3-Mercaptopropionitrile is the organosulfur compound with the formula HSCH<sub>2</sub>CH<sub>2</sub>CN. Containing both thiol and nitrile functional groups, it is a bifunctional compound. A colorless liquid, the compound has found some use as a masked form of thiolate.
it is typically prepared from 3-chloropropionitrile via initial reaction with thiourea. The resulting isothiouronium salt hydrolyzes to the thiol. A variation on this preparation involves isolation of the disulfide (SCH<sub>2</sub>CH<sub>2</sub>CN)<sub>2</sub>. Zinc reduction of this disulfide gives the thiol.
Thioethers derived from S-alkylation of 3-mercaptopropionitrile react with strong bases to give thiolate and acrylonitrile:
The conversion illustrates the retro-Michael reaction. The thiolate is then hydrolyzed