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 In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula (whereas normal methane has the formula ). In formulas, the group is often abbreviated as ...

group have all been replaced by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 In chemistry, a salt or ionic compound is a chemical compound consisting of an assembly of positively charged ions ( cations) and negatively charged ions (anions), which results in a compound with no net electric charge (electrically neutral). ...

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 Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...

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 The Hell–Volhard–Zelinsky halogenation reaction is a chemical transformation that transforms an alkyl carboxylic acid to the α-bromo derivative. It is a specialized and rare kind of halogenation. Examples An example of the Hell–Volhard� ...

. : + 3 → + 3 Another route to trichloroacetic acid is the oxidation of

trichloroacetaldehyde Chloral, also known as trichloroacetaldehyde or trichloroethanal, is the organic compound with the formula Cl3CCHO. This aldehyde is a colourless liquid that is soluble in a wide range of solvents. It reacts with water to form chloral hydrate, a o ...

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 A chemical peel is a treatment used to improve and smooth the texture of the skin. The skin on the face is most commonly treated, but peels can also be performed on the body. Chemical peels are intended to remove the outermost layers of the skin ...

and

tattoo removal Tattoo removal is a procedure to eliminate or significantly lighten a tattoo from the skin. People pursue removal for many reasons, including changes in personal taste, social or professional considerations, or a desire to relocate a tattoo. Mo ...

) 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 Ablation ( – removal) is the removal or destruction of something from an object by vaporization, chipping, erosive processes, or by other means. Examples of ablative materials are described below, including spacecraft material for ascent and ...

warts Warts are non-cancerous viral growths usually occurring on the hands and feet but which can also affect other locations, such as the genitals or face. One or many warts may appear. They are distinguished from cancerous tumors as they are caus ...

, including

genital warts Genital warts are a sexually transmitted infection caused by certain types of human papillomavirus (HPV). They may be flat or project out from the surface of the skin, and their color may vary; brownish, white, pale yellow, pinkish-red, or gray ...

. It can kill normal cells as well. It is considered safe for use for this purpose during pregnancy. The sodium salt (

sodium trichloroacetate Sodium trichloroacetate is a chemical compound with a formula of CCl3CO2Na. It is used to increase sensitivity and precision during transcript mapping. It was previously used as an herbicide starting in the 1950s but regulators removed it from th ...

) 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 Jöns is a Swedish given name and a surname. Notable people with the given name include: * Jöns Jacob Berzelius (1779–1848), Swedish chemist * Jöns Budde (1435–1495), Franciscan friar from the Brigittine monastery in NaantaliVallis Grati ...

, starting a long dispute between Dumas and Berzelius.

Popular culture

In the 1958 film ''

The Blob ''The Blob'' is a 1958 American science fiction horror film directed by Irvin S. Yeaworth Jr. from a screenplay by Theodore Simonson and Kate Phillips, based on an idea by Irving H. Millgate. It stars Steve McQueen (in his first leading role ...

'', 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