|Molar mass||282.46 g·mol−1|
|Appearance||Pale yellow or brownish yellow oily liquid with lard-like odor|
|Melting point||13 °C (55 °F; 286 K)|
|Boiling point||360 °C (680 °F; 633 K)|
|Solubility in Ethanol||Soluble|
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
|what is: / ?)(|
Oleic acid is a fatty acid that occurs naturally in various animal and vegetable fats and oils. It is an odorless, colourless oil, although commercial samples may be yellowish. In chemical terms, oleic acid is classified as a monounsaturated omega-9 fatty acid, abbreviated with a lipid number of 18:1 cis-9. It has the formula CH3(CH2)7CH=CH(CH2)7COOH. The term "oleic" means related to, or derived from, oil of olive, the oil that is predominantly composed of oleic acid.
Fatty acids (or their salts) do not often occur as such in biological systems. Instead fatty acids like oleic acid occur as their esters, commonly triglycerides, which are the greasy materials in many natural oils. Via the process of saponification, the fatty acids can be obtained.
Triglycerides of oleic acid compose the majority of olive oil, although there may be less than 2.0% as free acid in virgin olive oil, with higher concentrations making the olive oil inedible. It also makes up 59-75% of pecan oil, 61% of canola oil, 36-67% of peanut oil, 60% of macadamia oil, 20-85% of sunflower oil (the latter in the high oleic variant), 15-20% of grape seed oil, sea buckthorn oil, and sesame oil, and 14% of poppyseed oil. It is abundantly present in many animal fats, constituting 37 to 56% of chicken and turkey fat and 44 to 47% of lard.
As an insect pheromone
Oleic acid is emitted by the decaying corpses of a number of insects, including bees and Pogonomyrmex ants, and triggers the instincts of living workers to remove the dead bodies from the hive. If a live bee or ant is daubed with oleic acid, it is dragged off for disposal as if it were dead. The oleic acid smell also may indicate danger to living insects, prompting them to avoid others who have succumbed to disease or places where predators lurk.
Production and chemical behavior
The biosynthesis of oleic acid involves the action of the enzyme stearoyl-CoA 9-desaturase acting on stearoyl-CoA. In effect, stearic acid is dehydrogenated to give the monounsaturated derivative oleic acid.
Oleic acid undergoes the reactions of carboxylic acids and alkenes. It is soluble in aqueous base to give soaps called oleates. Iodine adds across the double bond. Hydrogenation of the double bond yields the saturated derivative stearic acid. Oxidation at the double bond occurs slowly in air, and is known as rancidification in foodstuffs or drying in coatings. Reduction of the carboxylic acid group yields oleyl alcohol. Ozonolysis of oleic acid is an important route to azelaic acid. The coproduct is nonanoic acid:
- H17C8CH=CHC7H14CO2H + 4"O" → H17C8CO2H + HO2CC7H14CO2H
Esters of azelaic acid find applications in lubrication and plasticizers.
A naturally occurring isomer of oleic acid is petroselinic acid.
In chemical analysis, fatty acids are separated by gas chromatography of methyl esters; additionally, a separation of unsaturated isomers is possible by argentation thin-layer chromatography.
Oleic acid (in triglyceride form) is included in the normal human diet as a part of animal fats and vegetable oils.
Oleic acid as its sodium salt is a major component of soap as an emulsifying agent. It is also used as an emollient. Small amounts of oleic acid are used as an excipient in pharmaceuticals, and it is used as an emulsifying or solubilizing agent in aerosol products.
Oleic acid is also used to induce lung damage in certain types of animals, for the purpose of testing new drugs and other means to treat lung diseases. Specifically in sheep, intravenous administration of oleic acid causes acute lung injury with corresponding pulmonary edema. This sort of research has been of particular benefit to premature newborns, for whom treatment for underdeveloped lungs (and associated complications) is often a matter of life and death.
Oleic acid is used as a soldering flux in stained glass work for joining lead came.
Oleic acid is a common monounsaturated fat in human diet. Monounsaturated fat consumption has been associated with decreased low-density lipoprotein (LDL) cholesterol, and possibly increased high-density lipoprotein (HDL) cholesterol. However, its ability to raise HDL is still debated.
Oleic acid may be responsible for the hypotensive (blood pressure reducing) effects of olive oil. Adverse effects also have been documented, however, since both oleic and monounsaturated fatty acid levels in the membranes of red blood cells have been associated with increased risk of breast cancer, although the consumption of oleate in olive oil has been associated with a decreased risk of breast cancer 
- Young, Jay A. (2002). "Chemical Laboratory Information Profile: Oleic Acid". Journal of Chemical Education 79: 24. Bibcode:2002JChEd..79...24Y. doi:10.1021/ed079p24.
- Thomas, Alfred (2000). "Fats and Fatty Oils". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a10_173. ISBN 3-527-30673-0.
- Villarreal-Lozoya, Jose E.; Lombardini, Leonardo; Cisneros-Zevallos, Luis (2007). "Phytochemical constituents and antioxidant capacity of different pecan Carya illinoinensis (Wangenh.) K. Koch] cultivars". Food Chemistry 102 (4): 1241. doi:10.1016/j.foodchem.2006.07.024.
- "Comparison of Dietary Fats Chart". Canola Council of Canada. Retrieved 2008-09-03.
- "The Inheritance of High Oleic Acid in Peanut". The Journal of Heredity 80 (3): 252–3. 1989.
- "Nutrient database, Release 25". United States Department of Agriculture.
- Untoro, J; Schultink, W; West, CE; Gross, R; Hautvast, JG (2006). "Efficacy of oral iodized peanut oil is greater than that of iodized poppy seed oil among Indonesian schoolchildren". The American Journal of Clinical Nutrition 84 (5): 1208–14. PMID 17093176.
- Nutter, Mary K.; Lockhart, Ernest E.; Harris, Robert S. (1943). "The chemical composition of depot fats in chickens and turkeys". Oil & Soap 20 (11): 231–4. doi:10.1007/BF02630880.
- Kokatnur, MG; Oalmann, MC; Johnson, WD; Malcom, GT; Strong, JP (1979). "Fatty acid composition of human adipose tissue from two anatomical sites in a biracial community". The American Journal of Clinical Nutrition 32 (11): 2198–205. PMID 495536.
- Purnamadjaja, Anies Hannawati; Russell, R. Andrew (2005). "Pheromone communication in a robot swarm: Necrophoric bee behaviour and its replication". Robotica 23 (6): 731–42. doi:10.1017/S0263574704001225.
- Ayasse, M.; Paxton, R. (2002). "Brood protection in social insects". In Hilker, M.; Meiners, T. Chemoecology of Insect Eggs and Egg Deposition. Berlin: Blackwell. pp. 117–48. ISBN 1-4051-0694-8.
- Krulwich, Robert (2009). "Hey I'm Dead! The Story Of The Very Lively Ant". NPR.
- Walker, Matt (2009-09-09). "Ancient 'smell of death' revealed". BBC - Earth News. Retrieved 2009-09-13.
- Cornils, Boy; Lappe, Peter (2000). "Dicarboxylic Acids, Aliphatic". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a08_523. ISBN 3-527-30673-0.
- B. Breuer, T. Stuhlfauth et H. P. Fock, Separation of fatty acids or methyl esters including positional and geometric isomers by alumina argentation thin-layer chromatography, J. of Chromatogr. Science 25 (1987), S. 302-306 
- Carrasco, F. (2009). "Ingredientes Cosméticos". Diccionario de Ingredientes (4th ed.). p. 428. ISBN 978-84-613-4979-1.
- Smolinske, Susan C. (1992). Handbook of Food, Drug, and Cosmetic Excipients. pp. 247–8. ISBN 978-0-8493-3585-3.
- Julien, M; Hoeffel, JM; Flick, MR (1986). "Oleic acid lung injury in sheep". Journal of Applied Physiology 60 (2): 433–40. PMID 3949648.
- Duncan, Alastair (2003). The Technique of Leaded Glass. p. 77. ISBN 0-486-42607-6.
- "You Can Control Your Cholesterol: A Guide to Low-Cholesterol Living". Merck & Co. Inc. Retrieved 2009-03-14.
- Rizzo, WB; Watkins, PA; Phillips, MW; Cranin, D; Campbell, B; Avigan, J (1986). "Adrenoleukodystrophy: Oleic acid lowers fibroblast saturated C22-26 fatty acids". Neurology 36 (3): 357–61. doi:10.1212/WNL.36.3.357. PMID 3951702.
- Teres, S.; Barcelo-Coblijn, G.; Benet, M.; Alvarez, R.; Bressani, R.; Halver, J. E.; Escriba, P. V. (2008). "Oleic acid content is responsible for the reduction in blood pressure induced by olive oil". Proceedings of the National Academy of Sciences 105 (37): 13811–6. Bibcode:2008PNAS..10513811T. doi:10.1073/pnas.0807500105. JSTOR 25464133. PMC 2544536. PMID 18772370.
- Pala, V.; Krogh, V.; Muti, P.; Chajes, V.; Riboli, E.; Micheli, A.; Saadatian, M.; Sieri, S.; Berrino, F. (2001). "Erythrocyte Membrane Fatty Acids and Subsequent Breast Cancer: A Prospective Italian Study". JNCI Journal of the National Cancer Institute 93 (14): 1088–95. doi:10.1093/jnci/93.14.1088. PMID 11459870.
- Martin-Moreno, Jose M.; et al, Walter C.; Gorgojo, Lydia; Banegas, Jose R.; Rodriguez-Artalejo, Fernando; Fernandez-Rodriguez, Juan C.; Maisonneuve, Patrick; Boyle, Peter (1994). "Dietary fat, olive oil intake and breast cancer risk". International Journal of Cancer 58 (6): 774. doi:10.1002/ijc.2910580604.
- FATTY ACIDS: STRAIGHT-CHAIN MONOENOIC (The AOCS Lipid Library)
- 9-octadecenoic acid (NIST Chemistry Webbook)