METHOD FOR PRODUCING a-HYDROXYCARBOXYLIC ACID DIMERIC CYCLIC ESTER

• US 20190330175A1
• Filed: 12/18/2017
• Published: 10/31/2019
• Est. Priority Date: 01/24/2017
• Status: Active Grant

• Current Assignee: Kureha Corporation
• Original Assignee: Kureha Corporation
• Inventors: YAMAJI, Haruyasu, Suzuki, Yoshinori, ONO, Toshihiko
• Granted Patent: US 11,046,665 B2
• Time in Patent Office: Days
• CPC Class Codes: C07D 319/12 not condensed with other rings
• CPC Class Codes: C08G 63/06 derived from hydroxycarboxylic acids
• CPC Class Codes: C08G 63/78 Preparation processes

Abstract

Provided is a method for producing a high purity α-hydroxycarboxylic acid dimeric cyclic ester while heavy-component formation from an α-hydroxycarboxylic acid oligomer is suppressed. An α-hydroxycarboxylic acid dimeric cyclic ester is obtained by performing a depolymerization reaction in the coexistence of an inorganic acid or an inorganic acid salt or a mixture thereof; and an organophosphorus compound.

Claims

1. A method for producing an α

-hydroxycarboxylic acid dimeric cyclic ester by subjecting an α

-hydroxycarboxylic acid oligomer containing an alkali metal ion to a depolymerization reaction,

the depolymerization reaction being performed in the coexistence of an inorganic acid or an inorganic acid salt or a mixture thereof; and

an organophosphorus compound; and

in the depolymerization reaction, the organophosphorus compound being supplementarily added not earlier than a time when purity of the α

-hydroxycarboxylic acid dimeric cyclic ester decreases by 1 wt. % compared to purity at a time when the reaction starts.

2. The method for producing an α

-hydroxycarboxylic acid dimeric cyclic ester according to claim 1, wherein the organophosphorus compound is added in an amount of from 0.01 wt. % to 2.0 wt. % relative to an amount of a reaction solution in the depolymerization reaction.

5. The method for producing an α

-hydroxycarboxylic acid dimeric cyclic ester according to claim 1, wherein a content of the alkali metal ion is from 0.0001 wt. % to 1.0 wt. % relative to an amount of the α

-hydroxycarboxylic acid oligomer.

6. The method for producing an α

-hydroxycarboxylic acid dimeric cyclic ester according to claim 1, wherein the organophosphorus compound is a phosphoric acid ester compound.

7. The method for producing an α

-hydroxycarboxylic acid dimeric cyclic ester according to claim 1, wherein the α

-hydroxycarboxylic acid oligomer is a glycolic acid oligomer.

8. A method for producing a polyglycolic acid, the method comprising the method for producing an α

-hydroxycarboxylic acid dimeric cyclic ester described in claim 1.

3. (canceled)

4. (canceled)