Patent ID: 7951937
Filing Date: 2011-05-31
Classification: C07H

Abstract:
1. A process of azeotropic removal of dimethylformamide, abbreviated as DMF, from a process stream containing DMF requiring its removal, the process stream being obtained in a process for preparation of 4,1′, 6′ trichlorogalactosucrose, abbreviated as TGS, or TGS-6-ester, comprising steps of: a. evaporating the process stream under reduced pressure to a concentrate to effect removal of a part of DMF azeotropically, this step being avoided if the process stream is already at a concentrate stage, b. diluting the concentrate of step (a.) with water, and repeating the evaporation followed by dilution and evaporation cycles under reduced pressure until DMF concentration reaches low enough to ensure efficient crystallization, and c. optionally submitting the concentrate of step (b.) for a further purification and isolation of TGS or TGS-6-ester.