Preparation of Ionic Liquid‐based Vilsmier Reagent from Novel Multi‐purpose Dimethyl Formamide‐like Ionic Liquid and Its Application

In continuation of research to explore the applied potential of DMF‐like ionic liquid, the ionic liquid version of N,N‐dimethyliminiumchloride (Vilsmier reagent) has been synthesized from DMF‐like ionic liquid and tested effectively for its capacity to achieve more useful organic transformations. The results show that DMF‐like ionic liquid is world's first task specific ionic liquid which has catalyzed numerous diverse type of reaction and is multipurpose in its application. Thus a new term for this DMF‐like ionic liquid has been coined that is DMF‐like "multipurpose" ionic liquid.     

Ionic Liquids as Reagent and Reaction Medium: Preparation of Alkyl Aryl Ethers

Summary. Room temperature ionic liquid, [bmIm]OH, is used as a green recyclable reaction medium and reagent for the alkylation of phenols in excellent yields. The recovered ionic liquid was reused five to six times with consistent activity.     

Task-Specific Ionic Liquid as Reagent and Reaction Medium for the One-Pot Horner–Wadsworth–Emmons–Type Reaction Under Microwave Irradiation

A task-specific imidazolium-based phosphinite ionic liquid (IL-OPPh₂) was used as the dual solvent–reagent for the synthesis of E-cinamates and coumarin derivatives via the one-pot Horner–Wadsworth–Emmons–type reaction. The ionic liquid containing its corresponding phosphinite moiety was reacted with α-chloro esters and benzaldehyde or salicylaldehyde derivatives in the presence of sodium methoxide under microwave irradiation to produce the related E-cinamates or coumarins, respectively. The satisfactory results were obtained with good yields, short reaction time, and simple experimental procedure.     

离子液体载催化剂和载试剂在有机合成中的应用

综述了离子液体载催化剂和载试剂在有机合成中的应用进展. 离子液体载催化剂是针对离子液体中催化剂难以回收利用的问题提出来的, 它不仅可以实现均相催化, 而且反应产物容易分离, 催化剂可以循环使用. 离子液体载有机试剂合成, 又称为离子液体相有机合成, 具有固相反应产物纯度高和液相反应反应快的优点. 在离子液体载无机试剂的反应中, 反应物毒性降低, 反应条件温和, 产物选择性好.     

A new diphenylphosphinite ionic liquid (IL-OPPh2) as reagent and solvent for highly selective bromination, thiocyanation or isothiocyanation of alcohols and trimethylsilyl and tetrahydropyranyl ethers

A new diphenylphosphinite ionic liquid (IL-OPPh₂) is introduced. This ionic liquid is used as both a reagent and a solvent to convert alcohols and trimethylsilyl and tetrahydropyranyl (THP) ethers into their corresponding alkyl bromides, thiocyanates or isothiocyanates in the presence of Br₂ and SCN⁻ at 80 °C. In this ionic liquid, bromination and thiocyanation of alcohols occurs highly selectively in the presence of trimethylsilyl and THP-ethers and also between different classes of alcohols. The use of this ionic liquid allows easy separation of the desired products from the phosphinate by-product.     

Determination of Gold by Flame Atomic Absorption Spectrometry with Hollow Fiber Liquid Phase Microextraction Using Room Temperature Ionic Liquids

A novel method to preconcentrate gold was developed employing a synergistic enhancement of a room temperature ionic liquid combined with hollow fiber liquid phase micro-extraction with flame atomic absorption spectrometry detection. The method is based on the complexation of gold with dithizone. The formed hydrophobic complex was subsequently extracted into the lumen of a hollow fiber. The organic phase was siphoned into FAAS for the determination. A room temperature ionic liquid and dithizone were used the enhancement reagent and chelating reagent, respectively. The addition of a room temperature ionic liquid led to a five-fold improvement in the extraction of gold. The 1-octanol was immobilized in the pores of the polypropylene hollow fiber as the liquid membrane and was also used as the acceptor solution. Some parameters that influenced extraction and determination were evaluated in detail, such as concentrations of the ionic liquid and dithizone, pH of samples, stirring rates, extraction time, and interferences. Under optimized conditions, a detection limit of 0.9 ng mL^?1 and an enrichment factor of 130 were achieved. The relative standard deviation (RSD) was 3.7% for Au (40 ng mL^?1, n = 5). The proposed method was successfully applied to the determination of gold in certified reference environmental samples and ore samples with satisfactory results.     

Determination of triclosan by cuvetteless UV–vis micro-spectrophotometry following simultaneous ultrasound assisted emulsification–microextraction with derivatization: Use of a micellar-ionic liquid as extractant

Two ultrasound-assisted emulsification–microextraction procedures based on the use of a micellar ionic liquid as extractant are proposed for triclosan determination in troublesome matrices such as cosmetics and wastewaters. Microvolume UV–vis spectrophotometry was used in order to quantify the yellow azoderivative formed. This compound is polar and water-soluble and hence, it is not extractable into conventional organic solvents. Two imidazolium based ionic liquids were used as extractants. An improvement in the extraction of the derivative was achieved when SDS was mixed with the ionic liquid. The use of ultrasound energy allows a fast emulsification of the system. All the parameters related to the emulsification–microextraction were carefully optimized (i.e., ionic liquid type and volume, SDS concentration, sonication time and amplitude, salt addition, disperser solvent, cooling of ionic liquid and centrifugation time). Matrix effects were assessed and external calibration was used in all cases. Several advantages such as high sample throughput, simplicity and low reagent consumption can be emphasized.     

Amberlyst-15® in ionic liquid: an efficient and recyclable reagent for the benzylation and hydroalkylation of β-dicarbonyl compounds

Benzylation and hydroalkylation of 1,3-dicarbonyl compounds using Amberlyst-15 immobilized in ionic liquid [Bmim][PF₆] as an efficient reusable reagent was studied. The reagent was compared with other solid acid reagents along with role of the ionic liquid. The effect of various reaction parameters like type of reagent, solvent, substrate molar ratio, reaction time, and temperature were studied. Present protocol is advantageous due to the ease in handling of reagent, simple work-up procedure, economical and environmentally benign process. The products were obtained in good to excellent yield and applicable to wide variety of substrates.     

Task specific ionic liquid as solvent,catalyst and reagent for regioselective ring opening of epoxides in water

Task specific ionic liquid as a novel and environmental eco-friendly green catalyst has been synthesized and used in the ring opening of epoxides under green conditions. This ionic liquids as solvent, catalyst and reagent afforded the corresponding thiocyanohydrins and azidohydrines with good regioselectivity and very short reaction times. The desired thiocyanohydrins and azidohydrines in 83–93% isolated yields.     

Rapid analysis of ultraviolet filters using dispersive liquid–liquid microextraction coupled to headspace gas chromatography and mass spectrometry

An ionic‐liquid‐based in situ dispersive liquid–liquid microextraction method coupled to headspace gas chromatography and mass spectrometry was developed for the rapid analysis of ultraviolet filters. The chemical structures of five ionic liquids were specifically designed to incorporate various functional groups for the favorable extraction of the target analytes. Extraction parameters including ionic liquid mass, molar ratio of ionic liquid to metathesis reagent, vortex time, ionic strength, pH, and total sample volume were studied and optimized. The effect of the headspace temperature and volume during the headspace sampling step was also evaluated to increase the sensitivity of the method. The optimized procedure is fast as it only required ∼7–10 min per extraction and allowed for multiple extractions to be performed simultaneously. In addition, the method exhibited high precision, good linearity, and low limits of detection for six ultraviolet filters in aqueous samples. The developed method was applied to both pool and lake water samples attaining acceptable relative recovery values.     

Separation and preconcentration of mercury in water samples by ionic liquid supported cloud point extraction and fluorimetric determination

We have developed a cloud point extraction procedure based on room temperature ionic liquid for the preconcentration and determination of mercury in water samples. Mercury ion was quantitatively extracted with tetraethyleneglycol-bis(3- methylimidazolium) diiodide in the form of its complex with 5,10,15,20-tetra-(4-phenoxyphenyl)porphyrin. The complex was back extracted from the room temperature ionic liquid phase into an aqueous media prior to its analysis by spectrofluorimetry. An overall preconcentration factor of 45 was accomplished upon preconcentration of a 20?mL sample. The limit of detection obtained under the optimal conditions is 0.08?μg mL^?1, and the relative standard deviation for 10 replicate assays (at 0.5?g mL^?1 of Hg) was 2.4%. The method was successfully applied to the determination of mercury in tap, river and mineral water samples.

Modified normal-phase ion-pair chromatographic methods for the facile separation and purification of imidazolium-based ionic compounds

Imidazolium- and oligo(imidazolium)-based ionic organic compounds are important in the design of room-temperature ionic liquid materials; however, the chromatographic analysis and separation of such compounds are often difficult. A convenient and inexpensive method for effective thin-layer chromatography (TLC) analysis and column chromatography separation of imidazolium-based ionic compounds is presented. Normal-phase ion-pair TLC is used to effectively analyze homologous mixtures of these ionic compounds. Subsequent separation of the mixtures is performed using ion-pair flash chromatography on normal-phase silica gel, yielding high levels of recovery. This method also results in a complete exchange of the counter anion on the imidazolium compounds to the anion of the ion-pair reagent.     

Synthesis and properties of a diastereopure ionic liquid with planar chirality

An imidazolium-based ionic liquid with cyclophane-type planar chirality was synthesized in an optically pure form for the first time. The resultant ionic liquid existed as a liquid at room temperature (T_g = −35 °C), and was found to be applicable as an NMR chiral shift reagent for racemic anions. Excellent robustness of the ionic liquid to a highly elevated temperature (270 °C) was proved from the viewpoints of isomerization and thermal decomposition.     

室温离子液体浸取分离牛磺酸与硫酸钠固体混合物

在多种1,3-二烷基咪唑室温离子液体中考察了牛磺酸的溶解性能,并利用对牛磺酸溶解度较大的氯化1-甲基-3-丁基咪唑离子液体([C₄MIm]Cl)为浸取剂,在较温和条件下实现了硫酸钠和牛磺酸固体混合物的分离.浸取得到的溶有牛磺酸的离子液体经乙醇离析后可高产率地得到牛磺酸(＞98.5%),纯度超过99.5%.此方法简化了牛磺酸/硫酸钠固体混合物的分离,离子液体可以重复使用多次.     

Br(o)nsted酸性离子液体在醛醇缩合反应中的应用

合成了一系列Br(o)nsted酸性离子液体并将其应用在醛醇缩合反应中.醛醇缩合产物由于极好的溶剂性质等被广泛用作溶剂和试剂.离子液体[BSmim][OTf]在甲醛和乙二醇缩合生成1,3-二氧五环的反应中表现出了极好的催化活性,甲醛转化率和主产物1,3-二氧五环选择性分别可以达到96.1％和92.4％.对影响离子液体催化性能的因素进行了探索,并对催化反应中的离子液体的用量、反应温度、反应时间以及反应物料比进行了考察.通过Hammett酸度函数法测定了所用到离子液体的酸性,结果表明离子液体酸性与其在缩合反应中的催化活性顺序完全一致,酸性越强催化性能越好.结合实验给出了离子液体[BSmim][OTf]催化甲醛和乙二醇缩合反应的可能的反应机理.该催化剂体系具有良好的催化性能,反应可以在较温和的条件下进行,实现了高活性和高选择性的目标,产物易分离,催化剂重复使用7次,其催化活性基本不变.并将该Br(o)nsted酸性离子液体进一步应用到其他醛(酮)醇缩合反应中.     

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。     

Brønsted酸性离子液体在醛醇缩合反应中的应用

合成了一系列Brønsted酸性离子液体并将其应用在醛醇缩合反应中.醛醇缩合产物由于极好的溶剂性质等被广泛用作溶剂和试剂.离子液体[BSmim][OTf]在甲醛和乙二醇缩合生成1,3-二氧五环的反应中表现出了极好的催化活性,甲醛转化率和主产物1,3-二氧五环选择性分别可以达到96.1%和92.4%.对影响离子液体催化性能的因素进行了探索,并对催化反应中的离子液体的用量、反应温度、反应时间以及反应物料比进行了考察.通过Hammett酸度函数法测定了所用到离子液体的酸性,结果表明离子液体酸性与其在缩合反应中的催化活性顺序完全一致,酸性越强催化性能越好.结合实验给出了离子液体[BSmim][OTf]催化甲醛和乙二醇缩合反应的可能的反应机理.该催化剂体系具有良好的催化性能,反应可以在较温和的条件下进行,实现了高活性和高选择性的目标,产物易分离,催化剂重复使用7次,其催化活性基本不变.并将该Brønsted酸性离子液体进一步应用到其他醛（酮）醇缩合反应中.     

Design of ionic liquid 3-methyl-1-sulfonic acid imidazolium nitrate as reagent for the nitration of aromatic compounds by in situ generation of NO(2) in acidic media

3-Methyl-1-sulfonic acid imidazolium nitrate ([Msim]NO(3)) as a new Br?nsted acidic ionic liquid and nitrating agent was prepared and used for the efficient nitration of aromatic compounds (even aniline derivatives). The dramatic effect of this reagent by in situ generation of nitrogen dioxide as a radical on aromatic compounds to give nitroarenes has been studied.     

Imidazolium ionic liquid as the background ultraviolet absorption reagent for determination of morpholinium cations by high performance liquid chromatography-indirect ultraviolet detection

A novel analytical method was developed for determining morpholinium cations lacking ultraviolet absorption groups.This determination was carried out by high performance liquid chromatographyindirect ultraviolet（HPLC-1UV） detection using imidazolium ionic liquid as background absorption reagents,and imidazolium ionic liquid aq.soln.-organic solvent as mobile phase by a reversed-phase C18 column.The background ultraviolet absorption reagents,imidazolium ionic liquids and organic solvents were investigated.The imidazolium ionic liquid in the mobile phase is not only the background ultraviolet absorption reagent for IUV,but also an active component to improve the separation of morpholinium cations.It was found that morpholinium cations could be adequately determined when0.5 mmol/L 1-ethyl-3-methylimidazolium tetrafluoroborate aq.soln./methanol（80：20,v/v） was used as mobile phase with an IUV detection wavelength of 210 nm.In this study,the baseline separation of Nmethyl,ethylmorpholinium cations（MEMo） and N-methyl.propylmorpholinium cations（MPMo） was successfully achieved in 8.5 min.The detection limits（S/N = 3） for MEMo and MPMo were 0.15 and0.29 mg/L,respectively.This simple and practical method has been successfully applied to the determination of two morpholinium ionic liquids synthesized by the chemistry laboratory.     

Synthesis of Cyclic Carbonate Catalyzed by DBU Derived Basic Ionic Liquids

In this work, 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU), 1,5‐diazabicyclo[4.3.0]‐5‐nonene (DBN), and imidazole (MIM)‐derived bromide ionic liquids (ILs) were synthesized and used to catalyze the cycloaddition reactions of carbon dioxide (CO₂) with several kinds of epoxides to form cyclic carbonates. The DBU derived bromide ionic liquid system was found to have the best catalytic activity among all the tested ILs. The influences of reaction conditions (including temperature, pressure and reaction time) on the reaction of CO₂ to propylene oxide (PO) were studied to show the best conditions of 120 °C, 1 MPa, 2.5 h catalyzed by 2 mol% DBU‐derived bromide ionic liquid, with the conversion of PO and the selectivity of propylene carbonate (PC) reaching 99% and 99%, respectively. Under the optimum reaction conditions, the ionic liquid system could be reused at least five times without decrease in selectivity and conversion. NMR spectroscopy and DFT calculations were used to reveal the hydrogen‐bond interaction between ionic liquids and reagent, based on which the reaction mechanism was proposed.