and phosphonium-based ILs and a citrate-based salt (C6H5K3O7) were evaluated for the single-step extraction and enrichment of three FQs (ciprofloxacin, enrofloxacin and norfloxacin) and three NSAIDs (diclofenac, naproxen and ketoprofen) from aqueous samples. Outstanding one-step extraction efficiencies of APIs close to 100% were obtained. Furthermore, the preconcentration factors of both FQs and NSAIDs were optimized by an appropriate manipulation of the phase-forming components compositions to tailor the volumes of the coexisting phases. Preconcentration factors of 1000-fold of both FQS and NSAIDs were obtained in a single-step process, without reaching the saturation of the IL-rich phase. The preconcentration of APIs up to mg L−1 allowed their easy and straightforward identification and quantification by a High-Performance Liquid Chromatography (HPLC) system coupled to an UV detector, as shown for both model systems (distilled water) and real effluent samples from a wastewater treatment plant. [ABSTRACT FROM AUTHOR]

A facile aromatic nucleophilic substitution (SNAr) reaction in recyclable [Omim]Br under relatively mild conditions has been described. An electrophile–nucleophile dual activation by [Omim]Br is also discovered based on control experiments, 1H NMR and IR spectroscopies. This chemistry provides an efficient and metal-free approach for the generation of Caryl–X (X=S, N, O) bonds, many of which are significant synthetic intermediates or drugs, making this methodology attractive to both synthetic and medicinal chemistry. [ABSTRACT FROM AUTHOR]

Vitamin E (VE) has significant biological activities and thus its acylation to increase its stability is of extreme interest. We developed an efficient and sustainable approach using imidazolium-based ionic liquids as dual solvent-catalysts for the esterification between α-tocopherol (the most active form of VE) and succinic anhydride. Although in literature it is reported that lipase can catalyze this reaction, hereby we demonstrate that the reaction observed in DMSO and DMF is catalyzed by the histidyl residues of the protein. Histidine and its analogue containing an imidazole ring were tested as organocatalysts for the production of α-tocopherol succinate. In light of the imidazole organocatalysis, commercially-available 3-alkyl-1-methyl imidazolium ILs [CnC1Im][X−] were investigated as dual solvent-catalysts for the esterification of α-tocopherol with succinic anhydride, and provided satisfactory yields and reaction rates. [C5C1Im][NO3−] can be recycled by water extraction, instead of organic solvent extraction to separate α-tocopherol succinate from [C5C1Im][NO3−], with an average yield of 94.1% for 4 subsequent batches, while the catalytic activity of the recycled ILs showed almost no loss after 4 batches. The developed protocol for the synthesis of α-tocopherol esters and IL recycling bears industrial potential due to the ease of use and the efficient recycling. [ABSTRACT FROM AUTHOR]

A series of novel heterogeneous catalysts were developed by immobilizing imidazolium-based functionalized ionic liquids on an FDU-type mesoporous polymer. Various techniques such as X-ray diffraction, N2 adsorption-desorption, and high resolution transmission electron microscopywere used to characterize the physicochemical properties of the catalysts. Ionic liquid-functionalized mesoporous polymers serve as efficient catalysts in the solvent free cycloaddition reactions of CO2 with epoxides without the use of any co-catalyst. The catalysts can be easily recovered and reused without a significant loss of activity. In comparison with the polystyrene (PS) and mesosilica SBA-15 supports, the FDU mesopolymer possesses both the mesoporous organic framework and abundant phenolic hydroxyl groups, which are key factors in improving the catalytic performance of supported ionic liquids. [ABSTRACT FROM AUTHOR]

An air stable, water soluble, and efficient ionic liquid-tagged Schiff base palladium complex was prepared. The synthesized complex was well characterized by NMR, mass spectrometry, FT-IR, UV-visible spectroscopy and powder X-ray diffraction. The complex was used as a catalyst for the Suzuki and Heck cross-coupling reactions in water. Good to excellent yields were achieved using a modest amount of the catalyst. In addition, the catalyst can be easily reused and recycled for six steps without much loss in activity, exhibiting an example of sustainable and green methodology. [ABSTRACT FROM AUTHOR]

Novel supported ionic liquid phase (SILP) gas purification materials have been developed to remove ammonia irreversibly from an ambient gas flow of nitrogen (1000 ppm NH3 in N2, wet and dry). In the applied SILP materials, thin films of imidazolium based ionic liquids and ionic solutions of metal complexes, namely [C8C1Im][NTf2], [C8C1Im][NTf2]/Cu(NTf2)2, [C8C1Im][NTf2]/Co(NTf2)2 and [CnC1Im]Cl/CuCl2 (n = 2, 4, 8), were dispersed onto the large surface area of polymer-based spherical activated carbon supports. For the [CnC1Im]Cl/CuCl2 (n = 2, 4, 8) based SILP materials the use of a humid gas flow significantly enhances NH3 absorption as demonstrated by a clear increase of breakthrough times. The irreversibility of the ammonia sorption and the broadband capability (e.g. Cl2, H2S and cyclohexane) of the prepared SILP absorber materials are reported and compared to typical standards for gas purification adsorber materials (ABEK regulations. [ABSTRACT FROM AUTHOR]

Certain ionic liquids (ILs) offer a potentially more sustainable and environmentally responsible alternative to organic solvents for many industrial applications, including biorefineries, where they are used to pretreat lignocellulose. To gain a more robust understanding of the roles of cations and anions in the process, we monitored the impact of the respective ILs on Panicum virgatum (switchgrass) in terms of lignin content, cellulose crystallinity, and enzymatic digestibility. The behaviors of four ILs, based on one of two cations, 1-ethyl-3-methylimidazolium ([C2mim]+) and cholinium ([Ch]+), and one of two anions, acetate ([OAc]-) and lysinate ([Lys]-), were compared. While all four ILs were effective in pretreating switchgrass, ILs containing [Lys]- anions provided greater delignification (70-80% vs. 16-50%) after addition of water as an anti-solvent and higher glucose yields (78-96% vs. 56-90%) compared to those obtained by the use of ILs containing [OAc]- anions. Measurements of the Kamlet-Taft parameters using a series of dyes indicated a greater hydrogen bond basicity for the ILs with [Lys]- anions as compared to acetate ILs. To understand the effective delignification ability of lysinate-based ILs, interaction energies of individual ions and ion pairs with a model dilignol substrate were determined by quantum chemical calculations. The results show that the addition of antisolvent significantly influenced the interaction energies governing lignin removal during the process. [ABSTRACT FROM AUTHOR]

novel ionic liquid functionalized magnetic nanoparticle was prepared by anchoring an imidazolium ionic liquid bearing triethylene glycol moieties on the surface of silica-coated iron oxide nanoparticles. The material proved to be an effective host for the immobilization of a Pd catalyst through a subsequent simple ion-exchange process giving a highly water dispersible, active and yet magnetically recoverable Pd catalyst (Mag-IL-Pd) in the Suzuki-Miyaura coupling reaction in water. The as-prepared catalyst displayed remarkable activity toward challenging substrates such as heteroaryl halides and ortho-substituted aryl halides as well as aryl chlorides using very low Pd loading in excellent yields and demonstrating high TONs. Since the catalyst exhibited extremely low solubility in organic solvent, the recovered aqueous phase containing the catalyst can be simply and efficiently used in ten consecutive runs without significant decrease in activity and at the end of the process can be easily separated from the aqueous phase by applying an external magnetic field. This novel double-separation strategy with negligible leaching makes Mag-IL-Pd an eco-friendly and economical catalyst to perform this transformation. [ABSTRACT FROM AUTHOR]

Novel solvent free task specific ionic liquid (TSIL) electrolytes for dye sensitised solar cells (DSSC) were synthesised and tested. Of great concern is the replacement of low-moderate toxicity second generation ILs, with high toxicity third generation TSILs. As most 1-butyl-3-methylimidazolium (Bmim) and especially 1-ethyl-3-methylimidazolium (Emim) based ILs have low toxicity, the designing of replacement TSILs of comparable toxicity is a challenge. Structural features of TSIL investigated herein were incorporation of heteroatoms into the side chain of imidazolium cations (i.e. ether, ester and amide) and anion (bromide, iodide, and triflimide [NTf2]). Preliminary toxicity screening against 20 microorganisms (8 bacteria and 12 fungi) found that all ILs, imidazolium salts, N-butylbenzimidazole (NBB) and guanidinium thiocyanate (GNCS) do not exhibit high antimicrobial toxicity. However NBB and a pentyl ester substituted IL displayed moderate toxicity to several strains of bacteria and fungi. Further toxicity testing to establish IC50 values shows several novel TSIL compounds and imidazolium salts are in fact less toxic to microorganisms (e.g. bacteria) than commonly used 1-ethyl-3-methylimidazolium iodide (EmimI) and 1,3-dimethylimidazolium iodide (DmimI). We have demonstrated that the presence of ether and either ester or amide groups in the structure of the cation of the TSIL and imidazolium salts reduces antimicrobial toxicity, which is consistent with the lowering of the lipophilicity of ILs. Iodide and bromide analogues have lower toxicity than the NTf2 examples in this study. The DSSC performance using these "greener" ILs in place of the standard EmimI compare quite favourably. Two low antibacterial toxicity iodide examples exhibit photocurrents of 9.27 mA cm-2 and 8.85 mA cm-2, respectively, achieving promising efficiencies of 3.39% and 3.31%, respectively (EmimI = 4.94%). DSSC performance is further improved by 15% minimum to 66% maximum, depending on IL chosen, by the presence of small amounts of moisture and DSSCs employing a low antibacterial toxicity iodide TSIL or imidazolium salt can surpass the performance of dry EmimI. Of note the DSSC containing TSIL NTf2 examples, performed poorly compared to the halide analogues, with the outcome that the most toxic TSILs under investigation are also the least preferred based on performance. [ABSTRACT FROM AUTHOR]

In the last decade, aqueous two-phase systems (ATPS) composed of ionic liquids (ILs) and inorganic salts have been largely explored as novel extractive platforms. The use of ILs as phase-forming components in ATPS has led to outstanding extraction performances compared to more traditional approaches. Nevertheless, despite those exceptional achievements, IL regeneration, recycling and reuse lagged behind and still remain a challenging task towards the development of greener cost-effective processes. Aiming at overcoming these shortcomings, the phase diagrams of novel ATPS composed of imidazolium-based ILs and Na2CO3 or Na2SO4 were determined and their extraction efficiencies for a model antioxidant - gallic acid - were evaluated. The most promising IL-based ATPS were then used in sequential two-step cycles (product extraction/IL recovery) so as to evaluate the efficacy on the IL recyclability and reusability. Extraction efficiency values ranging between 73% and 99% were obtained in four sequential partitioning experiments involving gallic acid while allowing the regeneration of 94-95% of the IL and further reutilization. Moreover, to support the vast applicability of the back-extraction routes and the recyclability concept proposed here, the most prominent systems were further tested with two additional antioxidants, namely syringic and vanillic acids. In both examples, the extraction efficiencies were higher than 97%. The remarkable results obtained in this work support the establishment of IL-based ATPS as a sound basis of greener cost-effective strategies with a substantial reduction in the environmental footprint and economical issues. [ABSTRACT FROM AUTHOR]

A series of cross-linked ionic polymers based on styrene-functionalized imidazolium salts with chloride, hexafluorophosphate, or tetrafluoroborate counter anions have been prepared and characterized using a range of analytical and spectroscopic techniques and electron microscopy. The polymer with the chloride anion is an efficient catalyst for the cycloaddition of carbon dioxide with epoxides to afford cyclic carbonates. The cross-linked polymer is insoluble in organic solvents and is highly stable and therefore can be easily recycled and reused. [ABSTRACT FROM AUTHOR]

Pretreatments of sugarcane bagasse for saccharification using different acid-catalysed imidazolium IL solutions (containing 20% water) at 130 °C for 30 min were investigated. At the same solution pH, pretreatment effectiveness in terms of glucan digestibility, delignification and xylan removal was similar for aqueous 1-butyl-3-methylimidazolium methane sulfonate (BMIMCH3SO3), 1-butyl-3-methylimidazolium methyl sulfate (BMIMCH3SO4), 1-ethyl-3-methylimidazolium chloride (EMIMCl) and 1-butyl-3-methylimidazolium chloride (BMIMCl). Decreasing solution pH of aqueous IL systems from 6.0 to 0.4 increased bagasse delignification and xylan removal, and as a result, improved glucan digestibility. The glucan digestibilities for bagasse samples pretreated by IL solutions with pH ≤0.9 were ＞90% after 72 h of enzymatic hydrolysis. Without pH adjustment, the effectiveness of these aqueous IL solutions (except BMIMCH3SO3 because of its low natural pH of 0.9) to deconstruct the biomass was poor and the glucan digestibilities of pretreated bagasse samples were ＜20%. These results show that pretreatment effectiveness of aqueous imidazolium ILs can simply be estimated from solution pH rather than hydrogen bond basicity (β) of the IL solution. [ABSTRACT FROM AUTHOR]

Brønsted acidic ionic liquids (ILs) have been synthesized and investigated as catalysts in esterification and transesterification reactions: simple and non-corrosive salts characterized by aliphatic cations associated with an “acidic” anion (in particular, [HSO4]−) gave the higher yields. A quite good correlation between IL acidity (H0) and catalytic ability was found although also the hydrophilic nature of the ionic medium probably affects the process efficiency. [ABSTRACT FROM AUTHOR]

A series of novel ionic liquids comprising two asymmetric phosphate-derived anions, namely dimethyl phosphorothioate and dimethyl phosphoroselenoate, and several imidazolium and non-imidazolium-based cations was prepared viaa facile synthetic route. Thermal degradation was studied by dynamic thermogravimetric analysis (TGA) revealing a slightly higher stability of the imidazolium ionic liquids and an overall low thermal stability for the phosphoroselenoate salts. Long-term moisture sorption analysis showed correlation with the polarity of the cation and differences in absorption and desorption kinetics. Finally, a Eucalyptus globuluskraft paper grade pulp was dissolved and subsequently regenerated to assess the degradation of the various molecular weight fractions by size exclusion chromatography. In addition, pre-extracted xylan was subjected to the same dissolution procedure to examine the degradation of low-molecular weight components in more detail. [ABSTRACT FROM AUTHOR]

This paper reports on a detailed study of the influence of salinity on the biological activity of 1-alkyl-3-methylimidazolium chlorides on two green algae Oocystis submarinaand Chlorella vulgaris, one diatom Cyclotella meneghinianaand one blue-green alga Geitlerinema amphibium. All these organisms inhabit the Baltic Sea, an environment naturally varying greatly in salinity. The toxicity effects of ILs towards cyanobacterial and algal organisms were tested in fresh water and in water of four different salinities—8, 16, 24 and 32 PSU—reflecting the whole range encountered in the Baltic Sea. Increasing the salinity was found to exert a significant influence on ionic liquid toxicity in all cases. The lower toxicity is probably due to the reduced permeability of ionic liquid cations through the algal cell walls. Higher chloride concentrations offer a good ion-pairing environment for imidazolium cations, which therefore compete with hydroxyl or silanol functional groups in cell-wall structures. The results of this work indicate that at higher salinities algal growth is inhibited to a significantly lesser extent. With the same IL concentration, the toxicity decreases by eight–ten times in the algae or about three times in the cyanobacterium in the 0–32 PSU salinity range. [ABSTRACT FROM AUTHOR]

A novel method to fabricate chemically linked conducting polymer–biopolymer composites that are intrinsically flexible and conducting for functional electrode applications is presented. Polypyrrole was synthesised in situ during the cellulose regeneration process using the 1-butyl-3-methylimidazolium chloride ionic liquid as a solvent medium. The obtained polypyrrole–cellulose composite was chemically blended and showed flexible polymer properties while retaining the electronic properties of a conducting polymer. Addition of an ionic liquid such as trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide, enhanced the flexibility of the composite. The functional application of these materials in the electrochemically controlled release of a model drug has been demonstrated. This strategy opens up a new design for a wide spectrum of materials for smart electronic device applications wherein the functionality of doping and de-doping of conducting polymers is retained and their processability issue is addressed by exploiting an ionic liquid route. [ABSTRACT FROM AUTHOR]

The design and synthesis of hemi-fluorinated perfluorooctanesulfonic acid (PFOS) alternatives is described using a Zn/CuI mediated Michael-type addition reaction in ionic liquids considering environmentally benign reaction conditions as well as products. One of the new potassium sulfonates showed promising surface tension activities when compared to that of the PFOS potassium salt. [ABSTRACT FROM AUTHOR]

Carbohydrates, as cheap mass-products, promise to be outstanding candidates as sustainable raw materials. To achieve the goal of carbohydrate utilisation as industry raw materials, environmental low impact conversions from sugars to high value products are needed. Here we present the conversion of reducing sugars into imidazole heterocycles. Imidazole formation was achieved by a one-pot conversion of reducing mono and disaccharides with amidines in a melt of ammonium carbonate. A range of disaccharides were converted into different 2-substituted imidazoles carrying a varying glycosylation pattern on the 4-tetrahydroxy butyl side chain. All conversions were performed without the need of protecting groups, using benign reagents and solvents. [ABSTRACT FROM AUTHOR]

A combined experimental and computational study on the imidazolium ionic liquid-promoted conversion of fructose to 5-hydroxymethylfurfural (HMF) was performed. In particular, 1-butyl-3-methyl-imidazolium bromide (BMImBr) was found to be unexpectedly effective for conversion of fructose into HMF without utilizing any other additive or catalyst. Under the optimized conditions, nearly 100% conversion of fructose with a 95% yield of HMF could be obtained. In addition, BMImBr could be easily recovered and reused over 6 times without significant loss of activity. This protocol represents a simple, recyclable and environmentally friendly pathway for HMF production. Furthermore, the detailed mechanism of the BMImBr-promoted conversion of fructose into HMF was also studied through an in situ FT-IR technique, NMR and density functional theory calculations, and demonstrated that the hydrogen bond interaction between BMImBr and fructose could play an important role in promoting the dehydration of fructose. This work also provides further understanding at the molecular level of the reaction process for ionic liquid-promoted conversion of fructose to HMF. [ABSTRACT FROM AUTHOR]

The catalytic potential of different fluoroboric acid-derived catalyst systems viz. aq HBF4, solid supported HBF4, metal tetrafluoroborates (inorganic salts), solid supported metal tetrafluoroborates, and tetrafluoroborate based ionic liquids (organic salts) were investigated for the three component reaction (3-MCR) of 1,2-diketone, aldehyde, and ammonium salts to form 2,4,5-trisubstituted imidazoles and the four component reaction (4-MCR) involving 1,2-diketone, aldehyde, amine and ammonium acetate to form 1,2,4,5-tetrasubstituted imidazoles. The HBF4–SiO2 was found to be the stand out catalyst for both the 3-MCR and 4-MCR processes. The next most effective catalysts are LiBF4 and Zn(BF4)2 to form 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles via the 3-MCR and 4-MCR, respectively. This is the first report on the unaddressed issue of competitive formation of 2,4,5-trisubstituted imidazole during the 4-MCR involving 1,2-diketone, aldehyde, amine and ammonium acetate and highlights the influence of the catalyst systems in controlling the selective formation of tetra substituted imidazole. The metal salt of weak protic acids drive selectivity towards tetra substituted imidazole in the order tetrafluoroborates ＞ perchlorates ＞ triflates. The catalytic potency of tetrafluoroborates was in the order Zn(BF4)2 ＞ Co(BF4)2 ＞ AgBF4≈ Fe(BF4)2 ＞ NaBF4≈ LiBF4≈ Cu(BF4)2. The developed protocols worked well for different diketones, various aryl, heteroaryl, and alkyl aldehydes and in the case of the preparation of 1,2,4,5-tetrasubstituted imidazoles different amines can be used. The effectiveness of different ammonium salts as nitrogen source has been investigated and ammonium acetate is proved to be the best. The HBF4–SiO2 is recyclable for five consecutive uses without significant loss of catalytic activity. [ABSTRACT FROM AUTHOR]

Ruthenium nanoparticles (Ru NPs) were synthesized from the reduction of Ru(2-methylallyl)2(cod) under an atmosphere of H2(g) in a series of phosphonium and imidazolium ionic liquids (ILs): [P4,4,4,1]NTf2, [P4,4,4,8]NTf2, [P4,4,4,14]X (for −X = −NTf2, −OTf, −PF6), [BMI]NTf2 and [BDMI]NTf2. The Ru NPs embedded in each of these ILs were used as biphasic hydrogenation catalysts for the reduction of cyclohexene. The properties of the NPs, in terms of NP stability and catalytic activity, were dependent on the nature of the IL and these differences were rationalized through a Walden plot analysis of the IL ionicity. This analysis supports the idea that the formation of ion associations, in terms of ion-pairs or supramolecular aggregates, plays a key role in IL stabilization of metal NPs. A correlation between this stabilization mechanism and the NP stability and catalytic activity is hypothesized. [ABSTRACT FROM AUTHOR]

Imidazolium salts can be classed as surfactants, detergents, ionic liquids, reagents, catalysts or solvents. A study of the toxicity and ecotoxicity of these salts yields valuable information for their use as pharmaceuticals as well as impact on the environment. Our approach to screen a series of chiral imidazolium salts for toxicity to bacteria and fungi, including clinical pathogen strains, has led to the identification of a ‘hit’ MRSA selective antimicrobial compound. Preliminary structure–activity-relationship (SAR) information (required position of l-phenylalanine and l-valine group) is also elucidated within this first generation of compounds. Conversely, most of the imidazolium salts were nontoxic (IC95 ＞ 2 mM) to the 12 fungi strains and 8 bacteria strains screened, and we propose that they are suitable candidates for ‘green chemistry’ applications. Ecotoxicity studies (Biodegradation ISO 14593 ‘CO2 Headspace Test’) of two bromide ionic liquids containing l-phenylalanine residues indicate that these ionic liquids passed the test (＞60% in 28 days) and classed as readily biodegradable. [ABSTRACT FROM AUTHOR]

Functional imidazolium ionic liquids have been developed as a new class of versatile catalysts. C2-symmetric and unsymmetric imidazolium-tagged bis(oxazoline) ligands were prepared, and the anions of the ligands were altered by ion-exchange reactions. The catalysts based on the new ligands and Cu(OTf)2 were applied in asymmetric Diels–Alder reactions between N-acryloyl/N-crotonoyloxazolidinones 15 and 1,3-cyclohexandiene/cyclopentadiene 16 in different ionic liquids and in dichloromethane (DCM). The catalysts achieved a high level of activity and enantioselectivity, as well as good recyclability: cycloadduct (S)-17ab was attained at 98% conversion and 97% ee in [Bmim]NTf2. Moreover, the catalyst could be recycled 20 times without an obvious loss of activity or enantioselectivity. By comparison, we deduced that the C2 symmetry of the new ligands was crucial for obtaining high ee values. Toxicity studies of the ligands were performed for the first time. [ABSTRACT FROM AUTHOR]

We described herein the use of imidazolium ionic liquids [bmim]PF6 and [bmim]BF4 in the selective, metal and catalyst-free synthesis of unsymmetrical diaryl selenides by electrophilic substitution in arylboron reagents with arylselenium halides (Cl and Br) at room temperature. This is a general substitution reaction and it was performed with arylboronic acids or potassium aryltrifluoroborates bearing electron-withdrawing or electron-donating groups, affording the corresponding diaryl selenides in good to excellent yields. The ionic liquid [bmim][PF6] was easily recovered and utilized for further substitution reactions. [ABSTRACT FROM AUTHOR]

Brønsted acid ionic liquids (BAILs) based on the 4-(3′-butyl-1′-imidazolio)-1-butanesulfonic acid cation were found to be very efficient polyesterification solvents and catalysts. Only 5–30 min at 90–110 °C was required to obtain high molar mass poly(12-hydroxydodecanoic acid) (Mw up to 40000 g mol−1). The polyesterification was faster in BAILs with the bis(trifluoromethylsulfonyl)imidide anion (Tf2N), but small amounts of ethers and double bonds arising from side reactions were detected in the final polymer. On the other hand, no side reactions took place in the BAIL with the hydrogen sulfate anion, except for the formation of a sulfonate ester intermediate that can further react with carboxylic acid groups to yield the expected ester. This intermediate, not observed in Tf2N-based BAILs, might be involved in the protection of hydroxy end groups from etherification side reactions in HSO4−-based BAILs. To explain the different behaviors of these BAILs, and since the acidity of H2SO4 is much higher than that of Tf2NH, it is suggested that the structure of these BAILs could be different: alkylsulfonic acid-substituted imidazolium for the former, while the latter could be just a mixture of imidazolium–sulfonate zwitterion and Tf2NH. The influence of reaction temperature, water elimination method and BAIL concentration on polyesterification are also discussed. [ABSTRACT FROM AUTHOR]

A series of hydrophilic N,N-dimethylpyrrolidinium- and N,N-dimethylpiperidinium-based ionic liquids (ILs) have been prepared and applied as reaction media in the Wacker oxidation of styrene by hydrogen peroxide using PdCl2 as the catalyst. The efficiency of these ILs was compared with hydrophilic and hydrophobic imidazolium systems (including those with nitrile functionalities). The nature of the ionic liquid strongly influences the product distribution. In particular, in hydrophobic ILs, relevant amounts of 1,3-diphenyl-1-butene arising from styrene dimerization were detected, in addition to the expected phenylmethylketone. The formation of 1,3-diphenyl-1-butene may be attributed to the formation of Pd(0) species from “ClPdOH” (probably formed during the Wacker process) in a side-reaction. Consequently, the ability of the IL to favor or disfavor the reoxidation of “ClPdOH” to “ClPdOOH” by hydrogen peroxide, giving an homogeneous phase or a biphasic system, appears to be the main factor affecting selectivity. [ABSTRACT FROM AUTHOR]

Experiments were conducted to study the effects of reaction conditions on the hydrolysis of miscanthus dissolved in 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]) catalyzed by H2SO4. It was determined that while there is a small co-inhibition effect associated with the simultaneous hydrolysis of the cellulosic and hemicellulosic portions of miscanthus, the largest rate decreases were observed for the hydrolysis of the hemicellulosic portion. This rate decrease was attributed to the chemical linkage between hemicellulose and lignin in miscanthus, which could be broken with chemical pretreatment. While chemical pretreatment increased the rate of the hydrolysis of the hemicellulosic component, delignification showed no further benefit. The rate of hydrolysis was determined to be first order in concentrations of β-1,4 glycosidic linkage and acid, and zero order in water concentration. The activation energy for the hydrolysis of the glycosidic linkages in the cellulosic and hemicellulosic components were determined to be 95 kJ mol−1 and 114 kJ mol−1 respectively. Progressive addition of water during the first hour of the reaction increased conversion and selectivity to saccharine products, while limiting dehydration of the sugars formed. The conversion of the cellulosic portion of miscanthus could be increased after the first hour of the reaction by increasing the reactor temperature. While miscanthus is only partially soluble in [Emim][Cl], it was found that the initial miscanthus loading could be increased to 9 wt% before significant yield decreases attributed to solubility limitations of the cellulosic component were observed. By proper adjustment of reaction conditions, it was possible to achieve yields of sugars approaching 84% from the cellulosic and hemicellulosic components of miscanthus, with minimal dehydration of the sugars to furans. [ABSTRACT FROM AUTHOR]

A new approach to improve the cellulase stability against 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]), based on coating of immobilized enzyme particles with hydrophobic ILs, is proposed. The stability of commercial cellulase (Celluclast®), immobilized onto a polymeric support (Amberlite XAD4), was first studied in ten different ionic liquids (ILs) at 50 and 80 °C. Hydrophobic ILs clearly enhanced the enzyme thermal stability. Butyltrimethyl-ammonium bis(trifluoromethylsulfonyl)imide ([N1114][NTf2]) enhances half-life time of the immobilized enzyme at 50 °C up to 4 times, while [Bmim][Cl] behaved as a powerful enzyme deactivating agent. Thus, the stability of cellulase in hydrophobic IL/[Bmim][Cl] mixtures was greatly improved with respect to [Bmim][Cl] alone. A stabilized cellulase derivative obtained by coating immobilized enzyme particles with [N1114][NTf2], has been then successfully used for the saccharification of dissolved cellulose in [Bmim][Cl] (i.e. up to 50% hydrolysis in 24 h) at 50 °C and 1.5 w/v water content. [ABSTRACT FROM AUTHOR]

Continuous-flow rhodium-catalysed hydroformylation of long chain alkenes has been achieved with selectivities to the desired linear aldehyde of 92% and minimum rhodium loss, using a xantphos-derived ligand attached to an imidazolium salt in a supercritical fluid–ionic liquid system. The effect of oxygen in the system can be ameliorated to some extent by adding a simple sulfonated triphenylphosphine to the catalytic solution. [ABSTRACT FROM AUTHOR]

A water-stable ionic liquid, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, [C4mim][CF3SO3], is herein proposed to be used in the formation of aqueous biphasic systems (ABS) with a large range of mono- and disaccharides, as well as polyols. Binodal curves, tie-lines, and densities and viscosities of the co-existing aqueous phases, were determined for each ternary system. The proposed systems are low-viscous offering enhanced features over conventional polymer-based ABS. In addition, the partitioning of model biomolecules, such as l-tryptophan, caffeine, and β-carotene, was further investigated to ascertain the applicability of such ABS. These systems are particularly interesting in the recovery of bioactive products from natural sources, while the availability of carbon-based sources to cells constitutes a major advantage in separations from fermentative media. Moreover, the use of carbohydrates in ionic-liquid-based ABS constitutes a step forward along the biorefinery concept envisaging sustainable conversions of biomass into a broad spectrum of bio-based products. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass composite fibers (southern yellow pine and bagasse) were successfully prepared directly from the ionic liquid, 1-ethyl-3-methylimidazolium acetate ([C2mim]OAc) with a dry-jet wet spinning process using short dissolution times (10–30 min) and temperatures above the glass transition temperature of lignin. Fibers could not be spun at all from solutions of pine dissolved using previously reported dissolution methods (110 °C, 16 h), while bagasse fibers spun using the higher temperature/shorter time method were stronger than those obtained using the lower temperature/longer time method. [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]

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]

Imidazolium-based ionic liquids continue to attract interest in many areas of chemistry because of their low melting points, relatively low viscosities, ease of synthesis, and good stabilities against oxidative and reductive conditions. However, they are not totally inert under many conditions due to the intrinsic acidity of hydrogen at the C-2 position in the imidazolium cation. In this work, this intrinsic acidity was exploited in combination with an organic superbase for the capture of CO2under atmospheric pressure. During the absorption of CO2, the imidazolium-based ionic liquid containing an equimolar superbase reacted with CO2to form a liquid carboxylate salt so that the equimolar capture of CO2with respect to the base was achieved. The effects of ionic liquid structures, types of organic superbases, absorption times, and reaction temperatures on the capture of CO2were investigated. Our results show that this integrated ionic liquid–superbase system is capable of rapid and reversible capture of about 1 mol CO2per mole of ionic liquid. Furthermore, the captured CO2can be readily released by either heating or bubbling N2, and recycled with little loss of its capture capability. This efficient and reversible catch-and-release process using the weak acidity of the C-2 proton in nonvolatile imidazolium-based ionic liquids provides a good alternative to the current CO2capture methods that use volatile alkanols, amines, or water. [ABSTRACT FROM AUTHOR]

An efficient one pot, two-step process was developed for the preparation of 5-hydroxymethylfurfural (5-HMF) from inulin in ionic liquids under mild conditions. In the first step, the ionic liquid 1-butyl-3-methyl imidazolium hydrogen sulfate ([BMIM][HSO4]) was used as both solvent and catalyst for the rapid hydrolysis of inulin into fructose with 84% fructose yield in 5 min reaction time. In the second step, 1-butyl-3-methyl imidazolium chloride ([BMIM][Cl]) and a strong acidic cation exchange resin were added to the mixture to selectively convert fructose into 5-HMF, giving a 5-HMF yield of 82% in 65 min at 80 °C, which is the highest 5-HMF yield reported by thus far for an inulin feedstock. [ABSTRACT FROM AUTHOR]

The article discusses the application of Ionic liquids (ILs) based on imidazolium tetrafluoroborate in the removal of aromatic sulfur-containing compounds from hydrocarbon mixtures. It presents the value of distribution coefficients (D) for each IL that absorbs benzothiophene (BT) and dibenzothiophene (DBT). It adds that the electrochemical approach such as electrochemical oxidation or reduction can be used to purify the IL from BT and DBT.

Two protic alkylimidazolium polyoxometalates, together with two corresponding aprotic N-methyl-alkylimidazolium polyoxometalates were synthesized and characterized by the methods of NMR, IR and TGA etc. Then, these salts were employed as catalysts for the epoxidation of cyclooctene in different media. The novel protic N-dodecylimidazolium peroxotungstate [HDIm]2[{WO(O2)2}2(μ–O)] was found to be a room temperature liquid molten salt (ionic liquid) and the most effective catalyst for the epoxidation of cyclooctene among these salts. The ionic liquid catalyst [HDIm]2[{WO(O2)2}2(μ–O)] can also be extended to the epoxidation of some other substrates. On the basis of this experimental observation, an efficient reaction-induced phase-separation catalyst system has been developed in this work. The reaction system can switch from tri-phase to emulsion and then to biphase and finally to all the catalyst self-precipitating at the end of the reaction, which made the recovery and reuse of the present catalyst very convenient. [ABSTRACT FROM AUTHOR]

In continuation of our earlier investigations, this report presents a rationale behind the design of a series of imidazolium based ionic liquids and their biodegradation using the CO2headspace test (ISO 14593 method, OECD 310). The effect on biodegradability of these salts through variation of the N-substituted side chains of imidazolium ions was examined further through incorporation of various functional groups and increased alkyl chain lengths. A series of anions containing moieties known to be biodegradable were also incorporated into a number of imidazolium based salts and examined in a similar fashion. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) are being considered as a promising class of potentially environmentally-friendly (“green”) solvents and materials for use in a variety of applications. However, ionic liquids are conventionally synthesized by batch, without known kinetics, in non-sustainable solvents. For ILs to be a truly “green” technology for widespread use, they must themselves be made in a correspondingly benign manner for low cost, as enabled by process development. This investigation will illustrate the kinetics and large solvent effects in the synthesis of 1-hexyl-3-methyl-imidazolium bromide in 10 different solvents: acetone, acetonitrile, 2-butanone, chlorobenzene, dichloromethane, dimethyl sulfoxide (DMSO), ethyl formate, ethyl lactate, methanol, and cyclopentanone. The kinetic rate constant for the synthesis in DMSO is over an order-of-magnitude larger than that in methanol. While the kinetic rate of these type of SN2 reactions is generally known to increase with solvent “polarity”, multi-parameter solvent descriptors, e.g.of Kamlet and Taft, are required to quantify these effects in a Linear Solvation Energy Relationship. These relationships are used with environmental and toxicity databases, such as the Rowan Solvent Selection Table, to rapidly optimize the solvent for favorable kinetics and minimal human and environmental impact. [ABSTRACT FROM AUTHOR]

Microbial biofilms are ubiquitous in nature and represent the predominant mode of growth of microorganisms. A general characteristic of biofilm communities is that they tend to exhibit significant tolerance to antimicrobial challenge compared with planktonic bacteria of the same species The antibiofilm activity of a series of 1-alkyl-3-methylimidazolium chloride ionic liquids has been evaluated against a panel of clinically significant microbial pathogens, including MRSA. A comparison of antimicrobial activity against planktonic bacteria and established biofilms is presented. In general, these ionic liquids possess potent, broad spectrum antibiofilm activity. [ABSTRACT FROM AUTHOR]

A series of imidazolium ionic liquids was prepared and screened against 7 bacterial strains. The incorporation of ether groups into the ester side-chain significantly reduced the toxicity compared with alkyl ester derivatives. Biodegradation data are also presented for 15 of the ionic liquids—including 6 examples which can be classed as readily biodegradable. [ABSTRACT FROM AUTHOR]