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Molecules 2018, 23(8), 2044; https://doi.org/10.3390/molecules23082044

Transesterification of Lactic Acid Oligomers with Ethanol, a Way to Anhydrous Ethyl Lactate: A Kinetic Study

1
Materials Research Centre, Brno University of Technology, 612 00 Brno, Czech Republic
2
Faculty of chemistry, Institute of Material Chemistry, Brno University of Technology, 612 00 Brno, Czech Republic
3
Faculty of chemistry, Institute of Environmental Chemistry, Brno University of Technology, 612 00 Brno, Czech Republic
*
Author to whom correspondence should be addressed.
Received: 24 July 2018 / Revised: 7 August 2018 / Accepted: 14 August 2018 / Published: 15 August 2018
(This article belongs to the Special Issue Green and Sustainable Solvents)
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Abstract

A new method for the preparation of anhydrous ethyl ester of lactic acid was studied. The selected method is based on catalytic transesterification of lactic acid oligomers, which were prepared for this purpose by autocatalytic oligomerization of lactic acid. In this work, a kinetic model for the case of catalytic alcoholysis of oligoesters was derived assuming a first-order reaction and equimolar content of reactants in the reaction mixture. The model makes it possible to obtain the values of the reaction rate and equilibrium constants and the equilibrium alcohol concentration by regression analysis at one time. The model was verified by measuring the rate of consumption of ethanol over the time at various reaction temperatures with anhydrous FeCl3 as the catalyst. The reaction was studied at overpressure under autogenous conditions in the temperature range of 100–180 °C. For the catalyst concentration of 1 mol %, the activation energy value was 64.35 kJ·mol−1. The dependence of equilibrium composition and rate constant on the temperature was obtained. The derived model is generally applicable to all first-order equilibrium reactions. The presumption is that the forward and reverse reactions are of the same order and have the same stoichiometry and equivalent amounts of reactants at the beginning of the reaction. View Full-Text
Keywords: ethyl lactate; transesterification; kinetics; lactic acid; oligomerization ethyl lactate; transesterification; kinetics; lactic acid; oligomerization
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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Figalla, S.; Petrůj, J.; Švestková, T. Transesterification of Lactic Acid Oligomers with Ethanol, a Way to Anhydrous Ethyl Lactate: A Kinetic Study. Molecules 2018, 23, 2044.

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