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1.
BrФnsted acidic ionic liquids based on imidazolium cation were employed as efficient catalysts and mediums for the ring opening of phthalic anhydride to synthesize half-esters. Good yields, short reaction time and mild reaction condition were achieved. Lower acidity of ionic liquid resulted in higher catalytic selectivity in the synthesis of half-esters. The minimum-energy geometries of sulfonic acid-functionalized ionic liquids based on imidazolium cation revealed that their acidities and catalytic selectivity in the synthesis of half-esters were related to their structures. 相似文献
2.
CAO Jun-gang CAO Hui-min LIN Ying-jie LIANG Da-peng DUAN Hai-feng HAN Song-yang ZHAO Xue-zhong 《高等学校化学研究》2011,27(5):780-783
Lewis acidic guanidinium ionic liquid(LAGIL) 2c was used as a novel, efficient and recyclable catalyst for aminolysis of epoxides under solvent-free and room temperature conditions, giving the corresponding β-amino alcohols with moderate to excellent regioselectivity(up to 91:9) in high yields(up to 97%). In addition, LAGIL 2c was recycled three times without any loss of catalytic activity and selectivity to the product. 相似文献
3.
合成了一系列Brønsted酸性离子液体并将其应用在醛醇缩合反应中.醛醇缩合产物由于极好的溶剂性质等被广泛用作溶剂和试剂.离子液体[BSmim][OTf]在甲醛和乙二醇缩合生成1,3-二氧五环的反应中表现出了极好的催化活性,甲醛转化率和主产物1,3-二氧五环选择性分别可以达到96.1%和92.4%.对影响离子液体催化性能的因素进行了探索,并对催化反应中的离子液体的用量、反应温度、反应时间以及反应物料比进行了考察.通过Hammett酸度函数法测定了所用到离子液体的酸性,结果表明离子液体酸性与其在缩合反应中的催化活性顺序完全一致,酸性越强催化性能越好.结合实验给出了离子液体[BSmim][OTf]催化甲醛和乙二醇缩合反应的可能的反应机理.该催化剂体系具有良好的催化性能,反应可以在较温和的条件下进行,实现了高活性和高选择性的目标,产物易分离,催化剂重复使用7次,其催化活性基本不变.并将该Brønsted酸性离子液体进一步应用到其他醛(酮)醇缩合反应中. 相似文献
4.
合成了一系列Br(o)nsted酸性离子液体并将其应用在醛醇缩合反应中.醛醇缩合产物由于极好的溶剂性质等被广泛用作溶剂和试剂.离子液体[BSmim][OTf]在甲醛和乙二醇缩合生成1,3-二氧五环的反应中表现出了极好的催化活性,甲醛转化率和主产物1,3-二氧五环选择性分别可以达到96.1%和92.4%.对影响离子液体催化性能的因素进行了探索,并对催化反应中的离子液体的用量、反应温度、反应时间以及反应物料比进行了考察.通过Hammett酸度函数法测定了所用到离子液体的酸性,结果表明离子液体酸性与其在缩合反应中的催化活性顺序完全一致,酸性越强催化性能越好.结合实验给出了离子液体[BSmim][OTf]催化甲醛和乙二醇缩合反应的可能的反应机理.该催化剂体系具有良好的催化性能,反应可以在较温和的条件下进行,实现了高活性和高选择性的目标,产物易分离,催化剂重复使用7次,其催化活性基本不变.并将该Br(o)nsted酸性离子液体进一步应用到其他醛(酮)醇缩合反应中. 相似文献
5.
Several Brønsted acidic functional ionic liquids (FILs) with an alkane sulfonic acid group were synthesized. These FILs as dual solvent-catalysts for Nipagin esterification reactions were investigated. The results indicated that [HSO3-pMIM]HSO4 has the best catalytic activity and recyclability among the various kinds of FILs investigated, and its structure was characterized by infrared and NMR. The [HSO3-pMIM]HSO4 could be easily separated from the reaction mixture and reused without noticeably decreasing the catalytic activity.
6.
Eucalyptus nitens wood samples were subjected to hydrothermal processing to obtain soluble saccharides from the hemicellulosic fraction. The hemicellulose-derived saccharides were employed as substrates for furfural production in biphasic media made up of water, methyl isobutyl ketone, and one acidic ionic liquid (1-butyl-3-methylimidazolium hydrogen sulfate or 1-(3-sulfopropyl)-3-methylimidazolium hydrogen sulfate). The reactions were carried out in a microwave-heated reactor to assess the effects of the most influential variables. Under selected operational conditions, the molar conversions of the precursors into furfural were within the range of 77–86%. The catalysts conserved their activity after reutilization in five consecutive reaction cycles. 相似文献
7.
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. 相似文献
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An improved method for the synthesis of carboxamide ligands containing thioether donor sites is described. This replaces the pyridine as the reaction medium used in the classical method by tetrabutylammonium bromide. The desired products, 1,4-bis[o-(R-2-carboxamidophenyl)]-1,4-dithiobutane, R = quinoline (1), furan (2), thiophene (3), pyridine (4), and pyrazine (5), were obtained in good yields and shorter reaction times. 相似文献
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A brief review of the work carried out at Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences for development of ionic liquid as green reaction media and catalysts is presented. This includes the processes of ionic liquid to be used as catalyst, reaction media, development of functional ionic liquid and methods for synthesis of immobilized ionic liquid. In the end, some prospects for development of ionic liquid are also addressed. 相似文献
12.
Abolghasem Davoodnia Amir Khojastehnezhad Mehdi Bakavoli Niloofar Tavakoli‐Hoseini 《中国化学》2011,29(5):978-982
Easily synthesized aldoximes have been converted to the corresponding nitriles under very mild conditions by a simple reaction using two halogen‐free SO3H‐functionalized ionic liquids, 3‐methyl‐1‐(4‐sulfonic acid)butylimi‐ dazolium hydrogen sulfate [MIM(CH2)4SO3H][HSO4] and 1‐(4‐sulfonic acid)butylpyridinium hydrogen sulfate [PY(CH2)4SO3H][HSO4], as catalyst and reaction medium without any additional organic solvent. The method was equally effective for aromatic aldoximes bearing electron‐donating and electron‐withdrawing substituents. Taking into account environmental and economical consideration, the protocol presented here has the merits of environmentally friendly, simple operation, easy work‐up and very good yields. The catalysts could be recycled and reused for several times without noticeably decreasing in their catalytic activities. 相似文献
13.
首次报道了Brønsted酸性离子液体介质中的二甘醇的脱水环化反应,考察了不同的离子液体、离子液体/二甘醇摩尔比、反应温度和时间对反应的影响。结果表明,Brønsted酸性离子液体作为反应介质能够促进脱水环化反应的有效进行,且在离子液体1-(3-磺酸根丙基)-3-甲基咪唑硫酸氢盐([SPmim]HSO4)中,二甘醇的转化率和1,4-二氧六环的选择性更高。采用Hammett指示剂法测定了离子液体的酸度函数H0,其酸性强弱顺序为[SPmim]HSO4 > [Bmim]HSO4 > [Amim]HSO4 > [Hmim]BF4> [Bmim]H2PO4 >[Amim]H2PO4 > [Hmim]Tsa,这与离子液体在脱水环化反应中的催化效果一致。当温度为170 ˚C,离子液体/二甘醇摩尔比为1:1时,二甘醇在[SPmim]HSO4中反应2 h,转化率可达到97.0%,1,4-二氧六环的选择性为89.3%。 相似文献
14.
ZhangGaoLE ZhenChuCHEN YiHU QinGuoZHENG 《中国化学快报》2005,16(2):201-204
In ionic liquid [Bmim][BF4], a series of disubstituted and trisubstituted thiourea derivatives were synthesized from phenyl and butyl isothiocyanate with a variety of amine in excellent yield. 相似文献
15.
作为一种新型低污染的绿色溶剂,离子液体近来受到多方关注。文章综述了离子液体合成和功能化设计方面的研究进展,微波和超声波辅助合成离子液体与常规方法相比所需反应时间短、产率高,表现出一定优势。 相似文献
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离子液体作为溶剂/催化剂用于卤代烃对胺的选择性烷基化反应 总被引:1,自引:0,他引:1
在三乙胺存在下,在离子液体([bmim]I和[bmim]PF6)中进行了各种卤代烃对胺类化合物中氨基的选择性烷基化反应.反应在相对温和的条件下进行,转化率和选择性优异.离子液体可以回收并重复使用. 相似文献
18.
酸性离子液体高选择性催化合成2,6-二甲基萘 总被引:1,自引:0,他引:1
研究了三乙胺氯铝酸盐(Et3NHCl-AlCl3)类离子液体催化剂的酸性及反应条件对1,2,4,5-四甲基苯与2-甲基萘转移烷基化合成2,6-二甲基萘(2,6-DMN)反应的影响规律.结果表明,通过调节Et3NHCl-AlCl3离子液体的酸强度和优化反应温度及反应时间等工艺条件可以高选择性地制备2,6-DMN.以Et3NHCl-AlCl3(x(AlCl3)=0.71)为催化剂,以环己烷为溶剂,在2-甲基萘∶四甲基苯摩尔比为1∶1和20℃的条件下反应6h,2-甲基萘的转化率可达48.8%,DMN的选择性和2,6-DMN占DMN的摩尔百分比分别达到81.2%和52.4%,2,6-DMN的收率可达20.8%.特别需要指出的是,在此优化条件下反应2h,2-甲基萘的转化率为3.7%时,2,6-DMN占DMN的摩尔百分比达到100%.以混合甲基萘和萘为转移烷基化反应原料时也高选择性地得到了2,6-DMN.对Et3NHCl-AlCl3的循环使用性能进行了考察,并分析了失活原因. 相似文献
19.
An ionic liquid (IL) BMIGaCh was prepared by directly mixing GaCl3 and 1-methyl-3-butylimidazolium chloride with molar ratio of 1/1 under argon atmosphere. The densities and surface tensions of this pure ionic liquid were determined in the temperature range of 268.15 to (338.15±0.1) K. A new theoretical model of ionic liquids, an interstice model, was applied to calculate the thermal expansion coefficient of IL BMIGaCh, a, and the magnitude order of its value calculated by the theory was the same as experimental one. Both Raman scattering and ab initio calculations indicate that GaCl4^- is the only species containing Ga in the ionic liquid BMIGaCl4. 相似文献
20.
Hossein Tavakol Gita Gaimech Shahryar Ghammamy Gholamreza Rezaei Bebahani 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):2464-2471
The synthesis of six tetraalkylammonium bromopentachlorophosphoride ionic liquids (ILs) is reported here. Their structures were determined by IR, 1H NMR, and 13C NMR spectroscopy. Moreover, thermogravimetric (TG) and differential thermal analysis (DTA) were used to investigate the thermal behavior of these compounds. The results show that these ILs have excellent thermal stability below 145°C, and by decreasing the size of the alkyl groups, the thermal stabilities will increase. Along with the experimental study, these compounds have been studied computationally at the B3LYP/LANL2DZ level of theory using the PC GAMESS/Firefly program package. From these calculations, optimized geometries, molecular parameters, and vibrational spectra of ILs have been calculated. In addition, calculated frequencies are compared with the experimental frequencies after correction by the appropriate scaling factor. This comparison shows that our theoretical data are in good agreement with the experimental results. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献