Oleic acid
Oleic acid is a monounsaturated omega-9
Omega-9 fatty acid
n−9 fatty acids are a family of unsaturated fatty acids which have in common a final carbon–carbon double bond in the n−9 position; that is, the ninth bond from the end of the fatty acid.-Background:Some n−9s are common components of animal fat and vegetable oil...

 fatty acid
Fatty acid
In chemistry, especially biochemistry, a fatty acid is a carboxylic acid with a long unbranched aliphatic tail , which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually derived from...

 found in various animal and vegetable fats. It has the formula CH3(CH2)7CH=CH(CH2)7COOH. It is an odorless, colourless oil, although commercial samples may be yellowish. The trans isomer of oleic acid is called elaidic acid
Elaidic acid
Elaidic acid is the major trans fat found in hydrogenated vegetable oils and occurs in small amounts in caprine and bovine milk . It is the trans isomer of oleic acid. The name of the elaidinization reaction comes from elaidic acid.Elaidic acid increases CETP activity, which in turn raises VLDL...

 (hence the name elaidinization for a reaction that switches cis isomers to trans isomers). The term "oleic" means related to, or derived from, oil
An oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....

 or olive
The olive , Olea europaea), is a species of a small tree in the family Oleaceae, native to the coastal areas of the eastern Mediterranean Basin as well as northern Iran at the south end of the Caspian Sea.Its fruit, also called the olive, is of major agricultural importance in the...



Triglyceride esters of oleic acid compose the majority of olive oil
Olive oil
Olive oil is an oil obtained from the olive , a traditional tree crop of the Mediterranean Basin. It is commonly used in cooking, cosmetics, pharmaceuticals, and soaps and as a fuel for traditional oil lamps...

, although there may be less than 2.0% as free acid in the virgin olive oil, with higher concentrations making the olive oil inedible. It also makes up 59-75% of pecan oil
Pecan oil
Pecan oil is an edible pressed oil extracted from the pecan nut. Like most nut oils, it tastes like the nut from which it was extracted. Pecan oil contains approximately 7% saturated fat, which is less than half the amount contained by olive oil, peanut oil or corn oil...

, 36-67% of peanut oil
Peanut oil
Peanut oil is an organic material oil derived from peanuts, noted to have the aroma and taste of its parent legume....

, 15-20% of grape seed oil
Grape seed oil
Not to be confused with Rapeseed oil.Grape seed oil is a vegetable oil pressed from the seeds of various varieties of Vitis vinifera grapes, an abundant by-product of winemaking.- Cooking :...

, sea buckthorn oil
Sea buckthorn oil
Sea-buckthorn identifies a group of species in the genus Hippophae, the most commonly used of which is Hippophae rhamnoides. Oil can be extracted from either the seeds or the pulp of the fruit.-Chemical constituents:...

, and sesame oil
Sesame oil
Sesame oil is an edible vegetable oil derived from sesame seeds. Besides being used as a cooking oil in South India, it is often used as a flavor enhancer in Chinese, Japanese, Korean, and to a lesser extent Southeast Asian cuisine.The oil from the nutrient rich seed is popular in alternative...

, and 14% of poppyseed oil
Poppyseed oil
Poppyseed oil is an edible oil from poppy seeds . The oil has culinary and pharmaceutical uses, as well as long established uses in the making of paints, varnishes, and soaps.Poppy seeds yield 45–50% oil...

It is abundantly present in many animal fats, constituting 37 to 56% of chicken and turkey fat, and 44 to 47% of lard
Lard is pig fat in both its rendered and unrendered forms. Lard was commonly used in many cuisines as a cooking fat or shortening, or as a spread similar to butter. Its use in contemporary cuisine has diminished because of health concerns posed by its saturated-fat content and its often negative...

, etc.

Oleic acid is the most abundant fatty acid in human adipose tissue
Adipose tissue
In histology, adipose tissue or body fat or fat depot or just fat is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat; fat in its solitary state exists in the liver and muscles. Adipose tissue is derived from lipoblasts...


As an insect pheromone

Oleic acid is emitted by the decaying corpses of a number of insects, including bee
Bees are flying insects closely related to wasps and ants, and are known for their role in pollination and for producing honey and beeswax. Bees are a monophyletic lineage within the superfamily Apoidea, presently classified by the unranked taxon name Anthophila...

s and Pogonomyrmex
Pogonomyrmex is a genus of harvester ants, occurring primarily in the deserts of North and South America. The genus name originated from the Greek language and refers to a beard-like structure, the psammophore, below the head , which can be found in most species of the subgenus sensu stricto...

Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...

s, and triggers the instincts of living workers to remove the dead bodies from the hive
A hive may refer to a beehive, an enclosed structure in which some honey bee species live and raise their young.Hive may also refer to:-Arts:* The Hives, a Swedish rock band* Hive , a DJ and producer in the drum and bass music genre...

. 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
Biosynthesis is an enzyme-catalyzed process in cells of living organisms by which substrates are converted to more complex products. The biosynthesis process often consists of several enzymatic steps in which the product of one step is used as substrate in the following step...

 of oleic acid results from the action of the enzyme stearoyl-CoA 9-desaturase
Stearoyl-CoA 9-desaturase
In enzymology, a stearoyl-CoA 9-desaturase is an enzyme that catalyzes the chemical reactionThe 4 substrates of this enzyme are stearoyl-CoA, ferrocytochrome b5, O2, and H+, whereas its 3 products are oleoyl-CoA, ferricytochrome b5, and H2O....

 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 alkene
In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...

s. It is soluble in aqueous base to give soap
In chemistry, soap is a salt of a fatty acid.IUPAC. "" Compendium of Chemical Terminology, 2nd ed. . Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford . XML on-line corrected version: created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN...

s called oleates. Iodine adds across the double bond. Hydrogenation of the double bond yields the saturated
Saturation (chemistry)
In chemistry, saturation has six different meanings, all based on reaching a maximum capacity...

 derivative stearic acid
Stearic acid
Stearic acid is the saturated fatty acid with an 18 carbon chain and has the IUPAC name octadecanoic acid. It is a waxy solid, and its chemical formula is CH316CO2H. Its name comes from the Greek word στέαρ "stéatos", which means tallow. The salts and esters of stearic acid are called stearates...

. Oxidation at the double bond
Double bond
A double bond in chemistry is a chemical bond between two chemical elements involving four bonding electrons instead of the usual two. The most common double bond, that between two carbon atoms, can be found in alkenes. Many types of double bonds between two different elements exist, for example in...

 occurs slowly in air, and is known as rancidification
Rancidification is the chemical decomposition of fats, oils and other lipids . When these processes occur in food, undesirable odors and flavors can result. In some cases, however, the flavors can be desirable . In processed meats, these flavors are collectively known as "warmed over flavor"...

 in foodstuffs or drying
Drying oil
A drying oil is an oil that hardens to a tough, solid film after a period of exposure to air. The oil hardens through a chemical reaction in which the components crosslink by the action of oxygen . Drying oils are a key component of oil paint and some varnishes...

 in coatings. Reduction of the carboxylic acid
Carboxylic acid
Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...

 group yields oleyl alcohol
Oleyl alcohol
Oleyl alcohol, octadecenol, or cis-9-octadecen-1-ol, is a fatty alcohol coming from inedible beef fat. It is also found in fish oil.Its chemical formula is 1836 or CH37-CH=CH-8OH.It is a non-ionic, unsaturated fatty alcohol....

. Ozonolysis
Ozonolysis is the cleavage of an alkene or alkyne with ozone to form organic compounds in which the multiple carbon–carbon bond has been replaced by a double bond to oxygen...

 of oleic acid is an important route to azelaic acid
Azelaic acid
Azelaic acid is an organic compound with the formula 72. This saturated dicarboxylic acid exists as a white powder. It is found in wheat, rye, and barley. It is a component of a number of hair and skin conditioners.-Production:...

. The coproduct is nonanoic acid:
H17C8CH=CHC7H14CO2H + 4"O" → H17C8CO2H + HO2CC7H14CO2H

Esters of azelaic acid find applications in lubrication and plasticizers.


The dominant use of oleic acid is as its sodium salt, which a major component of many kinds of soap. Small amounts of oleic acid are used as an excipient
An excipient is generally a pharmacologically inactive substance used as a carrier for the active ingredients of a medication. In many cases, an "active" substance may not be easily administered and absorbed by the human body; in such cases the substance in question may be dissolved into or...

 in pharmaceuticals, oleic acid 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) often is a matter of life and death.

Health effects

Positive health effects of the substance have been documented. Oleic acid may hinder the progression of adrenoleukodystrophy
Adrenoleukodystrophy is a rare, inherited disorder that leads to progressive brain damage, failure of the adrenal glands and eventually death. ALD is a disease in a group of genetic disorders called leukodystrophies, whose chief feature is damage to myelin...

 (ALD), a fatal disease that affects the brain and adrenal glands. Oleic acid may be responsible for the hypotensive (blood pressure
Blood pressure
Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...

 reducing) effects of olive oil. Adverse effects also have been documented, however, since both oleic and monounsaturated fat
Monounsaturated fat
In biochemistry and nutrition, monounsaturated fats or MUFA are fatty acids that have one double bond in the fatty acid chain and all of the remainder of the carbon atoms in the chain are single-bonded...

ty acid levels in the membranes of red blood cells have been associated with increased risk of breast cancer
Breast cancer
Breast cancer is cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas; those originating from lobules are known as lobular carcinomas...


External links

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