Patent ID: 6844450

Claim:
A process for the synthesis of racemic thioctic acid comprising the following stages: a) reaction of the alkyl ester of 6,8-di-halo-octanoic acid in an organic solvent with an aqueous solution of alkali disulfide in presence of a compound for phase transfer catalysis selected from the group consisting of quaternary animonium or phosphonium salts having the following general formula: where: A is nitrogen of phosphorus, X is selected from the group consisting of Cl, Br, I, HSO 4 and H 2 PO 4 and the substituents R 1 , R 2 , R 3 and R 4 are selected from the group consisting linear or branched alkyl radicals having one to twenty carbon atoms (C 1 -C 20 ), said substituents being identical or different one from the other; followed by the hydrolysis of the ester of racemic thioctic acid; wherein in the reaction taking place in stage a) the molar ratio alkali disulfide/alkyl ester of 6,8-di-halo-octanoic acid is between 0.8 and 1.2, and said quatemary ammonium or phosphonium salt is present in an amount of 0.5 to 10% in moles with respect to the alkyl ester of 6,8-di-halo-octanoic acid.