Physical and electrochemical properties of room-temperature dicyanamide ionic liquids based on quaternary phosphonium cations

The physicochemical and electrochemical properties of room temperature ionic liquids based on quaternary phosphonium cations together with a dicyanamide anion are presented in this report. The most dicyanamide-based phosphonium ionic liquids prepared were hydrophilic, except ionic liquids containing a long alkyl chain in the phosohonium cation. It was found that asymmetric phosphonium cations gave low-melting salts in combination with a dicyanamide anion. The dicyanamide-based phosphonium ionic liquids exhibited relatively low viscosities and high conductivities when compared to those of the corresponding ammonium ionic liquids. Particularly, the ionic liquids containing a methoxy group in the phosphonium cations indicated very low viscosities. Comparatively good electrochemical stability of the dicyanamide-based phosphonium ionic liquids was confirmed by voltammetric measurements. The thermogravimetric analysis suggested that the dicyanamide-based phosphonium ionic liquids showed higher thermal stability than those of the corresponding ammonium ionic liquids, indicating an improving effect of the phosphonium cations on the thermal stability.     

Chemical–physical properties of bis(perfluoroalkylsulfonyl)imide-based ionic liquids

The chemical–physical properties of hydrophobic ionic liquids, tailored as electrolyte components for supercapacitors and lithium batteries, were investigated and compared. The ionic liquid samples are based on bis(perfluroalkylsulfonyl)imide anions coupled with different types of cation. The effect of the cation as well as the main cationic aliphatic side group, in combination with different anions, on the chemical–physical properties of the investigated ionic liquid samples was evaluated and discussed. The activation energy for the conduction mechanism and the glass transition temperature were obtained by fitting the conductivity vs. temperature data.     

Toward greener separations of rare earths: Bifunctional ionic liquid extractants in biodiesel

Ionic liquids (ILs) containing quaternary phosphonium cations and phosphonic acid anions were explored as novel extractants for rare earths (RE) separation. They were considered to be bifunctional ionic liquid extractants (bif‐ILEs), since both cations and anions of ILs were involved in the extraction. Trihexyl(tetradecyl)phosphonium bis 2,4,4‐trimethylpentylphosphinate (Cyphos IL 104), as a bif‐ILE, together with propylene carbonate (PC), dimethyl carbonate (DMC), and soybean oil methyl ester (SBME, biodiesel) as diluents was employed in the extraction of RE(III) from aqueous solutions. Acidified Cyphos IL 104 (HNO₃‐Cyphos IL 104) exhibited high solubility in three diluents, and higher extraction efficiency than bis(2,4,4‐trimethylpentyl)phosphinic acid (Cyanex 272) because of the coextraction of RE(III) by quaternary phosphonium cation and phosphonic acid anion in organic phase. Additionally, this coextraction mechanism could eliminate the loss of IL. The physical properties and miscibility test results indicated that SBME was an excellent solvent for RE(III) extraction. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

Solvent-free synthesis of benzoic esters and benzyl esters in novel Brønsted acidic ionic liquids under microwave irradiation

Fischer esterifications of benzoic acid with a variety of alcohols and a variety of acids with benzyl alcohol could be promoted by four novel Brønsted acidic ionic liquids a–d that bear a benzyl on the imidazolium or pyridinium cation. The reactions were carried out smoothly without the need of added catalyst with good to excellent isolated yields (77–98.5%) under solvent-free microwave irradiation conditions in the presence of 50 mol% ionic liquids. These ionic liquids could be recovered easily and recycled three times without any significant loss in their catalytic activity.     

异丁烷与2-丁烯在含有抑制剂离子液体中的烷基化反应

含有AlCl^-₄和/或Al₂Cl^-₇阴离子的氯铝酸离子液体对异丁烷/2-丁烯烷基化反应具有很强的催化活性,但反应的选择性较差. 改变离子液体本身的阴、阳离子种类不能提高反应的选择性.在氯铝酸离子液体中引入CuCl等金属氯化物,能够有效地抑制烷基化过程中多聚、异构、歧化、氢转移、裂解等副反应的发生,大幅提高烷基化油中三甲基戊烷等高辛烷值组分含量. 相同反应条件下,CuCl+［Et₃NH］Cl-1.8AlCl₃烷基化反应中高辛烷值产物的含量远高于H₂SO₄烷基化油中相应组分含量.     

离子液体电化学窗口的研究进展

综述了离子液体及其电化学窗口的应用现状,总结了大量国内外研究离子液体电化学窗口的数据,包括AlCl3类、咪唑类、季铵盐类等离子液体. 电化学窗口的大小与离子液体的阴阳离子种类、工作电极和参比电极种类及离子液体中杂质有关. 通过分析阴阳离子种类、工作电极、参比电极的影响,得出阴极极限电势大小顺序为季铵盐"季鏻盐>吡咯烷>哌啶"吗啉>六亚甲基亚胺盐"咪唑>锍盐>吡啶,阳极极限电势的顺序为NTf2-"RFBF3->BF4->TSAC-> F(HF)2.3->CF3COO->HCOO-. 不同工作电极下,离子液体的电化学窗口按W>GC>Pt"Au顺序依次降低. 在研究离子液体时,钨是最好的工作电极材料. 以Li/Li+为参比电极测得的电势最正.     

Functionalization of nanoclays with ionic liquids for polypropylene composites

Cationic nanoclays were treated by ion exchange with various ionic liquids (ILs) containing cations and anions of different structure and/or molecular weight in order to investigate the effects of the IL structure and cation chain length on extent of clay dispersion, intercalation, and thermal stability. The modified clays containing imidazolium‐, pyridinium‐, and phosphonium‐based cations were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and X‐ray diffraction. Although the thermal stability of pure ILs was mostly controlled by the type of the anion present, high temperature thermal stability of the modified clays, at the IL cation loadings achieved in this work, was not significantly dependent on type, structure, or size of the cation. The latter parameters, however, were of significant importance in controlling degree of dispersion of the nanoclays during melt compounding with polypropylene (PP). Basal spacing increased proportionally to the size and type of the intercalated cations and showed little change in the PP composites. Although commercial organoclays were shown to be less thermally stable than IL modified clays, they exhibited larger basal spacing and better dispersion characteristics in the polyolefin matrix; however, they increased to the same extent the thermal stability of the PP matrix as the phosphonium modified clays. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Synthesis and physical property characterisation of phosphonium ionic liquids based on P(O)2(OR)2 and P(O)2(R)2 anions with potential application for corrosion mitigation of magnesium alloys

Phosphonium cation based ionic liquids (ILs) have become of interest due to their unique chemical and electrochemical stability as well as their promising tribological properties. At the same time, interest has also grown in the use of phosphate and phosphinate based ionic liquids for corrosion protection of reactive metals. In this work we describe the synthesis and characterization of six novel ionic liquids based on the tetraalkylphosponium cation coupled with organophosphate and organophosphinate anions and their sulfur analogues. The conductivity and viscosity of these ILs has been measured and discussed in terms of the nature of the interactions, effect of anion basicity and the extent of ionic character. The reaction of the IL with a ZE41 magnesium aerospace alloy surface is also demonstrated.     

Physical and electrochemical characterization of ionic liquids based on quaternary phosphonium cations containing a carbon–carbon double bond

Physical and electrochemical characterizations of novel two ionic liquids based on quaternary phosphonium cations containing an unsaturated carbon–carbon bond (triethyl(4-pentenyl)phosphonium and allyltributylphosphonium cations) are presented in this report. It was found that both unsaturated phosphonium cations gave low-melting salts in combination with a bis(trifluoromethylsulfonyl)amide anion. The thermogravimetric analysis suggested that the unsaturated phosphonium ionic liquids showed higher thermal stability than those of the corresponding saturated phosphonium ILs. The unsaturated phosphonium ionic liquids also exhibited relatively low viscosity and high conductivities when compared to those of the corresponding saturated phosphonium ionic liquids. These results indicate an improving effect of introducing a carbon–carbon double bond into the phosphonium cations on both the thermal stability and the transport property. The voltammetric measurements suggested that the triethyl(4-pentenyl)phosphonium-based ionic liquid showed a high cathodic stability, enabling the deposition and dissolution of metallic lithium in the phosphonium ionic liquid system.     

Effects of kinds of ionic liquid catalysts on alkylations of 1-and 2-methylnaphthalene with alkenes

Alkylations of 1-and 2-methylnaphthalene with long-chain alkenes in different alkyl-containing amine ionic liquids were investigated at room temperature. The effects of both anions and cations of ionic liquids on the alkylations were studied in detail. Results show that the anions determine, to a large extent, the physical and chemical properties of ionic liquids, but organic cations mainly influence physical properties, and have only a little impact on the catalytic performance. High conversion of alkylating agent and excellent selectivity for the desired products were obtained. The products and unreacted reactants were easily isolated from catalysis systems by extraction with cyclohexane. Thanks to the less expensive reagents and the easier synthesis process, methyl and ethylamine chloroaluminate ionic liquids could become novel practical catalysts for long-chain alkylation of methylnaphthalene with alkenes.     

Amino acid ionic liquids

The preparation of ionic liquids derived from amino acids, and their properties, are outlined. Since amino acids have both a carboxylic acid residue and an amino group in a single molecule, they can be used as either anions or cations. These groups are also useful in their ability to introduce functional group(s). Twenty different natural amino acids were used as anions, to couple with the 1-ethyl-3-methylimidazolium cation. The salts obtained were all liquid at room temperature. The properties of the resulting ionic liquids (AAILs) depend on the side groups of the amino acids involved. These AAILs, composed of an amino acid with some functional groups such as a hydrogen bonding group, a charged group, or an aromatic ring, had an increased glass transition (or melting) temperature and/or higher viscosity as a result of additional interactions among the ions. Viscosity is reduced and the decomposition temperature of imidazolium-type salts is improved by using the tetrabutylphosphonium cation. The chirality of AAILs was maintained even upon heating to 150 degrees C after acetylation of the free amino group. The amino group was also modified to introduce a strong acid group so as to form hydrophobic and chiral ionic liquids. Unique phase behavior of the resulting hydrophobic ionic liquids and water mixture is found; the mixture is clearly phase separated at room temperature, but the solubility of water in this IL increases upon cooling, to give a homogeneous solution. This phase change is reversible, and separation occurs again by raising the temperature a few degrees. It is extraordinary for an IL/water mixture to display such behavior with a lower critical solution temperature. Some likely applications are proposed for these amino acid derived ionic liquids.     

Influence of Alkyl Chain Length on Thermal Properties,Structure, and Self-Diffusion Coefficients of Alkyltriethylammonium-Based Ionic Liquids

The application of ionic liquids (ILs) has grown enormously, from their use as simple solvents, catalysts, media in separation science, or electrolytes to that as task-specific, tunable molecular machines with appropriate properties. A thorough understanding of these properties and structure–property relationships is needed to fully exploit their potential, open new directions in IL-based research and, finally, properly implement the appropriate applications. In this work, we investigated the structure–properties relationships of a series of alkyltriethylammonium bis(trifluoromethanesulfonyl)imide [TEA-R][TFSI] ionic liquids in relation to their thermal behavior, structure organization, and self-diffusion coefficients in the bulk state using DSC, FT-IR, SAXS, and NMR diffusometry techniques. The phase transition temperatures were determined, indicating alkyl chain dependency. Fourier-transformed infrared spectroscopy studies revealed the structuration of the ionic liquids along with alkyl chain elongation. SAXS experiments clearly demonstrated the existence of polar/non-polar domains. The alkyl chain length influenced the expansion of the non-polar domains, leading to the expansion between cation heads in polar regions of the structured IL. ¹H NMR self-diffusion coefficients indicated that alkyl chain elongation generally caused the lowering of the self-diffusion coefficients. Moreover, we show that the diffusion of anions and cations of ILs is similar, even though they vary in their size.     

Novel Dipyridinium Lipophile-Based Ionic Liquids Tethering Hydrazone Linkage: Design,Synthesis and Antitumorigenic Study

Novel dicationic pyridinium ionic liquids tethering amphiphilic long alkyl side chains and fluorinated counter anions have been successfully synthesized by means of the quaternization of the dipyridinium hydrazone through its alkylation with different alkyl halides. The resulting halogenated di-ionic liquids underwent a metathesis reaction in order to incorporate some fluorinated counter anions in their structures. The structures of all the resulting di-ionic liquids were characterized by several spectroscopic experiments. The antitumorigenic activities of the investigated compounds were further studied against three different human lung cancer cell lines. Compared to the standard chemotherapeutic agent, cisplatin, the synthesized di-ionic liquids exerted equal, even more active, moderate, or weak anticancer activities against the various lung cancer cell lines under investigation. The observed anticancer activity appears to be enhanced by increasing the length of the aliphatic side chains. Moreover, dicationic pyridinium bearing a nine carbon chain as counter cation and hexafluoro phosphate and/or tetrafluoro bororate as counter anion were selected for further evaluation and demonstrated effective and significant antimetastatic effects and suppressed the colonization ability of the lung cancer cells, suggesting a therapeutic potential for the synthesized compounds in lung cancer treatment.     

离子液体在有机反应中的应用

室温离子液体,由含氮的有机阳离子和无机阴离子组成,由于离子液体是很多化合物的溶剂,也能够溶解作为催化剂的过渡金属络合物,其阴离子还是潜在的配位体,故它们能起催化剂的功能,本文着重讨论这方面的发展状况。     

功能化离子液体催化合成甘油单月桂酸酯

合成了由吡啶、N-甲基咪唑、N-甲基-2-吡咯烷酮提供有机阳离子, 磷钨酸、对甲苯磺酸提供阴离子的6种离子液体。使用NMR、FT-IR和TG对离子液体表征, 并考察它们催化甘油与月桂酸酯化的催化效果。结果表明, 这些离子液体都具有较好的热稳定性, 以1-(丁基-4-磺酸基)-3-甲基咪唑磷钨酸盐离子液体的热稳定性最好。在最佳条件使用离子液体催化甘油与月桂酸反应时, 阴离子的种类对月桂酸的转化率影响较大, 以对甲苯磺酸为阴离子的离子液体催化反应时, 月桂酸转化率较以磷钨酸为阴离子的离子液体的高;1-(丁基-4-磺酸基)-3-甲基咪唑对甲苯磺酸盐离子液体做催化剂时甘油单月桂酸酯的产率最高。催化剂重复使用性方面, 离子液体重复使用5次催化活性没有明显变化。     

Diels–Alder Reaction of Cyclopentadiene and Alkyl Acrylates in the Presence of Pyrrolidinium Ionic Liquids with Various Anions

Abstract  

The conversion and stereoselectivity of transformation to endo and exo norbornene derivatives was determined in the Diels–Alder reaction of cyclopentadiene with alkyl acrylates. The reactions were carried out in the pyrrolidinium ionic liquids in the presence of metal chlorides and trifluoromethanesulfonates as the catalysts. Shorter reaction times and higher conversions of dienophile were observed in a comparison with analogous cycloadditions carried out in the presence of conventional organic solvents. A higher stereoselectivity to the endo isomer was found in the majority of cases. The ionic liquids composed of 1-butyl-1-methylpyrrolidinium cation (Pyrr_1.4) and various anions were used. The influence of ionic liquid anion and several metal chlorides and metal triflates used as the catalysts on the conversion was determined.     

离子液体萃取分离有机物研究进展

离子液体是一种结构可调的绿色溶剂,在催化、分离和电化学等领域具有广泛应用,特别是在有机物萃取分离方面,由于其低挥发性及功能可调,避免了传统有机溶剂可能导致的VOCs二次污染,有望成为绿色高效的新型萃取剂。本文系统地综述了离子液体在萃取分离烃类化合物、有机酸、醇类、酚类以及天然产物中的应用研究进展,详细论述了离子液体萃取分离有机物的萃取机理和影响因素,离子液体与溶质分子之间强的氢键、π-π、范德华力以及静电作用使其具有良好的萃取分离能力,表明离子液体是一类可替代有机溶剂实现高效萃取分离有机化合物的潜在溶剂。针对实际工作应用,还需解决其高黏度、高成本等问题,此外萃取后离子液体的回收仍是其大规模应用而需要亟待解决的难题。     

Green synthesis of symmetrical imidazolium based ionic liquids and their application in the preparation of ZnO nanostructures

Environmentally benign procedure for synthesis symmetrical imidazolium based ionic liquids has been achieved. These Ionic liquids dissolved in water have been used as a reaction medium for synthesis of different morphologies of ZnO nanostructures like nanocoral, spherical and nanosheet by reflux method. The structural and optical properties of these ZnO particles were studied by using XRD, SEM and UV–visible. The characteristic results revealed that the anion and cation of ionic liquids effect on band gap and morphology of the zinc oxide species. The results show that the longer alkyl chain at positions 1 and 3 of imidazole ring ionic liquid cause the nanosheet morphology.     

3-硝基-1,2,4-三唑-5-酮烷基咪唑离子液体的合成与表征

以N,N-二烷基咪唑(Cx-imi,x=3,4,5,6)为阳离子,3-硝基-1,2,4-三唑-5-酮(NTO)为阴离子合成了4种离子液体,利用元素分析、红外光谱和核磁共振表征其结构,并测定了其溶解性、密度、热性能和黏度。结果表明,NTO烷基咪唑离子液体在乙腈、N,N-二甲基甲酰胺(DMF)、二甲基亚砜(DMSO)等介电常数较大的有机溶剂中溶解性较好,密度在1.897g/cm3以上,固相到液相的热转变温度在-34.4℃以下,5%的热失重在220℃左右,热稳定性较好。     

Phase Equilibria of Binary and Ternary Systems Containing ILs,Dodecane, and Cyclohexanecarboxylic Acid

This paper reports both the binary and ternary phase behavior of ionic liquids for extracting cyclohexanecarboxylic acid (CCA) from dodecane. This system is a model for the extraction of acids representative of naphthenic acids found in crude oils. In order to develop an effective ternary liquid-liquid extraction system the preliminary selection of ionic liquids was based on CCA miscibility and the dodecane immiscibility with selected ILs. A wide range of ILs based on different cations, anions, cation alkyl-chain length, as well as the effect of temperature on the overall fluid phase behavior is reported. Factors such as variation of cation group, anion effect, alkyl-chain length, and temperature all impact the extraction to various degrees. The largest effects were found to be the lipophilicity of the IL cation and the co-ordination ability of the anion. While CCA capacity increased with lipophilicity of the cation, as did the dodecane. Highly coordinating anions such as trifluoroacetate and triflate demonstrated that highly efficient extraction could be obtained producing favorable tie-lines in the ternary phase diagram. Overall, this study demonstrates that ILs can selectively extract acids from hydrocarbon streams and offers possible treatment solutions for problems associated with the processing of high acid crude oils.

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