Certain carboxylic acids, particularly those with longer carbon chains (12-20 carbon atoms), are often called fatty acids because they are constituents of animal fats and oils. The fatty acids may be released from the fat by hydrolysis. Fatty acids may be easily prepared from other organic compounds by oxidation of the corresponding alcohol, aldehyde, or unsaturated hydrocarbon. They have the acidic properties and chemical reactivity typical of carboxyl compounds.
Salts of long-chain fatty acids (14 or more carbon atoms), or soaps, are important because of their ability to form emulsions with oils. A number of unsaturated fatty acids, such as oleic acid, occur in natural materials. The olefinic bonds lower the melting point of the acid and increase its reactivity, especially toward oxidation and addition. Vinegar is a dilute aqueous solution of acetic acid (Latin: acetum, Vinegar. Butyric (Latin: butyrum, butter) acid is one of the 14 fatty acids found in butter. Formic (Latin: formica, ant) acid is a protective chemical found in many ants.