A kind of preparation method of dihydrolipoic acid

Abstract

This invention discloses a method for preparing dihydrolipoic acid, relating to the field of pharmaceutical synthesis technology. The invention comprises the following steps: a) using a low-carbon alcohol as a reaction solvent, adding 6,8-dichlorooctanoic acid methyl ester, sodium sulfide nonahydrate, and sulfur, heating to reflux, and cooling and filtering after the reaction is completed; b) adding water and a metal reducing agent to the filtrate, heating to reflux under nitrogen protection, and then cooling to room temperature; c) adjusting the solution pH to 1-2 with dilute hydrochloric acid or the like, and recovering the alcoholic reaction solvent under reduced pressure; d) extracting the product with an organic solvent, and finally distilling under reduced pressure to obtain the product. This invention uses inexpensive 6,8-dichlorooctanoic acid methyl ester as the base raw material and readily available and inexpensive metal reducing agents, which can effectively reduce costs, have low requirements for reaction conditions, and reduce the difficulty of preparation.