ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Unique role of water content in enzymatic synthesis of ethyl lactate using ionic liquid as solvent

Brigitta Major, Gergely Németh, Katalin Bélafi-Bakó, and László Gubicza

Research Institute of Chemical and Process Engineering, University of Pannonia, Egyetem u. 10, 8200 Veszprém, Hungary

E-mail: gubicza@mukki.richem.hu

Received: 21 July 2009  Revised: 21 October 2009  Accepted: 23 November 2009

Abstract: Enzymatic synthesis of ethyl lactate was studied in organic solvents and in ionic liquids to determine optimal media for the reaction, and to investigate the effect of water content on the ester yield. Experiments proved that Cyphos 202 ionic liquid is the best solvent affording the highest ethyl lactate yields. Furthermore, 20 times less enzyme sufficed to carry out the reaction in this ionic liquid compared to organic solvents; ionic liquid could be applied as solvent. Using water removal, the ester yield decreased since a side reaction, dimerization of lactic acid, occurred as well. In contrast to these results, without water removal, the produced water was partly consumed by the decomposition of lactoyllactic acid to free lactic acid, increasing thus the substrate concentration of the mixture and enhancing the ester yield.

Keywords: ionic liquid - esterification - enzyme - water removal - lactic acid

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-009-0117-4

Chemical Papers 64 (2) 261–264 (2010)