Oleic acid is a

fatty acid In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an ...

that occurs naturally in various

animal Animals are multicellular, eukaryotic organisms in the Biology, biological Kingdom (biology), kingdom Animalia (). With few exceptions, animals heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, ...

and

vegetable fats and oils Vegetable oils, or vegetable fats, are oils extracted from seeds or from other parts of edible plants. Like animal fats, vegetable fats are ''mixtures'' of triglycerides. Soybean oil, grape seed oil, and cocoa butter are examples of seed ...

. It is an odorless, colorless oil, although commercial samples may be yellowish due to the presence of impurities. In chemical terms, oleic acid is classified as a

monounsaturated In biochemistry and nutrition, a monounsaturated fat is a fat that contains a monounsaturated fatty acid (MUFA), a subclass of fatty acid characterized by having a double bond in the fatty acid chain with all of the remaining carbon atoms being s ...

omega-9 fatty acid Omega−9 fatty acids (ω−9 fatty acids or ''n''−9 fatty acids) are a family of unsaturated fatty acids which have in common a final carbon–carbon double bond in the omega−9 position; that is, the ninth bond from the methyl end of the f ...

, abbreviated with a

lipid number In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, f ...

of 18:1 ''cis''-9, and a main product of Δ9-desaturase. It has the formula . The name derives from the Latin word ''

oleum Oleum (Latin ''oleum'', meaning oil), or fuming sulfuric acid, is a term referring to solutions of various compositions of sulfur trioxide in sulfuric acid, or sometimes more specifically to disulfuric acid (also known as pyrosulfuric acid). Ol ...

'', which means oil. It is the most common fatty acid in nature. The salts and esters of oleic acid are called oleates. It is a common component of oils, and thus occurs in many types of food, as well as in soap.

Occurrence

Fatty acids (or their salts) often do not occur as such in biological systems. Instead fatty acids such as oleic acid occur as their

ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...

s, commonly

triglyceride A triglyceride (from '' tri-'' and '' glyceride''; also TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids. Triglycerides are the main constituents of body fat in humans and other vertebrates ...

s, which are the greasy materials in many natural oils. Oleic acid is the most common monounsaturated fatty acid in nature. It is found in fats (triglycerides), the phospholipids that make membranes,

cholesteryl ester 300px, Cholesteryl oleate, a member of the cholesteryl ester family Cholesteryl esters are a type of dietary lipid and are ester derivatives of cholesterol. The ester bond is formed between the carboxylate group of a fatty acid and the hydroxyl g ...

s, and

wax ester A wax ester (WE) is an ester of a fatty acid and a fatty alcohol. Wax esters are the main components of three commercially important waxes: carnauba wax, candelilla wax, and beeswax.. Wax esters are formed by combining one fatty acid with one ...

Triglyceride A triglyceride (from '' tri-'' and '' glyceride''; also TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids. Triglycerides are the main constituents of body fat in humans and other vertebrates ...

s of oleic acid comprise the majority of

olive oil Olive oil is a vegetable oil obtained by pressing whole olives (the fruit of ''Olea europaea'', a traditional Tree fruit, tree crop of the Mediterranean Basin) and extracting the oil. It is commonly used in cooking for frying foods, as a cond ...

(about 70%). It also makes up 59–75% of

pecan oil Pecan oil is an edible pressed oil extracted from the pecan nut. Pecan oil is neutral in flavor and tastes of whatever seasoning is being used with it. Pecan oil contains 9.5% saturated fat, which is less than in olive oil (13.5%), peanut oil (16. ...

, 61% of

canola file:CanolaBlooms.JPG, Close-up of canola blooms file:Canola Flower.jpg, Canola flower Rapeseed oil is one of the oldest known vegetable oils. There are both Edible oil, edible and industrial forms produced from rapeseed, the seed of several ...

oil, 36–67% of

peanut oil Peanut oil, also known as groundnut oil or arachis oil, is a vegetable oil derived from peanuts. The oil usually has a mild or neutral flavor but, if made with roasted peanuts, has a stronger peanut flavor and aroma. It is often used in Americ ...

, 60% of

macadamia oil Macadamia oil, also known as macadamia nut oil, is a non-volatile oil extracted from the nuts of the macadamia tree (''Macadamia integrifolia''), indigenous to Australia. This oil is used in culinary applications as a frying or salad oil, and in c ...

, 20–80% of

sunflower oil Sunflower oil is the non-volatile oil pressed from the seeds of the sunflower (''Helianthus annuus''). Sunflower oil is commonly used in food as a frying oil, and in cosmetic formulations as an emollient. Sunflower oil is primarily compos ...

,(NDB ID: 04678, 04584) 15–20% of

grape seed oil Grape seed oil (also called grapeseed oil or grape oil) is a vegetable oil derived from the seeds of grapes. Grape seeds are a winemaking by-product, and oil made from the seeds is commonly used as an edible oil. Description Grape seed ...

sea buckthorn oil Sea buckthorn oil is a red-orange oil derived from sea buckthorn plants. The most commonly used species for this purpose is ''Hippophae rhamnoides''. Species belonging to this genus accumulate lipids in the mesocarp (the fruit pulp), so the oil ...

, 40% of

sesame oil Sesame oil is an edible vegetable oil derived from sesame seeds. The oil is one of the earliest-known crop-based oils. Worldwide mass modern production is limited due to the inefficient manual harvesting process required to extract the oil. ...

, and 14% of

poppyseed oil Poppyseed oil (also poppy seed oil and poppy oil) is an edible oil obtained from poppy seeds (specifically seeds of ''Papaver somniferum'', the opium poppy). Poppy seeds yield 45–50% oil. Like poppy seeds, poppyseed oil is highly palatable, ...

. High oleic variants of plant sources such as sunflower (~80%) and canola oil (70%) also have been developed.

Karuka The karuka (''Pandanus julianettii'', also called karuka nut and ''Pandanus'' nut) is a species of tree in the screwpine family (Pandanaceae) and an important regional food crop in New Guinea. The nuts are more nutritious than coconuts, and ar ...

contains 52.39% oleic acid. 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 a Quasi-solid, semi-solid white fat product obtained by rendering (animal products), rendering the adipose tissue, fatty tissue of a domestic pig, pig.

. Free oleic acid occurs in oils and fats as a product of the breakdown of triglycerides. Olive oil exceeding 2% free oleic acid is graded unfit for human consumption. See . It is a chemical signal use by some ants. Oleic acid is the most abundant fatty acid in human

adipose tissue Adipose tissue (also known as body fat or simply fat) is a loose connective tissue composed mostly of adipocytes. It also contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, Blood vessel, vascular endothel ...

, and second in abundance in human tissues overall, following

palmitic acid Palmitic acid (hexadecanoic acid in IUPAC nomenclature) is a fatty acid with a 16-carbon chain. It is the most common saturated fatty acid found in animals, plants and microorganisms.Gunstone, F. D., John L. Harwood, and Albert J. Dijkstra. The ...

Production and chemical behavior

The

biosynthesis Biosynthesis, i.e., chemical synthesis occurring in biological contexts, is a term most often referring to multi-step, enzyme-Catalysis, catalyzed processes where chemical substances absorbed as nutrients (or previously converted through biosynthe ...

of oleic acid involves the action of the enzyme

stearoyl-CoA 9-desaturase Stearoyl-CoA desaturase (Δ-9-desaturase or SCD-1) is an endoplasmic reticulum enzyme that catalyzes the rate-limiting step in the formation of monounsaturated fatty acids (MUFAs), specifically oleate and palmitoleate from stearoyl-CoA and pal ...

acting on

stearoyl-CoA Stearoyl-CoA is a coenzyme involved in the metabolism of fatty acids. Stearoyl-CoA is an 18-carbon long fatty acyl-CoA chain that participates in an unsaturation reaction. The reaction is catalyzed by the enzyme stearoyl-CoA desaturase, which is ...

. In effect,

stearic acid Stearic acid ( , ) is a saturated fatty acid with an 18-carbon chain. The IUPAC name is octadecanoic acid. It is a soft waxy solid with the formula . The triglyceride derived from three molecules of stearic acid is called stearin. Stearic acid ...

is dehydrogenated to give the monounsaturated derivative, oleic acid. Oleic acid undergoes the typical reactions of

carboxylic acids In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an Substituent, R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl ...

and

alkene In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or at the terminal position. Terminal alkenes are also known as Alpha-olefin, α-olefins. The Internationa ...

s. It is soluble in aqueous base to give

soap Soap is a salt (chemistry), salt of a fatty acid (sometimes other carboxylic acids) used for cleaning and lubricating products as well as other applications. In a domestic setting, soaps, specifically "toilet soaps", are surfactants usually u ...

s called oleates. Iodine adds across the double bond. Hydrogenation of the double bond yields the saturated derivative

Oxidation Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...

at the

double bond In chemistry, a double bond is a covalent bond between two atoms involving four bonding electrons as opposed to two in a single bond. Double bonds occur most commonly between two carbon atoms, for example in alkenes. Many double bonds exist betw ...

occurs slowly in air, and is known as

rancidification Rancidification is the process of complete or incomplete autoxidation or hydrolysis of fats and oils when exposed to air, light, moisture, or bacterial action, producing short-chain aldehydes, ketones and free fatty acids. When these processes ...

in foodstuffs and as

drying Drying is a mass transfer process consisting of the removal of water or another solvent by evaporation from a solid, semi-solid or liquid. This process is often used as a final production step before selling or packaging products. To be consider ...

in coatings. Reduction of the carboxylic acid group yields oleyl alcohol.

Ozonolysis In organic chemistry, ozonolysis is an organic reaction where the Saturated and unsaturated compounds, unsaturated bonds are Bond cleavage, cleaved with ozone (). Multiple carbon–carbon bond are replaced by carbonyl () groups, such as aldehydes ...

of oleic acid is an important route to

azelaic acid Azelaic acid (AzA), or nonanedioic acid, is an organic compound with the formula HOOC(CH2)7carboxylic acid, COOH. This saturated dicarboxylic acid exists as a white powder. It is found in wheat, rye, and barley. It is a precursor to diverse ind ...

. The coproduct is nonanoic acid: : Esters of azelaic acid find applications in lubrication and plasticizers. Neutralizing oleic acid with

ethanolamine Ethanolamine (2-aminoethanol, monoethanolamine, ETA, or MEA) is a naturally occurring organic chemical compound with the formula or . The molecule is bifunctional, containing both a primary amine and a primary alcohol. Ethanolamine is a colorl ...

s gives the protic ionic liquid monoethanolamine oleate.

Related compounds

The

trans isomer Trans- is a Latin prefix meaning "across", "beyond", or "on the other side of". Used alone, trans may refer to: Sociology * Trans, a sociological term which may refer to: ** Transgender, people who identify themselves with a gender that dif ...

of oleic acid is called

elaidic acid Elaidic acid is a chemical compound with the formula , specifically the fatty acid with structural formula , with the double bond (between carbon atoms 9 and 10) in ''trans'' configuration. It is a colorless solid. Its salts and esters are calle ...

or ''trans''-9-octadecenoic acid. These isomers have distinct physical properties and biochemical properties. Elaidic acid, the most abundant trans fatty acid in diet, appears to have an adverse effect on health. A reaction that converts oleic acid to elaidic acid is called

elaidinization Elaidinization is any chemical reaction which convert a cis- olefin to a trans- olefin in unsaturated fatty acids. This is often performed on fats and oils to increase both the melting point and the shelf life without reducing the degree of uns ...

. Another naturally occurring isomer of oleic acid is petroselinic acid. In chemical analysis, fatty acids are separated by gas chromatography of their methyl ester derivatives. Alternatively, separation of unsaturated isomers is possible by argentation thin-layer chromatography. In

ethenolysis In organic chemistry, ethenolysis is a chemical process in which internal olefins are degraded using ethylene () as the reagent. The reaction is an example of olefin metathesis, cross metathesis. The utility of the reaction is driven by the low ...

, methyl oleate, the ''methyl ester'' of the acid, converts to

1-decene Decene is an organic compound with the chemical formula . Decene contains a chain of ten carbon atoms with one double bond, making it an alkene. There are many isomers of decene depending on the position and geometry of the double bond. Dec-1- ...

and methyl 9- decenoate: : Several

organometallic Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and so ...

oleates exist: * Cobalt oleate * Copper oleate

Dietary sources

Uses

Oleic acid is used as a component in many foods, in the form of its triglycerides. It is a component of the normal human diet, being a part of animal fats and vegetable oils. Oleic acid as its sodium salt is a major component of soap as an

emulsifying agent An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids. Although ...

. It is also used as an

emollient A moisturizer, or emollient, is a cosmetic preparation used for protecting, moisturizing, and lubricating the skin. These functions are normally performed by sebum produced by healthy skin. The word "emollient" is derived from the Latin verb ''mo ...

. Small amounts of oleic acid are used as an

excipient An excipient is a substance formulated alongside the active ingredient of a medication. They may be used to enhance the active ingredient’s therapeutic properties; to facilitate drug absorption; to reduce viscosity; to enhance solubility; to i ...

in pharmaceuticals, and it is used as an emulsifying or solubilizing agent in aerosol products.

Niche uses

Oleic acid is 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 Pulmonary edema (British English: oedema), also known as pulmonary congestion, is excessive fluid accumulation in the tissue or air spaces (usually alveoli) of the lungs. This leads to impaired gas exchange, most often leading to shortness ...

. Oleic acid is used as a soldering flux in stained glass work for joining lead came.

Health effects

Oleic acid is the most common

monounsaturated fat In biochemistry and nutrition, a monounsaturated fat is a fat that contains a monounsaturated fatty acid (MUFA), a subclass of fatty acid characterized by having a double bond in the fatty acid chain with all of the remaining carbon atoms being s ...

in the human diet (~90% of all monounsaturated fats). Monounsaturated fat consumption has been associated with decreased

low-density lipoprotein Low-density lipoprotein (LDL) is one of the five major groups of lipoprotein that transport all fat molecules around the body in extracellular water. These groups, from least dense to most dense, are chylomicrons (aka ULDL by the overall density ...

(LDL) cholesterol, and possibly with increased

high-density lipoprotein High-density lipoprotein (HDL) is one of the five major groups of lipoproteins. Lipoproteins are complex particles composed of multiple proteins which transport all fat molecules (lipids) around the body within the water outside cells. They are t ...

(HDL) cholesterol. Oleic acid may be responsible for the

hypotensive Hypotension, also known as low blood pressure, is a cardiovascular condition characterized by abnormally reduced blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood and is ...

(

blood pressure Blood pressure (BP) is the pressure of Circulatory system, circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term ...

reducing) effects of

that is considered a health benefit. A 2017 review found that diets enriched in oleic acid are beneficial for regulating body weight. The United States

FDA The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...

has approved a health claim on reduced risk of coronary heart disease for high oleic (> 70% oleic acid) oils. Some oil plants have cultivars bred to increase the amount of oleic acid in the oils. In addition to providing a health claim, the heat stability and shelf life may also be improved, but only if the increase in monounsaturated oleic acid levels correspond to a substantial reduction in polyunsaturated fatty acid (especially

α-linolenic acid α-Linolenic acid, also known as ''alpha''-linolenic acid (ALA) (from Greek ''alpha'' denoting "first" and ''linon'' meaning flax), is an ''n''−3, or omega-3, essential fatty acid. ALA is found in many seeds and oils, including flaxseed, ...

) content. When the saturated fat or trans fat in a fried food is replaced with a stable high oleic oil, consumers may be able to avoid certain health risks associated with consuming saturated fat and

trans fat Trans fat is a type of unsaturated fat that occurs in foods. Small amounts of trans fats occur naturally, but large amounts are found in some processed foods made with partially hydrogenated oils. Because consumption of trans fats is associated ...

References

External links

FATTY ACIDS: STRAIGHT-CHAIN MONOENOIC
(The AOCS Lipid Library)
9-octadecenoic acid
(NIST Chemistry Webbook) {{Authority control 5α-Reductase inhibitors Fatty acids Excipients Insect pheromones Insect ecology Insect repellents Alkenoic acids Wood extracts