Octadecanoic acid, Stearic acid (C18), 18-Octadecanoic acid, 1,2-Octadecanedioic acid, Octadecylic acid, Stearin acid, C18 fatty acid

284.48 g/mol

57-11-4

C18H36O2

29156

0.847 g/cm3

69.3 °C

383 °C

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Stearic acid, with the chemical formula C18H36O2, is a saturated fatty acid commonly found in animal and plant fats. It is insoluble in water but dissolves in organic solvents such as acetone, chloroform, and alcohols, and is a weak acid with a slightly acidic pH when dissolved in oil or alcohol. While stable, it can undergo oxidation over time, forming hydroperoxides and other degradation products when exposed to air or light. Functionally, stearic acid serves as an emulsifying agent in cosmetics and personal care products, a thickening agent in creams and lotions, and a surfactant in soaps to enhance lather. Additionally, it acts as a lubricant in plastics, rubber, and metalworking industries, is a key ingredient in soap and detergent production through the formation of soap salts with alkalies, and is used as a plasticizer to improve the texture and flexibility of materials in the plastic industry.

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