Ionic liquids as additives in the pig liver esterase (PLE) catalysed synthesis of chiral disubstituted malonates

Wallert, Stefan; Drauz, Karlheinz; Grayson, Ian; Gröger, Harald; Marı́a, Pablo Domı́nguez de; Bolm, Carsten

doi:10.1039/b503010b

Cited by 58 publications

(31 citation statements)

References 38 publications

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“…However, some ionic liquids were not useful. For example, with 10 vol% BMIM(PF 6 ) as the ionic liquid the rate was slower than in buffer [29]. As noted above, fluoride containing anions may hydrolyze in water releasing hydrogen fluoride, so these anions should be avoided as cosolvents with water.…”

Section: Mêçíé~ëéë=~åç=bëíéê~ëéë=mentioning

confidence: 95%

Toward advanced ionic liquids. Polar, enzyme-friendly solvents for biocatalysis

Gorke

Srienc

Kazlauskas

2010

Biotechnol Bioproc E

249

159

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Ionic liquids, also called molten salts, are mixtures of cations and anions that melt below 100 o C. Typical ionic liquids are dialkylimidazolium cations with weakly coordinating anions such as (MeOSO 3 ) or (PF 6 ). 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. © KSBB hÉóïçêÇëW=áçåáÅ=äáèìáÇëI=ÇÉÉé=ÉìíÉÅíáÅ=ëçäîÉåíëI=ÜóÇêçä~ëÉëI=çñáÇçêÉÇìÅí~ëÉëI=éçäóãÉêáò~íáçå= = = = = IONIC LIQUIDS AND DEEP EUTECTIC SOLVENTSIonic liquids, also called molten salts, are mixtures of cations and anions that melt below 100 o C. The low melting point stems from a mismatch in the size of the anion and cation that prevents crystallization. Changing the structures of the anions or cations can tune the polarities and other properties. Even though they are salts, their polarities are only moderate, similar to ethanol. Ionic liquids have negligible vapor pressure. Ionic liquids are viscous, typically 0.1 Pas or more, which is similar to glycerol or honey.The first ionic liquid -ethylammonium nitrate (mp 12 o C) -was reported in 1914 [1], but attracted limited use. The first generation of widely studied ionic liquids used the dialkylimmidazolium and related cations reported in 1982 [2], Fig. 1. Varying the cation structure varied the properties of the ionic liquid. The anions were chloroaluminate or other metal halide anions, which react with water and thus are not suited for biotransformations. The second generation of ionic liquids, discovered a decade later [3], replaced the water r...

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Section: Mêçíé~ëéë=~åç=bëíéê~ëéë=mentioning

confidence: 95%

Toward advanced ionic liquids. Polar, enzyme-friendly solvents for biocatalysis

Gorke

Srienc

Kazlauskas

2010

Biotechnol Bioproc E

249

159

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“…[5][6][7] There is also an increasing number of studies on bio-catalytic reactions. 8,9 Solubilization of enzymes, and enzymatic reactions in ILs, [10][11][12] aqueous ILs, 13 or hydrated ILs 14 have been demonstrated in recent years with the aim of preparing a suitable matrix for enzymes. However, there has been little study of ILs to dissolve enzymes.…”

Section: ç Ionic Liquidsmentioning

confidence: 99%

Task Specific Ionic Liquids for Cellulose Technology

Ohno¹,

Fukaya²

2008

Chemistry Letters

298

158

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Design of ionic liquids for dissolution, depolymerization, and energy conversion of cellulose and their derivatives is described. Importance of physicochemical properties such as polarity and hydrogen-bonding ability of the ionic liquids is described, and some practical approaches to prepare novel ionic liquids as solvents for cellulose technology are reviewed with latest results. Ç IntroductionThe energy crisis is a major concern. There have been many discussions of substitute materials to replace petroleum and other decreasing natural fuel resources. These natural resources derive from plants, namely, sugar derivatives have been synthesized by plants with the aid of solar energy. Biomass can then be converted into hydrocarbon fuel under the ground. However, we cannot wait for plants to be turned spontaneously but slowly into hydrocarbons. An excellent strategy for providing a new energy source is the immediate use of the biomass. It is, however, ridiculous to convert edible crops or vegetables into energy materials. We do not want to go into details, but energy should be extracted from inedible biomass, such as cereal straws, corn bagasse, cotton, and even used papers. Cellulose is the major component of such biomass, and it can be depolymerized into glucose. Furthermore, energy can be taken from glucose with the aid of enzymes. For efficient energy conversion, it is necessary to dissolve and depolymerize cellulose under mild reaction conditions. Accordingly, it is essential to design solvents for cellulose and to propose a system with minimum energy.Cellulose is stabilized by intra-and inter-molecular hydrogen bonds so as to form tough bundles. Multiple hydrogen-bonding between cellulose molecules results in the formation of highly ordered crystalline regions; furthermore, these are mixed or covered by lignin. It is almost impossible to solubilize cellulose with water and common organic solvents. Some mixed systems composed of organic solvents, water, and salts have been proposed. In spite of the utility of these mixed solvent systems for cellulose, there remain some drawbacks such as volatility, generation of poisonous gas or waste, and difficulty of solvent recovery with small energy. It is not so difficult to combine the above requirements for a classical solvent system for cellulose, i.e., charge and organic compounds, and hydrogen-bonding ability. Organic salts typically fit this combination. In particular, organic salts with very low melting point should be good starting materials for the design of solvents for cellulose. In this review, we discuss the use of ionic liquids in cellulose processing.

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“…water, tetrahydrofuran, acetone, etc.) (Kaftzik et al, 2002;Zhao and Malhotra, 2002;Wallert et al, 2005;Li et al, 2008), and as a mixture of two different ILs (Kaar et al, 2003;Lee et al, 2008). In all cases, such reaction media have been seen to improve the solubility of substrates and/or products with hydrophobic moieties (e.g.…”

Section: Introductionmentioning

confidence: 97%