# US 5,332,834 A · Racemization of an enantomerically enriched .alpha.-aryl carboxylic acid

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- Number: US 5,332,834 A
- Document ID: US5332834A
- Status: Granted
- Kind: A
- Application number: 07/985,083
- Filed: 1992-12-02
- Granted: 1994-07-26
- Earliest claimed: 1992-12-02
- Assignees: Hoechst Celanese Corporation
- Inventors: Apurba Bhattacharya; John R. Fritch; Carl D. Murphy; Larry D. Zeagler; Carina Araullo-McAdams
- Web page: https://patentgrep.com/patent/US5332834A

## CPC

- C07C 51/487: by treatment giving rise to chemical modification (by chemisorption C07C51/47)
- C07C 51/43: by change of the physical state, e.g. crystallisation
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS

## Abstract

There is disclosed and claimed a process whereby S(+)-ibuprofen L-lysinate salt is produced by selective precipitation from a mixture containing enantiomers of ibuprofen and L-lysine. The quantity of L-lysine is not more than about a molar equivalent of the quantity of S(+)-ibuprofen in the ibuprofen enantiomeric mixture. The mother liquors after separating the above salt are enriched in R-ibuprofen which is racemized by a novel thermal racemization process and may then be recycled.

## Claims

### Claim 1

A process for racemization of an enantiomerically enriched .alpha.-arylcarboxylic acid, said process comprising heating said enantiomerically enriched .alpha.-arylcarboxylic acid at about 100.degree.-300.degree. C. for about 1-10 hours, in the substantial absence of other components.

### Claim 2

A process for racemization of an enantiomerically enriched .alpha.-arylcarboxylic acid, said process comprising heating said enantiomerically enriched .alpha.-arylcarboxylic acid at about 100.degree.-300.degree. C. for about 1-10 hours, in the substantial absence of solvent.

### Claim 3

A process for separation of an .alpha.-acrylcarboxylic acid of the formula Ar(R)CHCO.sub.2 H from an amino acid, said process comprising:
contacting a starting mixture containing said amino acid and said .alpha.-arylcarboxylic acid with an organic acid to produce a salt of said amino acid and said organic acid,
separating said salt from a material containing said .alpha.-arylcarboxylic acid in a proportion to said amino acid that is greater than that in said starting mixture,
wherein said organic acid is selected from the group consisting of carbonic, formic, acetic, propionic and C.sub.4 -C.sub.5 acids; R is selected from the group consisting of C.sub.1 -C.sub.8 alkyl and C.sub.1 -C.sub.8 substituted alkyl; Ar is selected from the group consisting of phenyl, substituted phenyl, 2-naphthyl, substituted 2-naphthyl, 2-fluorenyl, and substituted 2-fluorenyl; and said amino acid is selected from the group consisting of lysine, arginine, and histidine.