Chromatographic determination of biogenic amines in wines after treatment with ionic liquids as novel media

Room temperature ionic liquids (RTIL), 1‐butyl‐3‐methylimidazolium hexafluorophosphate ([C₄MIM][PF₆]), were used as the novel media for derivatization, extraction and preconcentration of biogenic amines (BAs) in wines. Six BAs, tryptamine (Try), phenylethylamine (Phe), putrescine (Put), cadaverine (Cad), tyramine (Tyr) and spermine (Spe) were selected as the model compounds and dansyl chloride (Dns‐Cl) as the derivatizing reagent. The derivatizations of amines were conducted in water‐IL two‐phase system, in which the partition property of related substance in the IL was investigated and the mechanism ( http://www.iciba.com/mechanism/ ) of derivation and extraction of amines was discussed. The influencing factors, including sample volume, derivatizing reagent concentration, pH value and ultrasound reaction time, were optimized. The Dns‐amines were separated by high‐performance liquid chromatography (HPLC), and detected with UVD at 254 nm. For each of the tested amines, a good linearity was obtained in the concentration range of 0.1–20 mg/L with the correlation coefficient (R) of 0.9814–0.9930. The limits of detection reached μg/L level and the relative standard deviations (RSD, n=3) were between 3.2 and 8.1%. Satisfactory recovery for each BA was obtained, ranging from 82.3 to 114.0%. The developed method was successfully applied to determine six BAs in red wines and Chinese yellow wine.     

Synthesis of multi-hydroxyl and sulfonyl dual-functionalized room temperature ionic liquids

Starting from the hydroxylamine (dimethyl amino ethanol, triethanolamine) and 1,3-propane sultone, a series of hydroxyl and sulfonyl dual-functionalized zwitterionic salts and corresponding acidic room temperature ionic liquids have been synthesized. The hydroxyl groups of the synthesized substances were confirmed by the 1H NMR measurement. These zwitterionic salts and ionic liquids may be used for synthesizing other functionalized ionic liquids or ionic liquid-polymer (polyelectrolyte).     

Emission-based optical carbon dioxide sensing with HPTS in green chemistry reagents: room-temperature ionic liquids

We describe the characterization of a new optical CO₂ sensor based on the change in the fluorescence signal intensity of 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) in green chemistry reagents—room-temperature ionic liquids (RTILs). As far as we are aware, this is the first time RTILs, 1-methyl-3-butylimidazolium tetrafluoroborate (RTIL-I) and 1-methyl-3-butylimidazolium bromide (RTIL-II), have been used as matrix materials with HPTS in an optical CO₂ sensor. It should be noted that the solubility of CO₂ in water-miscible ionic liquids is approximately 10 to 20 times that in conventional solvents, polymer matrices, or water. The response of the sensor to gaseous and dissolved CO₂ has been evaluated. The luminescence intensity of HPTS at 519 and 521 nm decreased with the increasing concentrations of CO₂ by 90 and 75% in RTIL-I and RTIL-II, respectively. The response times of the sensing reagents were in the range 1–2 min for switching from nitrogen to CO₂, and 7–10 min for switching from CO₂ to nitrogen. The signal changes were fully reversible and no significant hysteresis was observed during the measurements. The stability of HPTS in RTILs was excellent and when stored in the ambient air of the laboratory there was no significant drift in signal intensity after 7 months. Our stability tests are still in progress.      

Use of 1-alkyl-3-methylimidazolium hexafluorophosphate room temperature ionic liquids as chelate extraction solvent with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione

Possible use of room temperature ionic liquids (RTILs) as chelate extraction solvent was evaluated by using 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF₆]), 1-hexyl-3-methylimidazolium hexafluorophosphate ([hmim][PF₆]) and 1-octyl-3-methylimidazolium hexafluorophosphate ([omim][PF₆]). These RTILs showed high extraction performance for divalent metal cations with 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione (Htta). The extracted metals were back-extracted into 1 mol dm⁻³ nitric acid quantitatively. Furthermore, the extracted species were estimated as neutral hydrated complexes M(tta)₂(H₂O)_n (n= 1 or 2) for M = Ni, Cu and Pb and anionic complexes M(tta)₃⁻ for M = Mn, Co, Zn and Cd.     

室温离子液体催化巯基乙酸异辛酯的合成

巯基乙酸异辛酯是一种广泛应用于精细化工、树脂和塑料制造的中间体,尤其在聚氯乙烯无毒制品中有着重要用途[1],其合成方法的改进也成为研究的主要课题之一。巯基乙酸异辛酯的合成通常采用硫酸催化法[2],由于浓硫酸污染环境、腐蚀设备,特别是近年来环保法规对环境和安全性不断提高的要求,用固体酸(分子筛、离子交换树脂、固体超强酸)等取代H2SO4、HF、A lC l3等强腐蚀性酸作为催化剂的催化工艺获得明显进展[3],但这些催化剂也有自身的缺点[4]。室温离子液体是近年来受到极大关注的一类新材料,它为人们探索环境友好的催化体系和溶剂提供了…     

Electric double layer theory for room temperature ionic liquids on charged electrodes: Milestones and prospects

In this review, we shortly summarize the basic theoretical milestones achieved in the mean-field theory of room temperature ionic liquids on charged electrodes since the publication of Kornyshev's seminal article in 2007. We pay special attention to the behavior of the differential capacitance profile and the microscopic parameters of ions that can have a substantial influence on it. Among them are parameters of short-range specific interactions, ionic diameters, static polarizabilities, and permanent dipole moments. We also discuss the recent ‘nonlocal’ mean-field theories that can describe the overscreening behavior of the local ionic concentrations, as well as the crossover from overscreening to crowding.     

室温离子液体在分离科学研究中的新进展

室温离子液体作为一种重要的绿色溶剂,由于在金属离子、小分子有机物的萃取分离,气体吸附分离以及作为液相和气相色谱固定相等许多分离过程中体现出高分离效率和高选择性的特点,正在成为分离科学研究的前沿领域.着重总结了从2003—2006年的室温离子液体在分离科学领域中的新进展,并对其应用领域和发展前景做了展望.提出进一步加强离子液体的功能化和固定化技术及其在分离科学中的应用基础研究,探索离子液体有效的回收和再循环利用的新方法,是离子液体今后在分离科学研究中的一系列重要内容.     

Tetraalkylphosphonium-based ionic liquids

Ionic liquids are salts that are liquid at or near room temperature. Their wide liquid range, good thermal stability, and very low vapor pressure make them attractive for numerous applications. The general approach to creating ionic liquids is to employ a large, unreactive, low symmetry cation with and an anion that largely controls the physical and chemical properties. The most common cations used in ionic liquids are N-alkylpyridinium and N,N′-dialkylimidazolium. Another very effective cation for the creation of ionic liquids is tetraalkylphosphonium, [PR₁R₂R₃R₄]⁺. The alkyl groups, R_n, generally are large and not all the same. The halide salts of several phosphonium cations are available as starting materials for metathesis reactions used to prepare ionic liquids. The large phosphonium cations can combine with relatively large anions to make viscous but free flowing liquids with formula mass greater than 1000 g mol⁻¹. Some other more massive salts are waxes and glasses. The synthesis and the physical, chemical, and optical properties of phosphonium-ionic liquids having anions with a wide range of masses were measured and are reported here.     

两种咪唑类室温离子液体对Te纳米棒状结构生长的影响

分别以2种咪唑类室温离子液体为溶剂,通过简单的还原反应制备了碲(Te)一维纳米材料.利用X射线衍射(XRD)、透射电镜(TEM)和选区电子衍射(SAED)对样品进行了表征,并初步探讨了2种咪唑类室温离子液体对Te生长的影响.此外,实验中发现同时加入聚乙烯吡咯烷酮(PVP)和室温离子液体可以得到Te束状结构.     

The Mediated Detection of Hydrogen Sulfide in Room Temperature Ionic Liquids

The detection of H₂S was studied using several mediators in room temperature ionic liquids (RTILs) at a microelectrode. Each mediator was characterised voltammetrically, and H₂S was added to observe if any mediation took place. A successful mediator was 3,5‐tert‐butyl‐obenzoquinone. Cyclic voltammetry was carried out in [C₂mim][NTf2]. A reductive wave was observed and attributed to the two‐electron reduction of the mediator. No oxidative signal was observed. H₂S was flowed through the system. Cyclic voltammograms showed a decrease in the reductive wave of the mediator and the onset of an oxidative signal due to the reaction between the mediator and H₂S to form an adduct. This reaction is reversible and on purging the system with N₂, the original reductive signal of the mediator was recovered.     

Direct electrochemistry and electrocatalysis of myoglobin immobilized in hyaluronic acid and room temperature ionic liquids composite film

A novel biocomposite film based on hyaluronic acid (HA) and hydrophilic room temperature ionic liquid 1-ethyl-3-methyl-imidazolium tetrafluoroborate ([EMIM][BF₄]) was explored. Here, HA was used as a binder to form [EMIM][BF₄]-HA composite film and help [EMIM][BF₄] to attaching on glass carbon electrode (GCE) surface, while doping [EMIM][BF₄] in HA can effectively reduce the electron transfer resistance of HA. The composite film can be readily used as an immobilization matrix to entrap myoglobin (Mb). A pair of well-defined and quasi-reversible redox peaks of Mb was obtained at the Mb-[EMIM][BF₄]-HA composite film modified GCE (Mb-[EMIM][BF₄]-HA/GCE) through direct electron transfer between Mb and the underlying electrode. The Mb-[EMIM][BF₄]-HA/GCE showed an excellent electrocatalytic activity toward the reduction of H₂O₂. Based on the [EMIM][BF₄]-HA biocomposite film, a third-generation reagentless biosensor could be constructed for the determination of H₂O₂.     

Selective fluorescence quenching of polycyclic aromatic hydrocarbons by nitromethane within room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate

Recently discovered room temperature ionic liquids (RTILs) show tremendous promise to replace volatile organic compounds (VOCs). Investigation of these RTILs as solvents is in the very early stages. Before the full potential of these RTILs is realized, much more information about them as solvent systems must be obtained. The applicability of one such RTIL, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM PF₆), as a solvent toward analysis for polycyclic aromatic hydrocarbons (PAHs) is explored. The steady-state emission behavior of six PAHs along with the fluorescence quenching by nitromethane within BMIM PF₆ is investigated. The steady-state emission of six PAHs showed a bathochromic shift in BMIM PF₆ compared to acetonitrile, indicating possibly a more dipolar environment. Further, the nitromethane quenching of PAH emission strongly suggests a selective nature as the emission from alternant PAHs are quenched while that from nonalternant PAHs is not. The PAH-nitromethane quenching behavior within BMIM PF₆ is compared with that observed in the polar aprotic solvent acetonitrile, and a polar and similar viscosity (to BMIM PF₆) solvent system, 90 wt.% glycerol in water. It is observed that the PAH-nitromethane quenching within BMIM PF₆ and 90 wt.% glycerol in water is less efficient than in acetonitrile. This observation is suggested to arise from solvent viscosity.     

Peptide synthesis in room temperature ionic liquids

We demonstrate that chemical peptide coupling using modern coupling agents is efficient in rt ionic liquids. This new approach presents some advantages, especially in the case of hindered amino acids, which are not easy to couple under standard conditions, since high purities for the crude peptides were observed with respect to coupling in classical solvents.     

An efficient and green sonochemical synthesis of some new eco-friendly functionalized ionic liquids

Considerable stress to replace a lot of volatile organic compounds which were used as solvents in synthetic organic chemistry has been done for many chemical industries. A suitable solution for these problems is found by using the ionic liquids as a clean medium of working and avoiding the solvent effect. The present work describes a facile and green ultrasound-assisted procedure as an environmentally friendly alternative to traditional methods for the preparation of a series of 26 new functionalized imidazolium-based ionic liquids. Their structures were characterized by FT-IR, ¹H, ¹³C, ¹¹B, ¹⁹F, ³¹P NMR and mass spectra.     

室温离子液体协同增敏浊点萃取分光光度法测定痕量镉

本文建立了离子液体协同增敏浊点萃取-紫外可见分光光度法测定痕量镉的方法。离子液体和二硫代氨基甲酸钠(DDTC)分别用作增敏剂和络合剂,离子液体的加入能使测定镉的方法灵敏度提高3.2倍。非离子表面活性剂TritonX-100用作提取剂,当样品体系的温度高于TritonX-100的浊点温度时,镉与DDCT形成的络合物被萃取到TritonX-100中,经相分离紫外可见分光光度计检测。考查了离子液体,DDTC和TritonX-100的浓度、溶液酸度、干扰离子等实验条件对浊点萃取效率的影响。在最优化的实验条件下,测量镉的线性范围为1～100 ng·mL-1,方法的检出限为0.1 ng·mL-1,相对标准偏差RSD为4.3%,富集系数为96。该方法应用于测定于水样中的痕量镉具有满意的效果。     

Synthesis and preliminary use of novel acrylic ester-derived task-specific ionic liquids

Novel electrophilic alkenes bearing an ionic liquid-type appendage have been prepared and used in Diels-Alder cycloadditions, 1,4-additions, Heck couplings and Stetter reactions; this new type of support allows easy monitoring of the reactions by NMR and MS as well as simple and efficient work-up and isolation procedures.     

Partition coefficients of organic compounds in new imidazolium based ionic liquids using inverse gas chromatography

Partition coefficients of organic compounds in four ionic liquids: 1-ethanol-3-methylimidazolium tetrafluoroborate, 1-ethanol-3-methylimidazolium hexafluorophosphate, 1,3-dimethylimidazolium dimethylphosphate and 1-ethyl-3-methylimidazolium diethylphosphate were measured using inverse gas chromatography from 303.3 to 332.55 K. The influence of gas–liquid and gas–solid interfacial adsorption of different solutes on ionic liquids was also studied. Most of the polar solutes were retained largely by partition while light hydrocarbons were retained predominantly by interfacial adsorption on the ionic liquids studied in this work. The solvation characteristics of the ionic liquids were evaluated using the Abraham solvation parameter model.     

Synthesis of poly(glycolic acid) in ionic liquids

The synthesis of poly(glycolic acid) (PGA) by polyesterification of glycolic acid was studied using ionic liquids, mainly 1,3‐dialkylimidazolium salts, as reaction media. The ¹H NMR spectra of PGA oligomers were assigned and end‐group signals were used to follow the reaction. Low PGA yields were obtained by the direct polyesterification of glycolic acid at 200–240 °C, because of monomer evaporation during the reaction. On the other hand, PGAs of DP _n up to 45 were obtained by the postpolycondensation of a preformed oligomer in 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)amide (BMIm⁺Tf₂N^?). The precipitation of PGA in reaction medium at long reaction times limited the achievable molar mass. Rate constants were determined for catalyzed and noncatalyzed reactions, assuming a second‐order reaction mechanism. The efficiency of esterification catalysts such as Zn(OAc)₂ was low in these media, as only about twofold increases in reaction rate were observed. This was assigned to the preferential interaction of Zn²⁺ with ionic liquid anion instead of the polymer carboxylic acid end‐groups. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3025–3035, 2006     

Recent developments of task-specific ionic liquids in organic synthesis

Abstract

Task-specific ionic liquids (TSILs) have received increased attention over the past few years as it is possible to form any specific ionic liquid (IL) composition depending upon user's need of the desired physical, chemical, and biological properties. These fascinating materials have shown promising results in various areas such as organic synthesis, catalysis, and specially recent emerging trend of use as functionalized ILs for chiral and nanoparticle synthesis. Present review gives an update of recent developments in the field of TSILs with emphasis on their applications in organic synthesis.