Method for producing alkyl lactate

Patent metadata

Field	Value
Publication number	US-11186535-B2
Application number	US-201816492852-A
Country	US
Kind code	B2
Filing date	Jan 10, 2018
Priority date	Mar 15, 2017
Publication date	Nov 30, 2021
Grant date	Nov 30, 2021

Abstract

Provided is a method of efficiently preparing alkyl lactate from by-products which are generated during a process of converting lactic acid into lactide, or from poly(lactic acid) (PLA).

First claim

The invention claimed is:

1. A method of preparing alkyl lactate, the method comprising the steps of:
reacting by-products generated during a process of converting lactic acid into lactide or poly(lactic acid) (PLA) directly with alcohol and an acidic catalyst to prepare alkyl lactate (a trans-esterification reaction step);
neutralizing the prepared alkyl lactate to prepare a neutralized solution of pH 6 to pH 9 (a neutralization step); and
recovering alkyl lactate from the neutralized solution (a recovery step),
wherein the neutralization step is performed by ammonia gas.

2. The method of preparing alkyl lactate of claim 1 , wherein the by-products include one or more selected from the group consisting of meso-lactide, L-lactide, D-lactide, lactic acid, and lactic acid oligomers.

3. The method of preparing alkyl lactate of claim 1 , wherein the acidic catalyst of the trans-esterification reaction step is sulfuric acid, hydrochloric acid, or nitric acid.

4. The method of preparing alkyl lactate of claim 1 , wherein the number of moles of the acidic catalyst of the trans-esterification reaction step is included at a molar ratio of 0.01 to 0.06, based on the number of moles of the lactic acid produced by hydrolysis of the by-products or the poly(lactic acid).

5. The method of preparing alkyl lactate of claim 1 , wherein the alcohol of the trans-esterification reaction step is C1 to C4 alcohol.

6. The method of preparing alkyl lactate of claim 1 , wherein the alcohol of the trans-esterification reaction step is methanol or ethanol.

7. The method of preparing alkyl lactate of claim 1 , wherein the number of moles of the alcohol of the trans-esterification reaction step is included at a molar ratio of 2 to 5, based on the number of moles of the lactic acid produced by hydrolysis of the by-products or the poly(lactic acid).

8. The method of preparing alkyl lactate of claim 1 , wherein the recovery step is performed by vacuum distillation of the neutralized solution.

9. The method of preparing alkyl lactate of claim 8 , wherein the vacuum distillation is performed at a temperature of 30° C. to 90° C. and a pressure of 30 torr to 90 torr.

Assignees

• Cj Cheiljedang Corp

Inventors

• Kim Jieun
• Oh Changyub
• Lee Chang Suk
• Yang Young Lyeol

Classifications

• C07C67/54 Primary

  by distillation · CPC title

• C07C67/08

  by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds · CPC title

• C07C67/02 Primary

  by interreacting ester groups, i.e. transesterification · CPC title

• C07C67/03

  by reacting an ester group with a hydroxy group · CPC title

• C07C67/60

  by treatment giving rise to chemical modification (by chemisorption C07C67/56) · CPC title