Oleic acid is a mono-unsaturated omega-9 fatty acid found in various animal and vegetable sources. It has the formula CH3(CH2)7CH=CH(CH2)7COOH. The trans-isomer of oleic acid is called elaidic acid.
Oleic acid exhibits the reactions of carboxylic acids and alkenes. It is soluble in aqueous base to give salts called oleates. Iodine adds across the double bond. Hydrogenation of the double bond yields the saturated derivative called stearic acid. Oxidation at the double bond occurs slowly in air and is known as rancidification in foodstuffs and drying in coatings. Reduction of the carboxylic acid group yields oleyl alcohol.
As an excipient in pharmaceuticals, oleic acid is used as an emulsifying or solubilizing agent in aerosol products.