Synthesis of ethyl lactate from ammonium lactate solution by coupling solvent extraction with esterification

Ethyl lactate was synthesized selectively from aqueous ammonium lactate by coupling solvent extraction with esterification with ethanol. When ammonium lactate reacted directly with ethanol without solvent, the ethyl lactate yield was very low due to significant formation of byproducts such as oligomer and lactamide (Conv. 70%, Sel. 10% at 10 h). The significant improvement in ethyl lactate yield was obtained when lactic acid was extracted from ammonium lactate in tributyl phosphate and then it reacted with ethanol, where oligomer formation was decreased greatly (Conv. 78%, Sel. 95% at 10 h). Compared with the traditional method including acidulation of calcium lactate, extraction, and esterification, the present technique is potentially more economical since it enhances not only the productivity of lactic acid fermentation but also the efficiency of overall process from fermentation broth to ethyl lactate. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.