功能化离子液体室温催化合成乙酸苄酯

制备了N-甲基-N′-磺酸烷基-咪唑阴离子型功能化室温离子液体,研究了功能化室温离子液体(TSILs)于室温下催化乙酸和苯甲醇反应合成乙酸苄酯的新方法,考察了多种TSILs的催化性能。结果表明,所合成的TSILs具有很高的催化活性,乙酸和苯甲醇的摩尔比为1:1．3,在室温下反应2．5 h,乙酸苄酯的产率可达92％,选择性超过99％。由于生成的乙酸苄酯不溶于催化体系,反应产物与催化体系分层,通过简单的倾析便可实现产物分离,简化了分离过程。离子液体可以循环使用,而其催化活性没有明显降低。     

N-羧基吡啶功能化离子液体的表征

合成了系列新型N-羧基吡啶功能化离子液体, 利用1H NMR、13C NMR、IR、DSC对其进行表征并研究了其与常规溶剂的相溶性, 采用酸碱滴定法测量了系列离子液体的酸离解常数pKa值. N-羧基取代吡啶功能化离子液体的pKa值在2.5~4.0之间, 并随阳离子取代羧基碳链的增长而增大; 离子之间形成氢键及阴、阳离子的大小是影响离子液体熔点的主要因素. 阴离子越小, 熔点越高. 所合成的N-羧基吡啶功能化离子液体具有相同的相溶性且由取代羧基所决定, 与常见烷基咪唑离子液体相比, N-羧基吡啶功能化离子液体与丙酮、二氯甲烷并不相溶. 功能化离子液体的阳离子取代基是影响其物化性能的主要因素, 通过改变功能化基团碳链的长短及与不同阴离子进行组合, 可以对功能化离子液体物理、化学性能进行调节.     

离子液体对H2O2氧化环己烯制备反-1,2-环己二醇的催化作用

以H2O2为氧化剂,研究了离子液体为催化剂和溶剂,环己烯氧化生成反-1,2-环己二醇的反应。 考察了不同咪唑型离子液体、反应时间、反应温度和H2O2用量等对产率和选择性的影响, 实验结果表明,在7种咪唑型离子液体催化体系中,阳离子为咪唑环上含有1或2个羧基,阴离子为[PF6]的离子液体催化效果较好。 反应温度为100 ℃,n(H2O2)∶n(Cyclohexene)＝1.1∶1,反应5 h时,离子液体c（0.60 g,2.1 mmol）催化生成的反-1,2-环己二醇的产率和选择性分别为95%和97%,而离子液体f（0.20 g,0.6 mmol）催化生成的反-1,2-环己二醇的产率和选择性分别为84%和90%,从离子液体的用量来看,含2个羧基的离子液体f的催化效率更高。     

咪唑阴离子型碱性离子液体的合成及其催化Knoevenagel缩合反应

设计合成了由1-丁基-3-甲基咪唑阳离子与咪唑阴离子搭配的[bmim]Im新型碱性离子液体并对其碱性进行研究.[bmim]Im离子液体的碱性与[bmim]OH的碱性接近且强于[bmim]OAc.在水溶液及室温条件下,2%的[bmim]Im离子液体对系列芳香醛与活泼的亚甲基化合物之间的Knoevenagel缩合反应具有较好的催化性能,目标产物的收率达到86%～95%,选择性为100%.同时,该催化剂体系具有良好的循环性能.     

设计新型液液两相催化体系:π配体离子液体

 π配体催化剂与离子液体体系相结合有助于解决反应效率、产物分离和催化剂循环等一系列均相催化体系不易解决的难题. 近几年相关的研究逐渐深入,由简单地使用离子液体作为π配体催化反应的介质向利用离子液体自身结构的方向发展,相继出现了几类不同的研究思路. 例如,利用π配体催化剂与离子液体形成络合物,使用离子型π配体改善催化剂在离子液体中的溶解性,以及合成功能化阳离子或功能化阴离子的π配体离子液体. 本文结合这几类离子液体化学键联π配体(简称π配体离子液体)的研究进展,从离子液体功能化设计的角度探讨了π配体离子液体的合成思路,为设计具有更好催化性能的功能化离子液体体系提供借鉴.     

离子液体催化CO2与环氧化物合成环状碳酸酯

综述了离子液体催化CO2与环氧化物的环加成反应制备环状碳酸酯的研究进展。目前报道的离子液体主要包括咪唑盐、季铵盐、季鏻盐等。对比了传统离子液体与功能化离子液体对CO2环加成反应的催化活性、选择性以及催化作用机制。与传统的离子液体相比,功能化离子液体的羟基或羧基等官能团与卤素离子等Lewis碱之间存在协同效应,使得其对CO2与环氧化物的环加成反应具有更好的催化活性;将功能化离子液体固载于无机材料(SiO2,SBA-15,MCM-41等)或聚合物所得的多相催化剂不仅保持了官能团与阴离子之间的协同效应,而且载体与离子液体活性组分之间也显示出协同效应,使得该类催化剂具有很好的催化活性,稳定性好,可以多次重复使用,具有较好的工业化前景,是值得深入研发的一类催化材料。此外,离子液体对于手性环状碳酸酯的合成也具有较好的催化活性和立体选择性。     

功能化离子液体的催化作用及其应用

功能化离子液体是将功能团弓l入到离子液体的阳离子或阴离子上,从而赋予离子液体某种特殊性质．将具有催化活性的基团弓I入到离子液体的阳离子或阴离子上所得到的功能化离子液体,是一类新型的催化材料．除了具有优异的催化性能,其特殊的物理化学性质很容易实现产物与催化剂的分离,正在许多重要催化过程中发挥作用．本文主要介绍近年来我们关于功能化离子液体的制备、性质及其在催化反应中的应用等研究,同时指出了目前存在的问题,并对今后发展趋势进行了展望．     

锰卟啉功能化多元离子液体体系中苯乙烯及其衍生物环氧化反应

通过在中性锰卟啉分子中引入季铵阳离子和PF6-阴离子,制备了离子型锰卟啉化合物[MnTTMAPP][PF6]5,将其与[bmim]BF4及[bzmim]BF4混合构成锰卟啉功能化的多元离子液体复合体系(MnPy-MIL).实验发现,该体系可以高活性高选择性地催化苯乙烯及其衍生物的环氧化反应.与传统中性锰卟啉催化体系相比,离子型锰卟啉的抗氧化降解能力提高,卟啉自身聚合受到抑制,催化反应无需有机溶剂和轴向配体的参与,同时催化剂可以循环使用.少量水的存在可以提高MnPy-MIL体系的催化性能.     

多羧基咪唑离子液体的酸性表征

通过电位滴定法测得多羧基咪唑离子液体的离解常数pKa值(25 ℃)在1.43～1.92范围内, 说明多羧基咪唑离子液体酸性接近乙二酸, 比丁二酸以及乙酸强. 由于多羧基咪唑离子液体结构中咪唑环具有较强的吸电子诱导效应, 使多羧基咪唑离子液体具有中等强度的酸性. 三羧基咪唑离子液体酸性比含相同阴离子的二羧基咪唑离子液体酸性强. 阳离子相同、阴离子不同的多羧基咪唑离子液体酸性强弱顺序为: HSO4－ ＞ NO3－ ＞ PF6－ ＞ H2PO4－＞ Cl－、Br－ ＞ CF3CO2－ ＞ BF4－ ＞ CF3SO3－. 同时, 吡啶红外光谱探针法研究表明, 多羧基咪唑离子液体具有Brønsted酸性.     

离子液体催化甘油和尿素合成甘油碳酸酯（英文）

将一系列酸性、碱性和中性的功能化离子液体用于催化甘油和尿素合成甘油碳酸酯.结果表明,中性离子液体表现出更高的催化活性.离子液体阳离子和阴离子的协同效应促进了反应的进行,离子液体阳离子的正电性活化尿素,阴离子的负电性活化甘油,并且催化剂酸碱位点的平衡对催化反应过程也有一定的影响.此外,离子液体可以实现回收利用至少五次,且催化活性基本不变.采用功能化离子液体替代传统金属催化剂,减少了不可再生资源的利用,且所用原料为廉价易得的生物基原料,过程中也不使用有机溶剂,环境友好.     

Task-specific ionic liquids for carbon dioxide absorption and conversion into value-added products

Ionic liquids (ILs), by virtue of their special properties such as functional designability and high thermal stability, have been widely used as absorbent to CO₂ and catalyst for CO₂ conversion. This review summarizes the recent developments from 2019 to 2021 on task-specific ionic liquids (TSILs) with modulable properties by introducing specific functional groups to anions or/and cations for CO₂ absorption and conversion. The increase of basicity in TSILs by introducing amino/or amine groups or collaboration with multiple active sites of carboxyl, imidazolyl, pyridyl, and hydroxyl groups achieve high CO₂ affinity and absorption capacity. To solve the defects of high viscosity, ether groups are introduced to TSILs for CO₂ absorption. Besides, recent studies on CO₂ thermal catalytic conversion focused on the construction of C–O bonds and C–N bonds are also summarized. The catalytic activity of TSILs is enhanced by improving the synergy effect of different functional groups on anions and cations. It is expected that this minireview will provide the understanding of the current developments and perspective for practical CO₂ absorption and transformation by TSILs.     

La luminescence différée du styrène en solution vitreuse dans le méthylcyclohexane

The trapping of electrons and styrene cations and anions has been studied in a methylcyclohexane glass by the techniques of deferred luminescence. Radiothermoluminescence curves consist of two peaks, at 90 and 95°K, in this matrix. The second peak increases linearly with styrene concentration up to 2 × 10^?2M when it reaches a constant value, whereas the first peak increases from 10^?4 to 10^?3M and then decreases at higher concentrations and is not discernible at concentrations above 10^?2M. We propose two mechanisms which are qualitatively consistent with this behavior and are based essentially on the recombination of styrene cations with thermally detrapped electrons in the first peak and with anions in the second peak. Photothermoluminescence (i.e., thermoluminescence after photoionization with ultraviolet light) similarly consists of the 90 and 95°K peaks for a 10^?3M solution and of the 95° peak alone for a 10^?d M solution. Radiophotoluminescence excitation spectra at 77°K, corresponding to absorption spectra of trapped electrons and styrene anions, show that anions are the predominant negative species in 10^?2 molar solution, and trapped electrons in 10^?3 molar solution. Spectral analysis of radiothermoluminescenece shows the presence of two emission bands, one of which is identical with styrene fluorescence excited by the 254 Nm mercury line (λ_max = 292, 302, 307, and 317 Nm). The other band has three fairly poorly resolved maxima at 474, 486 and 496 nm and seems to correspond to the fluorescence of C₆H₅?H-CH₃ radicals formed during radiolysis.     

Conversion of pentynol to pentanone catalysed by Pd(II) metal centres

The cyclization of 3- or 4-pentyn-1-ol is catalysed by PdCl₂ or trans-[PdCl₂L₂] (L = R-camphorimine; R = Ph; Prⁱ; NMe₂) complexes at room temperature affording heterocyclic compounds, respectively, 2-methyl-2-pent-3-ynyloxy-tetrahydrofuran or 2-methyl-2-pent-4-ynyloxy-tetrahydrofuran which subsequently add water to give selectively 5-(2-methyl-tetrahydrofuran-2-yloxy)-pentan-2-one from both starting materials. By hydrolysis 5-(2-methyl-tetrahydrofuran-2-yloxy)-pentan-2-one undergoes ring cleavage to form 5-hydroxy-2-pentanone. The catalytic activity and selectivity of complexes trans-[PdCl₂L₂] (L = R-camphorimine) depend on the characteristics of the R group (NMe₂ > Prⁱ > Ph). The catalytic activity of PdCl₂ is comparable to that of trans-[PdCl₂L₂] (L = Ph-camphorimine) which is the less efficient catalyst.     

Benzene ring assembly promoted by a camphor derived palladium complex

Trans-[PdCl₂L₂] (1, L=3-NNMe₂C₁₀H₁₄O), under mild reaction conditions, acts as a catalyst for the cyclic trimerization of alkynes. The best performance is achieved for the reaction with PhCCMe that affords 1,3,5-trimethyl-2,4,6-triphenyl benzene with high activity and selectivity (ca. 99%). As a general trend the catalytic activity is higher for internal (PhCCMe, PhCCPh) than for terminal alkynes (HCCPh, HCC^tBu, HCCCO₂Me). Under more drastic experimental conditions the reaction of 1 with PhCCPh yields trans-[PdCl₂(PhCCPh)₂] and no catalytic activity is observed. The molecular structure of 1,3,5-trimethyl-2,4,6-triphenyl benzene was confirmed by X-ray diffraction analysis. The molecules were characterized by ¹H- and ¹³C-NMR spectroscopies, FAB-MS and, in some cases, elemental analyses.     

Very short F—H⋯F hydrogen bond in l‐argininium fluoride hydrogen fluoride

There are two symmetry‐independent formula units of the title compound, C₆H₁₅N₄O₂⁺·F^?·HF, per cell. Both cations have a zwitterionic form, protonated at both the guanidyl and amino groups. The two symmetry‐independent cations differ in their conformation. In one of them the C_γ atom is in a gauche position to both the amino and carboxyl groups, while in the other this atom is trans to the amino group. The two anions have very similar geometry. The F^? ions are strongly hydrogen bonded to an HF molecule [F—H?F 2.233 (2) and 2.248 (3) Å], thereby forming an asymmetric non‐linear bifluoride anion. These F?F distances are the shortest reported for an asymmetric HF₂^? anion.     

A highly active and selective chalcogen bond-mediated perchlorate channel

Artificial membrane transporters that either use chalcogen bonds to facilitate transmembrane flux of anions or show high selectivity toward perchlorate anions are rare.In this work,we report on one such novel monopeptide-based transporter system,featuring both chalcogen bonds for highly efficient anion transport and high transport selectivity toward ClO₄^-anions.Structurally,these monopeptide molecules associate with each other via H-bonds to produce H-bonded 1 D stack that ...     

The Application of Cryptand 22 as a Bifunctional Stationary Phase for Ion Chromatography

Poly (styrene/divinyl benzene) with cryptand 22 as an anchoring group was synthesized and applied as a bifunctional packing material for the separation of both cations and anions. At pH < 2, the resin can be protonated and applied as an anion exchanger for the separation of anions; with water as eluent, inorganic anions such as F^?, Cl^?, Br^?, NO₃^?”, I^? were well separated. After deprotonation at pH> 10, the resin became a cation exchanger and successfully separated alkali metal ions such as Li⁺, K⁺ and Cs⁺ with methanol as eluent. The effects of solvents, flow rate and temperature on the separation of various ions were also investigated.     

Low‐dimensional compounds containing bioactive ligands. IV. Unusual ionic forms of 5‐chloroquinolin‐8‐ol

Bis(5‐chloro‐8‐hydroxyquinolinium) tetrachloridopalladate(II), (C₉H₇ClNO)₂[PdCl₄], (I), catena‐poly[dimethylammonium [[dichloridopalladate(II)]‐μ‐chlorido]], {(C₂H₈N)[PdCl₃]}_n, (II), ethylenediammonium bis(5‐chloroquinolin‐8‐olate), C₂H₁₀N₂²⁺·2C₉H₅ClNO⁻, (III), and 5‐chloro‐8‐hydroxyquinolinium chloride, C₉H₇ClNO⁺·Cl⁻, (IV), were synthesized with the aim of preparing biologically active complexes of Pd^II and Ni^II with 5‐chloroquinolin‐8‐ol (ClQ). Compounds (I) and (II) contain Pd^II atoms which are coordinated in a square‐planar manner by four chloride ligands. In the structure of (I), there is an isolated [PdCl₄]²⁻ anion, while in the structure of (II) the anion consists of Pd^II atoms, lying on centres of inversion, bonded to a combination of two terminal and two bridging Cl⁻ ligands, lying on twofold rotation axes, forming an infinite [–μ₂‐Cl–PdCl₂–]_n chain. The negative charges of these anions are balanced by two crystallographically independent protonated HClQ⁺ cations in (I) and by dimethylammonium cations in (II), with the N atoms lying on twofold rotation axes. The structure of (III) consists of ClQ⁻ anions, with the hydroxy groups deprotonated, and centrosymmetric ethylenediammonium cations. On the other hand, the structure of (IV) consists of a protonated HClQ⁺ cation with the positive charge balanced by a chloride anion. All four structures are stabilized by systems of hydrogen bonds which occur between the anions and cations. π–π interactions were observed between the HClQ⁺ cations in the structures of (I) and (IV).     

Pd(II)-catalyzed acetalization of terminal olefins with electron-withdrawing groups in supercritical carbon dioxide: selective control and mechanism

Pd(II)-catalyzed acetalization of terminal olefins with electron-withdrawing groups was carried out smoothly in supercritical carbon dioxide under oxygen atmosphere when polystyrene-supported benzoquinone (PS-BQ) or Cu^II (Cu^I) chloride was employed as cocatalyst. The higher selectivity was achieved, without any chlorinated by-product detected, when using PS-BQ instead of Cu^II (or Cu^I) chloride. PS-BQ could be recycled with excellent catalytic activity remaining after each simple filtration. Chlorine ion was demonstrated to be a promoter. The different acetalization mechanisms were revealed by the subtle relationship of chlorine ion and benzoquinone (BQ) to the catalytic activity of PdCl₂/PS-BQ, Pd^II-CuCl₂ or Pd(OAc)₂/PS-BQ.     

Glycinium trichloro­acetate

The title compound, C₂H₆NO₂⁺·C₂Cl₃O₂⁻, crystallizes in the P4₁ space group with two glycinium cations and two trichloro­acetate anions in the asymmetric unit. The glycinium cations have nearly C_s point‐group symmetry which is only broken by the H atoms of the amine group. The trichloro­acetate anions show typical bond lengths and angles, one of the trichloro­methyl groups being disordered. Chains of alternating anions and cations run along the c axis. Within these chains, consecutive anion–cation pairs are bound via strong hydrogen bonds involving the carboxyl­ate anions and the carboxyl or amine groups of the cations. Weaker hydrogen bonds bind neighbouring chains together.