咪唑根碱性离子液体在水介质Knoevenagel反应中的催化作用

报道了咪唑根1-丁基-3-甲基咪唑([Bmim]Im)碱性离子液体的合成与表征,该离子液体具有强碱性和较好的热稳定性.碱性离子液体[Bmim]Im用于催化水介质中Knoevenagel反应,发挥了碱催化剂与相转移催化剂双重作用.此外,离子液体[Bmim]Im及其水溶液还具有良好的循环使用性能.水介质、低催化剂用量、室温...     

室温离子液体在过渡金属催化反应中的应用研究进展

室温离子液体(RTILs)是在室温或近于室温下呈液态的由离子构成的盐类．如图1所示，RTILs按阳离子类型可以分为4类：烷基季铵盐离子；烷基季鳞盐离子；N，N-二烷基咪唑离子和N-烷基吡啶离子．按阴离子可分为：氯化盐 AlX3(X=卤素)和含有RF1^-,PF6^-等阴离子的离子液体．     

离子液体的量化计算及分子动力学模拟研究进展

离子液体是由有机阳离子和无机/有机阴离子构成的盐类,一般在室温或接近于室温下呈液态,因此常被称为室温离子液体(RTIL).依据不同的划分标准,离子液体有多种分类方式:根据年代的不同可将离子液体分为第一代、第二代及第三代离子液体,例如:烷基咪唑和烷基吡啶的金属卤化物盐等[1];根据阳离子的不同可将离子液体分为季鏻     

聚离子液体催化碳酸乙烯酯与甲醇的酯交换反应

通过N-乙烯基咪唑鎓离子液体、 丙烯酸钠(NaAA)和交联剂二乙烯基苯(DVB)或1-乙烯基-3-三乙二醇基咪唑溴盐{[(EG)₃-DVIm]Br₂)}自由基聚合合成了一系列含羧酸根的聚离子液体. 将所合成的聚离子液体用于催化甲醇与碳酸乙烯酯(EC)酯交换反应制备碳酸二甲酯(DMC). 研究结果表明, 在甲醇和EC混合溶剂中具有最大溶胀度的聚离子液体催化剂poly[VOIm-AA-DVIm]活性最高. 在优化反应条件[120 ℃, 6 h, 1.0%(摩尔分数)催化剂用量, n(甲醇)/n(EC)=10∶1]下, DMC收率为76.6%, 选择性为90.1%, 达到了与均相催化剂1-丁基-3-甲基咪唑醋酸盐([BMIm]OAc)相当的活性.     

离子液体中芳烃侧链分子氧催化氧化反应研究

分别以离子液体[Hex-mim]BF4, [Bmim]BF4, [Bmim]PF6和[Omim]BF4为溶剂, Co(Ⅱ), Mn(Ⅱ)或Ni(Ⅱ)/NHPI(AIBN)为复合催化剂, 考察了不同离子液体-催化剂体系中常压分子氧氧化芳烃侧链烷基的反应. 在[Hex-mim]BF4中, Co(Ⅱ)或Mn(Ⅱ)/NHPI可有效地催化芳烃侧链烷基的分子氧氧化. 在优化条件下, 乙苯、正丙苯和正丁苯分别以高达90%, 94%和93%的收率得到相应的芳香酮; 甲苯和对位取代甲苯以32%~47%的收率被氧化为相应的芳香酸. 离子液体及金属催化剂体系在减压下除水后, 可循环使用.     

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.     

中性分子1,3-氮氧杂环-戊-2-酮与二(三氟甲基磺酸酰)亚胺锂形成的新型室温熔盐

在目前各种室温熔融盐(也称离子液体)体系的研究热点中,正离子多以咪唑离子、吡啶离子或其它有机季铵离子类为主,特别是烷基取代的咪唑阳离子是由咪唑环上3位N原子的孤对电子与H^ 或R^ 结合形成的,实际上是一种特殊的季铵离子,其性能较为稳定.本实验室先后制备了由具有酰胺基官能团的有机物与锂盐直接复合形成的室温熔盐．研究发现,该类物质中羰基氧呈强负电性,可     

手性胍盐离子液体的合成

离子液体作溶剂、催化剂进行有机合成反应是近几年来各国化学家关注的热点之一[1].究其原因主要是离子液体具有低熔点、不挥发、不易燃易爆等特点,使其能代替传统有机合成与工业催化工程中的易挥发性溶剂(VOCs).再就是离子液体作为一种离子溶剂,可能存在1018种二元离子液体,而现在实际应用中的分子溶剂大概600种,离子液体的多样性使得在实际应用中可以通过调节离子液体的结构来调节离子液体的性质,从而为反应提供合适的溶剂环境,从而提高反应的产率、选择性以及立体选择性等[2].手性离子液体的合成和离子液体中的不对称催化一直都是离子液体研究的一个重要方面.Wasserscheid等[3,4]最近报道了从"手性池"(Chiral pool)衍生的新手性离子液体的合成和特性.最近我们报道一类简单的胍盐室温离子液体的合成及性质[5,6],新型胍盐离子液体由于其独特的性质得到了大家的关注[7-8].而手性胍盐离子液体还未见文献报道,因此我们从简单易得的手性胺出发合成了一系列的手性胍盐离子液体(Scheme 1),以新的手性胍盐离子液体作为不对称性催化反应新体系的工作正在进行.     

香豆素在离子液体(BMIMBF4)中的电还原行

室温离子液体由大的有机阳离子(咪唑、吡啶、季铵和季等)和各种各样的阴离子[AlCl-4, PF-6, BF-4, CF3SO-3, (CF3SO3)2N-等]组成, 是一种新型的溶剂, 具有稳定性好、蒸气压小、毒性小和不易燃等优异的物理化学性质, 已引起了人们的广泛关注. 因而在这种新型溶剂中进行有机物电化学行为的研究, 用于评价其作为“绿色”电化学或新型电化学反应的可行性很有必要.     

手性离子液体研究进展

对近几年来手性离子液体的研究进展进行了全面综述,这些手性离子液体包括咪唑鎓盐、季铵盐、噁唑啉盐、噻唑啉盐、吡啶盐等;重点评述了手性离子液体的合成以及它们在有机化学中的应用,如作为反应溶剂和相转移催化剂、手性溶剂,手性助剂和手性位移试剂等。     

两种季铵盐型离子液体钯配合物的合成

以苯甲酰肼和4-醛基吡啶为原料,经过缩合反应制备亚胺型化合物1,分别与苄氯和对二苄氯结合制备了两个新型的离子液体型亚胺配体2和3,配体2和3分别与醋酸钯反应得到新型离子液体型钯配合物4和离子液体型自组装钯配合物5,其结构经¹H NMR,¹³C NMR,IR和MS确证。      

Rapid and accurate estimation of densities of room-temperature ionic liquids and salts

Volume parameters for room-temperature ionic liquids (RTILs) and salts were developed. For 59 of the most common imidazolium, pyridinium, pyrrolidinium, tetralkylammonium, and phosphonium-based RTILs, the mean absolute deviation (MAD) of the densities is 0.007 g cm-3; for 35 imidazolium-based room-temperature salts, the MAD is 0.020 g cm-3; and for 150 energetic salts, the MAD is 0.035 g cm-3. The experimental density (Y) for an alkylated imidazolium or pyridinium-based room-temperature ionic liquid is approximately proportional to its calculated density (X) in the solid state: Y = 0.948X - 0.110 (correlation coefficient: R2 = 0.998, for BF4-, PF6-, NTf2- -containing ionic liquids); Y = 0.934X - 0.070 (correlation coefficient: R2 = 0.999, for OTf-, CF3CO2-, N(CN)2- -containing ionic liquids).     

Syntheses of Methylene‐bridged Symmetric Bisimidazolium Picrates as High‐energetic Salts

Symmetric bisimidazolium picrates were synthesized by the quaternization of bisimidazolylmethylene and a metathesis reaction with silver picrate. The symmetric structures of the new picrate salts were confirmed by ¹H and ¹³C NMR spectral analysis and ESI‐MS. The structures of compounds 3a and 4a were also confirmed by X‐ray single crystal diffusion. The thermal properties of the compounds were determined by differential scanning calorimetry and thermogravimetric analysis. The picrates showed better thermal stabilities than did traditional azolium‐based ionic salts, with higher decomposition temperatures, and 3b had the lowest melting point. These results indicated that the electronic effect of the substituent groups obviously influenced the quaternization and the high‐energetic properties.     

Preparation and characterization of bis(trifluoromethyl)phosphanide salts of outstanding stability

The stable compounds [NEt(4)][P(CF(3))(2)] and [18-crown-6-K][P(CF(3))(2)] were synthesized in quantitative yields by treatment of HP(CF(3))(2) with ionic cyanides at low temperature. These novel salts were characterized by multinuclear NMR spectroscopy, elemental analysis, and vibrational spectroscopy. Excellent agreement of experimental and theoretical vibrational frequencies, calculated at the B3PW91 level of theory, clearly confirms the saltlike character of these compounds. Due to their ionic nature, these salts are excellent nucleophilic reagents for the transfer of P(CF(3))(2) groups, suitable for the synthesis of chiral bidentate bis(trifluoromethyl)phosphine containing compounds.     

Synthesis of 2,2'-biimidazolium-based ionic liquids: use as a new reaction medium and ligand for palladium-catalyzed suzuki cross-coupling reactions

Neat reactions of 2,2'-biimidazole with an excess of alkyl or polyfluoroalkyl iodides at 140 degrees C, followed by anion exchange with LiN(SO(2)CF(3))(2) or KPF(6), gave the diquaternary salts 3a-k in >80% yields. However, by controlling the reaction stoichiometry, 2,2'-biimidazole can also be monoquaternized with the same electrophiles at 100 degrees C under similar conditions. Subsequent metathesis reactions with LiN(SO(2)CF(3))(2) or KPF(6) resulted in the ionic liquids 4a-m in high yields. Thermal properties were determined with a differential scanning calorimeter (DSC) and a thermogravimetric analyzer (TGA). Most of the monoquaternary salts are room-temperature ionic liquids. 1,3,1'-Tributyl-2,2'-biimidazolium hexafluorophosphate was demonstrated to be an excellent solvent and ligand for palladium-catalyzed Suzuki cross-coupling reactions. The catalytic ionic liquid system may be recycled at least 14 times without a significant decrease in catalytic performance.     

Nitrogen-rich salts based on energetic nitroaminodiazido[1,3,5]triazine and guanazine

Highly dense nitrogen-rich ionic compounds are potential high-performance energetic materials for use in military and industrial venues. Guanazinium salts with promising energetic anions and a family of energetic salts based on nitrogen-rich cations and the 6-nitroamino-2,4-diazido[1,3,5]triazine anion (NADAT) were prepared and fully characterized by elemental analysis, IR spectroscopy, (1)H NMR and (13)C NMR spectroscopy, and differential scanning calorimetry (DSC). The crystal structures of neutral NADAT (2) and its biguanidinium salt 5 were determined by single-crystal X-ray diffraction (2: orthorhombic, Pnma; 5: monoclinic, P2(1)). Additionally, the isomerization behavior of 2 in solution was investigated by proton-decoupled (13)C and (15)N NMR spectroscopy. All the new salts exhibit desirable physical properties, such as relatively high densities (1.63-1.78 g cm(-3)) and moderate thermal stabilities (T(d) = 130-196 °C for 3-10 and 209-257 °C for 11-15). Theoretical performance calculations (Gaussian 03 and Cheetah 5.0) gave detonation pressures and velocities for the ionic compounds 3-15 in the range of 21.0-30.3 GPa and 7675-9048 m s(-1), respectively, which makes them competitive energetic materials.     

咪唑[1,5-a]吡啶鎓盐的合成、表征及生物活性测定

通过三组份串联反应合成一系列咪唑[1,5-a]吡啶鎓盐,利用1H NMR、13C NMR、MS以及X射线单晶衍射确定其结构,其中以二乙烯三胺与三乙烯四胺为原料获得预期外的结构。以青霉素作为对照,研究了化合物的抗菌性。结果表明,所合成的化合物对溶壁微球菌和乙型链球菌均有抗菌效果,化合物2的抗菌效果最好;含有杂原子O的化合物3对嗜麦芽单胞菌和肺炎克雷伯氏菌的抗菌能力优于青霉素;联苯桥联的刚性双齿咪唑[1,5-a]吡啶鎓(5)比乙基桥联的柔性双齿咪唑[1,5-a]吡啶鎓(4)的抗菌性更强;化合物6为单齿大π体系芳香环,其抗菌效果较好,而化合物7和8为双齿的大π体系芳香环,其抗菌效果较弱。     

One-Pot Wittig and Knoevenagel Reactions in Ionic Liquid as Convenient Methods for the Synthesis of Coumarin Derivatives

Efficient synthesis of a variety of 3-substituted coumarins via NaOMe-catalyzed Knoevenagel condensation and one-pot preparation of 3,4-unsubstituted coumarins in the presence of NaOMe via Wittig reaction in room-temperature ionic liquids are described. Knoevenagel condensation of 2-hydroxybenzaldehyde with dimethyl- and diethylmalonate was performed with excellent yields in room-temperature ionic liquids. Although diethyl- and dimethylchloromalonates were mostly recovered unchanged in Knoevenagel condensation, higher conversions were observed via Wittig reaction of these compounds with 2-hydroxybenzaldehyde derivatives and triphenylphosphine. Other 2-hydroxybenzaldehyde derivatives, methyl- and ethylchloroacetates, were reacted in ionic liquids to afford simple coumarins in good yields. These reactions widen the applicability of ionic liquid in organic synthesis.     

Methimazole-based ionic liquids

The alkylation reaction of 2-mercapto-1-methylimidazole 1a with iodoethane and chlorobutane produced S-alkylmethimazole halides 2a and 2b which were subjected to anion metathesis with two different metal salts (MA) to afford methimazole-based room-temperature ionic liquids 3a, 3b, and 3c in 82%, 85%, and 87% yields, respectively. S-Alkylation giving 2a and 2b suggests that methimazole reacts through the thione tautomer.     

Energetic ionic liquids based on lanthanide nitrate complex anions

Energetic ionic liquids based on anionic lanthanide nitrate complexes Cat(+) (3)[Ln(NO(3))(6)](3-), where Cat(+) is guanidinium, 4-aminotriazolium, 4-amino-1-methyltriazolium, 4-amino-1-ethyltriazolium, 4-amino-1-butyltriazolium, 1,5-diaminotetrazolium, and 1,5-diamino-4-methyltetrazolium, were prepared. The hexanitratolanthanate (-cerate) salts with the last two cations, which are the first CO-balanced energetic ionic liquids that are stable to hydrolysis and air, have impact sensitivities of about 27 J. These ionic liquids were obtained by an environmentally friendly, simple method using nitrate-containing precursors. All salts were fully characterized by IR and NMR spectroscopy, elemental analysis, and determination of thermal stability, phase behavior, density, and water content. According to theoretical calculations, these new compounds have potential as propellants.