salicylic acid(redirected from 2-hydroxybenzoic acid)
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(o-hydroxybenzoic acid), the simplest aromatic hydroxycarboxylic acid. A colorless crystalline compound that is poorly soluble in water but readily soluble in organic solvents. Melting point, 159°C; boiling point, 211°C (at 2.66 kilonewtons per sq m).
Salicylic acid is widespread in nature, especially in the form of the glycoside of its methyl ester, methyl salicylate. It is usually produced industrially by carboxylation of phenol (the Kolbe-Schmitt reaction). Salicylic acid has weak antiseptic and irritant properties and, at high concentrations, keratolytic properties. It is used topically in salve, paste, powder, and solution form for treating skin ailments. It is an ingredient of Las-sar’s paste, galmanin powder, and corn lotion and plaster. The sodium salt of salicylic acid (sodium salicylate), the amide (sali-cylamide), and acetylsalicylic acid (aspirin) are used as antipyretic, antirheumatic, anti-inflammatory, and analgesic agents. The phenyl ester of salicylic acid is used as an antiseptic, and p-aminosalicylic acid (PAS) is used as an antituberculosis drug.
Because of its antiseptic action, salicylic acid is used in the preservation of foods. Its esters are used in the manufacture of azo dyes and odoriferous substances, and the acid itself is used for the colorimetric identification of iron and copper and for the separation of thorium from other elements.