1‐Butyl‐3‐methylimidazolium Tetrafluoroborate ([Bmim]BF4) Ionic Liquid: A Novel and Recyclable Reaction Medium for the Synthesis of vic‐Diamines

Aziridines undergo ring opening smoothly with various arylamines 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 vicinal‐diamines in excellent yields with high regioselectivity. The recovered activated ionic liquids are recycled for four to five runs with no loss of activity.     

An Ionic Liquid as Catalyst Medium for Stereoselective Hydrogenations of Sorbic Acid with Ruthenium Complexes

The ionic liquid 1‐n‐butyl‐3‐methylimidazolium hexafluorophosphate (bmim PF₆) ( 6 ) has been studied as catalyst medium for biphasic homogeneous hydrogenations of sorbic acid ( 1 ). As catalyst we used the Cp*‐ruthenium‐complex [Cp*Ru(η⁴‐CH₃—CHCH—CHCH—COOH) (CF₃SO₃)] which efficiently enables the stereoselective hydrogenation of sorbic acid leading to the formation of cis‐3‐hexenoic acid ( 3 ) in selectivities of up to 90% with turnover frequencies of up to 1100 h^—1. Compared to other biphasic systems the hydrogenation in bmim PF₆ proceeds with enhanced activity. The kinetics can be described with a Michaelis Menten‐equation, and the activation energy for the whole process was determined to be E_A = 78 ± 5 kJ/mol.     

离子液体介质中催化合成生物柴油技术研究

生物柴油作为一种可替代再生性清洁能源,成为新能源领域研究和开发的热点之一.廉价的原料、新合成工艺和高效催化剂技术是降低生产成本,促使该项技术推广应用的发展方向.离子液体作为一种功能可设计的新型绿色溶剂和催化剂,在化学反应和过程开发中显示出了独特的应用前景.将离子液体用于生物柴油制备是近年来新发展的方向,回顾了离子液体在...     

Rhodium Acetate Dimer Immobilized in 1‐Butyl‐3‐methylimidazolium Hexafluorophosphate Ionic Liquid: a Novel and Recyclable Catalytic System for the Cyclopropanation of Alkenes

Alkenes undergo smooth cyclopropanation with ethyl diazoacetate using a catalytic amount of rhodium acetate dimer, Rh₂(OAc)₄, immobilized in the air‐ and moisture‐stable 1‐butyl‐3‐methylimidazolium hexafluorophosphate ionic liquid, [bmim]PF₆, to afford cyclopropanecarboxylates in excellent yields with high trans‐selectivity. The recovery of the catalyst is facilitated by the hydrophobic nature of [bmim]PF₆. The recovered ionic liquid containing Rh₂(OAc)₄ can be reused for three to five subsequent runs with only a gradual decrease in activity.     

离子液体与水混合溶剂捕捉吸收甲醇气体的研究

针对甲醇废气造成的大气污染和资源浪费问题,采用1-丁基-3-甲基咪唑四氟硼酸盐([bmim][BF4])为目标离子液体与水的混合溶剂,捕捉回收再利用废气中的甲醇。利用Aspen Plus对吸收进行工艺模拟与优化,最终确定[bmim][BF4]温度为30℃,流量比为3:1,吸收剂用量为380 kg/h。甲醇回收率达到99.7%。与水作吸收剂的传统工艺相比,解吸塔冷凝器节省循环水31.3%,再沸器节省加热蒸汽50.6%。     

[bmim]Cl/[FeCl_3] Ionic Liquid as Catalyst for Alkylation of Benzenewith 1-Octadecene

1 INTRODUCTION Linear alkylbenzenes (LAB), important interme- diates in the detergent industry, have usually been manufactured by alkylation of benzene with C10 14 olefins in the presence of HF or AlCl3 catalyst. It is known that HF or AlCl3, to some extent, is hazardous to the environment. Therefore, the HF or AlCl3 proc- ess is a typical example of a “non-green” process be- cause of cooling and separation problems, high oper- ating costs and safety aspects. Many efforts have bee…     

Process Variables of the Esterification Reaction of 3‐Pentadecylphenol and Acryloyl Chloride Catalyzed by an Ionic Liquid

An efficient method was investigated for the synthesis of 3‐pentadecylphenyl acrylate (PDPA) via one‐pot reaction of esterification in the presence of an ionic liquid as catalyst. In order to understand the esterification reaction process, a mathematical relationship between the yield of esterification and the process variables was established by employing central composite design. The maximum yield of esterification of 3‐pentadecylphenol (PDP) and acryloyl chloride (AC) catalyzed by imidazole ionic liquid was found to be 85 %. A statistical model predicted that the highest esterification reaction yield would be > 88 % under optimized reaction conditions. The predicted values for optimum process conditions thus obtained were in agreement with the experimental values, thereby indicating the suitability of the model.     

Ionic Liquid, 1‐n‐Butyl‐3‐methylimidazolium Bis(trifluoromethanesulfonyl)imide,Resulted in the First Catalyst‐Free Aminohalogenation of Electron‐Deficient Alkenes

The 2‐Ns‐based aminohalogenation of α,β‐unsaturated ketones has been achieved in an ionic liquid, 1‐n‐butyl‐3‐methylimidazolium bis(trifluoromethanesulfonyl)imide {[bmim][N(SO₂CF₃)₂]}. [Bmim][N(SO₂CF₃)₂] was found to be superior not only to classical organic solvents but also to its counterpart, [bmim][BF₄], which was proven to be successful in the TsNCl₂‐based aminohalogenation but failed to give any product for this reaction. The present process takes the advantage of 2‐NsNCl₂ as the stable nitrogen/halogen source in a one‐pot operation without the use of any metal catalysts, it is convenient to perform without special protection of inert gases. Eight examples were examined with good to excellent stereoselectivity (1:5 to one isomer) and modest to good chemical yields (53–72 %).     

Ionic Liquid as Catalyst and Reaction Medium: A Simple,Convenient and Green Procedure for the Synthesis of Thioethers,Thioesters and Dithianes using an Inexpensive Ionic Liquid, [pmIm]Br

An easily accessible and inexpensive room temperature ionic liquid, 1‐pentyl‐3‐methylimidazolium bromide, [pmIm]Br efficiently catalyzes the reaction of alkyl halides or acyl halides with thiols without any solvent at room temperature leading to the synthesis of thioethers and thioesters in high yields. This reaction has also been extended for the preparation of dithianes and transthioetherification. The ionic liquid is recovered and recycled for subsequent runs.     

Ionic liquids and nanotechnology: Synthesis of WO3 nanostructures by anodization as photoelectrocatalysts

Two ionic liquids, [BMIM][BF4] and [EMIM][BF4], have been used for the first time to synthesize ordered and well-defined WO₃ nanoplates by electrochemical anodization. Different amounts of these ionic liquids have been added to the electrolytes and their influence on the morphological, structural and photoelectrocatalytic properties of the WO₃ nanoplates has been extensively studied. The resulted nanostructures, especially those synthesized in the presence of 5%–10% ionic liquids, showed excellent photoelectrocatalytic performances under irradiation, due to their better morphology, size and arrangement. These results confirm the potentiality of ionic liquids, such as [BMIM][BF4] and [EMIM][BF4], in the synthesis by anodization of high-efficiency photoelectrocatalysts, which could be used in the energy and environmental fields.     

Oxidative Desulfurization of Model Diesel Using a Fenton‐Like Catalyst in the Ionic Liquid [Dmim]BF4

A Fenton‐like catalyst prepared from tetrabutylammonium chloride and ferric trichloride was characterized by Fourier transform infrared, UV‐vis and Raman spectroscopy. The catalyst (C₄H₉)₄NFeCl₄ (TBAFeCl₄) in an extraction and catalytic oxidative desulfurization (ECODS) system containing H₂O₂ and the ionic liquid (IL) 1‐decyl‐3‐methylimidazolium tetrafluoroborate ([Dmim]BF₄) exhibited high catalytic activity for the removal of dibenzothiophene (DBT) in model diesel. Desulfurization with the Fenton‐like catalyst TBAFeCl₄ in ECODS involves the structural distortion of DBT via polarization of the IL and its subsequent oxidation. The catalytic system could be recycled multiple times without significant decrease in desulfurization activity due to the high stability of the system.     

A New Application of Acetate‐Based Ionic Liquids: Potential Usage as Drying Materials

Acetate‐based ionic liquids (AcILs) are green and designable solvents applied in many fields. However, AcILs are found to be highly hygroscopic. On the one hand, the high hygroscopicity of AcILs influences their properties and structures. On the other hand, this hygroscopic property renders AcILs, and especially [EMIM][Ac], potentially useful as drying materials, a new application of AcILs proposed in this paper. These two traits could be interconnected, interdependent, and interconvertible, which implies that a shortcoming of AcILs, i.e., their hygroscopicity, leading to changes in their physical properties, could be turned into a useful feature, e.g., the potential usage as drying material, if it is dealt with properly.     

Design of Ionic Phosphites for Catalytic Hydrocyanation Reaction of 3‐Pentenenitrile in Ionic Liquids†

The synthesis and characterization of a novel class of ionic phosphites bearing either a single cationic group obtained by quaternization of aminophosphites or three cationic groups prepared by reaction of phosphorus trichloride with imidazolium phenols are reported. The catalytic hydrocyanation reaction of 3‐pentenenitrile (3PN) into adiponitrile has been performed in the presence of Ni(0) with ionic phosphite ligands, and a Lewis acid in biphasic ionic liquid/organic solvent system. The screening of several original cationic phosphites was performed and the experimental conditions were optimized for the tri‐cationic phosphite tris‐4‐[(2,3‐dimethylimidazol‐1‐yl)methyl]phenyl phosphite tris[bis(trifluoromethylsulfonyl)amide]. It is possible to obtain performance similar to molecular systems and the catalyst and the Lewis acid were immobilized in the ionic phase.     

Selective Hydrogenation of 1,3‐Butadiene to 1‐Butene by Pd(0) Nanoparticles Embedded in Imidazolium Ionic Liquids

The reduction of Pd(acac)₂ (acac=acetylacetonate), dissolved in 1‐n‐butyl‐3‐methylimidazolium hexafluorophosphate (BMI⋅PF₆) or tetrafluoroborate (BMI⋅BF₄) ionic liquids, by molecular hydrogen (4 atm) at 75 °C affords stable, nanoscale Pd(0) particles with sizes of 4.9±0.8 nm. Inasmuch as 1,3‐butadiene is at least four times more soluble in the BMI⋅BF₄ than butenes, the selective partial hydrogenation could be performed by Pd(0) nanoparticles embedded in the ionic liquid. Thus, the isolated nanoparticles promote the hydrogenation of 1,3‐butadiene to butenes under solventless or multiphase conditions. Selectivities up to 97% in butenes were observed in the hydrogenation of 1,3‐butadiene by Pd(0) nanoparticles embedded in BMI⋅BF₄ under mild reaction conditions (40 °C and 4 atm of hydrogen at constant pressure). Selectivities up to 72% in 1‐butene were achieved at 99% 1,3‐butadiene conversion, 40 °C and 4 atm of constant pressure of hydrogen. The amounts of butane (fully hydrogenated 1,3‐butadiene) and cis‐2‐butene products are marginal and the butenes do not undergo isomerisation process, indicating that the soluble Pd(0) nanoparticles possess a pronounced surface‐like rather than homogeneous‐like catalytic properties.     

Diversified Construction of Chromeno[3,4‐c]pyridin‐5‐one and Benzo[c]chromen‐6‐one Derivatives by Domino Reaction of 4‐Alkynyl‐2‐oxo‐2H‐chromene‐3‐carbaldehydes

Silver‐catalyzed three‐component, tandem reactions of 4‐alkynyl‐2‐oxo‐2H‐chromene‐3‐carbaldehydes, amines and various nucleophiles result in the formation of highly functionalized chromeno[3,4‐c]pyridin‐5‐ones in high yields. Gold‐catalyzed [4+2] cycloadditions of 4‐alkynyl‐2‐oxo‐2H‐chromene‐3‐carbaldehydes with alkynes or alkenes have also been achieved to afford benzo[c]chromen‐6‐ones efficiently.

     

Ionic Liquids as Size‐ and Shape‐Regulating Solvents for the Synthesis of Cobalt Nanoparticles

Over the last few years, ionic liquids (ILs) have emerged as an important class of reaction media for the synthesis of nanoparticles. The formation and stabilization of nanoparticles was investigated in different ILs to elucidate the effect of the chemical nature of the IL anion, cation and alkyl side chain of the imidazolium. In this context, Co₂(CO)₈ was employed as a precursor and thermally decomposed to the metallic cobalt nanoparticles in a series of selected ILs, where either the IL cation or anion was varied while keeping all of the other parameters constant. The results show that both the molecular volume of the anion and cation and the steric configuration are important aspects to control the formation and stability of nanoparticles in ILs.     

Investigation of enzymatic biodiesel production using ionic liquid as a co‐solvent

In this study, the lipase catalysed esterification reaction for biodiesel production was investigated in the presence of the ionic liquid [BMIM][PF₆]. Unlike regular organic solvents, many ionic liquids have no vapour pressure, and are therefore considered non‐volatile. When used in systems with enzyme catalysts, ionic liquids may enhance their activity, selectivity, and stability. The use of an enzyme (lipase) as a catalyst, and the ionic liquid as a solvent/immobilization agent also represents an environmentally friendly, “green” technology. Methyl acetate was used as the acyl acceptor as opposed to the more commonly used methanol due to the negative effects methanol and the glycerol by‐product has on lipase enzyme activity. The results of this research indicate that methyl oleate (i.e., biodiesel) was successfully produced, with an 80% overall biodiesel yield in the presence of ionic liquid, at a 1:1 ratio (v/v) to the amount of oil. This verified that the presence of an ionic liquid, at a specified amount, improved the activity of the lipase and the overall biodiesel yield. Results also indicate the addition of ionic liquid facilitated the separation of the methyl esters from the triacetylglycerol by‐product. The best conditions investigated was found to be: 14:1 molar ratio between oil and acyl acceptor; 20% (w immobilised lipase/w of oil; and a temperature in the range of 48–55°C. However, additional purification is required in order for the produced biodiesel to meet ASTM standards.     

Gold‐Catalyzed 5‐ and 6‐exo‐dig Selective Cyclizations of Alkynyl Silyl Enol Ethers: Efficient Method for [3+2] and [4+2] Annulations onto α,β‐Enones

An efficient method for the annulation of five‐ and six‐membered rings onto α,β‐enones is described via gold‐catalyzed 5‐ and 6‐exo‐dig selective cyclizations of alkynyl silyl enol ethers.     

[Bmim]Cl-xAlCl_3催化合成十二烷基苯

采用AlCl3和[Bmim]Cl不同摩尔比的[Bmim]C1-xA1C13离子液体为催化剂,研究了不同条件下1-十二烯与苯的烷基化反应。实验结果表明,以A1Cl3和[Bmim]Cl的摩尔比为2.0([Bmim]Cl-2A1C13)的离子液体为催化剂,在反应温度25℃、反应时间30 min,苯、烯及离子液体的摩尔比为5︰1︰0.03的条件下,正十二烯的转化率可达98.32%,2-LAB的选择性可达36.76%。离子液体和产物可形成易于分离的双液相,简化了催化剂与产物的分离操作。     

Synthesis of Highly Substituted Imidazo[1,5‐a]quinoxalines Through a Multicomponent Reaction Followed by Deprotection–Cyclization

An operationally simple and efficient, one‐pot, two‐step methodology has been developed for the assembly of medicinally important imidazo[1,5‐a]quinoxalines. The protocol involves the multicomponent reaction of aryl aldehydes, ortho‐N‐Boc‐phenylenediamines and azidochalcones in the presence of erbium triflate as a Lewis acid catalyst, followed by deprotection–cyclization with 10% trifluoroacetic acid, furnishing the desired compounds in moderate to good yields. By virtue of their convergence, two aromatic rings and four new bonds are generated during the course of this reaction protocol. The structure of one of the compounds was proved by X‐ray crystallography.