Biopak Technology, Ltd.

Chronopol, Inc.

Melville E Hillman

Edward S Lipinsky

George E Cremeans

Alex Cheung

Dan W Verser

Timothy J Eggeman

William Andrew Evanko

Kevin H Schilling

Manfred Meiser

Anthony E Allen

Richard G Sinclair

Richard A Markle

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 liquid-liquid 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.

Method to produce cyclic esters

Disclosed is a method for producing cyclic esters by the conversion of hydroxy carboxylic acids and their derivatives to their respective cyclic esters. Such cyclic esters, including lactide or glycolide, are particularly useful for producing polymers which can be used to make biodegradable materials, such as biodegradable packaging material. Various methods of cyclic ester production are disclosed, including liquid phase and vapor phase reactions. Also disclosed are various methods for recovering cyclic esters from product-containing streams.

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Hilliard, OH, United States of America

Melville E Hillman