离子液体中V2O5催化环己烯选择氧化合成 2-环己烯酮

研究了以V2O5为催化剂,H2O2为氧化剂,在室温离子液体中环己烯氧化制备2-环己烯酮的反应.考察了离子液体种类、反应温度、催化剂用量和氧化剂用量等因素对2-环己烯酮产率的影响.结果表明,在H2O2用量为110 mmol,V2O5/环己烯摩尔比为2%,反应温度为313 K的条件下,在[bmim]BF4离子液体中反应10 h后,环己烯的转化率和2-环己烯酮选择性分别为88.7%和91.1%.对含离子液体的催化体系的重复使用性能进行了考察.结果发现,随着使用次数的增加,环己烯的转化率以及2-环己烯酮的选择性有所下降.     

阳离子交换树脂/H_2O_2体系催化氧化环己烯的研究

在以改性阳离子交换树脂为催化剂、H2O2为氧化剂的催化氧化体系中,主要研究和考察了环己烯直接氧化制备1,2-环己二醇的反应,并优化得到了最佳合成工艺,在无溶剂,H2O2与环己烯的摩尔比为1.0:1.0、反应温度为70℃、反应时间为6.5h、催化剂用量为环己烯摩尔量10%的反应条件下,环己烯的转化率大于99.0%,产品1,2-环己二醇的选择性大于98.0%。阳离子交换树脂催化剂重复使用12次未见其活性和选择性明显下降。在此反应条件下,直链状的1-己烯也可高效和高选择性地转化为1,2-己二醇。     

Na_(12)[WZn_3(H_2O)_2(ZnW_9O_(34))_2]催化剂的制备及其催化活性

采用重结果法制备了催化剂Na12[WZn3(H2O)2(ZnW9O34)2](CatZn)。以1,2-丙二醇(1)催化选择性氧化制备羟基丙酮(2)为探针反应考察了CatZn的催化性能。在最佳反应条件[1 50 mmol,n(CatZn)∶n(1)=0.06,n(H2O)∶n(1)=1.4,n(H2SO4)∶n(1)=0.15,于70℃反应1.5 h]下,收率43.85%,选择性68.87%。     

Brφnsted酸性离子液体催化合成长链脂肪酸甲酯

本文合成了以1-丁基-3-甲基咪唑为阳离子,HSO4-、H2PO4-和BF4-为阴离子的Brφnsted酸性离子液体,并以长链脂肪酸与甲醇的酯化反应考察了这些Brφnsted酸性离子液体的催化性能。实验结果表明,1-丁基-3-甲基咪唑硫酸氢根鎓盐([bmim][HSO4])离子液体具有很高的催化活性,当n(醇)∶n(酸)∶n(离子液体)=6∶1∶0.25,反应温度为70℃,不分水酯化反应2h,长链脂肪酸甲酯的产率可达到93.4%以上,选择性达到100%;且产物酯与离子液体分离容易;离子液体经干燥处理后可以循环使用5次以上,催化活性没有明显降低。     

离子液体介质中FeCl3•6H2O催化下芳香醛与5,5-二甲基-1,3-环己二酮的缩合反应

考察了在离子液体1-正丁基-3-甲基咪唑四氟硼酸盐([bmim][BF₄])介质中, 芳香醛与5,5-二甲基-1,3-环己二酮的缩合反应. 实验结果表明, 在催化量的FeCl₃•6H₂O存在下, 该反应可高产率地生成氧杂蒽二酮类化合物3; 而在TMSCl/FeCl₃•6H₂O复合催化体系的催化下, 则得到氧杂蒽二酮类化合物的开环衍生物4, 反应具有非常好的选择性. 该论文提供的方法操作简单、产率高、选择性好而且对环境友好. 在反应结束后, 所用催化剂及离子液体都很容易回收, 并能有效重复使用.     

钨过氧酸盐离子液体催化过氧化氢氧化苯甲醇制苯甲酸

用甲基三辛基氯化铵和钨酸钠一步法合成甲基三辛基季铵钨酸盐离子液体[(CH3)N(n-C8H17)3]2W2O11,以该离子液体为催化剂,在无反应溶剂条件下催化过氧化氢氧化苯甲醇生成苯甲酸。 考察了反应温度、催化剂用量以及氧化剂过氧化氢用量对苯甲酸产率的影响。 确定优化条件：反应温度70 ℃,苯甲醇用量5 mmol,催化剂用量是底物的0.4%(摩尔分数),30%过氧化氢用量2 mL,苯甲醇的转化率可达99%,苯甲酸选择性为98%。 该方法具有反应条件温和、产率高和选择性好的优点。     

Pd/羧基功能化离子液体选择性催化氧化苯乙烯

 利用羧基对咪唑型离子液体的阳离子进行功能化,得到一系列具有不同羧基数目及与不同阴离子搭配的N-羧基功能化咪唑离子液体(TSILs), 进而构筑PdCl2/TSILs催化剂体系. 以过氧化氢为氧化剂,将PdCl2/TSILs用于选择性催化氧化苯乙烯合成苯乙酮. 研究结果表明, PdCl2/TSILs催化体系对目标反应具有理想的催化性能,羧基功能化离子液体的阳离子及其搭配的阴离子对苯乙酮的选择性和产率均有显著的影响. 阳离子的羧基数目越多,阳离子的不对称性越高, PdCl2/TSILs催化剂体系的活性越好. 含有相同阳离子的PdCl2/TSILs催化剂体系,其催化性能按照阴离子PF-6＜H2PO-4＜Cl-＜BF-4的顺序递增且与其酸强度顺序相反. 含有三羧基的功能化离子液体与PdCl2构筑的催化剂体系具有最佳的催化性能,在55 ℃下,该催化剂体系的转换频率值达到125 h-1, 苯乙烯可以完全转化且苯乙酮的选择性为91%.     

缺位Dawson型K10Na2H2P2W16O60在环己烯氧化中的催化作用

合成了二缺位杂多化合物K10Na2H2P2W16O60·18H2O,用IR、UV-vis、XRD及TG表征了其结构,考察了该化合物在过氧化氢氧化环己烯反应中的催化作用.研究结果表明,溶剂种类和反应温度对二缺位杂多化合物的催化性能有显著的影响,在叔丁醇中主要生成环己烯酮,在丙酮中主要生成环己二醇.在乙腈中主要生成环氧环己烷,其选择性随着反应温度升高和催化剂用量增加而降低,环己烯酮的选择性则逐步升高.催化剂与产物可通过温控固-液相分离,可以重复使用.     

离子液体[2-aemim]im催化Knoevenagel反应和异噁唑酮合成

以碱性离子液体1-(2-氨基乙基)-3-甲基咪唑咪唑盐([2-aemim]im)作为催化剂,催化Knoevenagel反应和4-芳亚甲基异噁唑-5(4H)-酮衍生物的合成。实验结果表明:在无溶剂条件下,该离子液体对Knoevenagel反应具有很高的催化活性,一系列芳香醛和活泼亚甲基化合物的反应在室温条件下2 min内顺利完成,均以90%以上的高产率生成取代烯烃产物.将该碱性离子液体用于催化乙酰乙酸乙酯或苯甲酰乙酸乙酯、盐酸羟胺和芳香醛三组分一锅法缩合制备4-芳亚甲基异噁唑-5(4H)-酮衍生物,具有反应时间较短、产率较高和后处理简单的特点。离子液体经简单处理后能多次循环使用。     

离子液体中微波辅助的 Lewis 酸催化纤维素制备 5-羟甲基糠醛

 以离子液体 1-丁基-3-甲基咪唑氯为溶剂, 以 CrCl3•6H2O 为催化剂, 直接转化纤维素生成 5-羟甲基糠醛 (HMF). 考察了微波辐射条件、反应温度、反应时间及催化剂用量对 HMF 产率的影响. 结果表明, 在最佳条件下, HMF 产率可达 55%.     

Direct Correlation Between the H/D Exchange Reaction and Conformational Changes of the Cation in Imidazolium-Based Ionic Liquid–D2O Mixtures

We present a study on the effects of deuterated water on the conformational equilibria of the imidazolium cation in aqueous mixtures of imidazolium-based ionic liquids at room temperature. We provide spectroscopic evidence that the conformational dynamics of the imidazolium cation in D₂O are directly related to the H/D exchange reaction of the C–H group at position 2 on the imidazolium ring. The relation is supported by comparing Raman spectra obtained from solutions prepared with H₂O and D₂O.     

微波照射下H2O2氧化1,2-环己二醇合成己二酸

以钨酸钠为催化剂在微波照射条件下,用30％H2O2使1,2-己二醇氧化开环合成己二酸。考察了照射时间、溶液pH值、不同催化剂及催化剂循环使用等对反应的影响,找出了反应的最佳条件。     

微波辅助合成有机膦功能化离子液体及对稀土离子的萃取

用微波辐射法,合成了5个含有机膦氧基团的离子液体：1-丙基-3-(3-二苯基氧膦基)丙基咪唑双(三氟甲基磺酰基)亚胺盐([PImC3P(O)Ph2][Tf2N])、1-己基-3-(3-二苯基氧膦基)丙基咪唑双(三氟甲基磺酰基)亚胺盐([HImC3P(O)Ph2][Tf2N])、1-丙基-3-(3-苯基乙氧基氧膦基)丙基咪唑双(三氟甲基磺酰基)亚胺盐([PImC3P(O)Ph(OEt)][Tf2N])、1-己基-3-(3-苯基乙氧基氧膦基)丙基咪唑双(三氟甲基磺酰基)亚胺盐([HImC3P(O)Ph(OEt)][Tf2N])和(3-苯基乙氧基氧膦基)丙基三乙胺双(三氟甲基磺酰基)亚胺盐([TENC3P(O)Ph(OEt)][Tf2N])。 用31P NMR、1H NMR、13C NMR、MS及FT-IR对产物结构进行了表征。 研究了这类离子液体对稀土Nd(III)的萃取性能。 结果表明,这类功能化离子液体可作为单一组分萃取稀土而无需加入有机稀释剂,离子液体结构对萃取效率影响很大,相同条件下季铵盐型结构的离子液体[TENC3P(O)Ph(OEt)][Tf2N]对稀土Nd(Ⅲ)的萃取效率最高。 稀土溶液pH值对萃取效率影响显著,近中性条件下(pH=6.63),对稀土Nd(Ⅲ)的萃取率最高。 用pH=1.00的盐酸溶液可以较好的从离子液体相反萃Nd(Ⅲ),反萃率可达94%。     

Convenient and Efficient Method for the Synthesis of Phthalocyanines and Metallophthalocyanines in Task-Specific 2-Hydroxyethyl Ionic Liquids

Tetramerization of substituted phthalonitriles in task-specific 2-hydroxylethyl-based imidazolium and ammonium ionic liquids at 100 °C gave corresponding phthalocyanines in moderate yield. Further the reaction of substituted phthalonitriles in the presence of transition-metal salts in ionic liquids gave the corresponding metallophthalocyanines. The 2-hydroxylethyl ammonium ionic liquids gave better yields of phthalocyanines than 2-hydroxylethyl imidazolium and nonhydroxyl functionalized ionic liquids. The isolation and separations of different phthalocyanines were accomplished by silica-gel column chromatography, and products were characterized by various spectroscopic techniques.     

On the involvement of NHC carbenes in catalytic reactions by iridium complexes, nanoparticle and bulk metal dispersed in imidazolium ionic liquids

D/H exchange reactions at C2, C4 and C5 of the imidazolium cation were observed in catalytic hydrogenation reactions promoted by classical Ir(I) colloid precursors and [Ir(0)](n) nanoparticles dispersed in deuterated imidazolium ionic liquids indicating the participation of carbene species in this media. However, no D/H exchange reaction was observed in cyclohexene hydrogenation promoted by iridium bulk metal dispersed in the ionic liquid [BMI]-d(3).NTf(2). The D/H labeling experiments suggest that the ionic liquids interact with the metal centers preferentially as aggregates rather than isolated ions.     

Chemical and thermal stability of N‐heterocyclic ionic liquids in catalytic C–H activation reactions

¹H‐NMR spectrum analyses are applied to study the chemical and thermal stability of selected N‐heterocyclic ionic liquids within the reaction system that can highly efficiently activate a C–H bond of methane and convert it into the C–O bond in methanol. Our results indicate that under such reaction conditions involving using a powerful Pt‐based catalyst and strong acidic solvent, the aromatic ring of an imidazolium cation becomes unstable generating an ammonium ion (NH₄⁺). Our results also suggest that the instability of the imidazolium ring is more chemically (participation in reactions) than thermally based. Modifications of the aromatic ring structure such as pyrazolium and triazolium cations can increase the chemical/thermal stability of ionic liquids under these reaction conditions. Copyright © 2014 John Wiley & Sons, Ltd.     

Degradation of polylactide using basic ionic liquid imidazolium acetates

Imidazolium acetate ionic liquids show high efficiency in the degradation of polylactides (PLA): degradation degree of PLA can reach almost 100 % in imidazolium acetate ionic liquids at 170°C and 1 h under atmospheric pressure, while the degradation degree of PLA remains close to 0 % using neutral 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4) and acidic ionic liquids at the same reaction conditions. With the increase of both the amount of acetate ionic liquid and the reaction temperature, the degradation degree of PLA increases. The structure of ionic liquids affects the degradation behavior of PLA: for cations, the proton from the C-2 position on the imidazolium ring is involved in the degradation of PLA; the degradation of PLA increases with the increase of the alkyl side-chain length of imidazolium cations; for anions, moderate basicity of the acetate ion contributes to the high activity of the imidazolium acetate ionic liquids in the degradation of PLA.     

Nonsolvent application of ionic liquids: organo-catalysis by 1-alkyl-3-methylimidazolium cation based room-temperature ionic liquids for chemoselective N-tert-butyloxycarbonylation of amines and the influence of the C-2 hydrogen on catalytic efficiency

1-Alkyl-3-methylimidazolium cation based ionic liquids efficiently catalyze N-tert-butyloxycarbonylation of amines with excellent chemoselectivity. The catalytic role of the ionic liquid is envisaged as "electrophilic activation" of di-tert-butyl dicarbonate (Boc(2)O) through bifurcated hydrogen bond formation with the C-2 hydrogen of the 1-alkyl-3-methylimidazolium cation and has been supported by a downfield shift of the imidazolium C-2 hydrogen of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][NTf(2)]) from δ 8.39 to 8.66 in the presence of Boc(2)O in the (1)H NMR and a drastic reduction of the catalytic efficiency with 1-butyl-2,3-dimethylimidazolium ionic liquids that are devoid of the C-2 hydrogen. The differential time required for reaction with aromatic and aliphatic amines has offered means for selective N-t-Boc formation during inter and intramolecular competitions. Preferential N-t-Boc formation with secondary aliphatic amine has been achieved in the presence of primary aliphatic amine. Comparison of the catalytic efficiency for N-t-Boc formation with a common substrate revealed that [bmim][NTf(2)] is superior to the reported Lewis acid catalysts.     

Investigations of coupling characters in ionic liquids formed between the 1-ethyl-3-methylimidazolium cation and the glycine anion

In this study, novel ionic liquids formed between the 1-ethyl-3-methylimidazolium cation [emim]+ and the glycine anion [Gly]- have been investigated theoretically. The relevant geometrical characteristics, energy properties, the characters of the intermolecular hydrogen bonds (H bonds), and the possibility of proton transfer as well as IR characteristics have been systematically discussed. The natural bond orbital (NBO) and atoms in molecule (AIM) analyses have also been applied to understand the nature of the interactions between ionic pairs in ionic liquids. The most stable geometries have been determined by analyzing the relative energies and interaction energies, where the C-H...O intermolecular H bonds involving the protons attached to the imidazolium ring have been found to possess partial covalent character in nature. Electron transfers from the lone pairs of the carbonyl O atom of [Gly]- to the C-H antibonding orbital of the [emim]+ can explain the elongation and red shift of the C-H stretching frequency. The interaction modes are more favorable when the carbonyl O atoms of [Gly]- interact with the C2-H of the imidazolium ring and the C-H of the methyl group through the formation of double H bonds. The origin of the high stability of the amino acid ionic liquids observed experimentally may be attributed to the nonexistence of the proton-transferred products (neutral pairs) together with the large energy needed for separation of the ionic pairs. Additionally, the characteristics of the IR spectra have been analyzed to demonstrate the variants of the molecular structure of the [emim]+[Gly]- ionic liquids.     

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.