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Article

Biocatalysis at Extreme Temperatures: Enantioselective Synthesis of both Enantiomers of Mandelic Acid by Transesterification Catalyzed by a Thermophilic Lipase in Ionic Liquids at 120 °C

Department of Chemistry in Pharmaceutical Sciences, Pharmacy Faculty, Complutense University of Madrid (UCM), Ciudad Universitaria, Plaza de Ramon y Cajal, s/n., 28040 Madrid, Spain
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Catalysts 2020, 10(9), 1055; https://doi.org/10.3390/catal10091055
Received: 15 August 2020 / Revised: 9 September 2020 / Accepted: 11 September 2020 / Published: 14 September 2020
The use of biocatalysts in organic chemistry for catalyzing chemo-, regio- and stereoselective transformations has become an usual tool in the last years, both at lab and industrial scale. This is not only because of their exquisite precision, but also due to the inherent increase in the process sustainability. Nevertheless, most of the interesting industrial reactions involve water-insoluble substrates, so the use of (generally not green) organic solvents is generally required. Although lipases are capable of maintaining their catalytic precision working in those solvents, reactions are usually very slow and consequently not very appropriate for industrial purposes. Increasing reaction temperature would accelerate the reaction rate, but this should require the use of lipases from thermophiles, which tend to be more enantioselective at lower temperatures, as they are more rigid than those from mesophiles. Therefore, the ideal scenario would require a thermophilic lipase capable of retaining high enantioselectivity at high temperatures. In this paper, we describe the use of lipase from Geobacillus thermocatenolatus as catalyst in the ethanolysis of racemic 2-(butyryloxy)-2-phenylacetic to furnish both enantiomers of mandelic acid, an useful intermediate in the synthesis of many drugs and active products. The catalytic performance at high temperature in a conventional organic solvent (isooctane) and four imidazolium-based ionic liquids was assessed. The best results were obtained using 1-ethyl-3-methyl imidazolium tetrafluoroborate (EMIMBF4) and 1-ethyl-3-methyl imidazolium hexafluorophosphate (EMIMPF6) at temperatures as high as 120 °C, observing in both cases very fast and enantioselective kinetic resolutions, respectively leading exclusively to the (S) or to the (R)-enantiomer of mandelic acid, depending on the anion component of the ionic liquid. View Full-Text
Keywords: Geobacillus thermocatenolatus; lipases; ethanolysis; ionic liquids; kinetic resolution; mandelic acid Geobacillus thermocatenolatus; lipases; ethanolysis; ionic liquids; kinetic resolution; mandelic acid
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MDPI and ACS Style

Ramos-Martín, J.; Khiari, O.; Alcántara, A.R.; Sánchez-Montero, J.M. Biocatalysis at Extreme Temperatures: Enantioselective Synthesis of both Enantiomers of Mandelic Acid by Transesterification Catalyzed by a Thermophilic Lipase in Ionic Liquids at 120 °C. Catalysts 2020, 10, 1055. https://doi.org/10.3390/catal10091055

AMA Style

Ramos-Martín J, Khiari O, Alcántara AR, Sánchez-Montero JM. Biocatalysis at Extreme Temperatures: Enantioselective Synthesis of both Enantiomers of Mandelic Acid by Transesterification Catalyzed by a Thermophilic Lipase in Ionic Liquids at 120 °C. Catalysts. 2020; 10(9):1055. https://doi.org/10.3390/catal10091055

Chicago/Turabian Style

Ramos-Martín, Jesús, Oussama Khiari, Andrés R. Alcántara, and Jose María Sánchez-Montero. 2020. "Biocatalysis at Extreme Temperatures: Enantioselective Synthesis of both Enantiomers of Mandelic Acid by Transesterification Catalyzed by a Thermophilic Lipase in Ionic Liquids at 120 °C" Catalysts 10, no. 9: 1055. https://doi.org/10.3390/catal10091055

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