Continuous method for preparing ethyl lactate

摘要

The invention concerns a continuous method for preparing ethyl lactate by esterifying lactic acid with ethanol, in the presence of a catalyst which comprises reacting said lactic acid with ethanol in an initial ethanol/lactic acid mol ratio not less than 2.5, in the presence of a catalyst, at a reflux of the reaction medium of about 100° C. under absolute pressure ranging between 1.5 to 3 bars. Said method is characterized in that it comprises continuously extracting from the esterification reaction medium a near-azeotropic water/ethanol gas mixture: than dehydrating said gas mixture directly using molecular sieves, than recuperating from said dehydration an ethanol gas stream capable of being recycled to the esterification reaction medium and a flow consisting of water and ethanol which is subjected to distillation wherefrom is obtained water and an azeotropic water/ethanol mixture which is injected into the distillation column head of the gas mixture extracted from the esterification reaction medium; then in continuously extracting crude ethyl lactate which is subjected to purification wherefrom are obtained high purity ethyl lactate and heavy products.