3Mercaptopropionic

3-Mercaptopropionic acid, also known as thiopropionic acid or mercaptopropanoic acid, is an organosulfur compound that features both a carboxyl group and a thiol group. Its molecular formula is C3H6O2S, and its structure can be represented as HOOC-CH2-CH2-SH (or, equivalently, HS-CH2-CH2-COOH). The molecule is a small, bifunctional building block that combines an acidic carboxyl group with a nucleophilic sulfhydryl group.

Physical and chemical properties

3-Mercaptopropionic acid typically appears as a colorless to pale-yellow liquid with a characteristic mercaptan odor. It is soluble in water and many organic solvents due to its polar carboxylate and thiol functionalities. The carboxyl group is the acidic site (pKa around 4–5), while the thiol group has a higher pKa (approximately 8–10), so the thiol can be deprotonated under basic conditions to form a thiolate. The sulfhydryl group is prone to oxidation, forming disulfides upon exposure to air or suitable oxidants.

Applications and uses

The compound serves as a versatile building block in organic synthesis, providing a readily available source of thiol functionality for coupling reactions, the formation of thioesters, and related transformations. It is used in research and pharmaceutical contexts as a precursor for more complex sulfur-containing molecules and as a reagent in thiolation procedures.

Safety and handling

3-Mercaptopropionic acid is a reactive and corrosive substance with a strong mercaptan odor. It can cause irritation to skin, eyes, and the respiratory tract. It should be handled with appropriate personal protective equipment in a well-ventilated area, stored away from oxidants, and protected from air exposure to minimize disulfide formation.

See also

Mercaptopropionic acids

Thiol-containing building blocks

thiol chemistry