离子液体的酸性测定及其催化的二苯醚／十二烯烷基化反应

 采用乙腈探针红外光谱法测定了［bmim］Cl／AlCl3类离子液体的酸性．结果表明，乙腈可以区分离子液体的酸类型（Bronsted酸或Lewis酸），同时可以指示离子液体的Lewis酸强度．使用［bmim］Cl／AlCl3类离子液体催化二苯醚与十二烯的烷基化反应，研究了离子液体的酸强度、反应温度和醚烯比对反应的影响，并与AlCl3催化体系进行对比．结果发现，该离子液体对二苯醚与十二烯烷基化反应的催化活性明显高于AlCl3．使用离子液体作催化剂显著提高了烷基化反应的产率，简化了产物的分离与提纯，且对环境友好．当控制反应温度为80℃，原料醚烯摩尔比为7，并采用酸强度适中的离子液体时，目标产物单十二烷基二苯醚的产率接近90％．     

离子液体的酸性测定及其催化的异丁烷／丁烯烷基化反应

 初次采用吡啶红外光谱探针法测定了离子液体的酸性．该方法能鉴别离子液体的Br¨onsted／Lewis酸类型，并可以粗略指示离子液体的Lewis酸强度．将［bmim］Cl／AlCl3类离子液体用于催化异丁烷与丁烯的烷基化反应，考察了酸强度、反应温度、压力和时间对产物分布的影响，并在最优操作条件下与传统的H2SO4催化剂进行了比较．结果表明，离子液体对烷基化反应的催化活性和选择性与H2SO4可比，而且它更容易与产物分离，不经任何处理可循环利用10次．     

Et_3NHCl-AlCl_3催化苯与1-十二烯烃烷基化反应机理的研究

本文利用同位素取代法考察了离子液体催化苯与烯烃烷基化反应机理.首先进行了Et3NHCl-AlCl3催化氘代苯与1-十二烯烃的反应,通过GC-MS及NMR分析产物结构,根据分析结果,在反应过程中一个D原子从苯环转移到侧链的1-碳.由此推断离子液体催化苯与长链烯烃的烷基化反应机理为:反应由Lewis酸AlCl3引发;AlCl3吸引1-十二烯烃的π电子向1-碳转移,形成碳正离子;碳正离子进一步与苯反应形成不稳定的σ络合物,σ络合物苯环上的sp3杂化碳相连的D+转移到侧链的负电1-C上取代AlCl3,生成产物2-十二烷基苯.     

复合离子液体催化碳四烷基化反应性的研究

合成了一种新型的酸性离子液体催化剂——复合离子液体，该离子液体的阴离子具有双金属的配位中心。同时，研究了复合离子液体催化异丁烷与丁烯烷基化反应的规律。结果表明，在搅拌速率大于1500r/min，反应低于20℃，烃酸比2∶1~3∶1，烷烯比大于15，反应停留5min~10min，使用丁烯-2为碳四烯烃反应原料下，复合离子液体催化碳四烷基化所得烷基化油的研究法辛烷值（RON）最高可达100以上，明显优于常规氯铝酸离子液体催化所得烷基化油的质量。     

[Bmim]Br-AlCl3催化苯与1-十二烯烃烷基化反应机理的研究

利用同位素取代法考察了[Bmim]Br-AlCl3催化苯与1-十二烯烃烷基化反应机理. 首先进行了[Bmim]Br-AlCl3催化氘代苯与1-十二烯烃的反应, 通过GC-MS及NMR分析产物十二烷基苯同分异构体的结构, 验证了氘原子与产物侧链1-位碳相连的结论. 示踪氘原子推导了烷基化反应机理, 结果表明: [Bmim]Br-AlCl3催化苯与长链烯烃的烷基化反应是由[Al2Cl6Br]－发生平衡移动, 生成Lewis酸AlCl3引发的; AlCl3吸电子作用使1-十二烯烃的π电子向1-碳转移, 在烯烃的2-碳上形成正电荷中心, 碳正离子与苯发生亲电反应生成不稳定的σ络合物, 与σ络合物环上的σ-C相连的D＋转移到负电的侧链1-C上形成C—D键, AlCl3离去, 生成产物2-十二烷基苯. Lewis酸催化机理为离子液体催化苯与长链烯烃的反应中, 2-十二烷基苯选择性高于H质子催化产物提供了理论依据.     

离子液体超酸清洁催化苯的烷基化反应

研究了在具有Lewis酸性的离子液体体系中进行的苯与烯烃及卤代烃的烷基化反应.以氯化1-甲基-3-乙基咪唑(MEIC)、氯化1-丁基吡啶(BPC)、氯化l-甲基-3-丁基咪唑(MBIC)及盐酸三甲胺(TMHC)季铵盐分别与AlCl3原位合成法制备离子液体催化体系.结果表明:以上各种离子液体均有很高的催化活性,反应转化率在较短的时间内达到100%.其中TMHC-A1Cl3离子液体单烷基化选择性达98.6%.与AlCl3相比,催化活性显著提高,生成烷基化产物不溶于离子液体,因而易于分离,催化剂可重复使用.     

吗啉基功能化酸性离子液体催化苯酚-叔丁醇选择性烷基化反应

研究了吗啉基磺酸功能化离子液体催化苯酚与叔丁醇的烷基化反应.考察不同的功能化离子液体、反应时间、反应温度、苯酚与叔丁醇的摩尔比以及离子液体的用量等反应条件对烷基化反应的影响,并考察了离子液体的循环使用.研究结果表明离子液体用量为20%苯酚时,在最佳优化条件下苯酚的转化率和选择性分别为92.4%和64.1%;离子液体重复使用三次,其催化活性不变.     

酸性离子液体催化的异丁烷/丁烯烷基化反应研究

以一系列酸性离子液体作为催化剂,考察了异丁烷/丁烯在不同离子液体中催化异丁烷与丁烯的烷基化反应,研究了离子液体在进行酸性和阴阳离子调整后对烷基化反应的影响.其中[MBSIM]OTf类离子液体催化所得目的产物三甲基戊烷含量最高可达69.8%,该类催化体系重复使用8次,催化性能没有明显下降.     

离子液体降低FCC汽油烯烃体积分数的研究

向FCC汽油中分别加入两种与FCC汽油不互溶的Lewis超强酸性离子液体\[Bmim\]Cl-AlCl3 和 \[R4N\]Cl-AlCl3形成液-液两相催化降烯烃体系。结果表明：在汽油辛烷值基本保持不变的基础上,FCC汽油的烯烃体积分数分别下降14.7%和13.1%, 均达到我国新配方汽油规定的烯烃体积分数v<35%的新标准。对离子液体降低FCC汽油的机理及影响因素进行了详细研究。结果表明,正是由于具备Lewis超强酸性的离子液体催化的烯烃与烷烃的烷基化、烯烃与芳烃的烷基化以及烯烃的二聚反应使得FCC汽油中烯烃体积分数显著下降。     

ZnCl2离子液体中高区域选择性合成对位柑菁醛

 二烷基咪唑或烷基吡啶卤化物与ZnCl2构成一类新型的具有Lewis酸性的离子液体,以其为催化剂和反应介质,通过月桂烯与丙烯醛的Diels-Alder反应高区域选择性地合成了对位柑菁醛. 结果表明,与常规有机溶剂-ZnCl2催化体系相比,该体系不仅显著地加快了反应速率,而且明显提高了对位柑菁醛的区域选择性. 当ZnCl2与二烷基咪唑或烷基吡啶卤化物的摩尔比为2∶1,温度为15 ℃时月桂烯几乎可完全转化为柑菁醛,且对位柑菁醛的区域选择性p/m＞18. 与氯铝酸盐离子液体相比,该离子液体对水和空气不敏感. 反应结束后,产物与离子液体自动分层,解决了传统均相催化体系中催化剂与产物不易分离的问题. 分离后的离子液体用正己烷清洗提纯后,重复使用4次,其催化活性和区域选择性基本保持不变.     

Efficient cyclodehydration of diethylene glycol in Brønsted acidic ionic liquids

Cyclodehydration of diethylene glycol using various Brønsted acidic ionic liquids as dual solvent-catalysts has been studied for the first time. Better results were obtained in the presence of 1-butyl-3-methylimidazolium hydrogen sulfate ([PSmim]HSO₄) compared with other Brønsted acidic ionic liquids. Effects of the reaction conditions such as reaction temperature, reaction time and molar ratio of ionic liquid to diethylene glycol have been investigated. High diethylene glycol conversion, 97.0 %, and high 1,4-dioxane selectivity, 89.3 %, were obtained in [PSmim]HSO₄ under optimum conditions. Hammett method was used to determine the acidity order of these ionic liquids and the results were consistent with the catalytic activities observed in the cyclodehydration reaction. Utilization of Brønsted acidic ionic liquids as dual solvent-catalysts has some advantages, e.g. high conversion of DEG, easy preparation and reuse of ionic liquids, avoiding toxic catalysts and solvents.     

碱性离子液体催化甘油合成1,2-甘油碳酸酯(英)

以离子液体为催化剂,在无溶剂体系中,考察了生物质平台化合物甘油转化1,2-甘油碳酸酯的反应.与酸性离子液体和常用无机碱性催化剂相比,碱性离子液体咪唑基1-丁基-3-甲基咪唑([Bmim]Im)、氢氧化1-丁基-3-甲基咪唑([Bmim]OH)、咪唑基1-烯丙基-3-甲基咪唑([Amim]Im)、氢氧化1-烯丙基-3-甲基咪唑([Amim]OH)在甘油与碳酸二甲酯的酯交换反应中表现出优异的活性.其中,以[Bmim]Im离子液体为催化剂时甘油转化率为98.4%和甘油碳酸酯选择性接近100%.另外,该离子液体可以回收重复利用3次后甘油转化率仍可达92%,甘油碳酸酯选择性可近100%.此碱性离子液体催化方法具有反应结果较好、产物分离简单、条件温和以及环境友好等特点.     

Computational approach to nuclear magnetic resonance in 1-Alkyl-3-methylimidazolium ionic liquids

A quantum-chemical computational approach to accurately predict the nuclear magnetic resonance (NMR) properties of 1-alkyl-3-methylimidazolium ionic liquids has been performed by the gauge-including atomic orbitals method at the B3LYP/6-31++G** level using different simulated ionic liquid environments. The first molecular model chosen to describe the ionic liquid system includes the gas-phase optimized structures of ion pairs and separated ions of a series of imidazolium salts containing methyl, butyl, and octyl substituents and PF6-, BF4-, and Br- anions. In addition, a continuum polarizable model of solvation has been applied to predict the effects of the medium polarity on the molecular properties of 1,3-dimethylimidazolium hexafluorophosphate (MmimPF6). Furthermore, the specific acidic and basic solute-solvent interactions have been simulated by a discrete solvation model based on molecular clusters formed by MmimPF6 species and a discrete number of water molecules. The computational prediction of the NMR spectra allows a consistent interpretation of the dispersed experimental evidence in the literature. The following are main contributions of this work: (a) Theoretical results state the presence of a chemical equilibrium between ion-pair aggregates and solvent-separated counterions of 1-alkyl-3-methylimidazolium salts which is tuned by the solvent environment; thus, strong specific (acidic and basic) and nonspecific (polarity and polarizability) solvent interactions are predicted favoring the dissociated ionic species. (b) The calculated 1H and 13C NMR properties of these ionic liquids are revealed as highly dependent on the nature of solute-solvent interactions. Thus, the chemical shift of the hydrogen atom in position two of the imidazolium ring is deviated to high values by the specific interactions with water molecules, whereas nonspecific interaction with water (as a solvent) affects, in the opposite direction, this 1H NMR parameter. (c) Last, current calculations support the presence of hydrogen bonding between counterions, suggesting the importance of this interaction in the properties of the solvent in the 1-alkyl-3-methylimidazolium ionic liquids.     

离子液体溶剂中5-氧代-5,6,7,8-四氢苯并吡喃衍生物的一种温和有效的合成

A one-pot synthesis of a series of 5-oxo-5,6,7,8-tetrahydro-4H-benzo-[b]-pyran derivatives via three-component coupling reactions of aldehydes, dimedone and malononitrilein room temperature ionic liquids （RTILs） without any catalyst has been reported. In the meantime, the reuse of ionic liquids and the effect of different ionic liquids as solvent on the reaction have also been investigated.     

Acidic Ionic Liquids as Efficient and Environmentally Benign Medium for the Synthesis of 2-Phenylbenzimidazole

2‐Substituted benzimidazoles have been synthesized in excellent yields under solvent‐free conditions using a series of acidic ionic liquids as catalysts. The results indicate that SO₃H‐functionalized ionic liquids show higher catalytic activities than other acidic ionic liquids. The effects of reaction conditions such as the amounts of ionic liquids, the ratio of reactants were investigated. A Hammett method was used to determine the acidity order of these ionic liquids and the results were found to be relevant to the catalytic activities observed in the synthesis reaction. Besides, the reaction mechanism was stimulated using DFT method.     

New, highly acidic ionic liquid systems and their application in the carbonylation of toluene

Based on the surprisingly high solubility of AlCl3 in ionic liquids of type [cation][(CF3SO2)2N], a new class of highly acidic, ionic systems has been developed. First tests in toluene carbonylation revealed high potential of these new acidic ionic liquids as catalyst for arene functionaliziation reactions.     

Efficient and convenient oxidation of cyclohexene to adipic acid with H<Subscript>2</Subscript>O<Subscript>2</Subscript> catalyzed by H<Subscript>2</Subscript>WO<Subscript>4</Subscript> in acidic ionic liquids

A simple, efficient, and eco-friendly catalytic system for the oxidation of cyclohexene to adipic acid with H₂O₂ catalyzed by H₂WO₄ in Brønsted acidic ionic liquids under solvent-free conditions has been developed. Reaction conditions such as the catalysts, the types of anions and cations for Brønsted acidic ionic liquids, reaction temperature, and the amount of hydrogen peroxide, were investigated. Moreover, the Hammett acidity functions (H ₀) of Brønsted acidic ionic liquids were determined using UV–visible spectrophotometry. The optimum reaction condition identified was n(H₂WO₄):n(Brønsted acidic ionic liquids):n(cyclohexene):n(H₂O₂) = 0.02:0.02:1:4.4, and the yield of adipic acid was 96% under the reaction scale of 10 mmol. The catalytic system can be easily recovered and reused for four reaction runs without significant loss of catalytic activity. Simple operation of the catalyst system and avoidance of the emission of nitrous oxide are the benefits of this work.     

Preparation of magnetic chitosan and graphene oxide-functional guanidinium ionic liquid composite for the solid-phase extraction of protein

A series of novel cationic functional hexaalkylguanidinium ionic liquids and anionic functional tetraalkylguanidinium ionic liquids have been synthesized, and then magnetic chitosan graphene oxide (MCGO) composite has been prepared and coated with these functional guanidinium ionic liquids to extract protein by magnetic solid-phase extraction. MCGO-functional guanidinium ionic liquid has been characterized by vibrating sample magnetometer, field emission scanning electron microscopy, X-ray diffraction spectrometer and Fourier transform infrared spectrometer. After extraction, the concentrations of protein were determined by measuring the absorbance at 278 nm using an ultra violet visible spectrophotometer. The advantages of MCGO-functional guanidinium ionic liquid in protein extraction were compared with magnetic chitosan, graphene oxide, MCGO and MCGO-ordinary imidazolium ionic liquid. The proposed method has been applied to extract trypsin, lysozyme, ovalbumin and bovine serum albumin. A comprehensive study of the adsorption conditions such as the concentration of protein, the amount of MCGO-functional guanidinium ionic liquid, the pH, the temperature and the extraction time were also presented. Moreover, the MCGO-functional guanidinium ionic liquid can be easily regenerated, and the extraction capacity was about 94% of the initial one after being used three times.     

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).