Process for the production of r(+) alpha-lipoic acid

摘要

Process for the synthesis of R(+)alpha-lipoic acid comprising the following stages: a) Salifying of racemic thioctic acid with R(+)alpha-methylbenzylamine; b) separation by filtration of the crystallized diastereoisomeric salt of R(+)alpha-lipoic acid-R(+)alpha-methylbenzylamine; c) purification by re-crystallization of the diastereoisomeric salt of R(+)alpha-lipoic acid-R(+)alpha-methylbenzylamine, in which the re-crystallization solvent consists of a mixture of non-polar/polar solvents; d) separation of the diastereoisomeric salt to obtain R(+)alpha-lipoic acid by reaction of said salt with acids selected from the group consisting of aliphatic hydroxy-carboxylic acids having 3 to 6 carbon atoms and aqueous phosphoric acid.