| abstract |
The invention relates to a method for producing R- and S-lipoic acid and R-dihydrolipoic acid comprising the following steps: (a) reaction of the compound of formula (2) with sodium sulphide and sulphur in methanol, whereby Ms represents SO<2>R`, and R and R` independently of one another represent C1-C6 alkyl, C3-C8-cycloalkyl, C3-C8-cycloalkylalkyl, aryl or aralkyl. The invention relates in particular to methods for producing pure R- or S-dihydrolipoic acid, which is either used directly or processed further to obtain R- and S-lipoic acid. The method is also used to produce medicaments. The invention also relates to a solution of sodium sulphide-trihydrate and sulphur in methanol, whereby the sulphur is present as a molar surplus in relation to the sodium sulphide-trihydrate, and to a kit that comprises the inventive solution. |