Search Results

The work reports the synthesis under solvent-free condition using the ionic liquid [Et₃NH][HSO₄] as a catalyst of fifteen novel 3-((dicyclohexylamino)(substituted phenyl/heteryl)-methyl)-4-hydroxy-2H-chromen-2-onederivatives 4a–o as potential antimicrobial agents. The structures of the synthesized compounds were confirmed by IR, ¹H-NMR, ¹³C-NMR, mass spectral studies and elemental analyses. All the synthesized compounds were evaluated for their in vitro antifungal and antibacterial activity. The compound 4k bearing 4-hydroxy-3-ethoxy group on the phenyl ring was found to be the most active antifungal agent. The compound 4e bearing a 2,4-difluoro group on the phenyl ring was found to be the most active antibacterial agent. The mode of action of the most promising antifungal compound 4k was established by an ergosterol extraction and quantitation assay. From the assay it was found that 4k acts by inhibition of ergosterol biosynthesis in C. albicans. Molecular docking studies revealed a highly spontaneous binding ability of the tested compounds to the active site of lanosterol 14α-demethylase, which suggests that the tested compounds inhibit the synthesis of this enzyme. The synthesized compounds were analyzed for in silico ADMET properties to establish oral drug like behavior and showed satisfactory results. To establish the antimicrobial selectivity and safety, the most active compounds 4e and 4k were further tested for cytotoxicity against human cancer cell line HeLa and were found to be non-cytotoxic in nature. An in vivo acute oral toxicity study was also performed for the most active compounds 4e and 4k and results indicated that the compounds are non-toxic. Full article

To improve the reactivity of the soda lignin, an acid ionic liquid 1-butyl-3-mthylimidazolium chloride ([BMIM]Cl) was used as the catalyst and solvent to degrade the soda lignin through hydrogenolysis. Structural elucidation of the lignin samples was conducted by using a combination of analytical methods including chemical analysis, ultraviolet spectrophotometry (UV spectrophotometry), Fourier transform infrared spectroscopy (FT-IR spectra), two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance (2D-HSQC NMR) techniques, and gel permeation chromatography (GPC). The antioxidant activities of the lignin samples were evaluated using the diammonium 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS⁺) radical scavenging and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging methods. The degradation mechanism was proposed based on the characterization results. The optimal reaction condition was as follows: the concentration of [BMIM]Cl in the solution was 10 wt %, the hydrogen initial pressure was 3 MPa, and the solution was heated for 4 h at 90 °C. After the reaction, the total hydroxyl content of the soda lignin increased by 81.3%, while the phenolic hydroxyl content increased by 23.1%. At the same time, the weight-average molar mass of the soda lignin sample decreased from 8220 to 6450 g/mol with an improved antioxidant activity. In addition, approximately 56.7% of the β-O-4 linkages were degraded in the lreaction. The main effect of the acid ionic liquid [BMIM]C1 was related to the cleavage of β-O-4 linkages. This study has shown the potential of using the catalyzed soda lignin as a natural polymer antioxidant. Full article

Synthesis of indolyl 4H-chromenes via a three-component reaction catalyzed by lipase in ionic liquidsis reported here for the first time. High yields (77–98%) were obtained when Mucor miehei lipase was used as the catalyst in [EMIM][BF₄]. Furthermore, [EMIM][BF₄] exhibited good reusability in this enzymatic reaction. This study affords a new example of lipase catalytic promiscuity and broadens the application range of ionic liquid in biocatalysis. Full article

In this study, an efficient process for high value utilization of biodiesel-derived glycerol was proposed via a simple reaction of acetalization catalyzed by novel catalysts of ester sulfate-functionalized ionic liquids (ILs). The relationship between the IL structure and its catalytic activity was investigated. The effects of reaction conditions, and the substrate adaptability, were also carefully studied. The results demonstrate that ester sulfate-functionalized IL shows excellent catalytic activity on the acetalization of glycerol with aldehyde (ketone). Under the optimized condition, 87% glycerol conversion was obtained with 99% acetal selectivity when glycerol was condensed with cyclohexanone. In particular, 29% of product consists of six-membered compound, an important fine chemical and an excellent precursor in organic chemistry, because of the significant steric-hindrance effect of IL catalyst. Furthermore, the IL catalyst shows good recyclability where insignificant activity loss was exhibited even after six runs. Full article

Homogeneous modification of cellulose with succinic anhydride was performed using tetrabutylammonium acetate (TBAA)/dimethyl sulfoxide (DMSO) mixed solvent. The molar ratio of succinic anhydride (SA) to free hydroxyl groups in the anhydroglucose units (AGU), TBAA dosage, reaction temperature, and reaction time were investigated. The highest degree of substitution (DS) value of 1.191 was obtained in a 10 wt% TBAA/DMSO mixed solvent at 60 °C for 60 min, and the molar ratio of SA/AGU was 6/1. The molar ratio of SA/AGU and the TBAA dosage showed a significant influence on the reaction. The succinoylated cellulose was characterized by ATR-FTIR, TGA, XRD, solid state CP/MAS ¹³C NMR spectroscopy (CP/MAS ¹³C NMR), and SEM. Moreover, the modified cellulose was applied for the adsorption of Cu²⁺ and Cd²⁺, and both the DS values of modified cellulose and pH of the heavy metal ion solutions affected the adsorption capacity of succinylated cellulose. The highest capacity for Cu²⁺ and Cd²⁺ adsorption was 42.05 mg/g and 49.0 mg/g, respectively. Full article

A facile, green, and efficient method for the direct oxidative amination of benzoxazoles using heterocyclic ionic liquid as catalyst has been developed. The reaction proceeded smoothly at room temperature and gave the desirable 2-aminobenzoxazoles with good to excellent yields (up to 97%). The catalyst 1-butylpyridinium iodide can be easily recycled and reused with similar efficacies for at least four cycles. Full article

It is widely believed that lipases in ionic liquids (ILs) possess higher enzyme activity, stability and selectivity; however, reaction equilibrium is always limited by product inhibition, and the product is difficult to separate from non-volatile ILs using distillation. To solve this problem, using trialkylphosphine oxide (TOPO) as a complexing agent, a novel biphase of reactive solvent and IL was firstly reported for caffeic acid phenethyl ester (CAPE) production from methyl caffeate (MC) and 2-phenylethanol (PE) catalyzed by lipase via transesterification. The effects of the reaction parameters and their action mechanism were investigated, and the inhibition of CAPE against bacterial wilt pathogen Ralstonia solanacearum was firstly measured. The MC conversion of 98.83% ± 0.76% and CAPE yield of 96.29% ± 0.07% were obtained by response surface methodology in the 25 g/L TOPO-cyclohexane/[Bmim][Tf₂N] (1:1, v/v); the complex stoichiometry calculation and FTIR spectrum confirmed that the reversible hydrogen-bond complexation between TOPO and caffeates significantly enhances the cooperative effect of two phases on the lipase-catalyzed reaction. The temperature was reduced by 14 °C; the MC concentration increased by 3.33-fold; the ratio of catalyst to donor decreased by 4.5-fold; and Km decreased 1.08-fold. The EC₅₀ of CAPE against R. solanacearum was 0.17–0.75 mg/mL, suggesting that CAPE is a potential in vitro inhibitor of plant pathogenic bacteria. Full article

Cellulose is the single largest component of lignocellulosic biomass and is an attractive feedstock for a wide variety of renewable platform chemicals and biofuels, providing an alternative to petrochemicals and petrofuels. This potential is currently limited by the existing methods of transforming this poorly soluble polymer into useful chemical building blocks, such as 5-hydroxymethylfurfural (HMF). Ionic liquids have been used successfully to separate cellulose from the other components of lignocellulosic biomass and so the use of the same medium for the challenging transformation of cellulose into HMF would be highly attractive for the development of the biorefinery concept. In this report, ionic liquids based on 1-butyl-3-methylimidazolium cations [C₄C₁im]⁺ with Lewis basic (X = Cl⁻) and Brønsted acidic (X = HSO₄⁻) anions were used to investigate the direct catalytic transformation of cellulose to HMF. Variables probed included the composition of the ionic liquid medium, the metal catalyst, and the reaction conditions (temperature, substrate concentration). Lowering the cellulose loading and optimising the temperature achieved a 58% HMF yield after only one hour at 150 °C using a 7 mol % loading of the CrCl₃ catalyst. This compares favourably with current literature procedures requiring much longer reactions times or approaches that are difficult to scale such as microwave irradiation. Full article

The hydrogenation activity of new N-acyl-benzotriazole Rh(I) and Ru(III) complexes in ionic liquid media is reported in this study. Both complexes were completely soluble in 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF₄], and they were able to catalyze the hydrogenation of styrene and 1-octene. While ethylbenzene conversion in styrene hydrogenation reached 84% when the Ru complex was used, 100% conversion was obtained with the Rh complex at 393 K in 6 h. Additionally, total conversion in 1-octene hydrogenation reached 100% with the Rh complex in [bmim][BF₄] media. The hydrogenation of styrene and 1-octene in dimethyl sulfoxide (DMSO) and toluene was also studied to compare the solvent effect on catalytic system. The effect of some catalytic parameters such as temperature, H₂ (g) pressure, and catalyst amount on the conversion was examined, and it was found that the conversion increased parallel to the increasing temperature and H₂ pressure. The recyclability of catalysts was also investigated, and it was revealed that the Rh complex in particular maintained the activity for at least 10 cycles. Full article

A group of imidazolium and pyridinium based ionic liquids has been synthetized, and their ability to dissolve and activate the catalysts used in hydrosilylation reaction of 1-octane and 1,1,1,3,5,5,5-heptamethyltrisiloxane was investigated. An organometallic catalyst as well as inorganic complexes of platinum and rhodium dissolved in ionic liquids were used, forming liquid solutions not miscible with the substrates or with the products of the reaction. The results show that application of such a simple biphasic catalytic system enables reuse of ionic liquid phase with catalysts in multiple reaction cycles reducing the costs and decreasing the amount of catalyst needed per mole of product. Full article

A convenient carbonylative approach to 2-oxazolidinone derivatives carried out using an ionic liquid (1-ethyl-3-methylimidazolium ethyl sulfate, EmimEtSO₄) as the solvent is presented. It is based on the sequential concatenation of two catalytic cycles, both catalyzed by the same metal species (auto-tandem catalysis): the first cycle corresponds to the oxidative monoaminocarbonylation of the triple bond of propargylic amines to give the corresponding 2-ynamide intermediates, while the second one involves the cyclocarbonylation of the latter to yield 2-(2-oxooxazolidin-5-ylidene)-acetamides. Reactions are carried out using a simple catalytic system consisting of PdI₂ in conjunction with an excess of KI, and the catalyst/solvent system could be recycled several times without appreciable loss of activity after extraction of the organic product with Et₂O. Full article

Cellulose nanocrystals (CNCs) are valuable nanomaterials obtained from renewable resources. Their properties make them suitable for a wide range of applications, including polymer reinforcement. However, due to their highly hydrophilic character, it is necessary to modify their surface with non-polar functional groups before their incorporation into a hydrophobic polymer matrix. In this work, cellulose nanocrystals were modified using a silane coupling agent and choline lactate, an ionic liquid derived from renewable resources, as a reaction medium. Modified cellulose nanocrystals were characterized by infrared spectroscopy, showing new peaks associated to the modification performed. X-ray diffraction was used to analyze the crystalline structure of functionalized cellulose nanocrystals and to optimize the amount of silane for functionalization. Poly(lactic acid) (PLA) nanocomposites containing 1 wt % of functionalized cellulose nanocrystals were prepared. They were characterized by field-emission scanning electron microscopy (FE-SEM) and mechanical tests. The use of choline lactate as reaction media has been shown to be an alternative method for the dispersion and silanization of the cellulose nanocrystals without the addition of an external catalyst. Full article

Ruthenium and molybdenum catalysts are widely used in synthesis of both small molecules and macromolecules. While major developments have led to new increasingly active catalysts that have high functional group compatibility and stereoselectivity, catalyst/product separation, catalyst recycling, and/or catalyst residue/product separation remain an issue in some applications of these catalysts. This review highlights some of the history of efforts to address these problems, first discussing the problem in the context of reactions like ring-closing metathesis and cross metathesis catalysis used in the synthesis of low molecular weight compounds. It then discusses in more detail progress in dealing with these issues in ring opening metathesis polymerization chemistry. Such approaches depend on a biphasic solid/liquid or liquid separation and can use either always biphasic or sometimes biphasic systems and approaches to this problem using insoluble inorganic supports, insoluble crosslinked polymeric organic supports, soluble polymeric supports, ionic liquids and fluorous phases are discussed. Full article

An efficient synthesis of novel 3,4-dihydropyrimidin-2(1H)-ones (DHPMs) and their derivatives, using Brønsted acidic ionic liquid [C₂O₂BBTA][TFA] as a catalyst, from the condensation of aryl aldehyde, β-ketoester and urea was described. Reactions proceeded smoothly for 40 min under solvent-free conditions and gave the desirable products with good to excellent yields (up to 99%). The catalyst could be easily recycled and reused with similar efficacies for at least six cycles. Full article

As alternative lubricant anti‐wear additives are sought to reduce friction and improve overall fuel economy, it is important that these additives are also compatible with current emissions control catalysts. In the present work, an oil‐miscible phosphorous‐containing ionic liquid (IL), trihexyltetradecylphosphonium bis(2‐ethylhexyl) phosphate ([P₆₆₆₁₄][DEHP]), is evaluated for its impact on three‐way catalysts (TWC) and benchmarked against the industry standard zinc‐dialkyl‐dithio‐phosphate (ZDDP). The TWCs are aged in different scenarios: neat gasoline (no‐additive, or NA), gasoline+ZDDP, and gasoline+IL. The aged samples, along with the as‐received TWC, are characterized through various analytical techniques including catalyst reactivity evaluation in a bench‐flow reactor. The temperatures of 50% conversion (T50) for the ZDDP‐aged TWCs increased by 30, 24, and 25 °C for NO, CO, and C3H6, respectively, compared to the no‐additive case. Although the IL‐aged TWC also increased in T50 for CO and C3H6, it was notably less than ZDDP, 7 and 9 °C, respectively. Additionally, the IL‐aged samples had higher water‐gas‐shift reactivity and oxygen storage capacity than the ZDDP‐aged TWC. Characterization of the aged samples indicated the predominant presence of CePO₄ in the ZDDP‐aged TWC aged by ZDDP, while its formation was retarded in the case of IL where higher levels of AlPO₄ is observed. Thus, results in this work indicate that the phosphonium‐phosphate IL potentially has less adverse impact on TWC than ZDDP. Full article

The effect of acidic ionic liquid (IL) as a new catalyst on the properties of wood-based panels bonded with urea-glyoxal (UG) resins was investigated. Different levels of N-methyl-2-pyrrolidone hydrogen sulfate ([HNMP] HSO₄ (0, 1, 2, 3 wt %)) were added to prepared UG resin. The resin was then used for preparing laboratory particleboard panels. Then, the properties of the prepared panels were evaluated. The structure of the prepared UG resin was studied by ¹³C NMR, and thermal curing behavior of the resin before and after the addition of IL was measured by DSC. Additionally, the main oligomers formed in the UG reaction were identified by matrix-assisted laser desorption/ionization time-of-flight (MALDI TOF) mass spectroscopy. The results indicated that IL can be used as an efficient catalyst for UG resin. The physicochemical tests indicated that the addition of [HNMP] HSO₄ from 0 to 3 wt % decreased the pH value of the glue-mix, and the pH decreased on curing to the same level as urea-formaldehyde resins. The gel accelerated with increasing catalyst content and with the decreasing of the pH in the UG resin. The panels prepared with IL had higher mechanical strength and dimensional stability compared to those made from UG resins containing NH₄Cl. Scanning electron microscope (SEM) micrographs showed that the panels prepared with ionic liquid presented low porous. DSC analysis showed that the addition of IL to the UG resin decrease the energy of activation of the curing reaction to render possible cross-linking. The MALDI TOF results indicated a preponderant linearity of the oligomers formed, implying a high energy of activation of curing for UG resins. Full article

An inorganic-organic porous silica network catalyst was prepared by linking silica nanoparticles using ionic liquid and followed by anion-exchange with phosphotungstate. Characterization methods of FT-IR, TG, SEM, TEM, BET, etc., were carried out to have a comprehensive insight into the catalyst. The catalyst was used for catalyzing cyclooctene epoxidation with high surface area, high catalytic activity, and convenient recovery. The conversion and selectivity of epoxy-cyclooctene could both reach over 99% at 70 °C for 8 h using hydrogen peroxide (H₂O₂) as an oxidant, and acetonitrile as a solvent when the catalyst was 10 wt. % of cyclooctene. Full article

Ionic liquids (ILs) are a convenient and inexpensive source of N-heterocyclic carbenes (NHCs). In this study, dialkyl imidazolium-based ILs are used as carbene precursors in a four-component synthesis of oxo triphenylhexanoates (OTHOs), where it was found that IL outperformed commonly used NHC precatalysts in terms of reaction efficiency. The reaction is highly stereoselective, delivering the anti-diastereomer (20:1 dr), and the OTHOs can be obtained in high-to-excellent yields. By virtue of the four-component reaction-setup, facile construction of the OTHO scaffold with a diverse set of functional groups (21 examples) can be achieved. In the context of sustainability, the IL can be recovered and reused several times without affecting selectivity or yield. Moreover, most compounds can be isolated by precipitation and filtration, mitigating the use of solvent-demanding chromatography. Full article

A fast and green method is developed for regioselective acylation of indoles in the 3-position without the need for protection of the NH position. The method is based on Friedel-Crafts acylation using acid anhydrides. The method has been optimized, and Y(OTf)₃ in catalytic amounts is found to be the best catalyst together with the commercially available ionic liquid [BMI]BF₄ (1-butyl-3-methylimidazolium tetrafluoro-borate) as solvent. The reaction is completed in a very short time using monomode microwave irradiation. The catalyst can be reused up to four times without significant loss of activity. A range of substituted indoles are investigated as substrates, and thirteen new compounds have been synthesized. Full article

A novel and green approach for efficient and rapid synthesis of 4-aryl-3-methyl-1-phenyl-1H-benzo[h]pyrazolo[3,4-b]quinoline-5,10-diones has been accomplished by the one-pot condensation reaction of aromatic aldehydes, 3-methyl-1-phenyl-1H-pyrazol-5-amine and 2-hydroxynaphthalene-1,4-dione using PEG₁₀₀₀-based dicationic acidic ionic liquid (PEG₁₀₀₀-DAIL) as a catalyst was reported. Recycling studies have shown that the PEG₁₀₀₀-DAIL can be readily recovered and reused several times without significant loss of activity. The key advantages are the short reaction time, high yields, simple workup, and recovered catalyst. Full article

The amidine organocatalyst 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) is an effective nucleophilic catalyst. Biocomposites with tuneable properties were successfully synthesized by ring-opening graft polymerization (ROGP) of propylene carbonate (PC) onto xylan using DBU as a catalyst in the ionic liquid (IL) 1-allyl-3-methylimidazolium chloride ([Amim]Cl). The effects of reaction temperature, reaction time and the molar ratio of PC to anhydroxylose units (AXU) in xylan were investigated. The physico-chemical properties of xylan-graft-poly(propylene carbonate) (xylan-g-PPC) copolymers were characterised by FT-IR, NMR, TGA/DTG, AFM and tensile analysis. The FT-IR and NMR results indicated the successful attachment of PPC onto xylan. TGA/DTG suggested the increased thermal stability of xylan after the attachment of PPC side chains. AFM analysis revealed details about the molecular aggregation of xylan-g-PPC films. The results also showed that with the increased DS of xylan-g-PPC copolymers, the tensile strength and Young’s modulus of the films decreased, while the elongation at break increased. Full article

There is increasing interest in the upgrading of C₅ furfural (FF) and C₆ 5-hydroxymethyl furfural (HMF) into C₁₀ and C₁₂ furoins as higher energy-density intermediates for renewable chemicals, materials, and biofuels. This work utilizes the organocatalytic approach, using the in situ generated N,S-heterocyclic carbene catalyst derived from thiazolium ionic liquids (ILs), to achieve highly efficient self-coupling reactions of FF and HMF. Specifically, variations of the thiazolium IL structure have led to the most active and efficient catalyst system of the current series, which is derived from a new thiazolium IL carrying the electron-donating acetate group at the 5-ring position. For FF coupling by this IL (0.1 mol %, 60 °C, 1 h), when combined with Et₃N, furoin was obtained in >99% yield. A 97% yield of the C₁₂ furoin was also achieved from the HMF coupling by this catalyst system (10 mol % loading, 120 °C, 3 h). On the other hand, the thiazolium IL bearing the electron-withdrawing group at the 5-ring position is the least active and efficient catalyst. The mechanistic aspects of the coupling reaction by the thiazolium catalyst system have also been examined and a mechanism has been proposed. Full article

We report here an efficient and green method for Biginelli condensation reaction of aldehydes, β-ketoesters and urea or thiourea catalyzed by Brønsted acidic ionic liquid [Btto][p-TSA] under solvent-free conditions. Compared to the classical Biginelli reaction conditions, the present method has the advantages of giving good yields, short reaction times, near room temperature conditions and the avoidance of the use of organic solvents and metal catalyst. Full article

A morpholine alkaline basic ionic liquid (IL) 1-butyl-3-methyl morpholine hydroxide ([Hnmm]OH) was synthesized and characterized by ¹H NMR and FT-IR. [Hnmm]OH is highly active in catalyzing the synthesis of biodiesel from the reaction of methanol with soybean oil. The influence of the reaction conditions, including the [Hnmm]OH catalyst amount, the molar ratio of methanol to soybean oil, reaction temperature and time, was investigated. Moreover, the pH and thermal stability of the catalyst was studied. The catalytic activity was affected by its alkalinity. The optimum reaction conditions were found as [Hnmm]OH amount of 4% (mass fraction), the methanol to soybean oil molar ratio of 8, temperature 70 °C and reaction time 1.5 h, the yield of Biodiesel reached 97.0%, and exhibits high stability upon recycling, the yield of Biodiesel is still more than 90% even after being reused for five times. A great advantage of using ILs is that it is very easy to separate the final products. After the reaction, a biphasic system was obtained. The top phase contains biodiesel and a little bit of methanol. Pure biodiesel can be isolated by vacuum evacuating the methanol. The bottom phase contains methanol, glycerol and ILs. Pure glycerol can be obtained simply by distillation. After distillation, pure ILs was obtained, which can be used directly for another reaction. The as prepared biodiesel shows very appealing properties. Full article

Catalysts obtained by the immobilisation of acidic ionic liquids (ILs) on solid supports offer several advantages compared to the use of catalytically active ILs themselves. Immobilisation may result in an increase in the number of accessible active sites of the catalyst and a reduction of the amount of the IL required. The ionic liquid films on the carrier surfaces provide a homogeneous environment for catalytic reactions but the catalyst appears macroscopically as a dry solid, so it can simply be separated from the reaction mixture. As another advantage, it can easily be applied in a continuous fixed bed reactor. In the present review the main synthetic strategies towards the preparation of supported Lewis acidic and Brønsted acidic ILs are summarised. The most important characterisation methods and structural features of the supported ionic liquids are presented. Their efficiency in catalytic reactions is discussed with special emphasis on their recyclability. Full article

Quaternary ammonium geminal Brønsted acid ionic liquids (GBAILs) based on zwitterionic 1,2-bis[N-methyl-N-(3-sulfopropyl)-alkylammonium]ethane (where the carbon number of the alkyl chain is 4, 8, 10, 12, 14, 16, or 18) and p-toluenesulfonic acid monohydrate were synthesized. The catalytic ionic liquids were applied in three-component Mannich reactions with an aldehyde, ketone, and amine at 25 °C in water. The effects of the type and amount of catalyst and reaction time as well as the scope of the reaction were investigated. Results showed that GBAIL-C₁₄ has excellent catalytic activity and fair reusability. The catalytic procedure was simple, and the catalyst could be recycled seven times via a simple separation process without noticeable decreases in catalytic activity. Full article

A mild, efficient, and environmentally benign protocol for the synthesis of tetrahydrobenzo[b]pyran derivatives in the presence of readily accessible, biodegradable, and choline hydroxide based ionic liquid as catalyst has been established. The key features of the reported methodology include good to excellent yields of desired products, simple work-up procedure and good recyclability of catalysts, which may be a practical alternative to the existing conventional processes for the preparation of 4-H pyrans to cater to the requirements of academia as well as industry. Full article

Poly(ethlyene terephthalate) waste from a local market was depolymerized by ethylene glycol (EG) in the presence of Lewis acidic ionic liquids [Bmim]ZnCl₃ and the qualitative analysis showed that bis(hydroxyethyl) terephthalate was the main product. Compared with ionic liquid [Bmim]Cl, the Lewis acidic ionic liquids showed highly catalytic activity in the glycolysis of poly(ethylene terephthalate) PET. Significantly, the conversion of PET and the yield of bis(hydroxyethyl) terephthalate were achieved at 100% and 83.8% with low catalyst ([Bmim]ZnCl₃) loading (0.16 wt %). Investigation also showed that the catalytic activity of [Bmim]ZnCl₃ was higher than that of [Bmim]MnCl₃. Catalyst [Bmim]ZnCl₃ can be reused up to five times and ¹H-NMR results show that the recovered catalyst is similar to the fresh one. A mechanism of the glycolysis of PET catalyzed by [Bmim]ZnCl₃ was proposed. Full article

In this study, various types of ionic liquids (ILs) were examined for catalytic activity in the pyrolysis of cellulose for the production of levoglucosenone, which is a valuable and versatile compound for the synthesis of a variety of novel compounds. Cellulose was simply mixed with the ILs and subjected for the pyrolysis, typically at 300 °C, to produce volatile products, including levoglucosenone, separated from the ILs phase. The type of IL anion significantly affected the catalysis, and the use of ILs bearing sulfonate anion resulted in distinguished yields of levoglucosenone and IL recoveries for the reutilization. Detailed thermogravimetric analysis and discussion on properties of ILs revealed the active and thermally stable nature of the sulfonate ILs. Catalytic pyrolysis with those ILs was applied to the conversion of other saccharides composed of glucose molecules, resulting in a preferential formation of levoglucosenone but at low yields as compared to that from cellulose. Full article

The ionic liquid 1-butyl-3-methylimidazolium methylselenite, [bmim][SeO₂(OCH₃)], was successfully used as solvent in the catalyst-free preparation of 3-arylselenylindoles by the reaction of indole with ArSeCl at room temperature. The products were obtained selectively in good yields without the need of any additive and the solvent was easily reused for several cycles with good results. Full article

The Brønsted-acidic ionic liquid 1-methyl-3-(4-sulfobutyl)imidazolium triflate [BMIM(SO₃H)][OTf] was demonstrated to act efficiently as solvent and catalyst for the halogenation of activated organic compounds with N-halosuccinimides (NXS) under mild conditions with short reaction times. Methyl aryl ketones were converted into α-halo and α,α-dihaloketones, depending on the quantity of NXS used. Ketones with activated aromatic rings were selectively halogenated, however in some cases mixtures of α-halogenated ketone and ring-halogenated ketones were obtained. Activated aromatics were regioselectively ring halogenated to give mono- and dihalo-substituted products. The [BMIM(SO₃H)][OTf] ionic liquid (IL-A) was successfully reused eight times in a representative monohalogenation reaction with no noticeable decrease in efficiency. An effective halogenation scale-up in this IL is also presented. The reactivity trend and the observed chemo- and regioselectiivities point to an ET process in these IL-promoted halofunctionalization reactions. Full article

In this research we have fabricated and tested Au/Dy₂O₃ composites for applications as Solid Oxide Fuel Cell (SOFC) electrocatalysts. The material was obtained by a process involving electrodeposition of a Au-Dy alloy from a urea/choline chloride ionic liquid electrolyte, followed by selective oxidation of Dy to Dy₂O₃ in air at high temperature. The electrochemical kinetics of the electrodeposition bath were studied by cyclic voltammetry, whence optimal electrodeposition conditions were identified. The heat-treated material was characterised from the morphological (scanning electron microscopy), compositional (X-ray fluorescence spectroscopy) and structural (X-ray diffractometry) points of view. The electrocatalytic activity towards H₂ oxidation and O₂ reduction was tested at 650 °C by electrochemical impedance spectrometry. Our composite electrodes exhibit an anodic activity that compares favourably with the only literature result available at the time of this writing for Dy₂O₃ and an even better cathodic performance. Full article

In the highly competitive market of fuel cells, solid alkaline fuel cells using liquid fuel (such as cheap, non-toxic and non-valorized glycerol) and not requiring noble metal as catalyst seem quite promising. One of the main hurdles for emergence of such a technology is the development of a hydroxide-conducting membrane characterized by both high conductivity and low fuel permeability. Plasma treatments can enable to positively tune the main fuel cell membrane requirements. In this work, commercial ADP-Morgane^® fluorinated polymer membranes and a new brand of cross-linked poly(aryl-ether) polymer membranes, named AMELI-32^®, both containing quaternary ammonium functionalities, have been modified by argon plasma treatment or triallylamine-based plasma deposit. Under the concomitant etching/cross-linking/oxidation effects inherent to the plasma modification, transport properties (ionic exchange capacity, water uptake, ionic conductivity and fuel retention) of membranes have been improved. Consequently, using plasma modified ADP-Morgane^® membrane as electrolyte in a solid alkaline fuel cell operating with glycerol as fuel has allowed increasing the maximum power density by a factor 3 when compared to the untreated membrane. Full article

The Brönsted acidic ionic-liquid [HO₃S(CH₂)₄mim] HSO₄, a novel dual catalyst–solvent, has been successfully applied in simultaneous microwave-assisted extraction and hydrolysis for the determination of flavonol glycosides in Ginkgo foliage. The parameters, namely the [HO₃S(CH₂)₄mim]HSO₄ concentration, microwave-irradiation power, microwave-irradiation time, and solid–liquid ratio, were optimized. The optimum conditions were: an amount of 1.5 M [HO₃S(CH₂)₄mim]HSO₄, a microwave-irradiation power of 120 W, an irradiation time of 15 min, and a solid–liquid ratio of 1:30 g/mL. Compared with traditional methods the proposed approach demonstrates higher efficiency in a shorter operating time, and is an efficient, rapid, and simple sample preparation method. Full article

The synthesis of magnetically separable quasi-homogeneous base catalyst and heterogeneous base catalyst is described. The quasi-homogeneous catalyst is achieved by supporting silane monomers functionalized with different amine groups directly on the surface of magnetite nanoparticles. The heterogeneous catalyst is prepared via a sol-gel process in which silane monomers containing different amine groups are copolymerized with tetraethoxysilane in the presence of magnetite nanoparticles functionalized with ionic liquid moieties. The reactivity of the quasi-homogeneous and the heterogeneous base catalysts is compared in the nitroaldol condensation. Full article

The present study tries to give an insight to the combination of the homogeneous and heterogeneous catalytic properties in a new class of materials. Well dispersed gold nanoparticles on an ionic liquid layer supported on a mineral carrier have been prepared. This work is concentrated on the characterizations and understanding of the interactions between all the components of the catalytic system. The application of the materials in the reaction of oxidation of carbon monoxide shows rather unexpected results—a good catalytic activity completely independent of the temperature. Full article

Ionic liquid with both Lewis and Brønsted acid sites has been synthesized and its catalytic activities for Michael addition were carefully studied. The novel ionic liquid was stable to water and could be used in aqueous solution. The molar ratio of the Lewis and Brønsted acid sites could be adjusted to match different reactions. The results showed that the novel ionic liquid was very efficient for Michael addition with good to excellent yields within several min. Operational simplicity, high stability to water and air, small amount used, low cost of the catalyst used, high yields, chemoselectivity, applicability to large-scale reactions and reusability are the key features of this methodology, which indicated that this novel ionic liquid also holds great potential for environmentally friendly processes. Full article

The ionic liquid 1,3-dimethylimidazolium methyl sulfate, [MMIm][MSO₄], together with a small amount of water (the amount taken up by the ionic liquid upon exposure to air), acts efficiently as both solvent and catalyst of the Knoevenagel condensation reactions of malononitrile with 4-substituted benzaldehydes, without the need for any other solvent or promoter, affording yields of 92%–99% within 2–7 min at room temperature. When L-proline is used as an additional promoter to obtain coumarins from o-hydroxybenzaldehydes, the reaction also proceeds in high yields. Work-up is very simple and the ionic liquid can be reused several times. Some of the coumarins obtained are described for the first time. Full article

An efficient synthesis of novel 1-aryl-3-(indole-3-yl)-3-(2-aryl-1,2,3-triazol-4-yl)propan-1-ones from indoles and 1-aryl-3-(2-aryl-1,2,3-triazol-4-yl)propan-1-one using a Brønsted acid ionic liquid [Sbmim][HSO₄] as catalyst is described. Satisfactory results with excellent yields and short reaction time were obtained in the experiments. The catalyst could be recovered conveniently and reused efficiently. Full article

Ruthenium(III) chloride-catalyzed acylation of a variety of alcohols, phenols, and thiols was achieved in high yields under mild conditions (room temperature) in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF₆]). The ionic liquid and ruthenium catalyst can be recycled at least 10 times. Our system not only solves the basic problem of ruthenium catalyst reuse, but also avoids the use of volatile acetonitrile as solvent. Full article

The Brønsted acid ionic liquid [PyN(CH₂)₄SO₃H][p-CH₃PhSO₃] has been reported as an efficient catalyst for the Michael addition reaction of indoles to α,β-unsaturated ketones. Satisfactory results were obtained, with excellent yields and a simple experimental procedure. The catalyst could be recycled and reused up to three times without any noticeable decrease in the catalytic activity. Full article

At elevated temperatures, the ionic liquid precursor (ILP) tetrabutylammonium hydroxide reacts with zinc acetate and the glass wall of the reaction vessel. While the reaction of OH^- with the glass wall is not surprising as such and could be considered a failed experiment, the resulting materials are interesting for a variety of applications. If done on purpose and under controlled conditions, the reaction with the glass wall results in uniform, well-defined hemimorphite Zn₄Si₂O₇(OH)₂·nH₂O and willemite Zn₂SiO₄ microcrystals and films. Their morphology can be adjusted by variation of the reaction time and reaction temperature. The hemimorphite can be transformed to Zn₂SiO₄ via calcination. The process is therefore a viable approach for the fabrication of porous films on glass surfaces with potential applications as catalyst support, among others. Full article

Several ionic liquids were applied as catalysts for the synthesis of cyclicurethanes from amino alcohols and pressurized CO2 in the presence of alkali metalcompounds as promoters. A comparative study was made for the catalytic performanceusing different ionic liquids, substrates, promoters, and pressures. The optimum catalyticsystem was BMIM-Br promoted by K₂CO₃, which, for 1-amino-2-propanol, produced cyclicurethane in 40% yield with a smaller yield of substituted cyclic urea and no oligomericbyproducts. For other amino alcohols, cyclic urethanes, cyclic ureas, and/or undesiredbyproducts were produced in different yields depending on the substrates used. Possiblereaction mechanisms are proposed. Full article

In this paper we report examples of the Heck reaction in the new moisture stable ambient temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF₆). We have found that the yield of product is comparable with Heck reactions carried out in DMF, the conventional solvent for this reaction, and that the ionic liquid/catalyst mixture can be recycled several times. Full article