3-Mercaptopropionic acid

3-Mercaptopropionic acid (3-MPA) is an organosulfur compound with the formula HSCH₂CH₂CO₂H. It is a bifunctional molecule, containing both carboxylic acid and thiol groups. It is a colorless oil. It is derived from the addition of hydrogen sulfide to acrylic acid.

3-Mercaptopropionic acid

Names
Preferred IUPAC name 3-Sulfanylpropanoic acid
Other names 3-MPA; 3-Mercaptopropanoic acid; β-Mercaptopropionic acid
Identifiers
CAS Number	107-96-0
3D model (JSmol)	Interactive image
Beilstein Reference	773807
ChEBI	CHEBI:44111
ChEMBL	ChEMBL358697
ChemSpider	6267
ECHA InfoCard	100.003.216
EC Number	203-537-0
Gmelin Reference	101294
PubChem CID	6514
UNII	B03TJ3QU9M
CompTox Dashboard (EPA)	DTXSID8026775
InChI InChI=1S/C3H6O2S/c4-3(5)1-2-6/h6H,1-2H2,(H,4,5) Key: DKIDEFUBRARXTE-UHFFFAOYSA-N
SMILES C(CS)C(=O)O
Properties
Chemical formula	C3H6O2S
Molar mass	106.14 g·mol−1
Density	1.218
Melting point	16.9 °C (62.4 °F; 290.0 K)
Boiling point	111 °C (232 °F; 384 K) at 15 mmHg[1]
Solubility in water	soluble
Solubility	ether benzene alcohol water
Acidity (pKa)	4.34
Refractive index (nD)	1.4911 at 21 °C
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H290, H301, H314, H332
Precautionary statements	P234, P260, P261, P264, P270, P271, P280, P301+P310, P301+P330+P331, P303+P361+P353, P304+P312, P304+P340, P305+P351+P338, P310, P312, P321, P330, P363, P390, P404, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Reactions and uses

It is competitive inhibitor of glutamate decarboxylase, and therefore acts as a convulsant. It has higher potency and faster onset of action compared to allylglycine.^[2]

It is used to prepare hydrophilic gold nanoparticles, exploiting the affinity of gold for sulfur ligands.^[3]

It is esterified with polyols to form thiol-based polymer cross-linking agents such as pentaerythritol-based pentaerythritol tetrakis(3-mercaptopropionate).^[4]

See also

• Allylglycine
• Thiolactic acid (2-mercaptopropionic acid)