2-Chlorobenzoic acid

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2-Chlorobenzoic acid
2-Chlorobenzoic acid - Vect.svg
Preferred IUPAC name
2-Chlorobenzoic acid
Other names
o-Chlorobenzoic acid
3D model (JSmol)
ECHA InfoCard 100.003.897
Molar mass 156.57 g·mol−1
Appearance white solid
Melting point 142 °C (288 °F; 415 K)
Boiling point 285 °C (545 °F; 558 K)
log P 2.039 [1]
Acidity (pKa) 2.89 [2] [3]
-83.56·10−6 cm3/mol
Safety data sheet Oxford MSDS[dead link]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

2-Chlorobenzoic acid is an organic compound with the formula ClC6H4CO2H. It is one of three isomeric chlorobenzoic acids, the one that is the strongest acid. This white solid is used as a precursor to a variety of drugs, food additives, and dyes.[4]

Synthesis and reactions[edit]

It is prepared by the oxidation of 2-chlorotoluene. The laboratory scale reaction employs potassium permanganate.[5] Alternatively it arises by the hydrolysis of α,α,α-trichloro-2-toluene.

The chloride is readily replaced by ammonia to 2-aminobenzoic acid. At elevated temperature it decarboxylates.[4]


  1. ^ 1.2-Chlorobenzoic acid; C7H5ClO2; ChemSpider. Chemspider.com (2015). at [1]
  2. ^ Clayton, G. D. and F. E. Clayton (eds.). Patty's Industrial Hygiene and Toxicology: Volume 2A, 2B, 2C: Toxicology. 3rd ed. New York: John Wiley Sons, 1981-1982., p. 1838
  3. ^ 2.2-Chlorobenzoic acid; C7H5ClO2 - PubChem. Pubchem.ncbi.nlm.nih.gov at [2]
  4. ^ a b Takao Maki, Kazuo Takeda "Benzoic Acid and Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a03_555.
  5. ^ H. T. Clarke and E. R. Taylor (1943). "o-Chlorobenzoic acid". Organic Syntheses.; Collective Volume, 2, p. 135