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1.
《Biochemical Engineering Journal》2010,49(3):295-314
The tremendous potential of room temperature ionic liquids as an alternative to environmentally harmful ordinary organic solvents is well recognized. Ionic liquids, having no measurable vapor pressure, are an interesting class of tunable and designer solvents, and they have been used extensively in a wide range of applications including enzymatic biotransformation. In fact, ionic liquids can be designed with different cation and anion combinations, which allow the possibility of tailoring reaction solvents with specific desired properties, and these unconventional solvent properties of ionic liquids provide the opportunity to carry out many important biocatalytic reactions that are impossible in traditional solvents. As compared to those observed in conventional organic solvents, the use of enzymes in ionic liquids has presented many advantages such as high conversion rates, high enantioselectivity, better enzyme stability, as well as better recoverability and recyclability. To date, a wide range of pronounced approaches have been taken to further improve the performance of enzymes in ionic liquids. This review presents the recent technological developments in which the advantages of ionic liquids as a medium for enzymes have been gradually realized. 相似文献
2.
Johnathan Gorke Friedrich Srienc Romas Kazlauskas 《Biotechnology and Bioprocess Engineering》2010,15(1):40-53
Ionic liquids, also called molten salts, are mixtures of cations and anions that melt below 100°C. Typical ionic liquids are
dialkylimidazolium cations with weakly coordinating anions such as (MeOSO3) or (PF6). Advanced ionic liquids such as choline citrate have biodegradable, less expensive, and less toxic anions and cations. Deep
eutectic solvents are also included in the advanced ionic liquids. Deep eutectic solvents are mixtures of salts such as choline
chloride and uncharged hydrogen bond donors such as urea, oxalic acid, or glycerol. For example, a mixture of choline chloride
and urea in 1:2 molar ratio liquefies to form a deep eutectic solvent. Their properties are similar to those of ionic liquids.
Water-miscible ionic liquids as cosolvents with water enhance the solubility of substrates or products. Although traditional
water-miscible organic solvents also enhance solubility, they often inactivate enzymes, while ionic liquids do not. The enhanced
solubility of substrates can increase the rate of reaction and often increases the regioor enantioselectivity. Ionic liquids
can also be solvents for non-aqueous reactions. In these cases, they are especially suited to dissolve polar substrates. Polar
organic solvent alternatives inactivate enzymes, but ionic liquids do not even when they have similar polarities. Besides
their solubility properties, ionic liquids and deep eutectic solvents may be greener than organic solvents because ionic liquids
are nonvolatile, and can be made from nontoxic components. This review covers selected examples of enzyme catalyzed reaction
in ionic liquids that demonstrate their advantages and unique properties, and point out opportunities for new applications.
Most examples involve hydrolases, but oxidoreductases and even whole cell reactions have been reported in ionic liquids. 相似文献
3.
Nucleoside chemistry represents an important research area for drug discovery, as many nucleoside analogs are prominent drugs and have been widely applied for cancer and viral chemotherapy. However, the synthesis of modified nucleosides presents a major challenge, which is further aggravated by poor solubility of these compounds in common organic solvents. Most of the currently available methods for nucleoside modification employ toxic high boiling solvents; require long reaction time and tedious workup methods. As such, there is constant effort to develop process chemistry in alternative medium to limit the use of organic solvents that are hazardous to the environment and can be deleterious to human health. One such approach is to use ionic liquids, which are ‘designer materials’ with unique and tunable physico-chemical properties. Studies have shown that methodologies using ionic liquids are highly efficient and convenient for the synthesis of nucleoside analogs, as demonstrated by the preparation of pharmaceutically important anti-viral drugs. This article summarizes recent efforts on nucleoside modification using ionic liquids. 相似文献
4.
Enzymatic selective acylation of glycosides in ionic liquids: significantly enhanced reactivity and regioselectivity 总被引:5,自引:0,他引:5
Mahn-Joo Kim Min Young Choi Jae Kwan Lee Yangsoo Ahn 《Journal of Molecular Catalysis .B, Enzymatic》2003,26(3-6):115-118
The enzymatic selective acylations of carbohydrates in ionic liquids were explored in both organic solvents and ionic liquids to see any significant differences in terms of reactivity and regioselectivity between two different classes of reaction media. Monoprotected glycosides (methyl-6-O-trityl-glucosides and galactosides) were chosen as the substrates with Candida rugosa lipase as an acylation enzyme. Two organic solvents, THF and chloroform, and two ionic liquids, [BMIM]+PF6− ([BMIM]+ = 1-butyl-3-methylimidazolium) and [MOEMIM]+PF6− ([MOEMIM]+ = 1-methoxyethyl-3-methylimidazolium), were employed as reaction media. The enzymatic reactions were performed in the presence of vinyl acetate at room temperature. It was observed that the reactions in ionic liquids took place more rapidly and more selectively than those in conventional organic solvents. 相似文献
5.
《Journal of Molecular Catalysis .B, Enzymatic》2009,56(3-4):110-117
The chemo-selectivity and the efficiency of the enzymatic acylation of 6-amino-1-hexanol have been studied in organic solvents distinct by their nature and their dissociation power, in solvent-free systems corresponding to free fatty acid or ethyl ester media and in different ionic liquids. In organic solvents and fatty acid ester media, a sequential reaction allowed the major production of the diacylated derivative at the equilibrium state. Conversely, the use of a solvent-free system with free fatty acid orientated the reaction exclusively towards the O-acylation by modifying the ionization state of the amino group and decreased the reaction time to reach the equilibrium state. Ionic liquids as 1-butyl-3-methyl imidazolium cation coupled with anions of low nucleophilicity significantly improved the efficiency of the reaction (substrate conversion and initial rate) and also led to the N,O-diacyl product. The nature of the reaction medium was shown to influence the ionization state of functional groups, then their capacity to react, and finally, the efficiency of the reaction. 相似文献
6.
Biocatalysis in ionic liquids - advantages beyond green technology 总被引:12,自引:0,他引:12
In recent years researchers have started to explore a particular class of organic solvents called room temperature ionic liquids - or simply ionic liquids - to identify their unique advantages for biocatalysis. Because they lack vapour pressure, ionic liquids hold potential as green solvents. Furthermore, unlike organic solvents of comparable polarity, they often do not inactivate enzymes, which simplifies reactions involving polar substrates such as sugars. Biocatalytic reactions in ionic liquids have also shown higher selectivity, faster rates and greater enzyme stability; however, these solvents present other challenges, among them difficulties in purifying ionic liquids and controlling water activity and pH, higher viscosity and problems with product isolation. 相似文献
7.
Biocatalytic transformations in ionic liquids 总被引:19,自引:0,他引:19
Room temperature ionic liquids are non-volatile, thermally stable and highly polar; they are also moderately hydrophilic solvents. Here, we discuss their use as reaction media for biocatalysis. Enzymes of widely diverging types are catalytically active in ionic liquids or aqueous biphasic ionic liquid systems. Lipases, in particular, maintain their activity in anhydrous ionic liquid media; the (enantio)selectivity and operational stability are often better than in traditional media. The unconventional solvent properties of ionic liquids have been exploited in biocatalyst recycling and product recovery schemes that are not feasible with traditional solvent systems. 相似文献
8.
Lipase‐catalyzed enantioselective transesterification of prochiral 1‐((1,3‐dihydroxypropan‐2‐yloxy)methyl)‐5,6,7,8‐tetrahydroquinazoline‐2,4(1H,3H)‐dione in ionic liquids
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The application of ionic liquids as solvents for transesterification of prochiral pirymidine acyclonucleoside using lipase (EC 3.1.1.3) Amano PS from Burkholderia cepacia (BCL) is reported. The effect of using medium reaction, acyl group donor, and temperature on the activity and enantioselectivity of BCL was studied. From the investigated ionic solvents, the hydrophobic ionic liquid [BMIM]PF6] was the preferred medium for enzymatic reactions. However, the best result was obtained in the mixture [BMIM][PF6]:TBME (1:1 v/v) at 50°C. Enzyme activity and selectivity in [BMIM][PF6]:TBME (1:1 v/v) was slightly higher in than in conventional organic solvents (for example, TBME), and in this condition, good activity and enantioselectivity were associated with unique properties of ionic liquid such as hydrophobicity and high polarity. Independently of solvents, monester of (R)‐configuration was obtained in excess. Under optimal conditions, desymmetrization of the prochiral compound using different acyl donors was performed. If vinyl butyrate was used as the acylating agent, BCL completely selectively acylated enantiotopic hydroxyl groups. 相似文献
9.
Use of salt hydrate pairs to control water activity for enzyme catalysis in ionic liquids 总被引:2,自引:0,他引:2
Salt hydrate pairs were used to control water activity in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate. It was shown that salt hydrate pairs behave essentially the same in ionic liquids as they do in organic solvents as long as they do not dissolve. Initial rate-water activity profiles were prepared for the immobilized Candida antarctica lipase catalyzed synthesis of 2-ethylhexyl methacrylate. The ability to use salt hydrate pairs for the control of water activity in ionic liquids should allow for improved comparison of enzyme activity and specificity in ionic liquids and conventional solvents. 相似文献
10.
Over-stabilization of Candida antarctica lipase B by ionic liquids in ester synthesis 总被引:5,自引:0,他引:5
P. Lozano T. De Diego D. Carrié Michel Vaultier J.L. Iborra 《Biotechnology letters》2001,23(18):1529-1533
Four different ionic liquids, based on dialkylimidazolium cations associated with perfluorinated and bis(trifluoromethyl)sulfonyl amide anions were used as reaction media for butyl butyrate synthesis catalyzed by free Candida antarctica lipase B at 2% (v/v) water content and 50 °C. Lipase had enhanced synthetic activity in all ionic liquids in comparison with two organic solvents (hexane, and 1-butanol), the enhanced activity being related to the increase in polarity of ionic liquids. The continuous operation of lipase with all the assayed ionic liquids showed over-stabilization of the enzyme. The reuse of free lipase in 1-butyl-3-methylimidazolium hexafluorophosphate in continuous operation cycles showed a half-life time 2300 times greater than that observed when the enzyme was incubated in the absence of substrate (3.2 h), and a selectivity higher than 90%. 相似文献
11.
Yoshikazu Abe Keisuke Kude Shuichi Hayase Motoi Kawatsura Katsuhiko Tsunashima Toshiyuki Itoh 《Journal of Molecular Catalysis .B, Enzymatic》2008,51(3-4):81-85
Ionic liquids are now recognized as solvents for use in lipase-catalyzed reactions; however, there still remains a serious drawback in that the rate of reaction in an ionic liquid is slower than that in a conventional organic solvent. To overcome this problem, attempts have been made to evolve phosphonium ionic liquids appropriate for lipase-catalyzed reaction; several types of phosphonium salts have been prepared and their capability evaluated for use as solvent for the lipase-catalyzed reaction. Very rapid lipase PS-catalyzed transesterification of secondary alcohols was obtained when 2-methoxyethyl(tri-n-butyl)phosphonium bis(trifluoromethanesulfonyl)imide ([MEBu3P][NTf2]) was used as solvent, affording the first example of a reaction rate superior to that in diisopropyl ether. 相似文献
12.
Enzyme catalysis in ionic liquids 总被引:15,自引:0,他引:15
Ionic liquids offer new possibilities for the application of solvent engineering to biocatalytic reactions. Although in many cases ionic liquids have simply been used to replace organic solvents, they have often led to improved process performance. Unlike conventional organic solvents, ionic liquids possess no vapor pressure, are able to dissolve many compounds, and can be used to form two-phase systems with many solvents. To date, reactions involving lipases have benefited most from the use of ionic liquids, but the use of ionic liquids with other enzymes and in whole-cell processes has also been described. In some cases, remarkable results with respect to yield, (enantio)selectivity or enzyme stability were observed. 相似文献
13.
Efficient conversion of glucose to 5-hydroxymethyl furfural (5-HMF), a platform chemical for fuels and materials, was achieved using CrCl2 or CrCl3 as the catalysts with inexpensive co-catalysts and solvents including halide salts in dimethyl sulfoxide (DMSO) and several ionic liquids. 5-HMF (54.8%) yield was achieved with the CrCl2/tetraethyl ammonium chloride system at mild reaction conditions (120 °C and 1 h). The 5-HMF formation reaction was found to be faster in ionic liquids than in the DMSO system. Effects of water in the reaction system, chromium valence and reaction temperature on the conversion of glucose into 5-HMF were discussed in this work. 相似文献
14.
Ionic liquids are considered as an alternative to organic solvents for catalysis. The literature in this field is reviewed
with focus on advantageous use of ionic liquids in biocatalysis and biotransformations. The overview reveals that the exploration
and mapping of ionic liquids with respect to biocatalysis is still sketchy. It is apparent that advantages can be gained in
view of activity, stability and selectivity. Furthermore, integration of reaction and separation has a high potential in the
field. The review presents quantitative data on the productivities, space–time yields, as well as stability as far as they
can be extracted from the literature.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
15.
Sanjib Kumar Karmee 《Applied microbiology and biotechnology》2009,81(6):1013-1022
Ascorbyl fatty acid esters act both as antioxidants and surfactants. These esters are obtained by acylation of vitamin C using
different acyl donors in presence of chemical catalysts or lipases. Lipases have been used for this reaction as they show
high regioselectivity and can be used under mild reaction conditions. Insolubility of hydrophilic ascorbic acid in non-polar
solvents is the major obstacle during ascorbic acid esters synthesis. Different strategies have been invoked to address this
problem viz. use of polar organic solvents, ionic liquids, and solid-phase condensation. Furthermore, to improve the yield
of ascorbyl fatty acid esters, reactions were performed by (1) controlling water content in the reaction medium, (2) using
vacuum to remove formed volatile side product, and (3) employing activated acyl donors (methyl, ethyl or vinyl esters of fatty
acids). This mini-review offers a brief overview on lipase-catalyzed syntheses of vitamin C esters and their biotechnological
applications. Also, wherever possible, technical viability, scope, and limitations of different methods are discussed. 相似文献
16.
Fabrication of biomass materials by a microwave-assisted method in ionic liquids allows the high value-added applications of biomass by combining three major green chemistry principles: using environmentally preferable solvents, using an environmentally friendly method, and making use of renewable biomass materials. Herein, we report a rapid and green microwave-assisted method for the synthesis of the cellulose/calcium silicate nanocomposites in ionic liquids and recycled ionic liquids. These calcium silicate nanoparticles or nanosheets as prepared were homogeneously dispersed in the cellulose matrix. The experimental results confirm that the ionic liquids can be used repeatedly. Of course, the slight differences were also observed using ionic liquids and recycled ionic liquids. Compared with other conventional methods, the rapid, green, and environmentally friendly microwave-assisted method in ionic liquids opens a new window to the high value-added applications of biomass. 相似文献
17.
Ionic liquids are receiving an upsurge of interest as ‘green’ solvents; primarily as replacements for conventional media in
chemical processes. Although ionic liquids are rather “young” modifier, their great potential in high-performance liquids
chromatography (HPLC) has already been demonstrated. This review presents an overview of the applications of ionic liquids
as mobile phase modifiers in HPLC. 相似文献
18.
19.
Synthesis of antiviral 5-halouracil nucleosides, also used as key precursors for the synthesis of other potential antiviral drugs, has been demonstrated using ionic liquids as convenient and efficient reaction medium. 相似文献
20.
Maria H. Katsoura Angeliki C. Polydera Loukas D. Tsironis Maria P. Petraki Sladjana Kostić Rajačić Alexandros D. Tselepis Haralambos Stamatis 《New biotechnology》2009,25(1-2):83-91
Biocatalytic lipophilization of hydroxycinnamic acids was performed in several BF4? and PF6? imidazolium ionic liquids using immobilized lipases. The influence of various reaction parameters on the performance of the biocatalytic process was pointed out, using as model reaction the esterification of ferulic acid. The biocatalytic lipophilization strongly depended on the ion composition of ionic liquids used. Conversions and initial reaction rates were significantly higher in PF6? as compared with BF4? ionic liquids and commonly used organic solvents. The high enzyme stability and the relative solubility of substrate versus product in PF6? ionic liquids can account for the improved synthesis of lipophilic ferulates. These lipophilic derivatives, when used at a concentration of up to 400-fold lower than the parental compound, efficiently inhibited the oxidation of isolated LDL, HDL and total serum in vitro. Moreover, it has been shown for the first time that the lipophilic ferulates improve the antioxidant efficiency of the HDL3c towards LDL in vitro oxidation. 相似文献