Solvent effects on Diels-Alder reaction in ionic liquids:A reaction density functional study

Extensive experimental studies have been performed on the Diels-Alder(DA)reactions in ionic liquids(ILs),which demonstrate that the IL environment can significantly influence the reaction rates and selectivity.However,the underlying microscopic mechanism remains ambiguous.In this work,the multiscale reaction density functional theory is applied to explore the effect of 1-butyl-3-methylimidazolium hexafluorophosphate([BMIM][PF_(6)])solvent on the reaction of cyclopentadiene(CP)with acrolein,methyl acrylate,or acrylonitrile.By analyzing the free energy landscape during the reaction,it is found that the polarization effect has a relatively small influence,while the solvation effect makes both the activation free energy and reaction free energy decrease.In addition,the rearrangement of local solvent structure shows that the cation spatial distribution responds more evidently to the reaction than the anion,and this indicates that the cation plays a dominant role in the solvation effect and so as to affect the reaction rates and selectivity of the DA reactions.

Highly selective extraction of aromatics from aliphatics by using metal chloride-based ionic liquids

The separation of aromatics from aliphatics is essential for achieving maximum exploitation of oil resources in the petrochemical industry.In this study,a series of metal chloride-based ionic liquids were prepared and their performances in the separation of 1,2,3,4-tetrahydronaphthalene(tetralin)/dodecane and tetralin/decalin systems were studied.Among these ionic liquids,1-ethyl-3-methylimidazolium tetrachloroferrate([EMIM][FeCl_(4)])with the highest selectivity was used as the extractant.Density functional theory calculations showed that[EMIM][FeCl_(4)]interacted more strongly with tetralin than with dodecane and decalin.Energy decomposition analysis of[EMIM][FeCl_(4)]-tetralin indicated that electrostatics and dispersion played essential roles,and induction cannot be neglected.The van der Waals forces was a main effect in[EMIM][FeCl_(4)]-tetralin by independent gradient model analysis.The tetralin distribution coefficient and selectivity were 0.8 and 110,respectively,with 10%(mol)tetralin in the initial tetralin/dodecane system,and 0.67 and 19.5,respectively,with 10%(mol)tetralin in the initial tetralin/decalin system.The selectivity increased with decreasing alkyl chain length of the extractant.The influence of the extraction temperature,extractant dosage,and initial concentrations of the system components on the separation performance were studied.Recycling experiments showed that the regenerated[EMIM][FeCl_(4)]could be used repeatedly.

Ionic liquids as the effective technology for enhancing transdermal drug delivery: Design principles, roles, mechanisms, and future challenges

Ionic liquids (ILs) have been proven to be an effective technology for enhancing drug transdermal absorption. However, due to the unique structural components of ILs, the design of efficient ILs and elucidation of action mechanisms remain to be explored. In this review, basic design principles of ideal ILs for transdermal drug delivery system (TDDS) are discussed considering melting point, skin permeability, and toxicity, which depend on the molar ratios, types, functional groups of ions and inter-ionic interactions. Secondly, the contributions of ILs to the development of TDDS through different roles are described: as novel skin penetration enhancers for enhancing transdermal absorption of drugs;as novel solvents for improving the solubility of drugs in carriers;as novel active pharmaceutical ingredients (API-ILs) for regulating skin permeability, solubility, release, and pharmacokinetic behaviors of drugs;and as novel polymers for the development of smart medical materials. Moreover, diverse action mechanisms, mainly including the interactions among ILs, drugs, polymers, and skin components, are summarized. Finally, future challenges related to ILs are discussed, including underlying quantitative structure-activity relationships, complex interaction forces between anions, drugs, polymers and skin microenvironment, long-term stability, and in vivo safety issues. In summary, this article will promote the development of TDDS based on ILs.

Separation of lithium and nickel using ionic liquids and tributyl phosphate

With the vigorous development of the electronics industry,the consumption of lithium continues to increase,and more lithium needs to be mined to meet the development of the industry.The content of lithium in the solution is much higher than that of minerals,but the interference of impurity ions increases the difficulty of extracting lithium ions.Therefore,we prepared an imidazole-based ionic liquid(1-butyl-3-methylImidazolium bis(trifluoromethyl sulfonyl)imide)(IL)for efficient lithium extraction from aqueous solutions by solvent extraction.Using an extraction consisting of 10%IL,85% tributyl phosphate(TBP),and 5% dichloroethane and an organic to aqueous phase ratio(O/A)of 2/1,over 64.23% of Li were extracted,and the extraction rate after five-stage extraction could reach more than 96%.The addition of ammonium ions to the solution inhibited the extraction of Ni,and the separation coefficient between lithium and nickel approached infinity,showing a very perfect separation effect.Fouriertransform infrared spectroscopy and slope methods were used to analyze the changes that occurred during extraction,revealing possible extraction mechanisms.In addition,the LiCl solution generated during the preparation of ionic liquids was mixed with the stripping solution,and the battery-grade lithium carbonate was prepared by Na_(2)CO_(3) precipitation,with a purity of 99.74%.This study provides an efficient and sustainable strategy for recovering lithium from the solution.

A simple hydroxypyridine ionic liquids for conversion of CO_(2)into quinazoline-2,4(1H,3H)-diones under atmospheric conditions

The transformation of CO_(2)into high value-added product is a promising pathway for utilizing CO_(2).However,the process tends to require harsh reaction conditions owing to CO_(2)chemical inertness.Designing a high efficiency catalytic system with environmentally benign characteristic are important determinants.In this work,protic ionic liquids[TMG][2-OPy]were prepared via one-step neutralization between 1,1,3,3-tetramethylguanidine and 2-hydroxypyridine,applying to the domain of synthesizing quinzoline-2,4(1 H,3H)-diones from CO_(2)and 2-aminobenzontiles without any solvent or metal,achieving the yield of 97%at 90℃for 8 h under atmospheric.A series of substrates with good to acceptable yield were detected,revealing the generality and universality of the catalyst.Furthermore,the system could be facilely reused for at least six runs,retaining the yield of 94%.A preliminary kinetic equation is calculated with the activation energy of 68 kJ·mol^(-1),and a plausible reaction mechanism was put forward.This study highlights that the[TMG][2-OPy]enables to activate CO_(2)carboxylation efficiently.

The opportunities and challenges of ionic liquids in perovskite solar cells

Metal halide perovskite solar cells(PSCs)have shown great potential to become the next generation of photovoltaic devices due to their simple fabrication techniques,low cost,and soaring power conversion efficiency(PCE).However,mismatched with the quickly updated PCEs,the improvement of device stability is challenging and still remains a critical hurdle in the path to commercialization.Recently,ionic liquids(ILs)have been found to play multiple roles in obtaining efficient and stable PSCs.These ILs usually consist of large organic cations and organic or inorganic anions,which have weak electrostatic attraction and are generally liquid at around 100℃.ILs are almost non-volatile,non-flammable,with high ionic conductivity and excellent thermal and electrochemical stability.The roles of ILs in PSCs vary with their composition,that is,the types of anions and cations.In this review,we summarize the roles of anions and cations in terms of precursor solutions,additives,perovskite/charge transport layer interface engineering,and charge transport layers.This article aims to set up a structure–property-stability-performance correlations conferred by the IL in PSC and provide assistance for the anion and cation selection for improving the quality of perovskite film,optimizing interface contact,reducing defect states,and improving charge extraction and transport characteristics.Finally,the application of IL in PSCs is discussed and prospected.

Ionic liquids-SBA-15 hybrid catalysts for highly efficient and solvent-free synthesis of diphenyl carbonate

Diphenyl carbonate(DPC)is one of the versatile carbonates,and is often used for the production of polycarbonates.In recent years,the catalytic synthesis of DPC has become an important topic but the development of a highly active metal-free catalyst is a great challenge.Herein,a series of ionic liquids-SBA-15 hybrid catalysts with different functional groups have been developed for the synthesis of DPC under solventfree condition,which are effective and clean instead of the metal-containing catalysts.It is found that in the presence of[SBA-15-IL-OH]Br catalyst,methyl phenyl carbonate(MPC)conversion of 80.5%along with 99.6%DPC selectivity is achieved,the TOF value is thrice higher than the best value reported by using transition metal-based catalysts.Moreover,the catalyst displays remarkable stability and recyclability.This work provides a new idea to design and prepare eco-friendly catalysts in a broad range of applications for the green synthesis of carbonates.

Complete degradation of high-loaded phenol using tungstate-based ionic liquids with long chain substituent at mild conditions

Phenol in waste water threatens human health and is difficultly to be decomposed by nature.Efficient degradation of high-loaded phenol in water under mild condition is still a great challenge.Herein,ionic liquids with tungstate anion were designed and prepared.It was found that dodecyltrimethylammonium tungstate could catalyzed degradation of phenol into gases and water thoroughly at 323 k in 8 h.Tungstate anion revealed good catalytic oxidative activity and long carbon chain group connecting with cation of ionic liquids enriched phenol around catalysts,which induced the complete degradation of phenol at mild conditions.Increasing the amounts of hydrogen peroxide benefited to the total degradation of phenol.In addition,the ionic liquid could be reused for its excellent thermal stability.Our work provided a different strategy to treat waste water containing phenol efficiently.

Preparation of Ionic Liquids Immobilized on FMIL-101 Catalysts for Conversion of CO_(2)to Propylene Carbonate

Metal-organic frameworks(MOFs)have attracted considerable research attention as a new type of porous material for catalytic applications.Herein,2,5-dihydroxyterephthalic acid was proposed to replace conventional terephthalic acid and reacted with chromic nitrate nonahydrate to synthesize a functional metal–organic framework(FMIL-101).This was then used to immobilize various compound ionic liquids to prepare three ionic liquids immobilized on FMIL-101 catalysts,namely,FMIL-101-[HeMIM]Cl/(ZnBr_(2))_(2),FMIL-101-[CeMIM]Cl/(ZnBr_(2))_(2),and FMIL-101-[AeMIM]Br/(ZnBr_(2))_(2).After characterization by Fourier-transform infrared spectroscopy,X-ray diffraction,ultraviolet spectroscopy,thermogravimetry,specific surface area analysis,and scanning electron microscopy,the catalysts were used to mediate cycloaddition reactions between carbon dioxide(CO_(2))and propylene oxide.The effects of reaction temperature,reaction pressure,reaction time,and catalyst dosage on the catalytic performance were investigated.The results revealed that the FMIL-101-supported CIL catalysts afforded the target product propylene carbonate with good catalytic performance and thermal stability.The optimal catalyst,FMIL-101-[CeMIM]Cl/(ZnBr_(2))_(2),displayed a propylene oxide conversion of 98.64%and a propylene carbonate selectivity of 96.63%at a reaction temperature of 110℃,a reaction pressure of 2.0 MPa,a catalyst dosage of 2.0%relative to propylene oxide,and a reaction time of 2.5 h.In addition,the conversion and selectivity of the catalyst decreased slightly after four cycles.Additionally,the catalyst decreased slightly in catalytic performance after being recycled four times.

Parameterization of COSMO-RS model for ionic liquids

The adjustable parameters in the popular conductor-like screening model for real solvents(COSMO-RS)within the Amsterdam density functional(ADF)framework have been re-optimized to fit for the systems containing ionic liquids(ILs).To get the optimal values of misfit energy constant a^0,hydrogen bond coefficient c_(hb)and effective contact surface area of a segment a_(eff),2283 activity coefficient data points at infinite dilution and 1433 CO_2 solubility data points exhaustively collected from references were used as training set.The average relative deviations(ARDs)of activity coefficients at infinite dilution and CO_2 solubility between experimental data and predicted values are 32.22%and17.61%,respectively,both of which are significantly lower than the original COSMO-RS versions.Predictions for other activity coefficients of solutes in ILs,solubility data of CO_2 in pure ILs and the binary mixtures of ILs at either high or low temperatures,and vapor–liquid equilibrium(VLE)for binary systems involving ILs have also been performed to demonstrate the validity of the parameterization of COSMO-RS model for ILs.The results showed that the predicted results by COSMO-RS model with the new optimized parameters are in much better agreement with experimental data than those by the original versions over a wide temperature and pressure range.The COSMO-RS model for ILs presented in this work improves the prediction accuracy of thermodynamic properties for the systems containing ILs,which is always highly desirable for general chemical engineers.

COSMO-RS prediction and experimental verification of 1,5-pentanediamine extraction from aqueous solution by ionic liquids

1,5-Pentanediamine(PDA)produced by biological fermentation becomes popular,but the separation of PDA from the broth is a typical difficult problem.In this work,the performance of 200 ionic liquids(ILs),formed by combining 25 cations and 8 anions,in the extraction of PDA from aqueous solution were evaluated using COSMO-RS model.The extraction mechanism was investigated with the help ofσ-profile and interaction energy analyses.Both the cation and anion have impacts on the extraction efficiency,where cation mainly influences the interaction of IL with PDA and anion affects the hydrophobicity of IL.The IL composed of long alkyl-chain in cation and the anion of[PF6]-or[TF2 N]-,which has theσ-profile more likely distributed in the nonpolar region but less distributed in the polar region,is favorable for extraction.The experimental liquid-liquid equilibrium demonstrated the effects of cation and anion on extraction performance,which validated the reliability of COSMO-RS model in IL screening for PDA extraction.The IL[IM-1,8][PF6]could serve as a promising extractant for the downstream separation process of the biological production of PDA.

CO_2 absorption with ionic liquids at elevated temperatures

COcapture with ionic liquids（ILs） has attracted many attentions, and most works focused on absorption ability at ambient temperatures, while seldom research was concerned at elevated temperatures.This not only limits the COabsorption application at elevated temperature, but also the determination of the operation condition of the COdesorption generally occurring at higher temperature. This work mainly reported COsolubilities in ILs at elevated temperatures and related properties were also provided. 1-alkyl-3-methylimidazolium bis（trifluoromethylsulfonyl）imide（[CnMIm][TfN]） ILs were selected as physical absorbents for COcapture in this work due to their relative higher COabsorption capacities and good thermal stabilities. The long-term stability tests showed that [CnMIm][TfN] is thermally stable at 393.15 K for long time. COsolubilities in [CnMIm][TfN] were systematically determined at temperatures from 353.15 K to 393.15 K. It demonstrated that COsolubility obviously increases with the increase of pressure while slightly decreases with increase of temperature. As the length of alkyl chain on the cation increases, COsolubility in ILs increases. Additionally, the thermodynamic properties including the Gibbs free energy, enthalpy, and entropy of COwere also calculated.

Ionic liquids for CO_(2) electrochemical reduction

Electrochemical reduction of CO_(2) is a novel research field towards a CO_(2)-neutral global economy and combating fast accelerating and disastrous climate changes while finding new solutions to store renewable energy in value-added chemicals and fuels.Ionic liquids(ILs),as medium and catalysts(or supporting part of catalysts)have been given wide attention in the electrochemical CO_(2) reduction reaction(CO_(2) RR)due to their unique advantages in lowering overpotential and improving the product selectivity,as well as their designable and tunable properties.In this review,we have summarized the recent progress of CO_(2) electro-reduction in IL-based electrolytes to produce higher-value chemicals.We then have highlighted the unique enhancing effect of ILs on CO_(2) RR as templates,precursors,and surface functional moieties of electrocatalytic materials.Finally,computational chemistry tools utilized to understand how the ILs facilitate the CO_(2) RR or to propose the reaction mechanisms,generated intermediates and products have been discussed.

Synthesis and Characterization of Dual Acidic Ionic Liquids

Novel ionic liquids with dual acidity, of which the cation contains Brφnsted acidity and anions contain Lewis acidity were synthesized. These ionic liquids obtained were identified by NMR, FF-IR, SDT and FAB-MS. Their acidities were determined by pyridine probe on IR spectrography.

DESIGN AND SYNTHESIS OF NOVEL CHIRAL IONIC LIQUIDS AND THEIR APPLICATION IN FREE RADICAL POLYMERIZATION OF METHYL METHACRYLATE

Two new chiral ionic liquids, 1 -((-)-menthoxycarbonylmethylene)-3-methylimidazolium hexafluorophosphateand 1-((-)-menthoxycarbonylmethylene)-3-hexadecylimidazolium hexafluorophosphate, were designed an d prepared. Theirchemical structures were characterized by ~1H-NMR. Reverse atom transfer radical polymerization of methyl methacrylate(MMA) in these two ionic liquids was carried out using AIBN/CuCl_2/bipy as the initiating system. The resultant well-definedpolymethyl methacrylate (PMMA) was employed as a macroinitiator to induce the atom transfer radical polymerization ofmenthyl methacrylate (MnMA) in chlorobenzene, which yielded a PMMA-b-PMnMA diblock copolymer with narrow polydispersity.

Extractive denitrogenation of shale oil using imidazolium ionic liquids

The potential applications of shale oil as a substitute energy source are adversely influenced due to its high nitrogen content.In this work,four imidazolium ionic liquids(ILs),i.e.,1-butyl-3-methylimidazolium chloride([Bmim]Cl),1-butyl-3-methylimidazolium acetate([Bmim]Ac),1-butyl-3-methylimidazolium acetate/ZnAc2([Bmim]Ac/ZnAc2)and 1-butyl-3-methylimidazolium chloride/ZnAc2([Bmim]Cl/ZnAc2),were used to extract the basic nitrides and neutral nitrides from shale oil.The influence of extraction time,temperature,properties of N-compounds,ILs structure,mass ratio of IL/oil,multiple cycles of denitrogenation,physical mixing of ILs and ILs recyclability on extractive denitrogenation was systematically investigated.The denitrogenation performance of all ILs was determined and investigated from micro-level view withσ-profile.It was observed that,ILs composed of anions with weaker HB acceptor capacity,have the higher N-extraction efficiency to the neutral nitrogen compounds with weaker HB acceptor capacity.More than 96%N-extraction efficiency was achieved at the end of a single extraction cycle for time<10 min under 40℃C and 1:1 of IL:oil(w/w),especially 100%N-extraction efficiency was realized for carbazole and indole.The N-extraction efficiency up to 60.1%and 53.7%for real shale oil was realized by[Bmim]Ac and[Bmim]Ac/ZnAc2,respectively,which are about 10%better than other non-hydrodenitrogenation technologies.Moreover,[Bmim]Ac and[Bmim]Ac/ZnAc2 exhibited almost the same extractive denitrogenation performance after regeneration.This work has developed a new approach to lessen the nitrogen content of shale oil effectively and economically.

An experimental study of the effect of ionic liquids on the low temperature oxidation of coal

Fourier transform infrared spectroscopy(FTIR) and constant heating rate experiments were performed to study the low temperature oxidation of coal treated by an ionic liquid,1-allyl-3-methylimidazolium chloride.The inerting effect of the ionic liquid toward the low temperature oxidation process is discussed.The results show that:(1) The hydroxyl content associated with hydrogen bonds,the aliphatic methyl content,the methylene group content,and the ether oxygen bond content are reduced in the treated coal.At the same time the content of aromatic C@C bonds is constant but these chemical bonds weaken and some substituted aromatic hydrocarbon content increases while other types decrease.This demonstrates that(AMIm)Cl dissolves and destroys the coal surface microstructure;(2) The oxygen consumption of the treated coal is less than what is seen in raw coal.The CO,CO 2,C 2 H 4,and C 2 H 6 content from the treated coal is reduced compared to the untreated coal;(3) The apparent activation energy for the oxidizing reaction is different in the treated and raw coals.Micro-structural changes and macroscopic gas production allow us to conclude that(AMIm)Cl can effectively inhibit low temperature oxidation of coal.

Separation of ionic liquids from dilute aqueous solutions using the method based on CO_2 hydrates

Ionic liquids （ILs） have been regarded as the potential novel solvents for improved analytical- and process-scale separation methods.The development of methods for the recovery of ILs from aqueous solutions to escape contamination and recycle samples will ultimately govern the viability of ILs in the future industrial applications. Therefore, in this paper a new method for separation of ILs from their dilute aqueous solutions and simultaneously purification of water was proposed on the basis of the CO2 hydrate formation. For illustration, the dilute aqueous solutions with concentrations of ILs ranging from 2× 10^-3 mol% to 2×10^-1 mol% were concentrated. The results show that the separation efficiency is very impressive and that the new method is applicable to aqueous solutions of both hydrophobic and hydrophilic ILs. Compared to the literature separation method based on the supercritical CO2, the new method is applicable to lower concentrations, and more importantly, its operation condition is mild.

Ionic liquids for high performance lithium metal batteries

The pursuit of high energy density has promoted the development of high-performance lithium metal batteries.However,it faces a serious security problem.Ionic liquids have attracted great attention due to their high ionic conductivity,non-flammability,and the properties of promoting the formation of stable SEI films.Deeply understanding the problems existing in lithium metal batteries and the role of ionic liquids in them is of great significance for improving the performance of lithium metal batteries.This article reviews the effects of the molecular structure of ionic liquids on ionic conductivity,Li^(+)ion transference number,electrochemical stability window,and lithium metal anode/electrolyte interface,as well as the application of ionic liquids in Li-high voltage cathode batteries,Li-O_(2) batteries and Li-S batteries.The molecular design,composition and polymerization will be the main strategies for the future development of ionic liquid-based electrolytes for high performance lithium metal battery.

Amide Ionic Liquids(AILs)/L-Proline Synergistic Catalyzed Asymmetric Mannich Reactions

Amide ionic liquids （MLs）/L-proline synergistic catalyzed Mannich reactions of isovaleraldehyde, methyl ketones, and aromatic amines were carried out in moderate to high yields （ up to 96% ） and high stereo selectivities （ 〉99% e. e. ）. The products were easily isolated by extraction; and the catalyst system was readily recycled at least thrice without significant loss of efficiency. The scope of the substrates was studied and the interpretation of the manifest improvement of the reaction rates and enantio-selectivity of the novel catalyst system was speculated.