Caprylic acid
Skeletal formula
Ball-and-stick model
Preferred IUPAC name
Octanoic acid
Other names
1-Heptanecarboxylic acid
Octylic acid
Octoic acid
C8:0 (lipid numbers)
3D model (JSmol)
ECHA InfoCard 100.004.253 Edit this at Wikidata
EC Number
  • 204-677-5
  • InChI=1S/C8H16O2/c1-2-3-4-5-6-7-8(9)10/h2-7H2,1H3,(H,9,10) checkY
  • InChI=1/C8H16O2/c1-2-3-4-5-6-7-8(9)10/h2-7H2,1H3,(H,9,10)
Molar mass 144.214 g/mol
Appearance Oily colorless liquid
Odor Faint, fruity-acid; irritating
Density 0.910 g/cm3[1]
Melting point 16.7 °C (62.1 °F; 289.8 K)[3]
Boiling point 239.7 °C (463.5 °F; 512.8 K)[1]
0.068 g/100 mL[1]
Solubility Soluble in alcohol, chloroform, ether, CS2, petroleum ether, acetonitrile
log P 3.05
Vapor pressure 0.25 Pa
Acidity (pKa)
  • 4.89[2]
  • 1.055 (2.06–2.63 K)
  • 1.53 (−191 °C)
−101.60·10−6 cm3/mol
297.9 J/K·mol
−636 kJ/mol
GHS labelling:
GHS05: Corrosive[4]
P264, P280, P301+P330+P331, P303+P361+P353, P304+P340+P310, P305+P351+P338+P310, P363, P405, P501
NFPA 704 (fire diamond)
Flash point 130 °C (266 °F; 403 K)
440 °C (824 °F; 713 K)
Lethal dose or concentration (LD, LC):
10.08 g/kg (orally in rats)[1]
Related compounds
Related compounds
Heptanoic acid, nonanoic 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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Caprylic acid (from Latin capra 'goat'), also known under the systematic name octanoic acid or C8 Acid, is a saturated fatty acid, medium-chain fatty acid (MCFA). It has the structural formula H3C−(CH2)6COOH, and is a colorless oily liquid that is minimally soluble in water with a slightly unpleasant rancid-like smell and taste.[1] Salts and esters of octanoic acid are known as octanoates or caprylates. It is a common industrial chemical, which is produced by oxidation of the C8 aldehyde.[5] Its compounds are found naturally in the milk of various mammals and as a minor constituent of coconut oil and palm kernel oil.[3]

Two other acids are named after goats via the Latin word capra: caproic acid (C6) and capric acid (C10). Together, these three fatty acids comprise 15% of the fatty acids in goat milk fat.


Caprylic acid is used commercially in the production of esters used in perfumery and also in the manufacture of dyes.[citation needed]

Caprylic acid is an antimicrobial pesticide used as a food contact surface sanitizer in commercial food handling establishments on dairy equipment, food processing equipment, breweries, wineries, and beverage processing plants. It is also used as disinfectant in health care facilities and public places. In addition, caprylic acid is used as an algicide, bactericide, fungicide, and herbicide in nurseries, greenhouses, garden centers, and interiors, and on ornamentation. Products containing caprylic acid are formulated as soluble concentrate/liquids and ready-to-use liquids.[6]

Caprylic acid plays an important role in the body's regulation of energy input and output, a function which is performed by the hormone ghrelin. The sensation of hunger is a signal that the body requires an input of energy in the form of food consumption. Ghrelin stimulates hunger by triggering receptors in the hypothalamus. In order to activate these receptors, ghrelin must undergo a process called acylation in which it acquires an acyl group, and caprylic acid provides this by linking at a specific serine site on ghrelin molecules. Other fatty acids in the same position have similar effects on hunger.[citation needed]

The acyl chloride of caprylic acid is used in the synthesis of perfluorooctanoic acid.[7]

Dietary uses

See also: Medium-chain triglyceride § Dietary relevance

Caprylic acid is taken as a dietary supplement. In the body, caprylic acid would be found as octanoate, or unprotonated caprylic acid.[8]

Some studies have shown that medium-chain triglycerides (MCTs) can help in the process of excess calorie burning, and thus weight loss;[9][10][11][12][13] however, a systematic review of the evidence concluded that the overall results are inconclusive.[14] Also, interest in MCTs has been shown by endurance athletes and the bodybuilding community, but MCTs have not been found to be beneficial to exercise performance.[13]

Medical uses

Caprylic acid has been studied as part of a ketogenic diet to treat children with intractable epilepsy.[15] Caprylic acid is currently being researched as a treatment for essential tremor.[15][16]

See also


  1. ^ a b c d e Budavari, Susan, ed. (1996), The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (12th ed.), Merck, ISBN 0911910123
  2. ^ Lide, D.R. (Ed.) (1990). CRC Handbook of Chemistry and Physics (70th Edn.). Boca Raton (FL):CRC Press.
  3. ^ a b Beare-Rogers, J.; Dieffenbacher, A.; Holm, J.V. (2001). "Lexicon of lipid nutrition (IUPAC Technical Report)". Pure and Applied Chemistry. 73 (4): 685–744. doi:10.1351/pac200173040685. S2CID 84492006.
  4. ^ Sigma-Aldrich Co., Octanoic acid. Retrieved on 2022-08-11.
  5. ^ Riemenschneider, Wilhelm (2002). "Carboxylic Acids, Aliphatic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a05_235. ISBN 978-3527306732.
  6. ^ EPA - Antimicrobials Division. Docket Number; EPA-HQ-OPP-2008-0477 Caprylic (Octanoic) Acid.
  7. ^ Savu, Patricia M. (2000). "Fluorinated Higher Carboxylic Acids". Kirk-Othmer Encyclopedia of Chemical Technology. p. 1. doi:10.1002/0471238961.0612211519012221.a01. ISBN 978-0-471-23896-6.
  8. ^ PubChem. "Octanoic acid". Retrieved 2019-05-15.
  9. ^ B. Martena; M. Pfeuffer; J. Schrezenmeir (2006). "Medium-chain triglycerides". International Dairy Journal. 16 (11): 1374–1382. doi:10.1016/j.idairyj.2006.06.015. PMC 2020023.
  10. ^ Takeuchi, H; Sekine, S; Kojima, K; Aoyama, T (2008). "The application of medium-chain fatty acids: edible oil with a suppressing effect on body fat accumulation". Asia Pacific Journal of Clinical Nutrition. 17 (Suppl 1): 320–3. PMID 18296368.
  11. ^ St-Onge, MP; Jones, PJ (2002). "Physiological effects of medium-chain triglycerides: potential agents in the prevention of obesity". The Journal of Nutrition. 132 (3): 329–32. doi:10.1093/jn/132.3.329. PMID 11880549.
  12. ^ Papamandjaris, AA; MacDougall, DE; Jones, PJ (1998). "Medium chain fatty acid metabolism and energy expenditure: obesity treatment implications". Life Sciences. 62 (14): 1203–15. doi:10.1016/S0024-3205(97)01143-0. PMID 9570335.
  13. ^ a b Clegg, M. E. (2010). "Medium-chain triglycerides are advantageous in promoting weight loss although not beneficial to exercise performance". International Journal of Food Sciences and Nutrition. 61 (7): 653–679. doi:10.3109/09637481003702114. PMID 20367215. S2CID 6128370.
  14. ^ Rego Costa AC, Rosado EL, Soares-Mota M (2012). "Influence of the dietary intake of medium chain triglycerides on body composition, energy expenditure and satiety: a systematic review". Nutr Hosp. 27 (1): 103–108. doi:10.3305/nh.2012.27.1.5369. PMID 22566308.
  15. ^ a b Voller, Bernhard; Lines, Emily; McCrossin, Gayle; Tinaz, Sule; Lungu, Codrin; Grimes, George; Starling, Judith; Potti, Gopal; Buchwald, Peter (2016-02-29). "Dose-escalation study of octanoic acid in patients with essential tremor". Journal of Clinical Investigation. 126 (4): 1451–1457. doi:10.1172/JCI83621. ISSN 0021-9738. PMC 4811161. PMID 26927672.
  16. ^ Lowell, Soren Y.; Kelley, Richard T.; Monahan, Marika; Hosbach-Cannon, Carly Jo; Colton, Raymond H.; Mihaila, Dragos (2018-12-25). "The Effect of Octanoic Acid on Essential Voice Tremor: A Double-Blind, Placebo-Controlled Study: Effect of Octanoic Acid on EVT". The Laryngoscope. 129 (8): 1882–1890. doi:10.1002/lary.27695. PMC 6592780. PMID 30585335.