454-29-5

6038-19-3

The general procedure for the synthesis of DL-homocysteine thiolactone hydrochloride from DL-homocysteine was as follows: 100 g of DL-methionine was added to a 3-liter cryogenic autoclave pre-cooled to -40°C in a dry ice-acetonitrile solvent mixture, followed by the slow addition of dry ammonia until DL-methionine in the concentrated liquid ammonia was completely dissolved. At a reaction temperature of -35 to -40°C, 60 g of chopped sodium metal was added in batches and the reaction process was followed by liquid chromatography. Upon completion of the reaction, stirring was stopped, the reaction mixture was allowed to stand, and the upper clear night layer was carefully transferred to another three-necked flask. Ammonium chloride was added to quench the reaction and the reaction mixture was allowed to warm up naturally to room temperature until ammonia was completely spilled. The resulting solid was a mixture of DL-homocysteine sodium salt, sodium chloride and ammonium chloride. Treatment by a cation exchange resin to remove sodium ions and subsequent adjustment of the eluate to pH 1 with concentrated hydrochloric acid resulted in 81 g of DL-homocysteine thiolactone hydrochloride in 79% yield.