Names | |
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Preferred IUPAC name (9Z)-Octadec-9-enoic acid | |
Other names Oleic acid (9Z)-Octadecenoic acid (Z)-Octadec-9-enoic acid cis-9-Octadecenoic acid cis-Δ9-Octadecenoic acid 18:1 cis-9 | |
Identifiers | |
3D model (JSmol) | |
ChEMBL | |
ChemSpider | |
DrugBank | |
ECHA InfoCard | 100.003.643 |
PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
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Properties | |
C18H34O2 | |
Molar mass | 282.468 g·mol−1 |
Appearance | colorless oily liquid with lard-like odor |
Density | 0.895 g/mL |
Melting point | 13 to 14 °C (55 to 57 °F; 286 to 287 K) |
Boiling point | 360 °C (680 °F; 633 K) [1] |
Insoluble | |
Solubility in Ethanol | Soluble |
-208.5·10−6 cm3/mol | |
Hazards | |
NFPA 704 (fire diamond) | |
Safety data sheet (SDS) | JT Baker |
Related compounds | |
Related compounds | Elaidic acid |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Oleic acid is a fatty acid that occurs naturally in various animal and vegetable fats and oils. 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 omega-9 fatty acid, abbreviated with a lipid number of 18:1 cis-9, and a main product of Δ9-desaturase. [2] It has the formula CH3−(CH2)7−CH=CH−(CH2)7−COOH. [3] [ page needed ] The name derives from the Latin word oleum , which means oil. [4] It is the most common fatty acid in nature. [5] 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.
Fatty acids (or their salts) often do not occur as such in biological systems. Instead fatty acids such as oleic acid occur as their esters, commonly triglycerides, 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 esters, and wax esters. [6]
Triglycerides of oleic acid comprise the majority of olive oil (about 70%). Olive oil exceeding 2% free oleic acid is graded unfit for human consumption. [7] It also makes up 59–75% of pecan oil, [8] 61% of canola oil, [9] 36–67% of peanut oil, [10] 60% of macadamia oil, 20–80% of sunflower oil, [11] 15–20% of grape seed oil, sea buckthorn oil, 40% of sesame oil, [3] and 14% of poppyseed oil. High oleic variants of plant sources such as sunflower (~80%) and canola oil (70%) also have been developed. [11] Karuka contains 52.39% oleic acid. [12] It is abundantly present in many animal fats, constituting 37 to 56% of chicken and turkey fat, [13] and 44 to 47% of lard.
Oleic acid is the most abundant fatty acid in human adipose tissue, [14] and second in abundance in human tissues overall, following palmitic acid.
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. [6]
Oleic acid undergoes the typical 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 and as 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: [15]
Esters of azelaic acid find applications in lubrication and plasticizers.
Neutralizing oleic acid with ethanolamines gives the protic ionic liquid monoethanolamine oleate. [16]
The trans isomer of oleic acid is called elaidic acid 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. [17] A reaction that converts oleic acid to elaidic acid is called elaidinization.
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. [18]
In ethenolysis, methyl oleate, the methyl ester of the acid, converts to 1-decene and methyl 9-decenoate: [19]
Type | Processing treatment [22] | Saturated fatty acids | Monounsaturated fatty acids | Polyunsaturated fatty acids | Smoke point | ||||
---|---|---|---|---|---|---|---|---|---|
Total [20] | Oleic acid (ω-9) | Total [20] | α-Linolenic acid (ω-3) | Linoleic acid (ω-6) | ω-6:3 ratio | ||||
Avocado [23] | 11.6 | 70.6 | 52–66 [24] | 13.5 | 1 | 12.5 | 12.5:1 | 250 °C (482 °F) [25] | |
Brazil nut [26] | 24.8 | 32.7 | 31.3 | 42.0 | 0.1 | 41.9 | 419:1 | 208 °C (406 °F) [27] | |
Canola [28] | 7.4 | 63.3 | 61.8 | 28.1 | 9.1 | 18.6 | 2:1 | 204 °C (400 °F) [29] | |
Coconut [30] | 82.5 | 6.3 | 6 | 1.7 | 0.019 | 1.68 | 88:1 | 175 °C (347 °F) [27] | |
Corn [31] | 12.9 | 27.6 | 27.3 | 54.7 | 1 | 58 | 58:1 | 232 °C (450 °F) [29] | |
Cottonseed [32] | 25.9 | 17.8 | 19 | 51.9 | 1 | 54 | 54:1 | 216 °C (420 °F) [29] | |
Cottonseed [33] | hydrogenated | 93.6 | 1.5 | 0.6 | 0.2 | 0.3 | 1.5:1 | ||
Flaxseed/linseed [34] | 9.0 | 18.4 | 18 | 67.8 | 53 | 13 | 0.2:1 | 107 °C (225 °F) | |
Grape seed | 10.4 | 14.8 | 14.3 | 74.9 | 0.15 | 74.7 | very high | 216 °C (421 °F) [35] | |
Hemp seed [36] | 7.0 | 9.0 | 9.0 | 82.0 | 22.0 | 54.0 | 2.5:1 | 166 °C (330 °F) [37] | |
High-oleic safflower oil [38] | 7.5 | 75.2 | 75.2 | 12.8 | 0 | 12.8 | very high | 212 °C (414 °F) [27] | |
Olive (extra virgin) [39] | 13.8 | 73.0 | 71.3 | 10.5 | 0.7 | 9.8 | 14:1 | 193 °C (380 °F) [27] | |
Palm [40] | 49.3 | 37.0 | 40 | 9.3 | 0.2 | 9.1 | 45.5:1 | 235 °C (455 °F) | |
Palm [41] | hydrogenated | 88.2 | 5.7 | 0 | |||||
Peanut [42] | 16.2 | 57.1 | 55.4 | 19.9 | 0.318 | 19.6 | 61.6:1 | 232 °C (450 °F) [29] | |
Rice bran oil | 25 | 38.4 | 38.4 | 36.6 | 2.2 | 34.4 [43] | 15.6:1 | 232 °C (450 °F) [44] | |
Sesame [45] | 14.2 | 39.7 | 39.3 | 41.7 | 0.3 | 41.3 | 138:1 | ||
Soybean [46] | 15.6 | 22.8 | 22.6 | 57.7 | 7 | 51 | 7.3:1 | 238 °C (460 °F) [29] | |
Soybean [47] | partially hydrogenated | 14.9 | 43.0 | 42.5 | 37.6 | 2.6 | 34.9 | 13.4:1 | |
Sunflower [48] | 8.99 | 63.4 | 62.9 | 20.7 | 0.16 | 20.5 | 128:1 | 227 °C (440 °F) [29] | |
Walnut oil [49] | unrefined | 9.1 | 22.8 | 22.2 | 63.3 | 10.4 | 52.9 | 5:1 | 160 °C (320 °F) [50] |
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. It is also used as an emollient. [51] Small amounts of oleic acid are used as an excipient in pharmaceuticals, and it is used as an emulsifying or solubilizing agent in aerosol products. [52]
E.O. Wilson found that oleic acid is used by ants; when a dead ant's corpse begins to emit oleic acid, other ants in the colony transport it away to the ant refuse pile. [53] [54] [55] [56]
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. [57]
Oleic acid is used as a soldering flux in stained glass work for joining lead came. [58]
Oleic acid is the most common monounsaturated fat in the human diet (~90% of all monounsaturated fats). [59] Monounsaturated fat consumption has been associated with decreased low-density lipoprotein (LDL) cholesterol, and possibly with increased high-density lipoprotein (HDL) cholesterol. [60] Oleic acid may be responsible for the hypotensive (blood pressure reducing) effects of olive oil that is considered a health benefit. [61] A 2017 review found that diets enriched in oleic acid are beneficial for regulating body weight. [62]
The United States FDA has approved a health claim on reduced risk of coronary heart disease for high oleic (> 70% oleic acid) oils. [63] 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) content. [64] 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. [65] [66]
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.
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 oils, or fats from seeds. Olive oil, palm oil, and rice bran oil are examples of fats from other parts of plants. In common usage, vegetable oil may refer exclusively to vegetable fats which are liquid at room temperature. Vegetable oils are usually edible.
Coconut oil is an edible oil derived from the kernels, meat, and milk of the coconut palm fruit. Coconut oil is a white solid fat below around 25 °C (77 °F), and a clear thin liquid oil at higher temperatures. Unrefined varieties have a distinct coconut aroma. Coconut oil is used as a food oil, and in industrial applications for cosmetics and detergent production. The oil is rich in medium-chain fatty acids.
A saturated fat is a type of fat in which the fatty acid chains have all single bonds between the carbon atoms. A fat known as a glyceride is made of two kinds of smaller molecules: a short glycerol backbone and fatty acids that each contain a long linear or branched chain of carbon (C) atoms. Along the chain, some carbon atoms are linked by single bonds (-C-C-) and others are linked by double bonds (-C=C-). A double bond along the carbon chain can react with a pair of hydrogen atoms to change into a single -C-C- bond, with each H atom now bonded to one of the two C atoms. Glyceride fats without any carbon chain double bonds are called saturated because they are "saturated with" hydrogen atoms, having no double bonds available to react with more hydrogen.
Linseed oil, also known as flaxseed oil or flax oil, is a colourless to yellowish oil obtained from the dried, ripened seeds of the flax plant. The oil is obtained by pressing, sometimes followed by solvent extraction.
Erucic acid is a monounsaturated omega-9 fatty acid, denoted 22:1ω9. It has the chemical formula: CH3(CH2)7CH=CH(CH2)11CO2H. It is prevalent in wallflower seed and other plants in the family Brassicaceae, with a reported content of 20 to 54% in high erucic acid rapeseed oil and 42% in mustard oil. Erucic acid is also known as cis-13-docosenoic acid and the trans isomer is known as brassidic acid.
Hemp oil is oil obtained by pressing hemp seeds. Cold pressed, unrefined hemp oil is dark to clear light green in color, with a nutty flavor. The darker the color, the grassier the flavour. It should not be confused with hash oil, a tetrahydrocannabinol-containing oil made from the Cannabis flower.
Grape seed 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.
Cottonseed oil is cooking oil from the seeds of cotton plants of various species, mainly Gossypium hirsutum and Gossypium herbaceum, that are grown for cotton fiber, animal feed, and oil.
Omega-6 fatty acids are a family of polyunsaturated fatty acids that have in common a final carbon-carbon double bond in the n-6 position, that is, the sixth bond, counting from the methyl end.
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 single-bonded. By contrast, polyunsaturated fatty acids (PUFAs) have more than one double bond.
Rice bran oil is the oil extracted from the hard outer brown layer of rice called bran. It is known for its high smoke point of 232 °C (450 °F) and mild flavor, making it suitable for high-temperature cooking methods such as stir frying and deep frying. It is popular as a cooking oil in East Asia, the Indian subcontinent, and Southeast Asia including India, Nepal, Bangladesh, Indonesia, Japan, Southern China and Malaysia.
Corn oil or maize oil (British) is oil extracted from the germ of corn (maize). Its main use is in cooking, where its high smoke point makes refined corn oil a valuable frying oil. It is also a key ingredient in some margarines. Corn oil is generally less expensive than most other types of vegetable oils.
Soybean oil is a vegetable oil extracted from the seeds of the soybean. It is one of the most widely consumed cooking oils and the second most consumed vegetable oil. As a drying oil, processed soybean oil is also used as a base for printing inks and oil paints.
Sunflower oil is the non-volatile oil pressed from the seeds of the sunflower. Sunflower oil is commonly used in food as a frying oil, and in cosmetic formulations as an emollient.
In biochemistry and nutrition, a polyunsaturated fat is a fat that contains a polyunsaturated fatty acid, which is a subclass of fatty acid characterized by a backbone with two or more carbon–carbon double bonds. Some polyunsaturated fatty acids are essentials. Polyunsaturated fatty acids are precursors to and are derived from polyunsaturated fats, which include drying oils.
Avocado oil is an edible oil extracted from the pulp of avocados, the fruit of Persea americana. It is used as an edible oil both raw and for cooking, where it is noted for its high smoke point. It is also used for lubrication and in cosmetics.
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 acid, abbreviated with a lipid number of 18:1 cis-6. It has the formula CH3(CH2)10CH=CH(CH2)4COOH. The term "petroselinic" means related to, or derived from, oil of Petroselinum, parsley. Despite its name, petroselinic acid does not contain any selenium. Petroselinic acid is a positional isomer of oleic acid.
Cooking oil is a plant or animal liquid fat used in frying, baking, and other types of cooking. Oil allows higher cooking temperatures than water, making cooking faster and more flavorful, while likewise distributing heat, reducing burning and uneven cooking. It sometimes imparts its own flavor. Cooking oil is also used in food preparation and flavoring not involving heat, such as salad dressings and bread dips.
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, it was restricted as a food oil due to its content of erucic acid, which in laboratory studies was shown to be damaging to the cardiac muscle of laboratory animals in high quantities and which imparts a bitter taste, and glucosinolates, which made many parts of the plant less nutritious in animal feed. Rapeseed oil from standard cultivars can contain up to 54% erucic acid.