Ibuprofen is isolated from tablets or other solids by dissolving the ibuprofen in an alkane or cycloalkane solvent, filtering off undissolved solid, and stripping the solvent from the ibuprofen by evaporation or by recrystallization at low temperatures.

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.

This invention provides a process to prepare optically active .alpha.-aryl propionic acids without the need for resolving a racemic mixture. In one embodiment of the process, an acetophenone is sequentially converted to a 1-alkyne, then to an .alpha.-aryl .beta.-silylated acrolein, and then to an acrylic acid, which is then asymmetrically hydrogenated to an optically active .alpha.-aryl propionic acid.

The invention relates to a novel non-catalytic enantioselective resolution process for the separation of enantiomer of arylpropionic acid drugs from the racemic mixture, which comprises dissolving the racemic mixture of the said drug an organic solvent, reacting this solution with an aqueous phase containing an ionic surfactant with or without a suitable co-surfactant, and an electrolyte in microemulsion/micellar/biphasic medium, reacting this mixture with an appropriate chiral amine at a temperature in the range of 0 to 70 degrees Celsius to obtain a diastereomeric salt, acid hydrolysing the diastereomeric salt to result in the pure enantiomer of the drug which is extracted by known methods.

The use of S(-)sodium 2-(4-isobutylphenyl)propionate (the sodium salt of S(+)-ibuprofen) in pharmaceutical compositions for the treatment of inflammation, pain and pyrexia is described. Preferred compositions comprise S(-)sodium 2-(4-isobutylphenyl)propionate dihydrate. Processes to prepare S(-)sodium 2-(4-isobutyl-phenyl)propionate and its use in a process to prepare S(+) 2-(4-isobutylphenyl)propionic acid of high enantiomeric purity are also described.