3-Mercaptopropionic Acid: An Important Organic Sulfur Compound

3-Mercaptopropionic acid (3-MPA), also known as β-mercaptopropionic acid or thio-propionic acid, is an organic compound featuring both a mercaptan group (-SH) and a carboxyl group (-COOH) in its molecular structure. Its unique bifunctional structure enables diverse applications across multiple fields, such as serving as a stabilizer for polyvinyl chloride (PVC), a chain transfer agent in polymerization, and as a pharmaceutical intermediate, catalyst, and biochemical reagent.

Technical Specifications

The technical specifications of 3-Mercaptopropionic acid form the foundation for its effective application in industrial and research settings. Key technical indicators are as follows:

Chemical Name: 3-Mercaptopropionic acid

English Name: 3-Mercaptopropionic acid

Aliases: β-Mercaptopropionic acid, Thio-lactic acid, Thiopropionic acid, Mercaptopropionic acid

CAS Number: 107-96-0

Molecular Formula: C₃H₆O₂S

Molecular Weight: 106.14 g/mol

Purity: Commercially available products typically require ≥99% purity.

Application Areas: Primarily used as a stabilizer for transparent PVC products, offering superior stability compared to other stabilizers. Additionally, it serves as an antioxidant, catalyst, biochemical reagent, and as a ligand in gold nanoparticle synthesis.

Physical and Chemical Properties

The physicochemical properties of 3-Mercaptopropionic Acid dictate its handling, storage, and reaction conditions:

Appearance: Colorless or pale yellow transparent oily liquid, occasionally crystalline.

Odor: Strong sulfurous odor, toxic.

Melting Point: 15–19°C (15 minus).

Boiling point: 110–111°C (110 minus) (15 mmHg).

Density: 1.218 g/mL (25 °C).

Solubility: Highly soluble in water, ethanol, diethyl ether, benzene, and other solvents.

Vapor pressure: 0.04 mmHg (20 °C).

Flash point: 93.4°C.

pH: Its aqueous solution is acidic; a 120 g/l aqueous solution has a pH of 2 at 20 °C.

Stability: Relatively stable under standard atmospheric conditions, but the presence of a thiol group and a carboxyl group makes it reactive. Avoid intense heating.

Toxicity and Hazards

Strict safety precautions must be observed when handling and storing 3-Mercaptopropionic Acid due to its toxicity and corrosivity:

Toxicity: Toxic if swallowed; emits strong sulfide odor; harmful if inhaled.

Corrosivity: Causes severe skin burns and eye damage; irreversible effects on eyes.

Environmental Hazards: Toxic to aquatic life; avoid discharge into the environment.

Precautions: Wear personal protective equipment including respirators, chemical safety goggles, acid/alkali-resistant coveralls, and chemical gloves during handling. Thoroughly wash skin after work and maintain good hygiene practices.

3-Mercaptopropionic acid plays a significant role in industrial and research applications due to its unique bifunctional structure and physicochemical properties. However, its potential toxicity and corrosiveness necessitate strict adherence to safety protocols to ensure personnel safety and environmental protection.