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, from 4 to 28. Fatty acids are a major component of the lipids in some species such as microalgae but in some other organisms are not found in their standalone form, but instead exist as three main classes of esters: triglycerides, phospholipids, and cholesteryl esters. In any of these forms, fatty acids are both important dietary sources of fuel for animals and important structural components for cells.
A triglyceride is an ester derived from glycerol and three fatty acids. Triglycerides are the main constituents of body fat in humans and other vertebrates, as well as vegetable fat. They are also present in the blood to enable the bidirectional transference of adipose fat and blood glucose from the liver, and are a major component of human skin oils.
Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include higher alkanes and lipids, typically with melting points above about 40 °C (104 °F), melting to give low viscosity liquids. Waxes are insoluble in water but soluble in organic, nonpolar solvents. Natural waxes of different types are produced by plants and animals and occur in petroleum.
Stearic acid ( STEER-ik, stee-ARR-ik) 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. The salts and esters of stearic acid are called stearates. As its ester, stearic acid is one of the most common saturated fatty acids found in nature following palmitic acid. The triglyceride derived from three molecules of stearic acid is called stearin.
A drying oil is an oil that hardens to a tough, solid film after a period of exposure to air, at room temperature. The oil hardens through a chemical reaction in which the components crosslink by the action of oxygen. Drying oils are a key component of oil paint and some varnishes. Some commonly used drying oils include linseed oil, tung oil, poppy seed oil, perilla oil, and walnut oil. Their use has declined over the past several decades, as they have been replaced by alkyd resins and other binders.
Myristic acid (IUPAC name: tetradecanoic acid) is a common saturated fatty acid with the molecular formula CH3(CH2)12COOH. Its salts and esters are commonly referred to as myristates or tetradecanoates. It is named after the binomial name for nutmeg (Myristica fragrans), from which it was first isolated in 1841 by Lyon Playfair.
A dicarboxylic acid is an organic compound containing two carboxyl functional groups (−COOH). The general molecular formula for dicarboxylic acids can be written as HO2C−R−CO2H, where R can be aliphatic or aromatic. In general, dicarboxylic acids show similar chemical behavior and reactivity to monocarboxylic acids. Dicarboxylic acids are also used in the preparation of copolymers such as polyamides and polyesters. The most widely used dicarboxylic acid in the industry is adipic acid, which is a precursor in the production of nylon. Other examples of dicarboxylic acids include aspartic acid and glutamic acid, two amino acids in the human body. The name can be abbreviated to diacid.
Caproic acid, also known as hexanoic acid, is the carboxylic acid derived from hexane with the chemical formula CH3(CH2)4COOH. It is a colorless oily liquid with an odor that is fatty, cheesy, waxy, and like that of goats or other barnyard animals. It is a fatty acid found naturally in various animal fats and oils, and is one of the chemicals that gives the decomposing fleshy seed coat of the ginkgo its characteristic unpleasant odor. It is also one of the components of vanilla and cheese. The primary use of caproic acid is in the manufacture of its esters for use as artificial flavors, and in the manufacture of hexyl derivatives, such as hexylphenols. Salts and esters of caproic acid are known as caproates or hexanoates. Several progestin medications are caproate esters, such as hydroxyprogesterone caproate and gestonorone caproate.
Caprylic acid (from the Latin word capra, meaning "goat"), also known under the systematic name octanoic acid, is a saturated fatty acid, medium-chain fatty acid (MCFA), and carboxylic acid. It has the structural formula CH3(CH2)6CO2H, and is a colorless oily liquid that is minimally soluble in water with a slightly unpleasant rancid-like smell and taste. Salts and esters of octanoic acid are known as octanoates or caprylates. It is a common industrial chemical, which is produced by oxidation of the C8 aldehyde. Its compounds are found naturally in the milk of various mammals and as a minor constituent of coconut oil and palm kernel oil.
Behenic acid (also docosanoic acid) is a carboxylic acid, the saturated fatty acid with formula C21H43COOH. In appearance, it consists of white solid although impure samples appear yellowish.
A saponifiable lipid is part of the ester functional group. They are made up of long chain carboxylic acids connected to an alcoholic functional group through the ester linkage which can undergo saponification, hence the name. The fatty acids are released on based catalyzed ester hydrolysis. The primary saponifiable lipids are triacylglycerides, glycerophospholipids, and the sphingolipids.
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.
Hexatriacontylic acid, or hexatriacontanoic acid is a 36-carbon-long carboxylic acid and saturated fatty acid.
Hentriacontylic acid is a carboxylic saturated fatty acid.
Cerotic acid, or hexacosanoic acid, is a 26-carbon long-chain saturated fatty acid with the chemical formula CH3(CH2)24COOH. It is most commonly found in beeswax and carnauba wax. It is a white solid, although impure samples appear yellowish.
Tricosylic acid, or tricosanoic acid, is a 23-carbon long-chain saturated fatty acid with the chemical formula CH3(CH2)21COOH.
Pentacosylic acid, or pentacosanoic acid, or hyenic acid, is a 25-carbon long-chain saturated fatty acid with the chemical formula CH3(CH2)23COOH.
Heneicosylic acid, or heneicosanoic acid, is the organic compound with the formula CH3(CH2)19CO2H. It is the straight-chain 21-carbon saturated fatty acid. It is a colorless solid.
Carboceric acid, or heptacosanoic acid or heptacosylic acid, is a 27-carbon long-chain saturated fatty acid with the chemical formula CH3(CH2)25COOH. Its name derives from a combination of the word "Carbon" and κηρός (Keros), meaning beeswax or honeycomb in Ancient Greek, since the acid can be found in the mineral ozokerite, also known as ozocerite.
Heptatriacontanoic acid, or heptatriacontylic acid, is a 37-carbon saturated fatty acid.
