Preparation of high purity and yield L-lactide

L-lactide was prepared from L-lactic acid using the stannous octoate as the catalyst. The effects of temperature and pressure on preparation of lactide were discussed in this paper. The high purity lactide can be obtained by washing with water and recrystallizing. The yield of the lactide reaches 40. 6%. The results of polarimeter, IR, chromatogram and mass spectrum show that the prepared L-lactide is pure.