Fatty acid
In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with a long 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 usually not found in organisms, but instead as three main classes of esters: triglycerides, phospholipids, and cholesterol esters. In any of these forms, fatty acids are both important dietary sources of fuel for animals and they are important structural components for cells.
Nonadecylic acid
Nonadecylic acid, or nonadecanoic acid, is a 19-carbon long saturated fatty acid with the chemical formula CH(CH)COOH. It forms salts called "nonadecylates". Nonadecylic acid can be found in fats and vegetable oils. It is also used by insects as pheromones.