- Oleic acid
Oleic acid Identifiers CAS number ChEMBL Jmol-3D images Image 1 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)
360 °C (633 K) (760mm Hg)
Solubility in water Insoluble Solubility in methanol Soluble Hazards MSDS JT Baker (what is: /?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Oleic acid is a monounsaturated omega-9 fatty acid 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 (hence the name elaidinization for a reaction that switches cis isomers to trans isomers). The term "oleic" means related to, or derived from, oil or olive.
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, 36-67% of peanut oil, 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, etc.
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 results from 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.
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. 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.
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. 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.
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Lipids: fatty acids SaturatedVFA: Acetic (C2) · Propionic (C3) · Butyric (C4) · Valeric (C5) · Caproic (C6) · Enanthic (C7) · Caprylic (C8) · Pelargonic (C9) · Capric (C10) · Undecylic (C11) · Lauric (C12) · Tridecylic (C13) · Myristic (C14) · Pentadecanoic (C15) · Palmitic (C16) · Margaric (C17) · Stearic (C18) · Nonadecylic (C19) · Arachidic (C20) · Heneicosylic (C21) · Behenic (C22) · Tricosylic (C23) · Lignoceric (C24) · Pentacosylic (C25) · Cerotic (C26) · Heptacosylic (C27) · Montanic (C28) · Nonacosylic (C29) · Melissic (C30) · Hentriacontylic (C31) · Lacceroic (C32) · Psyllic (C33) · Geddic (C34) · Ceroplastic (C35) · Hexatriacontylic (C36) n−3 Unsaturated n−6 Unsaturated n−9 Unsaturated
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