METHOD TO PRODUCE CYCLIC ESTERS

摘要

Disclosed is a novel integrated process for production of cyclic esters which includes recovery of starting materials, such as lactic acid from a dilute aqueous lactic acid-containing solution, by solvent extraction. The starting materials are then formed into cyclic esters by removal of water wherein the concentration of higher molecular weight oligomers is maintained below about 20 wt% of the reaction composition. The process further includes providing a recovery solvent for the reaction composition and separating the cyclic esters from the starting materials and higher molecular weight oligomers by liquidliquid equilibrium separation. The present invention is further directed toward independent novel unit operations of the overall process. The present invention provides for the efficient production and recovery of cyclic esters due to integration of the various unit operations by use of appropriate solvents and recycle streams. In addition, high rates of conversion of starting materials and high rates of selective production of cyclic esters are achieved by appropriate control of process parameters.