PURPOSE: To stably produce β-mercaptopropionic acid in high yield by reacting acrylonitrile with sodium hydrosulfide, then neutralizing and hydrolyzing the resultant alkali salt of the resultant β-mercaptopropionitrile.
CONSTITUTION: Acrylonitrile is added to an aqueous solution of an alkali hydrosulfide containing sulfur and an alkali hydroxide (preferably sodium hydroxide) and made to react therewith at 10-50°C, preferably 30-40°C temperature. The resultant reactional mixture is then added into an acid, preferably hydrochloric acid at 30-50°C temperature to neutralize an alkali salt of β- mercaptopropionitrile. The prepared β-mercaptopropionitrile is usually hydrolyzed at 100-120°C temperature to afford β-mercaptopropionic acid. Zinc dust is preferably added to the reactional mixture after the hydrolysis to carry out the reducing reaction. The resultant compound is then preferably extracted with isopropyl ether to distill the obtained extract. Dithiodipropionic acid formed as a by product is subjected to the reducing cleavage by the reducing reaction to produce the objective β-mercaptopropionic acid.
NISHIHATA YUTAKA
MORITA TAKAYUKI
INOUE KAYO
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