Trichloroacetic acid is an analogue of acetic acid where chlorine atoms replace hydrogen atoms in the methyl group. It is prepared by reacting chlorine with acetic acid in the presence of a catalyst. Trichloroacetic acid is widely used in biochemistry to precipitate macromolecules and was previously used as an herbicide. Its discovery in 1839 contributed to the evolving theory of organic radicals and valences, starting a dispute between its discoverer and another chemist.

1. Trichloroacetic acid
Trichloroacetic acid (TCA; TCAA; also known as
trichloroethanoic acid) is an analogue of acetic acid in
which the three hydrogen atoms of the methyl group have
all been replaced by chlorine atoms. Salts and esters of
trichloroacetic acid are called trichloroacetates.
1 Synthesis
It is prepared by the reaction of chlorine with acetic acid
in the presence of a suitable catalyst.
CH
3COOH + 3Cl
2 → CCl
3COOH +3HCl
2 Use
It is widely used in biochemistry for the precipitation of
macromolecules, such as proteins, DNA, and RNA. TCA
and DCA are both used in cosmetic treatments (such as
chemical peels and tattoo removal) and as topical medica-
tion 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.[4][5]
Its sodium salt was used as an herbicide starting in the
1950s but regulators removed it from the market in the
late 1980s and early 1990s.[6][7][8][9][10]
3 History
The discovery of trichloroacetic acid by Jean-Baptiste
Dumas in 1839 delivered a striking example to the slowly
evolving theory of organic radicals and valences.[11]
The
theory was contrary to the beliefs of Jöns Jakob Berzelius,
starting a long dispute between Dumas and Berzelius.[12]
4 See also
• Chloroacetic acids
5 References
[1] NIOSH Pocket Guide to Chemical Hazards
#0626National Institute for Occupational Safety
and Health (NIOSH)
[2] Budavari, Susan, ed. (1996), The Merck Index: An Ency-
clopedia of Chemicals, Drugs, and Biologicals (12th ed.),
Merck, ISBN 0911910123
[3] Databog fysik kemi, F&K Forlaget 11. udgave 2009
[4] “Trichloroacetic Acid or Bichloroacetic Acid for Genital
Warts (Human Papillomavirus)". WebMD.
[5] Wiley DJ, Douglas J, Beutner K, Cox T, Fife K, Moscicki
AB, Fukumoto L (2002). “External genital warts: Diag-
nosis, treatment, and prevention”. Clinical Infectious Dis-
eases. 35 (Suppl 2): S210–S224. doi:10.1086/342109.
PMID 12353208.
[6] TCA-sodium in the Pesticide Properties DataBase
(PPDB), accessed June 20, 2014
[7] G. S. Rai and C. L. Hamner Persistence of Sodium
Trichloroacetate in Different Soil Types Weeds 2(4) Oct.
1953: 271-279
[8] OECD Trichloroacetic Acid CAS N°: 76-03-9 Accessed
June 20, 2014
[9] EPA December 1991. trichloroacetic acid (TCA) EPA
Cancellation 12/91 Accessed June 20, 2014
[10] PAN Trichloroacetic acid, sodium salt
[11] Dumas (1839). “Trichloroacetic acid”.
Annalen der Pharmacie. 32: 101–119.
doi:10.1002/jlac.18390320109.
[12] William Albert Noyes (1927). “Valence”. Proceedings of
the American Philosophical Society. 66: 287–308. JSTOR
3301070.
6 External links
• International Chemical Safety Card 0586
• CDC - NIOSH Pocket Guide to Chemical Hazards
1

2. 2 7 TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES
7 Text and image sources, contributors, and licenses
7.1 Text
• Trichloroacetic acid Source: https://en.wikipedia.org/wiki/Trichloroacetic_acid?oldid=756023371 Contributors: Stone, Kierant, Se-
curiger, Academician, Rich Farmbrough, Cacycle, Benjah-bmm27, Versageek, Countmippipopolous, V8rik, DePiep, Rjwilmsi,
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XLinkBot, Jytdog, Addbot, DOI bot, Yavonae, Paperclip047, SamatBot, Quercus solaris, Luckas-bot, Yobot, CheMoBot, Amirobot,
Xqbot, GrouchoBot, D'ohBot, Nirmos, Tom.Reding, RedBot, Pikiwyn, Oktanyum, Onel5969, RjwilmsiBot, The chemistds, Louisajb,
ClueBot NG, Pashihiko, DeepikaSN, Oliviaschoulorentzen, JZNIOSH, Kashifct, Tronvillain, Emily Temple-Wood (NIOSH), KasparBot,
PiousCorn, TerpeneOtto, Tcakim and Anonymous: 33
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