2-Mercaptopropionic acid

Chemical properties

Clear colorless to slightly yellow liquid. Oily liquid; Melting point 10 ℃; Boiling point d-95 ~ 100 ℃ / 2133Pa, dl- 98.5 ~ 99.0 ℃ / 1866Pa; Density I-D19.24 1.193; Refractive index dl-nD: 1.4823; Optical rotation[α] D-45.47; soluble in water, ethanol and ether.

Chemical properties

Thiolactic acid has a roasted, meaty odor.

The Uses of 2-Mercaptopropionic acid

Depilatory, hair-waving preparations.

The Uses of 2-Mercaptopropionic acid

Thiolactic acid (TLA) can be used as a building block in the synthesis of:

• Thiolactomycin via oxathiolanone intermediate.
• 4-Thiazolidinones by reacting various Schiff bases with thioglycolic acid.
• 1,4-Naphthoquinone derivatives containing sulfur atom for antibacterial and antiviral activity studies.

It can also be used as a bidental chelating agent for the surface modification of titanium dioxide (TiO₂) nanoparticles for the removal of cadmium from waste water.

Preparation

By electrolysis of the corresponding sulfide, S(SCHMeCO2H)2.

Definition

ChEBI: 2-mercaptopropanoic acid is a mercaptopropanoic acid.

Taste threshold values

Taste characteristics at 15 ppm: meaty, sulfury, brothy, and brown.

General Description

An oily liquid with an unpleasant odor. Toxic by ingestion and skin absorption. Used as a depilatory and in hair waving preparations.

Air & Water Reactions

Soluble in water and denser than water.

Reactivity Profile

2-Mercaptopropionic acid is an organosulfide/organic acid. Organosulfides are incompatible with acids, diazo and azo compounds, halocarbons, isocyanates, aldehydes, alkali metals, nitrides, hydrides, and other strong reducing agents. Reactions with these materials generate heat and in many cases hydrogen gas. Many of these compounds may liberate hydrogen sulfide upon decomposition or reaction with an acid. Carboxylic acids donate hydrogen ions if a base is present to accept them. They react in this way with all bases, both organic (for example, the amines) and inorganic. Their reactions with bases, called "neutralizations", are accompanied by the evolution of substantial amounts of heat. Neutralization between an acid and a base produces water plus a salt. Carboxylic acids with six or fewer carbon atoms are freely or moderately soluble in water; those with more than six carbons are slightly soluble in water. Soluble carboxylic acid dissociate to an extent in water to yield hydrogen ions. The pH of solutions of carboxylic acids is therefore less than 7.0. Many insoluble carboxylic acids react rapidly with aqueous solutions containing a chemical base and dissolve as the neutralization generates a soluble salt. Carboxylic acids in aqueous solution and liquid or molten carboxylic acids can react with active metals to form gaseous hydrogen and a metal salt. Such reactions occur in principle for solid carboxylic acids as well, but are slow if the solid acid remains dry. Even "insoluble" carboxylic acids may absorb enough water from the air and dissolve sufficiently in 2-Mercaptopropionic acid to corrode or dissolve iron, steel, and aluminum parts and containers. Carboxylic acids, like other acids, react with cyanide salts to generate gaseous hydrogen cyanide. The reaction is slower for dry, solid carboxylic acids. Insoluble carboxylic acids react with solutions of cyanides to cause the release of gaseous hydrogen cyanide. Flammable and/or toxic gases and heat are generated by the reaction of carboxylic acids with diazo compounds, dithiocarbamates, isocyanates, mercaptans, nitrides, and sulfides. Carboxylic acids, especially in aqueous solution, also react with sulfites, nitrites, thiosulfates (to give H2S and SO3), dithionites (SO2), to generate flammable and/or toxic gases and heat. Their reaction with carbonates and bicarbonates generates a harmless gas (carbon dioxide) but still heat. Like other organic compounds, carboxylic acids can be oxidized by strong oxidizing agents and reduced by strong reducing agents. These reactions generate heat. A wide variety of products is possible. Like other acids, carboxylic acids may initiate polymerization reactions; like other acids, they often catalyze (increase the rate of) chemical reactions.

Health Hazard

TOXIC; inhalation, ingestion or skin contact with material may cause severe injury or death. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.

Fire Hazard

Combustible material: may burn but does not ignite readily. When heated, vapors may form explosive mixtures with air: indoors, outdoors and sewers explosion hazards. Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated. Runoff may pollute waterways. Substance may be transported in a molten form.

Safety Profile

Poison by ingestion. Moderately toxic by inhalation. When heated to decomposition it emits toxic fumes of SOx. See also SULFIDES and MERCAPTANS.