3-Mercaptopropionitrile Explained

3-Mercaptopropionitrile is the organosulfur compound with the formula HSCH₂CH₂CN.^[1] 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.

Preparation and reactions

it is typically prepared from 3-chloropropionitrile via initial reaction with thiourea. The resulting isothiouronium salt hydrolyzes to the thiol.^[2] A variation on this preparation involves isolation of the disulfide (SCH₂CH₂CN)₂. Zinc reduction of this disulfide gives the thiol.^[3]

Thioethers derived from S-alkylation of 3-mercaptopropionitrile react with strong bases to give thiolate and acrylonitrile:

RSCH₂CH₂CN + KOBu-t → RSK + CH₂=CHCN + HOBu-t The conversion illustrates the retro-Michael reaction. The thiolate is then hydrolyzed

RSK + H⁺ → RSH + K⁺

References

1. Book: Encyclopedia of Reagents for Organic Synthesis. 2001-04-15. Wiley. 978-0-471-93623-7. 1. en. 10.1002/047084289x.rn02347. 242662674 .
2. R. Eric Gerber. Carlos Hasbun. Larisa G. Dubenko. Mei Fong King. Donald E. Bierer. 10.15227/orgsyn.077.0186. β-Mercaptopropionitrile. Organic Syntheses. 77. 186. 2000.
3. Klose, J.. Reese, C. B.. Song, Q.. Preparation of 2-(2-cyanoethyl)sulfanyl-1H-isoindole-1,3-(2H)-dione and related sulfur-transfer agents. Tetrahedron. 1997. 53. 42 . 14411–14416. 10.1016/S0040-4020(97)00924-1.