Hexanoic acid

Hexanoic acid, also known as caproic acid, is the carboxylic acid derived from hexane with the chemical formula CH
. 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. The primary use of hexanoic acid is in manufacture of its esters for artificial flavors, and in the manufacture of hexyl derivatives, such as hexylphenols.[1] Salts and esters of hexanoic acid are known as hexanoates or caproates.

Hexanoic acid
Skeletal formula
Ball-and-stick model
IUPAC name
Hexanoic acid
Other names
Caproic acid; n-Caproic acid; C6:0 (Lipid numbers)
3D model (JSmol)
ECHA InfoCard 100.005.046
EC Number
  • 205-550-7
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 pictograms GHS05: CorrosiveGHS06: Toxic
GHS Signal word Danger
H311, H314, H318
P260, P264, P280, P301+330+331, P302+352, P303+361+353, P304+340, P305+351+338, P310, P312, P321, P322, P361, P363, P405, P501
NFPA 704 (fire diamond)
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilHealth code 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
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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Infobox references

Two other acids are named after goats: caprylic (C8) and capric (C10). Along with hexanoic 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 alsoEdit


  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