Trichloroacetic acid (TCA; TCAA; also known as trichloroethanoic acid) is an analogue of

acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main compone ...

in which the three

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

atoms of the methyl group have all been replaced by

chlorine Chlorine is a chemical element; it has Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between ...

atoms. Salts and

ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...

s of trichloroacetic acid are called trichloroacetates.

Synthesis

Trichloroacetic acid was discovered by

Jean-Baptiste Dumas Jean Baptiste André Dumas (; 14 July 180010 April 1884) was a French chemist, best known for his works on organic analysis and synthesis, as well as the determination of atomic weights (relative atomic masses) and molecular weights by measuri ...

in 1830. It is prepared by the reaction of chlorine with

in the presence of a suitable catalyst such as

red phosphorus Red phosphorus is an Allotropes of phosphorus, allotrope of phosphorus. It is an amorphous polymeric red solid that is stable in air. It can be easily converted from white phosphorus under light or heating. It finds applications as matches and fir ...

. This reaction is Hell–Volhard–Zelinsky halogenation. : + 3 → + 3 Another route to trichloroacetic acid is the oxidation of trichloroacetaldehyde.

Use

It is widely used in

biochemistry Biochemistry, or biological chemistry, is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology, a ...

for the precipitation of macromolecules, such as

proteins Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, re ...

DNA Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...

, and

RNA Ribonucleic acid (RNA) is a polymeric molecule that is essential for most biological functions, either by performing the function itself (non-coding RNA) or by forming a template for the production of proteins (messenger RNA). RNA and deoxyrib ...

. TCA and DCA are both used in cosmetic treatments (such as chemical peels and tattoo removal) and as

topical medication A topical medication is a medication that is applied to a particular place on or in the body. Most often topical medication means application to body surface area, body surfaces such as the skin or mucous membranes to treat ailments via a large ...

for chemoablation of warts, including genital warts. It can kill normal cells as well. It is considered safe for use for this purpose during pregnancy. The sodium salt ( sodium trichloroacetate) was used as an

herbicide Herbicides (, ), also commonly known as weed killers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page f ...

starting in the 1950s but regulators removed it from the market in the late 1980s and early 1990s.

Environmental and health concerns

According to the European Chemicals Agency, "This substance causes severe skin burns and eye damage, is very toxic to aquatic life and has long lasting toxic effects."

History

The discovery of trichloroacetic acid by

in 1839 delivered a striking example to the slowly evolving theory of organic radicals and valences. The theory was contrary to the beliefs of Jöns Jakob Berzelius, starting a long dispute between Dumas and Berzelius.

Popular culture

In the 1958 film '' The Blob'', a bottle of trichloroacetic acid is tossed at the Blob in a futile attempt to fend it off.

References

External links

*
CDC - NIOSH Pocket Guide to Chemical Hazards
{{DEFAULTSORT:Trichloroacetic Acid Acetic acids IARC Group 2B carcinogens Trichloromethyl compounds Organic compounds with 2 carbon atoms