Prodn. of lactide from aq. lactic acid

摘要

Prodn. of lactide is effected using a starting material comprising (a) a mixt. of an aq. lactic acid soln. and an organic solvent which has a b.pt. of 210-300 deg C, which is water-immiscible and in which lactide is soluble at temps. above 200 deg C, or (b) an aq. soln. of a trialkylammonium lactate salt whose trialkylamine component has a b.pt. of 210-300 deg C. The process comprises heating the starting material to 100-200 deg C to distil off H2O, adding a transesterification catalyst, heating the mixt. to 200-280 deg C while distilling off H2O, and separating lactide from the reaction mixt.