Ionic liquids mixtures

The term Supported Ionic Liquid Phase (SILP) catalysis has recently been introduced into the literature to describe the heterogenisation of a homogeneous catalyst system by confining an ionic liquid solution of catalytically active complexes on a solid support [68], In comparison to the conventional liquid-liquid biphasic catalysis in organic-ionic liquid mixtures, the concept of SILP-catalysis offers very efficient use of the ionic liquid. Figure 7.10 exemplifies the concept for the Rh-catalysed hydroformylation. 

The heme enzyme chloroperoxidase (CPO), produced by the marine fungus Caldariomycesfumago, is a versatile enzyme which exhibits a broad spectrum of chemical reactivities and it is recognized as a most promising biocatalyst for synthetic applications. Recently, pure (R)-phenyl methylsulfoxide (ee > 99 %) was prepared by chemo- and stereo-selective oxidation of phenyl methylsulfide with CPO in citrate buffer-ionic liquid mixtures. ... 

Hanke, C.G. and Lynden-Bell, R.M., A simulation study of water-dialkylimid-azolium ionic liquid mixtures, /. Phys. Chem. B, 107,10878, 2003. 

Baltazar, Q.Q., Leininger, S.K., and Anderson, J.L., Binary ionic liquid mixtures as gas chromatography stationary phases for improving the separation selectivity of alcohols and aromatics compounds, /. Chromatogr. A., 1182, 119-127, 2008. 

Fletcher, K. A., Baker, S. N., Baker, G. A., and Pandey, S., Probing solute and solvent interactions within binary ionic liquid mixtures. New. Chem., 27,1706-1712, 2003. 

Subtilisin is an endoprotease that has been used in the enantioselective hydrolysis of N-acylamino acid esters (Figure 10.16) into the corresponding (S)-amino acid derivatives. An organic solvent, such as acetonitrile, is often added to improve the solubility of the amino acid derivative, and this function can also be performed by an ionic liquid mixture [133, 134, 135]. 

Figure 10.21 Enantioselective sulfoxidation catalyzed by CPO in aqueous-ionic liquid mixtures.

Fig. 8.6. Liquid-liquid equilibria of alcohol-ionic liquid mixtures [105], The left side shows the LLE curves of l-butyl-3-methyl-imidazolium-PF6 mixtures with alcohols (ethanol, blue 1-propanol, red and 1-butanol, green symbols). The experimental curves (solid symbols) show a shape different from the calculated LLE curves, but the upper critical-solution temperatures (UCST) are surprisingly well met. On the right side, the trends of the UCST with a modification of the 1-alkyl-group of the anion (butyl = 4, octyl = 8) is shown. Again, the COSMO-RS predictions (open symbols, same color code as on the left) are in surprisingly good agreement with the experimental data.

Preparation of AlCl3-[BMIM]Cl-Toluene Ionic Liquid Mixture ([2 1] 3)... 

Fig. 8 Correlation between the II NMR chemical shift of the ethanol OH-proton ( OH-shift ) and the H NMR chemical shift of the cationic C2-proton ( C2-H-shift ) in equimolar ethanol-[C2mim]-based ionic liquid mixtures referred to the methyl protons of ethanol and cationic side...

The efficient solvation of water [96,110,112, 113] outlined above can be exploited in condensation reactions, in which water formed during the course of the reaction is deactivated by absorption , which can improve conversion and/or selectivity. For example, in the catalytic oxidation of an alcohol to the aldehyde [140, 141], water is formed as by-product which can undergo further reaction with the aldehyde to yield unwanted carboxylic acid. In ionic liquids, neither a reduced rate of reaction nor the formation of carboxylic acid is observed, even in the presence of up to 1 equiv. of water. However, at higher concentrations of water (absorption from air or accumulated by-product) the selectivity of aldehyde decreases, and the carboxylic acid is formed instead. Upon vigorous drying of the catalyst-ionic liquid mixture, the selectivity of the system is restored [141],... 

Rebelo LPN, Najdanovic-Visak V, Gomes de Azevedo R et al. (2005) Phase behaviour and thermodynamic properties of ionic liquids, ionic liquid mixtures, and ionic liquid solutions. In Rogers, RD, Seddon KR eds) Ionic liquids IIIA fundamentals, progress, challenges, and... 

Bala S, Tang S, Aaron MS (2009) Improved i-butene/iio-butane alkylation with acidic ionic liquids and tunable acid/ionic liquid mixtures. J Catal 268 243—250... 

Vafiadi C, Topakas E, Nahmias VR, Faulds CB, Christakopoulos P (2009) Feruloyl esterase-catalysed synthesis of glycerol sinapate using ionic liquids mixtures. J Biotechnol 139 124-129... 

Based on their work on supercritical CO2 (see also Scheme 23), Reetz and Leitner introduced a technologically new and interesting continuous flow process for enzymatic reactions [65]. The group designed a protocol for enzymatic reactions, namely the lipase-catalyzed acylation (CAL B) of octan-1 -ol by vinyl acetate in ionic liquids (l-butyl-3-methylimidazolium bis(trifluo-romethanesulfonimide) [BMIM] [BTA]) using supercritical CO2 as the mobile phase (Scheme 25). The alcohol is pumped through the biphasic system and the products are obtained in solvent-free form in a cold trap. The enzyme/ionic liquid mixture can be recycled in batchwise or continuous flow operations. 

Ionic liquid mixtures such as a 4 6 mixture of methyl and dimethyl ammonium nitrate The incorporation of imidazol derivates results in a better stability up to r = 180°C with a conductivity of 0.1 Scm [26]. The stabilisation of the ionic liquids is possible by introducing the substances into a porous silica matrix [27,28]. A typical liquid is the l-butyl-3-methyldiazoniumderivate with addition of BF4 and H3PO4 to fit the acidity. The system shows a thermal stability up to T = 300°C with a conductivity up to 80mScm [29]. 

DSSCs prepared from this quasi-solid-state ionic liquid gel were stable under light at 60 °C for 1,000 h and had an efficiency of 6.3 % under simulated AM 1.5 frill sunlight, and the gelator had no influence on the performance of the solar cell. It was proposed that, after complete dissolution of the organogelator at elevated temperatures, the gelator molecules built up nanoscale fibrils due to the formation of hydrogen bonds by the amide and urea units and thus formed a three-dimensional network. This led to gelation of the ionic liquid mixture and hindered flow of the liquid. 

Samohyl, I. Application of TmesdeU s model of mixtures to ionic liquid mixture. Comput. Math. Appl. 53(2), 182-197 (2007)... 

The chloroaluminate ionic liquid mixtures are governed by the following primary equilib-... 

For the extraction experiments, tributylphosphate (TBP) 97 % with density and viscosity of 972.7 and 3.88 x 10 kg m s respectively, was also dissolved in the ionic liquids. TBP was obtained from Sigma-Aldrich. The properties of the saturated TBP/ionic liquid mixtures used for the experiments are shown in Table 3.2. 

Hydrodynamics, pressure drop, and mass transfer during liquid-liquid flows were investigated in two different systems, viz. in glass microchannels with circular cross section of 0.2 mm ID (Fig. 3.3a, b) using an ionic liquid and deionised water, and in Teflon channels of different sizes, i.e. 0.2-2 mm ID (Fig. 3.3c) using either different TBP/ionic liquid mixtures (30 %, v/v) (Table 3.2) and aqueous nitric acid solutions, relevant to spent nuclear fuel reprocessing, or ionic Uquid and deionised water. The internal diameter of the microchannels was measured using a microscope (Nikon Eclipse ME 600). 

Fig. 5.15 Non-dimensional circulation time as a function of the non-dimensional plug length for the three TBP/ionic liquid mixtures (30 %, v/v) at mixture velocity of 0.02 m s ...

In Fig. 6.8 the effect of residence time for 3 different types of TBP/ionic liquid mixtures (30 %, v/v) at constant nitric acid concentration of 3 M, at flow rate ratio equal to 1 is shown. It is observed that by increasing the residence time, the dioxouranium(VI) extraction also increases. As mentioned earlier, within 14.5 s, the extraction of dioxouranium(VI) reaches 91 % of the equilibrium value for [C4mim] [NTf2l, while in the cases of [Ciomim][NTf2] and [P666i4][NTf2] it reaches 84 % and 88 % of the equilibrium value, respectively. Within 9.7 s, it can be seen that for each case the dioxouranium(VI) extraction reaches almost 80 % of the equilibrium value. The largest increase in %E was found for the less viscous TBP/ionic liquid system. 

Extraction of lignin from bagasse using the ionic liquid mixture [C2mim][ABS] was successfully achieved at atmospheric pressure with over 93% yield and the extracted lignin was of a relatively uniform molecular weight. In their study, the compositions of ionic liquid mixture... 

The influence of pure organic solvents or organic solvent/ionic liquid mixtures on the resolution of racemic phenylethylamine catalysed by CALB using various acyl donors was studied [16]. The results revealed that the choice of both acyl donor and reaction medium is crucial for generating products with high enantioselectivity. 

In a continuous flow hydroformyiation with a rhodium phosphite catalyst in an SCF-ionic liquid mixture, after two to three runs the activity and regioselectivity... 

Common UCST behaviour has also been observed for mixtures consisting of two ionic liquids with the same anion and a different cation.Less common lower eritical solution temperature (LCST) behaviour has been observed for binary ionic liquid mixtures with benzene,chloroalkanes " and polymers. Interestingly, the LCST behaviour of benzene with an imidazo-lium-based ionic liquid changed via hour-glass to UCST behaviour when the imidazolium alkyl chain length was increased.Moreover, imidazolium-based ionic liquids were found to form clathrate structures with benzene at low temperatures, whereas the solid-liquid equilibria (SLE) of other organics or water with ionic liquids are simple eutectic systems. 

The phase behaviours of binary and ternary ionic liquid mixtures with carbon dioxide,organics " and water " have been determined using COSMO-RS. In the COSMO-RS framework, ionic liquids are considered to be completely dissociated into cations and anions. Ionic liquids are thus taken as an equimolar mixture of two distinct ions, which contribute as two different compounds. Because ionic liquids only dissociate in the presence of strongly polar substances, the COSMO-RS prediction of the phase behaviour of ionic liquid systems with polar compounds (water and alcohols) is more accurate than that of ionic liquid systems with nonpolar compounds (carbon dioxide and organics). Especially the COSMO-RS prediciton of the solubility of (relatively nonpolar) carbon dioxide in ionic liquids shows considerable deviations ( 15 %) from experimental values. lUPAC Technical Reports document the measurements of the thermodynamic and thermophysical properties of l-hexyl-3-methylimidazolium bis [(trifluoromethyl)sulfonyl]amide and the recommended values. ... 

Figure 1.2 Molar conductivity nf ionic liquid mixtures with various molecular solvents as a function of their mole fraction. The curves represent M rComimirBF 1-propylene...

---