Hexanoic acid

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Hexanoic acid
Skeletal formula
Ball-and-stick model
CAS number 142-62-1 YesY
PubChem 8892
ChemSpider 8552 YesY
KEGG C01585 YesY
ChEBI CHEBI:30776 YesY
Jmol-3D images Image 1
Molecular formula C6H12O2
Molar mass 116.16 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]
Solubility in water 1.082 g/100 mL[1]
Solubility soluble in ethanol, ether
Acidity (pKa) 4.88
Viscosity 3.1 mP
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point 103 °C (217 °F; 376 K)[2]
Autoignition temperature 380 °C (716 °F; 653 K)
Explosive limits 1.3-9.3%
LD50 3000 mg/kg (rat, oral)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Hexanoic acid (caproic acid), is the carboxylic acid derived from hexane with the general formula C5H11COOH. 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 give 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 the manufacture of its esters for artificial flavors, and in the manufacture of hexyl derivatives, such as hexylphenols.[1]

The salts and esters of this acid are known as hexanoates or caproates.

Two other acids are named after goats: caprylic (C8) and capric (C10). Along with hexanoic acid, these total 15% in goat milk fat.

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.


  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 from the IFA
  3. ^ Ginkgo.html