Oleic acid
IUPAC name (9Z)-Octadec-9-enoic acid
Other names (9Z)-Octadecenoic acid (Z)-Octadec-9-enoic acid cis-9-Octadecenoic acid cis-Δ9-Octadecenoic acid Oleic acid 18:1 cis-9
Identifiers
CAS number	112-80-1 Y
ChEMBL	CHEMBL8659 N
Jmol-3D images	Image 1
SMILES CCCCCCCC\C=C/CCCCCCCC(O)=O
Properties
Molecular formula	C18H34O2
Molar mass	282.4614 g/mol
Appearance	Pale yellow or brownish yellow oily liquid with lard-like odor
Density	0.895 g/mL
Melting point	13-14 °C (286 K)
Boiling point	360 °C (633 K) (760mm Hg)[1]
Solubility in water	Insoluble
Solubility in methanol	Soluble
Hazards
MSDS	JT Baker
N (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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. It has the formula CH₃(CH₂)₇CH=CH(CH₂)₇COOH.^[2] The term "oleic" means related to, or derived from, oil or olive, the oil of which is predominantly derived from oleic acid.

Occurrence[link]

Fatty acids (or as their salts) do not often occur as such in biological systems. Instead fatty acids like oleic acid occur as their esters, commonly the triglycerides, which are the greasy materials in many natural oils. Via the process of saponification, the fatty acids can be obtained.

Triglyceride esters of oleic acid compose the majority of olive oil, 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,^[3] 36-67% of peanut oil,^[4] 15-20% of grape seed oil, sea buckthorn oil, and sesame oil,^[2] and 14% of poppyseed oil.^[5] It is abundantly present in many animal fats, constituting 37 to 56% of chicken and turkey fat^[6] and 44 to 47% of lard.

Oleic acid is the most abundant fatty acid in human adipose tissue.^[7]

As an insect pheromone[link]

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^[8] or ant^[9][10] 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.^[11]

Production and chemical behavior[link]

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:^[12]

H₁₇C₈CH=CHC₇H₁₄CO₂H + 4"O" → H₁₇C₈CO₂H + HO₂CC₇H₁₄CO₂H

Esters of azelaic acid find applications in lubrication and plasticizers.

The trans isomer of oleic acid is called elaidic acid (hence the name elaidinization for a reaction that converts oleic acid to elaidic acid.

Uses[link]

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 in pharmaceuticals, oleic acid is used as an emulsifying or solubilizing agent in aerosol products.^[13] 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.^[14] 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[link]

Positive health effects of the substance have been documented. Oleic acid may hinder the progression of adrenoleukodystrophy (ALD), a fatal disease that affects the brain and adrenal glands.^[15] Oleic acid may be responsible for the hypotensive (blood pressure reducing) effects of olive oil.^[16] Oleic acid also keeps cell membranes soft and fluid, allowing helpful anti-inflammatory substances like omega-3 fatty acid to penetrate the cell membrane more easily and preventing the negative effects of bad cholesterol.^[17] 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.^[18]

References[link]

External links[link]

• [1]
• NIST Chemistry Webbook