Determination of Homologue Imidazolium Ionic Liquid Cations by Ion Chromatography Using a Carboxyl Acid Cation-Exchange Column with Direct Conductivity Detection

An investigation into the determination of four imidazolium ionic liquid cations by ion chromatography using a carboxyl acid cation exchange column and direct conductivity detection was carried out. This research has developed a simple, selective, and accurate ion chromatographic method for separation of imidazolium ionic liquid cations. Detection limits (S/N = 3) for the cations were 3.2–24.3 mg/L. Relative standard deviations (RSD, n = 5) for peak areas were less than 1.6%. The method has been successfully applied to the determination of two ionic liquids synthesized by organic chemistry lab.     

Determination of Imidazolium Ionic Liquid Cations by Ion-Pair Chromatography Using a Monolithic Column and Direct Conductivity Detection

Determination of four imidazolium ionic liquid cations by ion-pair chromatography was carried out using direct conductivity detection. Chromatographic separations were performed on a silica-based monolithic column with 1-heptanesulfonic acid sodium + acetonitrile + citric acid as eluent. Carbon number rule and influence of acetonitrile on the retention of imidazolium cations were discussed. Detection limits (S/N = 3) for the cations were 2.1–55.9 mg L^?1. Relative standard deviations (RSD, n = 5) for peak areas were less than 3.0%. The method has been successfully applied to the determination of two ionic liquids synthesized by organic chemistry lab.     

离子色谱-直接电导检测法分离测定吗啉离子液体阳离子

建立了离子色谱-直接电导检测法分析N-甲基乙基吗啉([MEMo]+)、N-甲基丙基吗啉([MPMo]+)2种吗啉离子液体阳离子的方法。采用磺酸型阳离子交换色谱柱,以乙二胺-乙腈为流动相,研究了色谱柱、流动相、色谱柱温度对吗啉阳离子保留的影响,并讨论了保留规律。结果表明,吗啉阳离子的保留基本属于离子交换模式,是一个放热过程。在柱温30℃,流速1.0 mL/min,以0.1 mmol/L乙二胺-0.5%乙腈(用盐酸调节至pH 5.0)为流动相条件下,[MEMo]+和[MPMo]+阳离子可在4 min内得到基线分离,检出限(S/N=3)分别为0.08、0.13 mg/L,峰面积的相对标准偏差(RSD,n=5)不大于1.5%。将此方法用于测定实验室合成的吗啉离子液体样品,加标回收率为94.0%～106.0%。方法准确、可靠、快速,具有较好的实用性,可满足离子液体样品的检测要求。     

离子液体中卤素离子杂质的离子色谱-直接电导检测法分析

研究了离子色谱-直接电导检测法分离测定离子液体中的卤素离子(F~-、Cl~-、Br~-)杂质.采用Shim-pack IC-A3阴离子交换色谱柱,考察了淋洗液种类及浓度、流速和色谱柱温度对分离测定的影响.最佳色谱条件为:以1.25 mmol/L邻苯二甲酸氢钾为淋洗液,流速1.5 mL/min,色谱柱温45 ℃.在此条件下可以基线分离卤素离子,且NO~-_3、BF~-_4、SO~(2-)_4不干扰测定.该法测定卤素离子的检出限(S/N=3)为0.02 ～0.11 mg/L,峰面积的相对标准偏差(n=5)不大于0.7%,F~-、Cl~- 和Br~- 的标准曲线的线性范围分别为0.1 ～50、0.1 ～50、0.5 ～100 mg/L.将方法用于烷基咪唑四氟硼酸盐离子液体中卤素离子杂质的测定,加标回收率为98% ～102%.     

吡啶离子液体阳离子的离子色谱法分析

建立了离子色谱-直接电导检测法分离测定3种吡啶离子液体阳离子(N-乙基吡啶、N-丁基吡啶和N-己基吡啶阳离子)的方法.采用磺酸型阳离子交换色谱柱,以乙二胺-柠檬酸-乙腈为淋洗液,考察了淋洗液种类和浓度以及色谱柱温度对离子液体阳离子保留的影响.实验发现,吡啶阳离子的保留过程是放热过程,其同系物的保留符合碳数规律.优化的色...     

IC Determination of Halide Impurities in Ionic Liquids

An ion chromatographic (IC) method has been developed for determination of trace levels of halide impurities in various types of ionic liquids (ILs). The advantage of this method is that all relevant halide species can be measured in a single chromatographic analysis. Separation of halides was performed on a Dionex AS9-HC column using an eluent consisting of 20 mM NaOH and 10% (v/v) acetonitrile, delivered at 1.5 mL min⁻¹. Using this eluent, fluoride, chloride and bromide were well resolved from each other, but iodide was co-eluted with tetrafluoroborate (BF₄⁻) present as a counter-anion in tetrafluoroborate-based ILs. The same eluent was also used successfully for the determination of halides in highly hydrophobic ILs, such as those based on bis-(trifluoromethanesulfonyl)imide (TFSI⁻) and bis-perfluoroethylsulfonylimide (BETI⁻). In this case, 50% (v/v) acetonitrile aqueous was needed to dissolve the sample before injection, and this did not adversely affect the separation. Detection limits in the measured solution were 0.1, 0.2 and 1.0 ppm for chloride, bromide and iodide, respectively, by conductivity detection, and 0.02 ppm for iodide by UV detection.     

Toxicity Measurement of Imidazolium Ionic Liquids Using Acute Toxicity Test

Ionic liquids (ILs) can be considered as environmentally friendly solvent, but they have the ability to dissolve in water and accumulate in the environment. Therefore, the toxicity of ILs should be assessed in order to prevent their harm to human and environment. This study was carried out to investigate the toxicity of ILs towards marine and freshwater fish. Three ILs have been tested, which are 1-Butyl-3-methylimidazolium hydrogen sulfate and 1-Butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide toward marine fish and 1-Hexyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide toward freshwater fish. Two different marine fish were employed, which are: Cephalopholis cruentata (grouper) and Lates calcarifer (barramundi). For freshwater fish, male Poecilia reticulate (guppy) was employed. The toxicity tests were conducted according to OECD (Organisation for Economic Cooperation and Development) guideline 203. For 1-Butyl-3-methylimidazolium hydrogen sulphate [BMIM][HSO4], the median lethal concentration (LC50) estimated toward Cephalopholis cruentatato be 199.98 mg.L^-1. For 1-Butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide [BMIM][TFSI], LC50 estimated toward LatesCalcariferto be 374.11 mg.L^-1. While, for 1-Hexyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, [HMIM][NTf2], LC50 estimated toward Poecilia Reticulate to be 207.49 mg.L^-1. All the LC50 values obtained can be identified as practically nontoxic liquids based on Acute Toxicity Rating Scale by Fish and Wildlife Service (FWS). As to our knowledge, there is no previous reported toxicity studies of [BMIM][HSO4] and [BMIM][TFSI] on marine fish and [HMIM] [NTf2] on freshwater fish. Thus, this paper can be used as a benchmark for researchers who are dealing with these three ILs.     

聚合物在咪唑类离子液体中的溶解

离子液体（ILs）具有难挥发、热稳定、宽液程和高电导率等独特优点,在聚合物领域中的应用受到越来越多的关注。由于ILs内部的复杂相互作用力,ILs的溶剂化能力还不能像分子溶剂那样有定量的方法来表征,特别是ILs与聚合物的相容性没有一个统一的判据。本文从咪唑基ILs内部的四个主要相互作用力出发,简述了ILs内部的相互作用对...     

离子对色谱法同时分离测定吡啶及咪唑离子液体阳离子

建立了用紫外检测的反相离子对色谱梯度淋洗同时分离测定4种吡啶离子液体阳离子和5种咪唑离子液体阳离子的方法。实验采用ZORBAX Eclipse XDB-C18反相色谱柱,以离子对试剂水溶液(用柠檬酸调节pH值)+乙腈为流动相,考察了离子对试剂种类和浓度、乙腈浓度和色谱柱温度对保留的影响,探讨了相关保留规律,确定最佳色谱条件为:流速1.0 mL/min、柱温30℃,以1.0 mmol/L庚烷磺酸钠水溶液(pH 4.0)-乙腈为淋洗液进行梯度洗脱。在此条件下,4种吡啶阳离子和5种咪唑阳离子在15 min内达到基线分离。检出限(S/N=3)为0.31～0.54 mg/L,峰面积的相对标准偏差为0.10%～0.75%。将该方法用于实验室合成的离子液体样品分析,加标回收率为94%～98%。该方法准确、可靠,具有较好的实用性。     

Extraction of Metal Ions from Aqueous Solutions Using Imidazolium Based Ionic Liquids

This article represents a step towards how to choose an ionic liquid as the solvent to improve metal ion (Ag⁺ and Pb²⁺) extraction. The liquid-liquid solvent extraction is proposed with the following imidazolium ionic liquids (ILs): 1-ethyl-3-ethylimidazolium, or 1-butyl-3-ethylimidazolium, or 1-hexyl-3-ethylimidazolium bis{(trifluoromethyl)sylfonyl}imide [EEIM][NTf₂], or [BEIM][NTf₂], or [HEIM][NTf₂], or 1-butyl-3-ethylimidazolium hexafluorophosphate [BEIM][PF₆], or 1-hexyl-3-ethylimidazolium hexafluorophosphate [HEIM][PF₆] and the popular 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF₆] for comparison. The effect of anion type (NTf₂⁻ versus PF₆⁻) and the effect of structural components of an ionic liquid including alkyl chain length at the cation and the ethyl substituent instead methyl at the cation, on the extraction and re-extraction processes by using dithizone as a metal chelator, were studied at 296 K. Dithizone was employed to form neutral metal-dithizone complexes with heavy metal ions to extract them from aqueous solution into the ILs. Electronic Supplementary Material  The online version of this article () contains supplementary material, which is available to authorized users. Presented at the 236th ACS National Meeting, August 17–21, Philadelphia, USA.     

离子色谱-直接电导检测法测定离子液体的阴离子p-甲苯磺酸根

建立了离子液体阴离子p-甲苯磺酸根的离子色谱-直接电导检测分析方法。采用Shim-pack IC-A3季铵型阴离子交换色谱柱,考察了流动相种类和色谱柱温度对分离测定p-甲苯磺酸根的影响。确定最佳色谱条件为:以1.2 mmol/L柠檬酸-15%乙腈混合水溶液(pH 5.0)为流动相,流速1.0 mL/min,柱温45℃。在此条件下,p-甲苯磺酸根与常见无机阴离子(氟离子、氯离子、溴离子和硝酸根)可以获得很好的分离。该方法测定p-甲苯磺酸根的线性范围为4～100 mg/L,检出限(S/N=3)为1.22 mg/L,保留时间和峰面积的相对标准偏差(n=5)分别为0.42%和1.8%。将方法用于离子液体中p-甲苯磺酸根的测定,加标回收率为99.6%。     

Multifunctional Characteristics of Carbon Fibers Modified with Imidazolium Ionic Liquids

A multifunctional designing approach is of great importance for advanced composite applications. This study assessed the use of ionic liquids (ILs) to modify the surface of carbon fiber (CF) and impart multifunctional characteristics to it. For that, ethanolic solutions of different ILs, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium chloride and 1-(2-hydroxyethyl)-3-methylimidazolium chloride, at different concentrations, were used to treat the CF. Fourier-transform infrared spectroscopy confirmed the presence of IL on the CF surface. The contact angle for 1% w/v IL-treated CF and DGEBA epoxy decreased by up to 35%, corresponding to an increase in surface energy of fiber, accompanied by an increase of 91% in interfacial shear strength. These enhancements were achieved with the hydroxy-functionalized IL, showing the tunability of CF properties through the N-imidazolium substituent. An increase in crystallite size along the basal plane was also found due to the ordering of the graphitic structure on the surface. Moreover, there was a decrease in electrical resistivity of 77%. In all, the imidazolium ILs were considered a promising approach to induce multifunctional characteristics, namely enhanced interfacial strength and electrical conductivity, to unsized CF, which can also be beneficial for recycled fibers without deteriorating their inherent surface properties.     

Determination of Hexafluorophosphate Ionic Liquid Anion by Reversed-phase Ion-pair Chromatography Coupled with Direct Conductivity Detection

建立了反相离子对色谱-直接电导检测六氟磷酸根(PF6-)离子液体阴离子的分析方法.用Diamonsil C18反相色谱柱为分离柱,以离子对试剂-柠檬酸-乙腈混合水溶液为流动相,考察了离子对试剂、乙腈含量、pH值及色谱柱温度对六氟磷酸根保留的影响,并讨论了相关保留机理.在优化的色谱条件下,即流动相为0.05 mmol/L氢氧化四丁铵-0.038 mmol/L柠檬酸- 35％乙腈(pH5.5),流速1.0 mL/min,色谱柱温度40℃时,PF6-与其它常见阴离子(F-、Clˉ、Brˉ、NO3ˉ、SO42-、BF4-)达到基线分离且保留时间在15 min内.方法检出限(S/N=3)为0.25mg/L,标准曲线的线性范围为0.5～ 100.0 mg/L,峰面积和保留时间的相对标准偏差(n=5)分别为0.17％和0.15％.该法用于1-丁基-3-甲基咪唑六氟磷酸盐和1-丙基-2,3-二甲基咪唑六氟磷酸盐两种离子液体中PF6-的测定,加标回收率分别为99％和104％.该方法简单、准确、可靠,实用性好.     

1,3-二取代咪唑类离子液体熔点预测

以16种咪唑类四氟硼酸盐和22种咪唑类六氟磷酸盐为研究对象, 采用QSAR(quantitative structure-activity relationship)方法和遗传算法对其熔点与结构的定量构效关系进行了研究, 以实现对两类咪唑类离子液体熔点的预测. 建立的咪唑类四氟硼酸盐三参数模型相关系数R2为0.89, 咪唑类六氟磷酸盐四参数模型相关系数R2为0.85; 使用留一法对两模型进行内部验证的相关系数R2分别为0.82和0.77, 两预测模型具有真实有效性; 使用测试集对两模型进行外部验证, 所得两模型的平均预测绝对误差分别为11.43和7.78 K, 优于文献报道水平, 可得出结论, 两模型均具有较好的熔点预测能力.     

Pseudohalogen Chemistry in Ionic Liquids with Non-innocent Cations and Anions

Within the second funding period of the SPP 1708 “Material Synthesis near Room Temperature”,which started in 2017, we were able to synthesize novel anionic species utilizing Ionic Liquids (ILs) both, as reaction media and reactant. ILs, bearing the decomposable and non-innocent methyl carbonate anion [CO₃Me]⁻, served as starting material and enabled facile access to pseudohalide salts by reaction with Me₃Si−X (X=CN, N₃, OCN, SCN). Starting with the synthesized Room temperature Ionic Liquid (RT-IL) [nBu₃MeN][B(OMe)₃(CN)], we were able to crystallize the double salt [nBu₃MeN]₂[B(OMe)₃(CN)](CN). Furthermore, we studied the reaction of [WCC]SCN and [WCC]CN (WCC=weakly coordinating cation) with their corresponding protic acids HX (X=SCN, CN), which resulted in formation of [H(NCS)₂]⁻ and the temperature labile solvate anions [CN(HCN)_n]⁻ (n=2, 3). In addition, the highly labile anionic HCN solvates were obtained from [PPN]X ([PPN]=μ-nitridobis(triphenylphosphonium), X=N₃, OCN, SCN and OCP) and HCN. Crystals of [PPN][X(HCN)₃] (X=N₃, OCN) and [PPN][SCN(HCN)₂] were obtained when the crystallization was carried out at low temperatures. Interestingly, reaction of [PPN]OCP with HCN was noticed, which led to the formation of [P(CN)₂]⁻, crystallizing as HCN disolvate [PPN][P(CN⋅HCN)₂]. Furthermore, we were able to isolate the novel cyanido(halido) silicate dianions of the type [SiCl_0.78(CN)_5.22]²⁻ and [SiF(CN)₅]²⁻ and the hexa-substituted [Si(CN)₆]²⁻ by temperature controlled halide/cyanide exchange reactions. By facile neutralization reactions with the non-innocent cation of [Et₃HN]₂[Si(CN)₆] with MOH (M=Li, K), Li₂[Si(CN)₆] ⋅ 2 H₂O and K₂[Si(CN)₆] were obtained, which form three dimensional coordination polymers. From salt metathesis processes of M₂[Si(CN)₆] with different imidazolium bromides, we were able to isolate new imidazolium salts and the ionic liquid [BMIm]₂[Si(CN)₆]. When reacting [Mes(nBu)Im]₂[Si(CN)₆] with an excess of the strong Lewis acid B(C₆F₅)₃, the voluminous adduct anion {Si[CN⋅B(C₆F₅)₃]₆}²⁻ was obtained.     

Modeling of Ionic Conductivity in Inorganic Compounds with Multivalent Cations

Russian Journal of Electrochemistry - This work is dedicated to search for promising ion-conducting crystals by using of high-throughput computer screening of the ICSD database of inorganic...     

反相离子对色谱-直接电导检测法分析六氟磷酸根离子液体阴离子

建立了反相离子对色谱-直接电导检测六氟磷酸根(PF6-)离子液体阴离子的分析方法。用DiamonsilC18反相色谱柱为分离柱,以离子对试剂-柠檬酸-乙腈混合水溶液为流动相,考察了离子对试剂、乙腈含量、pH值及色谱柱温度对六氟磷酸根保留的影响,并讨论了相关保留机理。在优化的色谱条件下,即流动相为0.05 mmol/L氢氧化四丁铵-0.038 mmol/L柠檬酸-35%乙腈(pH 5.5),流速1.0 mL/min,色谱柱温度40℃时,PF6-与其它常见阴离子(F-、Cl-、Br-、NO3-、SO24-、BF4-)达到基线分离且保留时间在15 min内。方法检出限(S/N=3)为0.25 mg/L,标准曲线的线性范围为0.5～100.0 mg/L,峰面积和保留时间的相对标准偏差(n=5)分别为0.17%和0.15%。该法用于1-丁基-3-甲基咪唑六氟磷酸盐和1-丙基-2,3-二甲基咪唑六氟磷酸盐两种离子液体中PF6-的测定,加标回收率分别为99%和104%。该方法简单、准确、可靠,实用性好。     

以咪唑离子液体为紫外吸收试剂的高效液相色谱/间接紫外检测法分离测定烷基磺酸盐

建立了以咪唑离子液体为背景紫外吸收试剂间接检测无紫外光吸收的烷基磺酸盐的高效液相色谱法。该方法采用反相C18色谱柱,以咪唑离子液体-有机溶剂为流动相,实现了2种烷基磺酸盐的分离和检测。研究了检测波长、有机溶剂和咪唑离子液体种类、浓度、pH值等因素对分离和测定的影响,探讨了保留规律,优化了色谱条件。结果表明,在柱温30℃,流速1.0 mL/min,检测波长210 nm,以0.7 mmol/L 1-乙基-3-甲基咪唑四氟硼酸盐水溶液(2 mmol/L磷酸二氢钠-磷酸调至pH 3.0)-甲醇(55∶45)作为流动相,戊烷磺酸钠和庚烷磺酸钠可在10 min内完全分离,线性范围分别为0.8~200 mg/L和2.5~200 mg/L,线性系数均达到0.999以上,检出限分别为0.24,0.75 mg/L。将方法应用于环境水样的测定,加标回收率为98.3%~99.1%,相对标准偏差小于1.5%。该方法准确、可靠,可以满足定量分析的要求。     

Diffusion Coefficients of Imidazolium Based Ionic Liquids in Aqueous Solutions

Diffusion coefficients of the ionic liquids [C₂MIM][EtSO₄], [C₄MIM][OcSO₄], [C₂MIM][NTf₂] and [C₄MIM][NTf₂] in water at high dilution have been measured using the Taylor dispersion technique. Data on the diffusion coefficients have been obtained for each solute at six temperatures between 288 and 313 K. The data have been fitted by the Arrhenius equation and activation energies of diffusion have been determined. Effective radii of the ionic liquid molecules have also been obtained using the Stokes–Einstein relationship.     

UPLC a Powerful Tool for the Separation of Imidazolium Ionic Liquid Cations

Ultra-performance liquid chromatography (UPLC) in reversed-phase (RP), ion pair (IP) and hydrophilic interaction chromatography (HILIC) has been investigated for the separation of imidazolium-based ionic liquid (IL) cations. Among the three stationary phases (i.e., C18, C8 and phenyl) studied under RP conditions the phenyl phase provided much stronger retention for the IL cations. Four acids (hydrochloric, methanesulfonic, perchloric and trifluoroacetic) as mobile phase additives were compared in light of their effects on the retention of IL cations. It was shown that the retention of all IL cations decreased upon acidification of the mobile phase, possibly due to suppression of residual silanol ionization. Very fast (~3 min) and efficient RP-UPLC separation of six cations was achieved by gradient elution with acetonitrile?Cwater mobile phase containing 2.5 mmol L^?1 perchloric acid. In IP-UPLC all solutes were well resolved in about 4 min by gradient elution with acetonitrile?Cwater mobile phase containing 1 mmol L^?1 sodium 1-octanesulfonate as ion pairing reagent. Finally, under HILIC conditions by using isocratic elution with acetonitrile?Cwater (85:15, v/v) mobile phase containing 5 mmol L^?1 ammonium formate (pH 3.2) the separation time was reduced to less than 2 min while maintaining excellent peak shapes and sufficient resolution. Compared to current LC systems UPLC allowed considerably faster separations with better peak shapes.