Caproic acid
Skeletal formula
Ball-and-stick model
Preferred IUPAC name
Hexanoic acid
Other names
Hexoic acid; Hexylic acid; Butylacetic acid; Pentylformic acid; 1-Pentanecarboxylic acid; C6:0 (Lipid numbers)
3D model (JSmol)
ECHA InfoCard 100.005.046 Edit this at Wikidata
EC Number
  • 205-550-7
  • InChI=1S/C6H12O2/c1-2-3-4-5-6(7)8/h2-5H2,1H3,(H,7,8) checkY
  • InChI=1/C6H12O2/c1-2-3-4-5-6(7)8/h2-5H2,1H3,(H,7,8)
Molar mass 116.160 g·mol−1
Appearance Oily liquid[1]
Odor goat-like
Density 0.929 g/cm3[2]
Melting point −3.4 °C (25.9 °F; 269.8 K)[1]
Boiling point 205.8 °C (402.4 °F; 478.9 K)[1]
1.082 g/100 mL[1]
Solubility soluble in ethanol, ether
Acidity (pKa) 4.88
−78.55·10−6 cm3/mol
Viscosity 3.1 mP
GHS labelling:
GHS05: CorrosiveGHS06: Toxic
H311, H314
P260, P264, P280, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P321, P322, P361, P363, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
Flash point 103 °C (217 °F; 376 K)[2]
380 °C (716 °F; 653 K)
Explosive limits 1.3-9.3%
Lethal dose or concentration (LD, LC):
3000 mg/kg (rat, oral)
Related compounds
Related compounds
Pentanoic acid, Heptanoic 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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Caproic acid, also known as hexanoic acid, is the carboxylic acid derived from hexane with the chemical formula CH3(CH2)4COOH. It is a colorless oily liquid with an odor that is fatty, cheesy, waxy, and like that of goats[1] or other barnyard animals. It is a fatty acid found naturally in various animal fats and oils, and is one of the chemicals that gives the decomposing fleshy seed coat of the ginkgo its characteristic unpleasant odor.[3] It is also one of the components of vanilla and cheese. The primary use of caproic acid is in the manufacture of its esters for use as artificial flavors, and in the manufacture of hexyl derivatives, such as hexylphenols.[1] Salts and esters of caproic acid are known as caproates or hexanoates. Several progestin medications are caproate esters, such as hydroxyprogesterone caproate and gestonorone caproate.

Two other acids are named after goats: caprylic acid (C8) and capric acid (C10). Along with caproic acid, they account for 15% of the fat in goat's milk.

Caproic, caprylic, and capric acids (capric is a crystal- or wax-like substance, whereas the other two are mobile liquids) are not only used for the formation of esters, but also commonly used "neat" in: butter, milk, cream, strawberry, bread, beer, nut, and other flavors.

See also


  1. ^ a b c d e f The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (11th ed.), Merck, 1989, ISBN 091191028X
  2. ^ a b Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  3. ^ "Ginkgo.html". Archived from the original on 2008-12-26. Retrieved 2007-03-08.