The names of fatty acids that make up the fats in the world around us can be so familiar that we rarely consider where these names came from. While fatty acids now have systematic names and precise scientific names that describe their structure, these are rarely used. The old names, known as trivial or common names, are still generally preferred. Given my predilection for knowing the why and wherefore of things, I ended up looking up where these names originated from. This is the non-systematic and, hopefully mostly accurate, result of my reading.
| Trivial names (or common names) are non-systematic historical names, which are the most frequent naming system used in literature. Most common fatty acids have trivial names in addition to their systematic names. These names frequently do not follow any pattern, but they are concise and often unambiguous. |
Formic acid (C1:0). The smallest of the short-chain fatty acids, formic acid contains only one carbon atom. The name “formic” originates from Formica, the Latin name for a genus of ants commonly known as wood ants. Wood ants typically secrete formic acid as a defense mechanism and one species, Formica rufa, can squirt the acid from its acidopore several feet if alarmed. Formic acid was first distilled from a large number of crushed ants of this species by the English naturalist John Ray in 1671.
Acetic acid (C2:0). The name acetic acid actually derives from acetum, the Latin word for vinegar. Acetic acid without any water is called glacial acetic acid, the name referring to the ice-like crystals that form at slightly-below room temperature.
Propionic acid (C3:0). Propionic acid was named by the French chemist Jean-Baptiste Dumas in 1847, from the Greek words prōtos, meaning first, and piōn, meaning fat, because it is the smallest fatty acid that can exhibit the properties of the longer-chain fatty acids.
Butyric acid (C4:0). Butyric acid makes up 3–4% of the fatty acids in butterfat, after which it is named from the Latin word for butter, butyrum.
Valeric acid (C5:0). This is found naturally in the perennial flowering plant valerian (Valeriana officinalis), from which it gets its name, and is also responsible for the typical odor of valerian roots that can be reminiscent of unwashed feet.
Caproic acid (C6:0).
Caprylic acid (C:8).
Capric acid (C10). Capronic, caprylic, and capric acid are all named after the domestic goat (Capra aegagrus hircus), as these three fatty acids make up around 15% of the fat in goats milk. Caprylic and capric acid also apparently have a rather goat-like odor about them.
Lauric acid (C12:0). Found in the leaves and berries of Laurus nobilis, from where this fatty acid gets its name, these leaves are more commonly known to us as bay leaves.
Myristic acid (C:14). This fatty acid was first isolated from nutmeg, the oil of which is mostly composed of myristic acid, in 1841 by Lyon Playfair and is named after the latin name for the nutmeg tree (Myristica fragrans).
Palmitic acid (C16:). As its name indicates, it is a major component of the oil from the fruit of oil palms in which it was discovered by Edmond Frémy in 1840.
Sapienic acid (16:1). Not a fatty acid you will find in your food (unless you are a cannibal), sapienic acid is unique to humans and is found in the sebum on the skin. It takes its name from our species name Homo sapiens.
Margaric acid (C:17). Found only in small amounts in the fat and milk fat of ruminants. First discovered by French chemist Michel Eugène Chevreul in 1813 it was named after the pearly appearance of the fatty acid after extraction, the w from Greek margaritēs/márgaron, meaning pearl-oyster or pearl. Margaric acid gave its name to margarine, as the principal raw material in the early formulations of margarine was beef fat.
Stearic acid (C18:0). This name comes from the Greek word “stéar”, which means tallow, of which stearic acid is a major constituent.
Oleic acid (18:1).The term “oleic” means related to, or derived from, olive oil, which is predominantly composed of oleic acid.
Vaccenic acid (18:1). A naturally occurring trans-fatty acid found in the fat and dairy products of ruminants. The name was derived from vacca, the Latin word for a cow.
Linoleic acid (18:2). The word “linoleic” derives from the Latin name of the Flax plant, Linum usitatissimum (also known as linseed), in which it is found, and oleic in reference to the olive because saturating the omega-6 double bond produces oleic acid.
alpha-Linolenic acid (18:3). This name derives from linoleic acid (linoleic + -ene) with the “ene” signifying it has one extra double bond.
Arachidic acid (C:20). Not in fact found in spider fat, this fatty acid gets its name from the peanut plant Arachis hypogaea, in which it makes up 1.1%–1.7% of peanut oil.
Arachidonic acid (20:4). Also not in fact named after spiders, so named as it is structurally related to arachidic acid, containing the same number of carbon atoms. However, the four double bonds give it very different properties.
