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

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of purifying L-lactide - cyclic dimer (diester) of lactic acid, a monomer for producing biodegradable polymeric materials used as coatings or containers for food products, as well as in the medical industry. The process of purifying L-lactide from impurities is carried out in a vertical device with a jacket by crystallisation of raw lactide from melt, followed by smelting the impurities from solid raw lactide in an inert gas stream under vacuum by gradually increasing the temperature of solid lactide at a rate of 0.1-0.2°C/min. Heat supply to the solid raw lactide is carried out both through the heat exchange surface (by supplying the coolant into the device jacket), and through the direct contact of solid lactide with the flow of heated inert gas with a temperature equal to the temperature of the coolant.

EFFECT: reducing the duration of the process and increasing the yield of L-lactide.

1 dwg, 2 ex