chemistry

Oleic acid

Oleic acid is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Oleic acid rather than just read about it. In short: 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.

Key takeaways

Oleic acid belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Oleic acid to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Oleic acid from memory before moving on to harder problems.

Reference excerpt

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. It has the formula CH3−(CH2)7−CH=CH−(CH2)7−COOH. 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. 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 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. Triglycerides of oleic acid comprise the majority of olive oil (about 70%). It also makes up 59–75% of pecan oil, 61% of canola oil, 36–67% of peanut oil, 60% of macadamia oil, 20–80% of sunflower oil, 15–20% of grape seed oil, sea buckthorn oil, 40% of sesame oil, and 14% of poppyseed oil. High oleic variants of plant sources such as sunflower (~80%) and canola oil (70%) also have been developed. It is abundantly present in many animal fats, constituting 37 to 56% of chicken and turkey fat, and 44 to 47% of lard. Oleic acid is the most abundant fatty acid in human adipose tissue, and second in abundance in human tissues overall, following palmitic acid. 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 Fatty acid § Free fatty acids. Some ants use it as a chemical signal.

Production and chemical behavior 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 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:

H17C8CH=CHC7H14CO2H + 4"O" → HO2CC7H14CO2H + H17C8CO2H Esters of azelaic acid find applications in lubrication and plasticizers. Neutralizing oleic acid with ethanolamines gives the protic ionic liquid monoethanolamine oleate.

Related compounds 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. 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. In ethenolysis, methyl oleate, the methyl ester of the acid, converts to 1-decene and methyl 9-decenoate:

CH3(CH2)7CH=CH(CH2)7CO2Me + CH2=CH2 → CH3(CH2)7CH=CH2 + MeO2C(CH2)7CH=CH2 Several organometallic oleates exist:

Cobalt oleate Copper oleate

Dietary sources

Biological activity Oleic acid is an endogenous agonist of the TLX, a previously orphan nuclear receptor. It is peripherally selective, necessitating the use of synthetic drugs to act on this receptor for potential medical applications. The drug amdiglurax (NSI-189, ALTO-100) has been reported to act as a highly potent agonist of the TLX.

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. It is also used as an emollient. 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.

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. 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 the human diet (~90% of all monounsaturated fats). Monounsaturated fat consumption has been associated with decreased low-density lipoprotein (LDL) cholesterol, and possibly with increased high-density lipoprotein (HDL) cholesterol. Oleic acid may be responsible for the hypotensive (blood pressure reducing) effects of olive oil 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 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) 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.

See also Oleylamine – the corresponding amine Oleamide – the corresponding amide

References

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Oleic acid

Start with the simplest possible case. Write down what Oleic acid claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Oleic acid before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Oleic acid ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Oleic acid

In research: Oleic acid appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Oleic acid in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Oleic acid is common in secondary-school and first-year university syllabi. It links to neighbouring topics 5α-Reductase inhibitors, Alkenoic acids, Excipients, so understanding it makes those chapters shorter.
In everyday life: Look for Oleic acid outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Oleic acid in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Oleic acid means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Oleic acid out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Oleic acid in simple terms?

Why does Oleic acid matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Oleic acid?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Oleic acid.