C18H36O2

C18H36O2 is the molecular formula for stearic acid, also known as octadecanoic acid. It is a saturated long-chain carboxylic acid with 18 carbon atoms. In structural form, it can be represented as CH3-(CH2)16-COOH, an unbranched chain ending in a carboxyl group. The molecule has a molecular weight of about 284.48 g/mol. Stearic acid is a solid at room temperature, with a melting point around 69–70°C, and it is poorly soluble in water but soluble in nonpolar organic solvents.

Stearic acid occurs naturally as a major component of animal fats and of various vegetable fats and oils, including cocoa butter and palm oil. Commercial production is typically achieved by saponification of fats and oils followed by purification, or by hydrogenation of unsaturated precursors to yield high saturation. It is commonly sourced from tallow and plant-derived fats.

Uses for stearic acid are broad. In industry, it is a key ingredient in soap manufacture, where it acts as a surfactant and helps harden bars. It is also used in cosmetics and personal care products as a conditioning and thickening agent, as well as in lubricants, plastics, and candles. In biochemical contexts, stearic acid serves as a model fatty acid for studies of lipid metabolism and membrane biology.

Safety and handling are generally straightforward; stearic acid is considered of low toxicity and is widely regarded as safe for use in foods, cosmetics, and household products when used per regulatory guidelines.