Lactic Acid → 1,4-Dioxane-2,5-dione, 3,6-dimethyl-, (3R,6S)-rel-

Beteiligte Stoffe

Reaktionsschritte

Succinic anhydride is often a significant component of the intermediate-boiling impurities. Succinic anhydride can be separated from meso-lactide by washing the meso-lactide stream with a weakly basic aqueous phase. A suitable pH of the washing solution is in the range of from about 7.2 to about 11. This is believed to hydrolyze the succinic anhydride to form succinic acid. Some of the lactide may also be hydrolyzed to form mainly linear oligomers and possibly some lactic acid. The succinic acid is much more soluble in the basic aqueous phase than in the lactide phase, and will partition to the aqueous phase. The aqueous and organic phases are then separated to form a washed meso-lactide stream having a reduced level of succinic anhydride and perhaps other intermediate-boiling impurities. The washed meso-lactide stream can be recycled as described before.

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