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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 9 (1997), S. 261-267 
    ISSN: 0899-0042
    Keywords: industrial scale ; phenylalanine ; enhancing enantioselectivity ; membrane solvent ; chiral extraction ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We describe the use of emulsion liquid membrane technology to perform chiral separations on low molecular weight species. We have reviewed liquid membrane technology in the context of existing process scale chiral separations. We illustrate the potential of this new technique by presenting our results on the selective extraction of phenylalanine enantiomers, using copper (II) N-decyl-(L)-hydroxyproline as a chiral selector in an emulsion liquid membrane configuration. This is compared with an analogous batch solvent extraction system. Initial batch enantiomeric excesses of greater than 40% were observed with the emulsion liquid membrane system compared with around 25% for the solvent extraction system. It was also noted that the system is not limited by the equilibrium capacity constraints of the solvent extraction system. We have shown that kinetic chiral liquid membrane technology offers high productivity and flexibility compared with analogous process scale chiral technologies. Recent transfer of highly specific chiral reversed-phase high-performance liquid chromatographic chemistries have shown that “one-stop” enantiomeric excesses of commercial interest (〉95%) are achievable using kinetic chiral liquid membrane systems. Solvent and temperature selection strategies also have been outlined as means of increasing the enantioselectivity of existing liquid membrane extraction chemistries. Chirality 9:261-267, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 68 (1997), S. 417-424 
    ISSN: 0268-2575
    Keywords: liquid membrane ; enantioselectivity ; lactic acid ; industrial effluent ; selectivity enhancement ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: -Liquid membranes have been suggested as a clean technology due to characteristics such as high specificity, intensity and productivity as well as low emissions and energy utilisation. However when applying liquid membrane systems to real problems, in this paper chiral extraction of phenylalanine and lactic acid extraction from an industrial effluent, problems have been encountered with the specificity of the liquid membrane system used. Relatively low enantioselectivities (maximum 2·4) were observed with the chiral emulsion liquid membrane system investigated (maximum 1·6), although this was in excess of an analogous solvent extraction system studied. In lactic acid extraction, although batch extraction from model solutions was in excess of 75% in 2 min, when a real lactic acid containing industrial effluent was used the extent of extraction was reduced to around 20%. This effect was found to result from the co-extraction of other anions present in the effluent. In the case of chloride ions, a co-transport mechanism was noted. Thermal and photometric back-extraction strategies have been suggested as a means of enhancing overall liquid membrane extraction selectivities. © 1997 SCI.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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