Abstract: This invention relates to a process for the continuous production of optically pure lactide from an aqueous solution of lactic acid by means of two reactive distillations followed by a main distillation column with a side-draw refluxer. The first reactive distillation is used for the preparation of lactic acid oligomers and the second reactive distillation used for the depolymerization of the thus obtained lactic acid oligomers to lactide. The crude lactide generated from the second reactive distillation is further purified in the main distillation column with a side-draw refluxer being connected to.

Abstract: This invention relates to a method for the continuous production of optically pure lactide comprising a first reactive distillation system, a second reactive distillation system, a main distillation system and the side-draw refluxer. For each of the four systems a novel horizontally top-mounted condenser is used in order to decrease its total pressure drop and thus reduce side-reactions associated with high bottom temperature. In addition, a wiped film evaporator, a short path evaporator or a combination thereof is utilized for the concentration of the purge stream from the second reactive distillation, in a purpose of removing the metal contaminants contained in the purge stream and depolymerizing the contained unconverted lactic acid oligomers to crude lactide, all of which give additional advantages for the lactide production.