Preparation and Characterization of Three Room-Temperature Ionic Liquids

Zhao, Hua; Malhotra, Sanjay V.; Luo, Robert G.

doi:10.1080/0031910031000155452

Cited by 40 publications

(17 citation statements)

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“…Density data for some of the studied ILs are already available in the open literature but only at atmospheric pressure, 19,46,50,[51][52][53][54][55][56][57][58] and the relative deviations between the experimental data obtained in this work are presented in Figures 2(a) ] density values are lower (within 0.6 %) than Kato et al 55 and slightly higher (within 0.2 %) than Aki et al 56 58 and also show positive deviations (1.7 %) from Noda et al 46 These deviations can be due essentially to the salt's purity, including water and halides content, and also to the experimental technique adopted.…”

Section: Resultsmentioning

confidence: 99%

PρT Measurements of Imidazolium-Based Ionic Liquids

et al. 2007

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Experimental density measurements are reported, and the derived thermodynamic properties, such as the isothermal compressibility, the isobaric expansivity, and the thermal pressure coefficient are presented as Supporting Information for several imidazolium-based ionic liquids (ILs), namely, 1-ethyl-3-methyl-imidazolium bis-(trifluoromethylsulfonyl)imide [C 2 mim][NTf 2 ], 1-heptyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [C 7 mim][NTf 2 ], 1-octyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [C 8 mim][NTf 2 ], 1-ethyl-3-methylimidazolium tetrafluoroborate [C 2 mim][BF 4 ], and 1-butyl-3-methyl-imidazolium tricyanomethane [C 4 mim][C(CN) 3 ] in the pressure (0.10 < p/MPa < 30.00) and temperature (293.15 < T/K < 393.15) domains. These ILs were chosen to provide an understanding of the influence of the cation alkyl chain length and the anion influence on the properties under study. Experimental densities are correlated with the Tait equation with an average absolute deviation (AAD) less than 0.04 %. Experimental densities are in good agreement with the densities obtained by some recent predictive methods proposed in the literature.

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Section: Resultsmentioning

confidence: 99%

PρT Measurements of Imidazolium-Based Ionic Liquids

et al. 2007

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“…For the biphasic systems involving C n MIM·PF 6 ( n = 4-7), both the initial reaction rate and the maximum yield clearly decreased with the elongation of the alkyl chain ( i.e . increasing n value) of the IL cation, possibly partly because of the increase in viscosity of the IL with increasing n value [ 20 , 25 , 32 ], which may lead to a decrease of substrate and product mass transfer rate between the two phases. Alternatively, both the slightly lower partition coefficients of TMSB and TMSBOL between IL and buffer (Table 2 ) and the lower biocompatibility of IL with Candida parapsilosis CCTCC M203011 cells (Fig.…”

Section: Resultsmentioning

confidence: 99%

Using a water-immiscible ionic liquid to improve asymmetric reduction of 4-(trimethylsilyl)-3-butyn-2-one catalyzed by immobilized Candida parapsilosis CCTCC M203011 cells

et al. 2009

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BackgroundWhole cells are usually employed for biocatalytic reduction reactions to ensure efficient coenzyme regeneration and to avoid problems with enzyme purification and stability. The efficiency of whole cell-catalyzed bioreduction is frequently restricted by pronounced toxicity of substrate and/or product to the microbial cells and in many instances the use of two-phase reaction systems can solve such problems. Therefore, we developed new, biphasic reaction systems with biocompatible water-immiscible ionic liquids (ILs) as alternatives to conventional organic solvents, in order to improve the asymmetric reduction of 4-(trimethylsilyl)-3-butyn-2-one (TMSB) to (S)-4-(trimethylsilyl)-3-butyn-2-ol {(S)-TMSBOL}, a key intermediate for synthesis of 5-lipoxygenase inhibitors, using immobilized Candida parapsilosis CCTCC M203011 cells as the biocatalyst.ResultsVarious ILs exerted significant but different effects on the bioreduction. Of all the tested water-immiscible ILs, the best results were observed with 1-butyl-3-methylimidazolium hexafluorophosphate (C4MIM·PF6), which exhibited not only good biocompatibility with the cells but also excellent solvent properties for the toxic substrate and product, thus markedly improving the efficiency of the bioreduction and the operational stability of the cells as compared to the IL-free aqueous system. 2-Propanol was shown to be the most suitable co-substrate for coenzyme regeneration, and it was found that the optimum volume ratio of buffer to C4MIM·PF6, substrate concentration, buffer pH, 2-propanol concentration and reaction temperature were 4/1 (v/v), 24 mM, 5.5, 130 mM and 30°C, respectively. Under these optimized conditions, the maximum yield and the product e.e. wer 97.7% and >99%, respectively, which are much higher than the corresponding values previously reported. The efficient whole-cell biocatalytic process was shown to be feasible on a 250-mL scale.ConclusionThe whole cell-catalyzed asymmetric reduction of TMSB to (S)-TMSBOL can be substantially improved by using a C4MIM·PF6/buffer biphasic system instead of a single-phase aqueous system and the resulting biocatalytic process appears to be effective and competitive on a preparative scale.

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“…40,41 Charcoal was used to remove color and impurities from crude Ils, 42 and a silica gel column was further employed to remove trace impurities. Water was evaporated through a rotary evaporator under vacuum at 50 ℃.…”

Section: Il Preparationsmentioning

confidence: 99%