METHOD FOR L-LACTIDE OBTAINING Russian patent published in 2017 - IPC C07D319/12 

FIELD: biotechnology.

SUBSTANCE: invention relates to an improved method for purification of L-lactide - lactic acid cyclic dimer (diester), a monomer for production of biodegradable polymeric materials used as coatings or food containers, as well as in medical industry, where the alkyl lactate oligomerization process is carried out in the presence of a mixture of homogeneous and heterogeneous catalysts at an elevated temperature of 180 to 210-220°C in a batch reactor with stirring while supplying an inert gas and continuously withdrawing the vapors of the co-product - alcohol. After obtaining of an oligomer of a given degree of oligomerization, a heterogeneous catalyst is separated from the oligomers remaining in the reactor, which, together with the homogeneous catalyst, is sent to the depolymerization step, which is carried out by the known methods, usually in a film mode under vacuum.

EFFECT: reduced duration of the oligomerization stage.

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