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1.
Maruyama T Yamamura H Kotani T Kamiya N Goto M 《Organic & biomolecular chemistry》2004,2(8):1239-1244
Lipase-catalyzed alcoholysis between vinyl acetate and 2-phenyl-1-propanol was investigated in dialkylimidazolium-based ionic liquids. Although native lipase powder exhibited very low activity in an ionic liquid, forming a poly(ethylene glycol)(PEG)-lipase complex improved the lipase activity in the ionic liquid. The activity of the PEG-lipase complex was higher in ionic liquids than in common organic solvents (n-hexane, isooctane and dimethylsulfoxide). Fluorescence measurements using 4-aminophthalimide revealed that the ionic liquids were more hydrophilic than the organic solvents used for non-aqueous enzymology. A kinetic study of lipase-catalyzed alcoholysis in an ionic liquid ([Bmim][PF6]) revealed that the Michaelis constant (Km) for 2-phenyl-1-propanol in the ionic liquid was half that in n-hexane, suggesting that the ionic liquid stabilized the enzyme-substrate complex. Finally, we carried out enantioselective alcoholysis of 1-phenylethanol in ionic liquids employing the PEG-lipase complex, and obtained high enantioselectivity, comparable to that in n-hexane. 相似文献
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Basic Ionic Liquid: A Reusable Catalyst for Knoevenagel Condensation in Aqueous Media 总被引:1,自引:0,他引:1
GAO Guo-hua LU Liang ZOU Ting GAO Jin-bao LIU Ye HE Ming-yuan 《高等学校化学研究》2007,23(2):169-172
IntroductionThe Knoevenagel condensation of aldehydes/ketones and activated methylene compounds is one ofthe most common synthetic methods to produce func-tionalized alkenes. Theα,β-unsaturated productsobtained by this method have been widely used as th… 相似文献
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磁性离子液体是指能够吸附在磁铁上,在外加磁场作用下具有一定磁化强度的离子液体。本文综述了自2004年磁性离子液体概念提出至今在各领域的应用,其可以催化吡咯、3-甲基噻吩等单体合成导电高分子纳米微球,同时起到溶剂和模板的作用;还可以通过外加磁场调整产物的微观结构和形貌,从而得到不同的纳米结构;它也可以充当Lewis酸催化剂,催化傅克反应等一系列化学反应,并可以回收重复使用,而且回收有望通过磁场简单实现;与碳纳米管以共价键结合可以制备具有磁性的碳纳米管。除此之外,磁性离子液体在光控顺磁性超分子体系、吸收有机挥发物等领域的应用在近年也陆续有报道。 相似文献
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A second generation Hoveyda-Grubbs ruthenium carbene complex bearing an ionic liquid tag was prepared and shown to be a highly reactive catalyst for the ring-closing metathesis of di-, tri- and tetrasubstituted diene and enyne substrates in minimally ionic solvent systems ([Bmim]PF6/CH2Cl2, 1:9-1:1 v/v). Both the catalyst and the ionic liquid can be conveniently recycled and repeatedly reused (up to 17 cycles) with only a very slight loss of activity. The ionic liquid tag is crucial to the high level of recyclability of the catalyst since the original second generation Grubbs and Hoveyda-Grubbs catalysts rapidly lose their activity when recycled in the ionic liquid layer. 相似文献
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PEG型酸性温控离子液体中芳香酸和醇的酯化反应 总被引:4,自引:0,他引:4
报道了该催化体系在芳香酸和醇酯化反应中的应用. 研究发现, 该离子液体具有优良的催化性能, 产品易分离, 催化剂可循环使用且活性不降低, 催化剂不易流失, 实现了均相催化剂的高效回收和再利用. 相似文献
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The internal redox esterification of α,β-unsaturated aldehydes and alcohols was carried out using different ionic liquids (ILs) as catalysts and reaction solvents. The basic ionic liquid, 1-butyl-3-methylimidazolium acetate ([bmim]OAc), exhibited the best activity for this reaction. The influences of the amount of ionic liquid catalyst and reaction time on yield of saturated ester have been investigated. The results showed that ionic liquid anions have a crucial effect on the redox esterification of α,β-unsaturated aldehydes and alcohols. The nucleophilic carbenes generated in situ from the ionic liquid cation were believed to be actual active species for this reactions. 相似文献
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In this paper, a survey has been undertaken to clarify the possible reasons for the electrocatalytic activity obtained by the presence of ionic liquid in carbon paste electrode (CPE). For this purpose, the effect of the addition of traces of ionic liquid to conventional CPE was investigated. Fe(CN)63?/4? was used as a probe and two ionic liquids, namely n‐octylpyridinum hexafluorophosphate and 1‐octyl‐3‐methylimidazolium hexaflourophosphate were tested for their electrocatalytic activity. The reasons for this electrocatalytic behavior were evaluated and it was found that different factors such as increase in the ionic conduction of the binder, decrease in the resistance of the modified electrode, increase in ion exchange properties of the electrode and the inherent catalytic activity of ionic liquids are responsible for the considerable improved electrochemical response obtained in the presence of traces of ionic liquid. 相似文献
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采用含不同碳链长度咪唑环的烷基功能化离子液体修饰介孔材料SBA-15,并通过X-射线衍射、元素分析、N2吸附-脱附、红外光谱和扫描电镜等方法研究了离子液体修饰对SBA-15结构的影响.以三乙酸甘油酯的水解为探针反应,考察了甲基、丁基、辛基等不同链长烷基取代咪唑类离子液体修饰的SBA-15固定化Burkholderia cepacia脂肪酶(BCL)的酶活、最适反应条件及稳定性等酶学性质.结果表明,离子液体修饰后材料保持了原有的介孔结构,其固定化酶对温度及低pH的敏感度降低,比活力及稳定性均显著提高.其中甲基功能化离子液体修饰的SBA-15固定化酶的比活力最高,是原粉SBA-15固定化酶的2.4倍;辛基功能化离子液体修饰的SBA-15固定化酶的热稳定性、储存稳定性、重复使用性及有机溶剂耐受性最佳. 相似文献
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室温离子液体中水溶性铑膦配合物催化1-己烯氢甲酰化反应的研究 总被引:2,自引:0,他引:2
研究了水溶性膦配体铑配合物在若干离子液体中的1-己烯氢甲酰化反应性能.通过改变离子液体的阴阳离子结构,可使水溶性TPPTS-铑配合物在离子液体中表现出较高的卜己烯氢甲酰化反应活性和选择性;在[BMI]BF4离子液体中加入适量的水,可提高TPPTS-铑配合物的催化活性;在[BMI]BF4离子液体中,水/有机两亲性膦配体与铑形成的配合物,反应后催化剂与产物自动分层,实现催化剂的循环使用.本文结果表明,水溶性膦配体铑配合物的催化活性与其在离子液体中的溶解度密切相关. 相似文献
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A simple, efficient, and green protocol for Knoevenagel condensation of Meldrum's acid and aldehydes in ionic liquid at room temperature without any catalyst is described. The reaction has been performed in different ionic liquids. The enhancement in the rate is observed in Brönsted acidic ionic liquid 1‐methylimidazolium trifluoroacetate [Hmim]Tfa, which furnishes quantitative yields with 4–30 min in most of the cases. Furthermore, ionic liquid is easily reused without any appreciable loss in activity. 相似文献
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Amino-functionalized ionic liquid as a nucleophilic scavenger in solution phase combinatorial synthesis 总被引:3,自引:0,他引:3
A new functionalized ionic liquid, 1-aminoethyl-3-methylimidazolium hexafluorophosphate was synthesized from 1-methylimidazole and 2-bromoethylamine hydrobromide. This ionic liquid was found to be an efficient scavenger for removing excess electrophiles, such as benzoyl chloride, p-toluenesulfochloride, phenyl isothiocyanate, and p-chlorophenyl isocyanate, in a solution-phase parallel synthesis. The resulting ionic liquid derivatives can be separated directly from the reaction mixture. Desired products were obtained with high purity. Only 1.5-2.0 equiv of this scavenger was needed with a sequestration time of less than 35 min. In addition, the used ionic liquid can be regenerated and recycled several times without significant loss of activity. 相似文献
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The concept of supported ionic liquid catalysis (silc) has successfully been applied to hydrogenation reactions, which significantly reduced the required amounts of ionic liquid phase and enabled the usage of fixed-bed technology; the resulting catalysts exhibited high activity and outstanding stability. 相似文献
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The typical Knoevenagel condensation was carried out smoothly in the presence of a basic ionic liquid of N,N,N′,N′-tetramethyl-N′-hexyl-ethylenediammonium tetrafluoroborate ([TMHEDA]BF4), and 99% of yield was obtained using ethyl cyanoacetate and benzaldehyde as substrates at 60 °C for 1 h. Four reuses of the ionic liquid without dramatic decrease in catalytic activity for Knoevenagel condensation demonstrated the good stability and operability of the ionic liquid. Moreover, the typical nucleophilic addition reactions were also accomplished by the same ionic liquid to check its feasibility. The dual function of the basic ionic liquid both as solvent and catalyst, combined with simple product separation and recycling, is expected to contribute to the development of a green and environmentally friendly strategy. 相似文献
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在离子液体作为反应介质的条件下,以六氟异丙基氯甲基醚的氟代反应合成了七氟醚。 探讨了氟代反应机理,考察了[bpy]BF4、[bmim]BF4、[bepy]BF4、[bmim]PF6对反应产率的影响,研究了氟化剂、水和温度对反应产率的影响。 结果表明,以[bepy]BF4为反应介质,高比表面积的KF和微量的水有利于固态KF的部分离解进入有机相形成高活性的F-从而减少副产物,收率达到94.6%。 离子液体可重复使用3次以上,其活性没有明显下降。 相似文献
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A simple, efficient, and green protocol for synthesis of coumarin-3-carboxylic acids is described via Knoevenagel condensation of Meldrum's acid with ortho-hydroxyaryl aldehydes in [Hmim]Tfa ionic liquid, which was found to give better results than other ionic liquids. Furthermore, ionic liquid is easily reused without any appreciable loss in activity. 相似文献
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Summary. Room temperature ionic liquid, [bmIm]OH, is used as a green recyclable reaction medium and reagent for the alkylation of phenols in excellent yields. The recovered
ionic liquid was reused five to six times with consistent activity. 相似文献
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Study on One‐pot Biginelli‐like Synthesis of Pyrazolo[3,4‐d]pyrimidines in Bronsted Acidic Ionic Liquid Under Sonication and its Mechanism
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Bhautik B. Thummar Umesh P. Tarpada Dipak K. Raval 《Journal of heterocyclic chemistry》2014,51(6):1740-1746
Pyrazolo[3,4‐d]pyrimidine derivatives were synthesized using ionic liquid, 1‐butylimidazolium tetrafluoroborate, under ultrasound irradiation at ambient condition without any added catalyst. Mechanistic pathway based on the catalytic role of ionic liquid has been proposed. This method offers the advantages of simple procedure, milder reaction condition, easier workup and improved yield over the conventional method. The ionic liquid could be recycled at least three times with marked retention in its activity. 相似文献