Continuous reduced pressure dimeric cyclic ester production

Details Continuous reduced pressure dimeric cyclic ester production Continuous reduced pressure dimeric cyclic ester production

1992-03-12

1994-02-22

Dentz, Bernard

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C07D31912

Patent

active

052888819

ABSTRACT:
An improved process for converting oligomers of alphahydroxycarboxylic acids, such as glycolic and lactic acid, to dimeric cyclic esters, such as glycolide and lactide. The continuous process is conducted at reduced pressures and depolymerizing temperatures in a heated columnar depolymerization zone, coupled with an essentially unheated receiver for unconverted oligomer. By feeding the oligomer to the upper end of the column while coordinating the feed rate with the depolymerization temperature such that a fraction of the oligomer is converted to a vapor product stream containing the cyclic ester and another fraction of the oligomer exits the column at its lower end and passes to the receiver vessel, the dimeric cyclic ester is produced at high production rates and the oligomer is subjected to minimal thermal stress.

REFERENCES:
patent: 1095205 (1914-05-01), Gruter
patent: 2668162 (1954-02-01), Lowe
patent: 5023349 (1991-06-01), Bhatia
patent: 5053522 (1991-10-01), Muller

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