An efficient conjugate hydrothiocyanation of chalcones with a task-specific ionic liquid

A new and efficient method of conjugate hydrothiocyanation of chalcones along with the preparation of a probe for demonstrating the utility of the resulting β-thiocyanato ketones in heterocyclic synthesis is reported. Chalcones undergo an efficient conjugate hydrothiocyanation with the task-specific ionic liquid (TSIL), 1-n-butyl-3-methylimidazolium thiocyanate ([bmim]SCN) followed by reaction with AcONH₄ or an amine to afford chemically and pharmaceutically interesting 2-amino-1,3-thiazines at room temperature in a one-pot procedure. After isolation of the product, the ionic liquid [bmim]OH could be used for the synthesis of [bmim]SCN, thus allowing recycling of the TSIL for further use.     

Ionic liquid promoted one-pot synthesis of 3-aminoimidazo[1,2-a]pyridines

3-Aminoimidazo[1,2-a]pyridines have been synthesized in good to excellent yields in the presence of the ionic liquid 1-butyl-3-methylimidazolium bromide [bmim]Br, the reaction workup is simple and the ionic liquid can be easily separated from the product and reused.     

A one-pot, four-component synthesis of α-carboline derivatives

A one-pot method for the efficient and simple synthesis of novel 1H-indolo[2,3-b]pyrazolo[4,3-e]pyridines via a four-component condensation reaction of indolin-2-one, 3-oxo-3-phenylpropanenitrile, and various hydrazines and aldehydes in the ionic liquid 1-butyl-3-methylimidazolium bromide ([bmim]Br) is reported.     

Solvent free nucleophilic introduction of fluorine with [bmim][F]

1-n-Butyl-3-methylimidazolium fluoride ([bmim][F]) proved very efficient fluorinated reagent for nucleophilic substitution over sulfonate esters and alkyl halides. Preparation of the ionic liquid as well as its use as the reagent has been performed to be the more eco-friendly as possible. No organic solvent is needed for the fluoride introduction, reaction times are reduced by using microwave as the heating source, and the ionic liquids carefully recycled. Furthermore, no special care has to be taken as the presence of water in [bmim][F] was not deleterious to the transformation yield.     

1-Butyl-3-methylimidazolium p-toluenesulfinate: a novel reagent for synthesis of sulfones and β-ketosulfones in ionic liquid

A novel task-specific ionic liquid, 1-butyl-3-methylimidazolium p-toluenesulfinate, [bmim][p-TolSO₂] has been synthesized and used as a nucleophile for the reaction with alkyl bromides and phenacyl bromides to prepare sulfones and β-ketosulfones in excellent yields (80-93%) in [bmim][BF₄] ionic liquid. The isolated yields of sulfones and β-ketosulfones were higher in [bmim][BF₄] than other organic solvents at room temperature.     

Partial molar volumes of selected gases in some ionic liquids

The partial molar volume of a gas that is dissolved at high dilution in a solvent is required to express the influence of pressure on Henry's constant as well as to describe the volume change (expansion) of the liquid caused by the dissolved gas. The correlations of recently published experimental results for the solubility of some selected gases (CO₂, Xe, CH₄, CF₄, H₂, CO, O₂) in three imidazolium-based ionic liquids (1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF₆]), 1-n-butyl-3-methylimidazolium methyl sulfate ([bmim][CH₃SO₄]), and 1-n-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([hmim][Tf₂N])) determined by the synthetic method were re-evaluated by also considering the experimentally determined volumetric properties. The new evaluation does not change the published results for Henry's constants, but additionally yields reliable information on the partial molar volume of those gases in the mentioned ionic liquids at temperatures from about 293 to 413 K.     

Potassium carbonate as a base for the N-alkylation of indole and pyrrole in ionic liquids

The methodology for the N-alkylation of indole and pyrrole using potassium carbonate in 1-n-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF₄] as the sustainable reaction media with acetonitrile as the cosolvent is described herein. Our approach provides good yields with alkyl halides as well as sulfonates as the electrophiles. Cesium carbonate was also found to be a consistent base in the N-alkylation. The proposed methodology is simple and mild with easy workup.     

An ionic liquid-mediated expeditious route to the syntheses of diaryl sulfoxides

A fast and efficient protocol is proposed for the synthesis of diaryl sulfoxides in the ionic liquid 1-butyl-3-methylimidazolium chloroaluminate, [bmim]Cl·AlCl₃, N=0.67, by employing arenes and thionyl chloride. The ionic liquid plays a dual role of Lewis acid catalyst and solvent, under ambient conditions, offering good yields of the product. The influence of the Lewis acidity of the ionic liquid on the extent of conversion is studied.     

Electrochemical behavior of nickel in electrolytes based on 1-n-butyl-3-methylimidazolium tetrafluoroborate ionic liquid for capacitor applications

Electrochemical studies were performed using Ni electrodes in solutions of a mixture of ethylene glycol or of γ-butyrolactone with 1-n-butyl-3-methylimidazolium tetrafluoroborate ionic liquid. The aim of the study was to evaluate the use of these systems in electrochemical double-layer capacitor. Cyclic voltammetry experiments showed a potential range at which the Ni electrode behaved as a polarizable electrode. Ni oxidizes at high anodic potentials. Inside the potential range without electrochemical activity, the capacitance and the solution resistance, which were evaluated by impedance electrochemical spectroscopy, were compared for the two solutions tested. Conductivity measurements of the electrolytes with different compositions were also acquired. The results of cyclic voltammetry indicated that the Ni has a wide electrochemical window and low current peak densities of oxidation in the γ-butyrolactone medium than in ethylene glycol medium. The γ-butyrolactone and 1-n-butyl-3-methylimidazolium tetrafluoroborate ionic liquid solutions had the highest conductivity values. Decreased 1-n-butyl-3-methylimidazolium tetrafluoroborate ionic liquid content in different solvent mixtures resulted in an increase in the capacitance value at the Ni/electrolyte interface. The highest capacitance values were obtained for Ni in ethylene glycol and 1-n-butyl-3-methylimidazolium tetrafluoroborate medium.     

离子液体中NaHSO4催化芳香醛与1,3-环己二酮的缩合反应

以NaHSO₄为催化剂, 在离子液体1-丁基-3-甲基咪唑四氟硼酸盐([bmim]BF₄)介质中, 由芳香醛与1,3-环己二酮衍生物制备了9-芳基-2,3,4,5,6,7-六氢-2H-氧杂蒽-1,8-二酮衍生物. 在沸水浴中反应1～2 h, 产率达81.2%～93.0%. 该方法反应时间短, 产率高, 催化剂价廉易得, 而且对环境友好.     

Synthesis of benzofurans in ionic liquid by a PdCl2-catalyzed intramolecular Heck reaction

PdCl₂-catalyzed intramolecular Heck reaction was conducted in ionic liquid, 1-n-butyl-3-methylimidazolium tetraborate ([BMIm] BF₄), substituted benzofurans were obtained in modest to satisfactory yields. The ionic liquid containing Pd catalyst can be used four times with a little loss of activity.     

Extraction and isolation of shikimic acid from Ginkgo biloba leaves utilizing an ionic liquid that dissolves cellulose

Shikimic acid, the starting material in the commercial synthesis of oseltamivir phosphate (Tamiflu?), was efficiently extracted and isolated from Ginkgo biloba leaves utilizing the ionic liquid 1-butyl-3-methylimidazolium chloride ([bmim]Cl), which dissolves cellulose.     

Ionic liquid promoted synthesis of 3-(2′-benzothiazolo)-2,3-dihydroquinazolin-4(1H)-ones

3-(2′-Benzothiazolo)-2,3-dihydroquinazolin-4(1H)-ones have been synthesized in high yields in the presence of 1-butyl-3-methylimidazolium bromide [bmim]Br as an ionic liquid; the reaction work-up is simple and the ionic liquid can be easily separated from the product and reused.     

Synthesis of vinyl sulfides under base-free conditions using selenium ionic liquid

A very simple procedure is described for the efficient synthesis of vinyl sulfides by hydrothiolation of terminal alkynes using 1-n-butyl-3-methylimidazolium methylselenite, [bmim][SeO₂(OCH₃)]. The reaction proceeds cleanly under mild, base-free conditions and was performed with aromatic and aliphatic thiols.     

离子液体[bmim]Cl-CrCl2促进的Reformatsky反应研究

用无水氯化铬(CrCl2)和氯化1-丁基-3-甲基咪唑([bmim]Cl)制备了离子液体[bmim]Cl-CrCl2, 考察了CrCl2与[bmim]Cl物质的量比以及离子液体与底物物质的量比对Reformatsky反应的影响, 研究了[bmim]Cl-CrCl2促进不同底物发生的Reformatsky反应. 结果表明, 离子液体[bmim]Cl-CrCl2不仅能促进醛、酮与α-溴代酸酯的反应, 以极好的产率得到β-羟基酸酯; 而且能较好地诱导α-溴代苯乙酮与醛、酮的反应, 以较高的产率得到β-羟基酮. 该离子液体经处理后可以重复使用, 是一种Reformatsky反应的绿色化学方法.     

室温离子液体促进的5-亚芳基巴比妥酸衍生物的合成

在室温离子液体1-丁基-3-甲基咪唑四氟硼酸盐([bmim]BF₄)存在下, 采用室温研磨和微波辐射的方法, 由芳香醛和巴比妥酸或硫代巴比妥酸经Knoevenagel缩合反应, 制备了相应的5-亚芳基巴比妥酸或5-亚芳烃基硫代巴比妥酸衍生物. 在室温研磨条件下反应2 h, 产率为78%～96%, 在微波辐射功率为160 W时反应20 s, 产率为82%～98%, 产物结构经¹H NMR确证.     

Bi(OTf)3/[bmim]BF4 as novel and reusable catalytic system for the synthesis of furan, pyrrole and thiophene derivatives

Bi(OTf)₃ immobilized in 1-butyl-3-methylimidazolium tetrafluoroborate [bmim]BF₄ has been utilized for the first time as a novel and reusable catalytic system for the synthesis of heteroaromatics such as furan, pyrrole and thiophene derivatives from 1,4-diketones. This new procedure offers significant improvements in reaction rates and yields. The recovered ionic liquid containing bismuth triflate can be reused for subsequent runs with only a gradual decrease in activity.     

Three-Component,One-Pot Synthesis of Benzo[b][1,4]oxazines in Ionic Liquid 1-Butyl-3-methylimidazolium Bromide

Benzo[b][1,4]oxazines have been synthesized in good to excellent yields in the presence of the ionic liquid 1-butyl-3-methylimidazolium bromide [bmim]Br under relatively mild conditions without any added catalyst, The method offers the advantages of good yields and short reaction times, and the ionic liquid can be easily separated from the product and reused.     

[Bmim]BF4 ionic liquid: a novel reaction medium for the synthesis of β-amino alcohols

Epoxides undergo smooth ring-opening with aryl amines in 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF₄) or 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF₆) ionic liquids under mild and neutral conditions to afford the corresponding β-amino alcohols in excellent yields with high regioselectivity.     

[Bmim]PF6 and BF4 ionic liquids as novel and recyclable reaction media for aromatic amination

Activated aryl halides undergo smooth nucleophilic substitution reactions with secondary amines in 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF₆) or 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF₄) ionic liquids (ILs) at room temperature to afford the corresponding arylamines in excellent yields under mild and neutral conditions.