Hydroxide Ionic Liquid Research Articles

Sustainable Synthesis of D‐Glucose Based IL: A Renewable Organo Catalyst for the Efficient Synthesis of Dihydropyrano Coumarins

A convenient, direct, one‐pot highly efficient microwave‐assisted synthesis of biomass‐derived D‐glucose‐based hydroxide ionic liquid via a simple three‐step approach has been described. The key features of the method include rapidness, eco‐friendliness, and excellent yields. To the best of our knowledge, this is the first methodology for synthesizing D‐Glucose‐based sugar ionic liquid (GSIL) under microwave irradiation. The developed catalyst allowed us to synthesize diverse dihydropyrano[3,2‐c]‐chromenes upto 95% yield in 30‐90 min stirring at 80 ̊C under mild conditions. The scope of the study was investigated using 30 instances. Developed GSILs exhibited excellent catalytic activity as well as good recyclability. Overall, the catalyst showed excellent value in green chemistry parameters such as atom economy (95%), E‐factor (0.05), carbon efficiency (100%), process mass intensity (1.62), and reaction mass efficiency (0.860).

Synthesis, anti-microbial, and docking studies of functionalized chromenyl phosphonates using ionic liquid catalyst.

Synthesis of functionalized chromenyl phosphonates by the reaction among 2-hydorxybenzaldehydes, dicyanoethane, and dialkyl phosphonates that was promoted by choline hydroxide ionic liquid catalyzes the simultaneous, Knoevenagel, Pinner, and phospha-Michael reactions, under neat condition at room temperature. Important phosphorus-containing compounds can be produced at a reasonable cost because of the mild reaction conditions and the inexpensive promoter choline hydroxide. Furthermore, the desired products can be obtained without the need for any extraction or chromatography steps. An alternate technique for the simple and high-yield synthesis of functionalized chromenyl phosphonates is offered by this protocol. The synthesized compounds were studied by anti-microbial activity and docking studies. The title compounds molecular docking investigations demonstrated their efficacy as therapeutic agents against DNA Gyrase B and Aspergillus niger endoglucanase in both antibacterial and antifungal inhibition, and they identified compounds 4a, 4d, 4l, 4p, and 4q as promising candidates for microbial treatment, with binding affinities ranging from -6.9 to -7.4kcal/mol.

Tetrabutylammonium hydroxide (TBAH) ionic liquid for the sustainable and efficient production of α-hydroxyphosphonates

Ionic liquids were known as eco-solvents/catalysts, encourages the clean hydrophosphonylation of aldehydes to produce structurally various α-hydroxyphosphonates in a well-organized and ecologically friendly manner. This study used tetrabutylammonium hydroxide (TBAH) used to addition phosphite nucleophiles to aldehydes under neat condition, resulting in different α-hydroxyphosphonates that are essential components of the modern chemical industry. The current method produces targeted compounds from a wide range of aromatic, and heteroaromatic aldehydes with various substitution. The current protocol has high impact because it allows for the formation of desired products in good yields. This catalyst is applicable for gram scale synthesis of the targeted product and without any additional energy (Microwave, ultrasonication, ball milling and thermal heating). Some reported methods used various external sources (mechano-chemical) for the synthesis of α-hydroxyphosphonates.

Eco-friendly, Fact and Green Synthesis of Methanobenzo[d]naphtho[1,2- g][1,3]Oxazocines using 1-Butyl-3-methylimidazolium Hydroxide under Solvent-free Ball Milling

Abstract: A green, solvent-free, and efficient strategy for the assembly of methanobenzo[ d]naphtho[1,2-g][1,3]oxazocine heterocycles using 1‑butyl‑3‑methylimidazolium hydroxide ([bmim]OH) ionic liquid under ball-milling solvent-free condition has been developed. For this purpose, the synthesis of methanobenzo[d]naphtho[1,2-g][1,3]oxazocine derivatives was carried out in a single step and one-pot reaction using 2-naphthol and quinolinium salts with the catalyst, 1‑butyl‑3‑ methylimidazolium hydroxide ([bmim]OH), at room temperature. This protocol's specific advantages are environmentally benign media, high yield, easy purification and short experimental time.

Synthesis of carboxymethylcellulose from corn straw waste: comparison between pre-treatments with sodium hydroxide and low-cost ionic liquid

Synthesis of carboxymethylcellulose from corn straw waste: comparison between pre-treatments with sodium hydroxide and low-cost ionic liquid

Pretreatment of corn cobs and corn stalks with tetrabutyl phosphate hydroxide ionic liquid to enhance enzymatic hydrolysis process

The abundant lignocellulosic biomass used to produce biofuels was considered the most promising alternative to fossil fuels. In view of this, many studies directly use ionic liquids (ILs) to pretreat lignocellulose for subsequent fermentation. Herein, the strong proton acceptor tetrabutyl phosphorus hydroxide (TBPH) aqueous solution was employed to pretreat corn cobs and corn stalks. The effects of pretreatment time (0.5–2 h), temperature (20–80 ℃), TBPH aqueous solution concentration (10–40 wt%) and liquid to solid ratio (4 wt/wt-9 wt/wt) on the components and sugar yield were investigated. For the pretreatment of corn cob and corn stalk, the sugar yield was 90.75% and 80.84%, which were about 4 and 4.6 folds of the raw materials (unpretreated corn cob: 22.5% and unpretreated corn stalk: 17.7%). Characterization results confirmed that the lignin and hemicellulose were significantly removed, and the cellulose crystals remained intact. Before and after pretreatment, the two raw materials changed from the initial dense surface morphology to porous and therefore contributed to enhancing the accessibility of cellulose during enzymatic hydrolysis. Furthermore, the sugar yield could still be maintained above 70% after the TBPH aqueous solution was reused 5 times. These results provide guidance for the conversion of other biomass to sugar and further fermentation to prepare the essential products.

Ionic liquid extraction of silkworm pupa protein and its biological characteristics

• A novel extraction method for silkworm pupa protein has been demonstrated. • The CH-IL extraction increased protein content by 12.14%. • The solubility, emulsification, and foaming capacity of the CH-IL extracted protein were enhanced. Silkworm ( Bombyx mori ) pupa protein (SPP) is a high-quality source of animal protein with substantial nutritional benefits and health value. To develop an efficient extraction method for SPP that is environmentally friendly, we selected choline hydroxide ionic liquid (CH-IL) as the extraction solvent and performed orthogonal experiments to optimize the extraction conditions. We demonstrated that 3% CH-IL, a solid-to-liquid ratio (g/mL) of 1:30, an extraction temperature of 40 °C, and an extraction time of 1 h facilitated the most efficient extraction. Compared to the conventional alkali solubilization–acid precipitation method, the CH-IL extraction increased protein content by 12.14%. Protein structure analysis showed that the β-sheet content increased by 10.98% and that of disulfide bonds reduced by 16.4%. The processing properties of the CH-IL extracted protein showed that the solubility, emulsification, and foaming capacity were enhanced by 82.87%, 15.44%, and 18.97%, respectively. The physical properties of SPP remarkably improved relative to the increased stretching of the polypeptide chains. The findings of this study provide technical knowledge that will enhance the processing performance of pupal proteins.

Assessing the Alkyl Chain Effect of Ammonium Hydroxides Ionic Liquids on the Kinetics of Pure Methane and Carbon Dioxide Hydrates

In this study, four ammonium hydroxide ionic liquids (AHILs) with varying alkyl chains were evaluated for their kinetic hydrate inhibition (KHI) impact on pure carbon dioxide (CO2) and methane (CH4) gas hydrate systems. The constant cooling technique was used to determine the induction time, the initial rate of hydrate formation, and the amount of gas uptake for CH4-AHILs and CO2-AHILs systems at 8.0 and 3.50 MPa, respectively, at 1 wt.% aqueous AHILs solutions. In addition, the effect of hydrate formation sub-cooling temperature on the performance of the AHILs was conducted at experimental temperatures 274.0 and 277.0 K. The tested AHILs kinetically inhibited both CH4 and CO2 hydrates at the studied sub-cooling temperatures by delaying the hydrate induction time and reducing the initial rate of hydrate formation and gas uptake. The hydrate inhibition performance of AHILs increases with increasing alkyl chain length, due to the better surface adsorption on the hydrate crystal surface with alkyl chain length enhancement. TPrAOH efficiently inhibited the induction time of both CH4 and CO2 hydrate with an average inhibition percentage of 50% and 84%, respectively. Tetramethylammonium Hydroxide (TMAOH) and Tetrabutylammonium Hydroxide (TBAOH) best reduced CH4 and CO2 total uptake on average, with TMAOH and Tetraethylammonium Hydroxide (TEAOH) suitably reducing the average initial rate of CH4 and CO2 hydrate formation, respectively. The findings in this study could provide a roadmap for the potential use of AHILs as KHI inhibitors, especially in offshore environs.

Heterogeneity in the microstructure and dynamics of tetraalkylammonium hydroxide ionic liquids: insight from classical molecular dynamics simulations and Voronoi tessellation analysis.

Microscopic structural and dynamic heterogeneities were investigated for three ionic liquids (ILs), namely tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), and tetrabutylammonium hydroxide (TBAH), by employing classical molecular dynamics (MD) simulations. Structural heterogeneity was explored through radial distribution functions, domain analysis from Voronoi tessellation, spatial distribution functions, combined distribution functions, and structure factors. Radial distribution functions reveal that TEAH has a slightly different structure than TPAH and TBAH. The domain analysis shows that the three ILs have structural heterogeneity. The cations form continuous domains and the anions form discreet domains. The anions are trapped in the voids formed by the cationic domains. When the cation has sufficiently longer alkyl chains, the polar domains become discontinuous. The total structure factor reveals that a pre-peak is absent in TEAH due to a short alkyl chain. The cation head-anion partial structure factor further confirms this phenomenon. Polar and non-polar domains can be better distinguished in the ILs with longer alkyl chains. This distinctive structural behaviour leads to dynamic heterogeneity, which plays an important role in the applications related to ion transportation. To shed light on dynamic heterogeneity, we have calculated the mean square displacements, vibrational density of states, van Hove correlation, and non-Gaussian parameter. The diffusion of ions is lowest in TPAH among all the ILs. The dynamics are highly sluggish in these ILs. The peaks in the low frequency vibrational density of states undergo redshift with an increase in the alkyl chain length. The van Hove correlation functions and non-Gaussian parameter suggest the presence of dynamic heterogeneity in all three ILs. Dynamic heterogeneity is discussed through van Hove correlation functions and the non-Gaussian (NG) parameter was calculated to account for the deviation from Gaussian behaviour. The NG parameter suggests that TEAH has different dynamics than TPAH and TBAH.

A mesoporous nickel oxide nanosheet as an electrode material for supercapacitor application using the 1-($$2^{\prime }$$,$$3^{\prime }$$-dihydroxypropyl)-3-methylimidazolium hydroxide ionic liquid electrolyte

NiO nanosheets were deposited on the surface of a stainless steel substrate by using a facile, environmentally friendly, reflux deposition approach for supercapacitor (SC) applications. X-ray diffraction patterns and field emission scanning electron microscopy images revealed the formation of a face centred cubic crystal structure with a uniform, compact, smoothly ordered nanosheet like structure. This study focuses on the electrochemical supercapacitive properties of NiO nanosheets with respect to cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy techniques in a 1-(\(2^{\prime }{,}3^{\prime }\)-dihydroxypropyl)-3-methylimidazolium hydroxide [DHPMIM][OH] ionic liquid (IL) as an electrolyte. The electrochemical study revealed that NiO (0.3 M) showed a high-specific capacitance of \(\hbox {205.5 F g}^{-1}\) and an excellent cycling stability (80% specific capacitance retention after 5000 cycles) in the [DHPMIM][OH] IL electrolyte. Thus, the result showed that NiO nanosheets act as an active electrode material hold for SCs.

Silanization of Iron Oxide Magnetic Nanoparticles with ionic liquids based on amino acids and its application as heterogeneous catalysts for Knoevenagel condensation reactions

Iron oxide magnetic nanoparticles (MNPs) stabilized with silane ligands, containing choline hydroxide and amino acid ionic liquid functionalities, have been prepared. The appropriate silane ligands have been synthesized; the choline hydroxide propyl silane ligand in a process inspired in the industrial production of choline hydroxide and the amino acid ionic liquids in a straight forward acid-base process using the former compound. The synthesized materials have been fully characterized by elemental analysis, X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR), UV–vis diffuse reflectance spectroscopy (DRUV-vis), thermogravimetric analysis (TG-DTG), N2 adsorption-desorption, transmission electron microscopy (TEM) and voltammetry solid state techniques. Ionic liquid stabilized magnetic nanoparticles have been very effective as heterogeneous basic catalysts in Knoevenagel condensation reaction at room temperature. The catalyst containing choline hydroxide ionic liquid (Chol-MNPs) exhibited highest catalytic activity and can easily be recovered under an external magnetic field and subsequently reused several times.

Supported choline hydroxide (ionic liquid) on mesoporous silica as heterogeneous catalyst for Knoevenagel condensation reactions

In this work hybrid mesoporous SBA-15 and mesoporous silica microspheres functionalized with choline hydroxide ionic liquid have been prepared. A two-step process inspired by the industrial production of choline hydroxide has been developed to synthesize the hybrid SBA-15 material with choline hydroxide ionic liquid (Chol-SBA-15) and the hybrid SBA-15 material with choline hydroxide ionic liquid and hexamethyldisilizane as capping agent (Chol-HMDS-SBA-15). For the preparation of hybrid mesoporous silica microspheres (Chol-MSMs), a co-condensation method has been employed with an ionic liquid prepared by reaction of 3-(glycidyloxypropyl)trimethoxysilane and trimethylamine in aqueous media. The synthesized materials have been fully characterized by elemental analysis, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), N2 adsorption-desorption, transmission electron microscopy (TEM) and 13C CP/MAS NMR spectroscopy. These materials have been tested successfully as catalysts in Knoevenagel condensation of benzaldehyde with RCH2C≡N (R = CN (malononitrile), CO2Et (ethyl cyanoacetate)). The catalyst Chol-MSMs showed high catalytic activity, 99% of conversion and 99% of selectivity towards ethyl 2-cyano-3-phenylacrylate in 2 h of reaction and using ethanol as solvent. In addition, their reusability without loss of activity has been demonstrated.

IONIC LIQUID ASSISTED ACETYLENE PARTIAL HYDROGENATION OVER SURFACE OF PALLADIUM NANOPARTICLES

The loss of acetylene partial hydrogenation selectivity over bare palladium catalyst is observed by aging. In this study, 1-butyl-3-methyl imidazolinium hydroxide ionic liquid (BMIm[OH]) is loaded on Pd/[Formula: see text]–Al2O3 solid catalyst for enhancing the selectivity and different experimental techniques such as surface area measurements and catalytic performance have been performed to characterize the modified catalyst. Results revealed that the addition of ionic liquid maintains higher selectivity of partial hydrogenation over Pd/[Formula: see text]–Al2O3 catalyst for more than 30[Formula: see text]h especially at the temperature of acetylene complete removal ([Formula: see text]C). The activation energies of partial and complete acetylene hydrogenation on bare and ionic liquid loaded Pd/[Formula: see text]–Al2O3 are also calculated and utilized to clarify the obtained results.

Influence of hydroxyl group position and temperature on thermophysical properties of tetraalkylammonium hydroxide ionic liquids with alcohols.

In this work, we have explored the thermophysical properties of tetraalkylammonium hydroxide ionic liquids (ILs) such as tetrapropylammonium hydroxide (TPAH) and tetrabutylammonium hydroxide (TBAH) with isomers of butanol (1-butanol, 2-butanol and 2-methyl-2-propanol) within the temperature range 293.15–313.15 K, with interval of 5 K and over the varied concentration range of ILs. The molecular interactions between ILs and butanol isomers are essential for understanding the function of ILs in related measures and excess functions are sensitive probe for the molecular interactions. Therefore, we calculated the excess molar volume (VE) and the deviation in isentropic compressibility (Δκs) using the experimental values such as densities (ρ) and ultrasonic sound velocities (u) that are measured over the whole compositions range at five different temperatures (293.15, 298.15, 303.15, 308.15 and 313.15 K) and atmospheric pressure. These excess functions were adequately correlated by using the Redlich–Kister polynomial equation. It was observed that for all studied systems, the VE and Δκs values are negative for the whole composition range at 293.15 K. And, the excess function follows the sequence: 2-butanol>1-butanol>2-methyl-2-propanol, which reveals that (primary or secondary or tertiary) position of hydroxyl group influence the magnitude of interactions with ILs. The negative values of excess functions are contributions from the ion-dipole interaction, hydrogen bonding and packing efficiency between the ILs and butanol isomers. Hence, the position of hydroxyl group plays an important role in the interactions with ILs. The hydrogen bonding features between ILs and alcohols were analysed using molecular modelling program by using HyperChem 7.

Research on Producing Biodiesel from Waste Oil with 1-Methyl-3-butyl Imidazole Hydroxide Ionic Liquid as a Catalyst

1-Methyl-3-butyl imidazole hydroxide ionic liquid, which was used as a catalyst for producing biodiesel from waste oil, was synthesized and characterized by Fourier transform-infrared spectroscopy and nuclear magnetic resonance spectroscopy. The effects of relevant factors on the transesterification were investigated by a designing orthogonal test. The physicochemical properties of the products were measured and the blending test of the produced biodiesel with 0# diesel was also examined. The experimental results showed that the 1-methyl-3-butyl imidazole hydroxide ionic liquid was a novel highly active and reusable biodiesel production catalyst. The conversion of fatty acid methyl ester reached 95.7% at the optimized reaction conditions of 3 wt% of catalyst addition amount to feed oil, 8:1 alcohol to oil molar ratio, 70°C of reaction temperature, and 110 min of reaction time. The biodiesel product indicated better fluidity at low temperature and high flash point except that the iodine value was a little high. The main physicochemical properties of the product attained to the standard of 0# diesel and the produced biodiesel could be blended with 0# diesel in all proportions before application. The performance of the diesel was improved by blending with the biodiesel.

Evaluation of the enantioselectivity of glycogen-based synergistic system with amino acid chiral ionic liquids as additives in capillary electrophoresis

In this paper, two novel amino acid chiral ILs, tetramethylammonium-l-arginine (TMA-l-Arg) and tetramethylammonium-l-aspartic acid (TMA-l-Asp), were applied for the first time in CE enantioseparation to evaluate their potential synergistic effect with glycogen as chiral selector. As observed, significantly improved separation of tested enantiomers were obtained in the chiral ILs/glycogen synergistic systems compared to the single glycogen separation system. Several primary parameters affecting the enantioseparation, such as amino acid ILs (AAILs) concentration, glycogen concentration and buffer pH, were systematically investigated. An achiral tetramethylammonium hydroxide ionic liquid (TMA-OH) modified separation system was also evaluated to validate the superiority of the novel chiral ILs/glycogen synergistic systems. To further optimize the overall synergistic systems, the effect of three other parameters, including buffer concentration, applied voltage and capillary temperature were simultaneously analyzed by a central composite design (CCD), and excellent enantioseparations were achieved with the optimized parameters. The results indicate that the application of chiral ILs/glycogen synergistic systems is a promising way in chiral separation science.

Electrochemical Tailoring of Honeycomb-Structured ZnO Thin Films by Interfacial Surfactant Templating

Zinc oxide thin films with honeycomb structures can be electrochemically produced by interfacial surfactant templating. Newly synthesized 4-amino-1-(2,3-dihydroxy propyl) pyridinium hydroxide ionic liquid exhibiting the hydroxyl functionalized ionic liquids (HFILs) was used in electrodeposition. This method utilizes amphiphile assemblies at the solid-liquid interface (i.e., the surface of a working electrode) as a template to gain the precisely tailor zinc oxide nanostructures. The results described here will provide a useful foundation to design and optimize greener protocol for the electrochemical construction of inorganic nanostructures thin films for possible application of films in nanotechnology field. Moreover, it is believed that this electrochemical tailoring approach can be extended to fabricate other porous metal oxide materials with a unique morphology or shape.

A computational study on the chemical fixation of carbon dioxide with 2-aminobenzonitrile catalyzed by 1-butyl-3-methyl imidazolium hydroxide ionic liquids

The mechanism of chemical fixation of carbon dioxide with 2-aminobenzonitrile catalyzed by 1-butyl-3-methyl imidazolium hydroxide ([Bmim]OH) ionic liquid has been extensively investigated by the density functional theory (DFT) calculations. The purpose is to show the detailed reaction mechanism, and in particular to better understand the role of [Bmim]OH played in the reaction as a catalyst. Three mechanistic pathways are proposed and evaluated. Our calculations indicate that the real activate catalyst is the N-heterocyclic carbine (NHC). In the favored pathway, it is found that the attack of C3 atom of NHC to C1 atom, the C1–O2 bond cleavage, and the C1–N2 bond formation have close activation free energies. Therefore, each of them can determine the reaction rate with variation in the reaction conditions. Furthermore, it is shown that the scCO 2 solution does not change significantly the potential energy surface profile.

Fast synthesis of nanostructured ZnO particles from an ionic liquid precursor tetrabutylammonium hydroxide

Microwave irradiation could allow a more efficient and homogeneous heating of the reaction mixture to result in a fast synthesis. We propose a facile route for the synthesis of ZnO particles from an ionic liquid precursor with the assistance of microwave heating in which the ionic liquid has multifunctions (adsorbing microwave and acting as solvent, reactant, template) in the particle formation process. It demonstrates that ZnO particles with uniform size and morphology could be synthesized from tetrabutylammonium hydroxide ionic liquid precursor by the microwave heating method. Room temperature photoluminescence spectroscopy is measured to reveal the optical property of the as-obtained products. Moreover, the photocatalytic activity of the synthesized ZnO particles for the degradation of Rhodamine B is investigated.

Microwave-assistant synthesis of inorganic particles from ionic liquid precursors

The structurally similar ionic liquid precursors are explored for synthesis of inorganic particles by the microwave heating method. During the synthesis, the ionic liquid precursors have multi-functions such as reactant, solvent and template. Specifically it has good adsorbing property for microwave to result in a fast synthesis. It demonstrates that a wide variety of metal oxide or hydroxide particles with uniform size, morphology could be synthesized from tetrabutylammonium hydroxide (TBAH) or tetraethylammonium hydroxide (TEAH) ionic liquid precursors by the microwave heating method. The formation mechanism of the synthesized particles is proposed based on the experimental results.