Hoechst Celanese Corporation

Larry D Zeagler

Carl David Murphy

Apurba Bhattacharya

John R Fritch

Carina A McAdams

Carina Araullo-McAdams

A process is provided whereby S(+)-ibuprofen or R(-)-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 one of the enantiomers in the ibuprofen enantiomeric mixture. Upon precipitation of one ibuprofen enantiomer from the mixture, the overall precipitate and reaction mixture can be held for a sufficient period of time at a second temperature to allow the first precipitate to redissolve into the reaction mixture and the other ibuprofen enantiomer to precipitate out of the mixture in the salt form. Optically active ibuprofen is racemized by being heated at 100.degree. C. to 300.degree. C. in the substantial absence of other materials.

Selective precipitation of .alpha.-aryl carboxylic acid salts

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.

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Corpus Christi, TX, United States of America

Larry D Zeagler