Salicylic Acid

salicylic acid or 2-hydroxybenzoic acid, C₆H₄(OH)CO₂H, a colorless, crystalline organic carboxylic acid that melts at 159°C;; it is soluble in ethanol and ether but is only slightly soluble in water. It is prepared commercially by heating sodium phenolate (the sodium salt of phenol) with carbon dioxide under pressure to form sodium salicylate, which is treated with sulfuric acid to liberate salicylic acid. Salicylic acid and its derivatives are toxic when consumed in large amounts. Sodium salicylate is used to a small extent as a food preservative and as an antiseptic in mouthwashes and toothpastes. The major use of salicylic acid is in the preparation of its ester derivatives; since it contains both a hydroxyl (−OH) and a carboxyl (−CO₂H) group, it can react with either an acid or an alcohol. The hydroxyl group reacts with acetic acid to form the acetate ester, acetylsalicylic acid (see aspirin). Several useful esters are formed by reaction of the carboxyl group with alcohols. The methyl ester, methyl salicylate (also called oil of wintergreen since it produces the fragrance of wintergreen), is formed with methanol; it is used in food flavorings and in liniments. The phenyl ester, phenyl salicylate, or salol, is formed with phenol; it is used in medicine as an antiseptic and antipyretic. This ester hydrolyzes, not in the acidic stomach, but in the alkaline intestines, releasing free salicylic acid. The menthyl ester, menthyl salicylate, which is used in suntan lotions, is formed with menthol.

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salicylic acid

White, crystalline solid organic compound used chiefly to make aspirin and other pharmaceutical products, including methyl salicylate (oil of wintergreen, for medicines and flavourings), phenyl salicylate (for sunburn creams and pill coatings), and salicylanilide (a cutaneous fungicide). Its molecular structure, with the formula C₆H₄(OH)COOH, consists of a six-membered aromatic ring (see aromatic compound) having a hydroxyl group (−OH) and a carboxyl group (−COOH) bonded to adjacent carbon atoms; as such, it is both a phenol and a carboxylic acid. It and certain derivatives occur naturally in some plants, particularly species of Spiraea and Salix (willow). Large amounts are used in producing certain dyes.

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salicylic acid

a white crystalline slightly water-soluble substance with a sweet taste and bitter aftertaste, used in the manufacture of aspirin, dyes, and perfumes, and as a fungicide. Formula: C₆H₄(OH)(COOH)

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salicylic acid [¦sal·ə¦sil·ik ′as·əd]

(organic chemistry)

C₆H₄(OH)COOH White crystals with sweetish taste; soluble in alcohol, acetone, ether, benzene, and turpentine, slightly soluble in water; discolored by light; melts at 158°C; used as a chemical intermediate and in medicine, dyes, perfumes, and preservatives.

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Salicylic Acid 

(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.