Oleic acid is a

fatty acid In chemistry, particularly 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, fr ...

that occurs naturally in various

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

and

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

. It is an odorless, colorless oil, although commercial samples may be yellowish. In chemical terms, oleic acid is classified as a

monounsaturated In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food. The term often refers specifically to triglycerides (triple est ...

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 fat ...

, abbreviated with a

lipid number In chemistry, particularly 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, fr ...

of 18:1 ''cis''-9, and a main product of Δ9 desaturase. It has the formula CH₃(CH₂)₇CH=CH(CH₂)₇COOH. The name derives from the Latin word ''oleum'', which means oil. It is the most common fatty acid in nature. The salts and esters of oleic acid are called oleates.

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 oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ar ...

s, commonly

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

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,

cholesterol ester 300px, Cholesterol oleate, a member of the cholesteryl ester family Cholesteryl ester, a dietary lipid, is an ester of cholesterol. The ester bond is formed between the carboxylate group of a fatty acid and the hydroxyl group of cholesterol. Chole ...

s, and

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

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

s of oleic acid comprise the majority of

olive oil Olive oil is a liquid fat obtained from olives (the fruit of ''Olea europaea''; family Oleaceae), a traditional tree crop of the Mediterranean Basin, produced by pressing whole olives and extracting the oil. It is commonly used in cooking: f ...

(about 70%). Olive oil exceeding 2% free oleic acid is graded unfit for human consumption. 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 takes on the flavor of whatever seasoning is being used with it. Pecan oil contains 9.5% saturated fat, which is less than in olive oil (13.5%), p ...

, 61% of

canola Close-up of canola blooms Canola flower Rapeseed oil is one of the oldest known vegetable oils. There are both edible and industrial forms produced from rapeseed, the seed of several cultivars of the plant family Brassicaceae. Historically, i ...

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 American ...

, 60% of

macadamia oil Macadamia oil (or macadamia nut oil) is the non-volatile oil collected from the nuts of the macadamia (''Macadamia integrifolia''), a native Australian plant. It is used in food as a frying or salad oil, and in cosmetic formulations as an emollien ...

, 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 composed ...

,(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. A by-product of the winemaking industry, it is typically used for edible applications. Uses Cooking Grape seed oil has a moderatel ...

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 th ...

, 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. O ...

, 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, h ...

. 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 family Pandanaceae and an important regional food crop in New Guinea. The nuts are more nutritious than coconuts, and are so popular ...

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 semi-solid white fat product obtained by rendering the fatty tissue of a pig.Lard
entry in the o ...

. Oleic acid is the most abundant fatty acid in human

adipose tissue Adipose tissue, body fat, or simply fat is a loose connective tissue composed mostly of adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular e ...

, 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 Li ...

Production and chemical behavior

The

biosynthesis Biosynthesis is a multi-step, enzyme-catalyzed process where substrates are converted into more complex products in living organisms. In biosynthesis, simple compounds are modified, converted into other compounds, or joined to form macromolecules. ...

of oleic acid involves the action of the enzyme

stearoyl-CoA 9-desaturase Stearoyl-CoA desaturase (Δ-9-desaturase) 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 palmitoyl-CoA ...

acting on stearoyl-CoA. 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 waxy solid and its chemical formula is C17H35CO2H. Its name comes from the Greek word στέαρ "''stéar''", which means tallow. ...

dehydrogenated In chemistry, dehydrogenation is a chemical reaction that involves the removal of hydrogen, usually from an organic molecule. It is the reverse of hydrogenation. Dehydrogenation is important, both as a useful reaction and a serious problem. At ...

to give the monounsaturated derivative, oleic acid. Oleic acid undergoes the reactions of carboxylic acids and

alkene In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...

s. It is soluble in aqueous base to give

soap Soap is a salt of a fatty acid used in a variety of cleansing and lubricating products. In a domestic setting, soaps are surfactants usually used for washing, bathing, and other types of housekeeping. In industrial settings, soaps are use ...

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

saturated Saturation, saturated, unsaturation or unsaturated may refer to: Chemistry * Saturation, a property of organic compounds referring to carbon-carbon bonds ** Saturated and unsaturated compounds **Degree of unsaturation ** Saturated fat or fatty ac ...

derivative

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

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 oc ...

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 considered ...

in coatings. Reduction of the

carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic ...

group yields

oleyl alcohol Oleyl alcohol , or ''cis''-9-octadecen-1-ol, is an unsaturated fatty alcohol with the molecular formula or the condensed structural formula . It is a colorless oil, mainly used in cosmetics. It can be produced by the hydrogenation of oleic a ...

Ozonolysis In organic chemistry, ozonolysis is an organic reaction where the unsaturated bonds of alkenes (), alkynes (), or azo compounds () are cleaved with ozone (). Alkenes and alkynes form organic compounds in which the multiple carbon–carbon b ...

of oleic acid is an important route to

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

. The coproduct is nonanoic acid: :H₁₇C₈CH=CHC₇H₁₄CO₂H + 4"O" → HO₂CC₇H₁₄CO₂H + H₁₇C₈CO₂H Esters of azelaic acid find applications in lubrications and plasticizer.

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: Arts, entertainment, and media * Trans (festival), a former festival in Belfast, Northern Ireland, United Kingdom * ''Trans'' (fil ...

of oleic acid is called

elaidic acid Elaidic acid is a chemical compound with the formula , specifically the fatty acid with structural formula HO(O=)C–(CH2–)7CH=CH–(CH2–)8H, with the double bond (between carbon atoms 9 and 10) in ''trans'' configuration. It is a colorless ...

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 Petroselinic acid is a fatty acid that occurs naturally in several animal and vegetable fats and oils. It is a white powder and is commercially available. In chemical terms, petroselinic acid is classified as a monounsaturated omega-12 fatty aci ...

. 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 cross metathesis. The utility of the reaction is driven by the low cost of ethylene ...

, methyl oleate, the ''methyl ester'' of the acid, converts to 1-decene and methyl 9- decenoate: : CH₂=CH₂ → CH₃(CH₂)₇CH=CH₂ + MeO₂C(CH₂)₇CH=CH₂

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, included for the purpose of long-term stabilization, bulking up solid formulations that contain potent active ingredients in small amounts (thus often referred ...

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, also known as pulmonary congestion, is excessive edema, liquid accumulation in the parenchyma, tissue and pulmonary alveolus, air spaces (usually alveoli) of the lungs. It leads to impaired gas exchange and may cause hypoxemia an ...

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

Nanoparticles

Oleic acid is widely used in the solution phase synthesis of

nanoparticle A nanoparticle or ultrafine particle is usually defined as a particle of matter that is between 1 and 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 1 ...

s, functioning as a to control the size and morphology of nanoparticles.

Health effects

Oleic acid is the topmost

monounsaturated fat Monounsaturated fats are fatty acids that have one double bond in the fatty acid chain with all of the remainder carbon atoms being single-bonded. By contrast, polyunsaturated fats have more than one double bond. Molecular description Fatty aci ...

in the human diet. 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 densit ...

(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 ty ...

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

hypotensive Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the systolic blood pressure (the top number) and the dias ...

(

blood pressure Blood pressure (BP) is the pressure of 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 "blood pressure" r ...

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

) 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, also called trans-unsaturated fatty acids, or trans fatty acids, is a type of unsaturated fat that naturally occurs in small amounts in meat and milk fat. It became widely produced as an unintentional byproduct in the industrial pro ...

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