Trichloroacetic acid

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Trichloroacetic acid
Trichloroacetic acid structure.svg
Preferred IUPAC name
Trichloroacetic acid
3D model (JSmol)
ECHA InfoCard 100.000.844 Edit this at Wikidata
RTECS number
  • AJ7875000
  • InChI=1S/C2HCl3O2/c3-2(4,5)1(6)7/h(H,6,7)
  • ClC(Cl)(Cl)C(O)=O
Molar mass 163.38 g·mol−1
Appearance Colorless to white, crystalline solid
Odor Sharp, pungent [1]
Density 1.63 g/cm3
Melting point 57 to 58 °C (135 to 136 °F; 330 to 331 K)[2]
Boiling point 196 to 197 °C (385 to 387 °F; 469 to 470 K)[2]
1000 g/100 mL[2]
Vapor pressure 1 mmHg (51.1 °C)[1]
Acidity (pKa) 0.66[3]
−73.0·10−6 cm3/mol
3.23 D
GHS labelling:
GHS05: CorrosiveGHS09: Environmental hazard
H314, H410
P260, P264, P273, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P391, P405, P501
NFPA 704 (fire diamond)
Lethal dose or concentration (LD, LC):
5000 mg/kg orally in rats[2]
NIOSH (US health exposure limits):
PEL (Permissible)
REL (Recommended)
TWA 1 ppm (7 mg/m3)[1]
IDLH (Immediate danger)
Related compounds
Chloroacetic acid
Dichloroacetic acid
Related compounds
Acetic acid
Trifluoroacetic acid
Tribromoacetic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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as trichloroethanoic acid) is an analogue of acetic acid in which the three hydrogen atoms of the methyl group have all been replaced by chlorine atoms.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.


It is prepared by the reaction of chlorine with acetic acid in the presence of a suitable catalyst such as red phosphorus. This reaction is Hell–Volhard–Zelinsky halogenation.

+ 3 Cl
+ 3 HCl

Another route to trichloroacetic acid is the oxidation of trichloroacetaldehyde.


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 medication 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] The sodium salt (sodium trichloroacetate) 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]

Environmental and health concerns[edit]

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."[10]

Trichloroacetic acid was placed on the California Proposition 65 List in 2013 "as a chemical known to the state to cause cancer".[11]


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.[12] The theory was contrary to the beliefs of Jöns Jakob Berzelius, starting a long dispute between Dumas and Berzelius.[13]

Popular Culture[edit]

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

See also[edit]


  1. ^ a b c d e NIOSH Pocket Guide to Chemical Hazards #0626 National Institute for Occupational Safety and Health (NIOSH)
  2. ^ a b c d Budavari, Susan, ed. (1996), The Merck Index: An Encyclopedia 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: Diagnosis, treatment, and prevention". Clinical Infectious Diseases. 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. ^ "Trichloroacetic acid". C&L Inventory. European Chemical Agency. Retrieved 14 March 2022.
  11. ^ "Trichloroacetic Acid". The Proposition 65 List. California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment. Retrieved 14 March 2022.
  12. ^ Dumas (1839). "Trichloroacetic acid". Annalen der Pharmacie. 32: 101–119. doi:10.1002/jlac.18390320109.
  13. ^ William Albert Noyes (1927). "Valence". Proceedings of the American Philosophical Society. 66: 287–308. JSTOR 3301070.

External links[edit]