Patent ID: 9630942
Date: 2017-04-25
CPC Classifications: B01J,C07D

Claim:
1. A method for synthesizing L-lactide or D-lactide comprising the following steps: (1) carrying out dehydration and polycondensation of L-lactate or D-lactate by: to produce lactic acid oligomers with a weight-average molecular weight of 600-1500 Da; (2) carrying out catalytic distillation of the lactic acid oligomers from step (1) to form crude L-lactide or D-lactide by: to produce distilled white crude L-lactide or D-lactide; (3) washing the crude L-lactide or D-lactide from step (2) with an alkaline solution having a mass concentration of 1-10% alkali, then washing to neutral using deionized water, and (4) vacuum drying the washed L-lactide or D-lactide at 20° C.-40° C. for 24-36 h to thereby obtain L-lactide or D-lactide.