benzoic acid(redirected from benzenecarboxylic acid)
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the simplest aromatic acid, C6H5COOH; it forms clear, lustrous crystals. It was first isolated by sublimation at the beginning of the 17th century from benzoic resin (benzoin gum), hence its name. Its melting point is 122° C. Benzoic acid is readily soluble in organic solvents; it is poorly soluble in water. It sublimates readily and is distilled with steam. Benzoic acid is obtained by the oxidation of toluene with nitric or chromic acid, as well as by the decarboxylation of phthalic acid.
Benzoic acid in the form of complex esters and salts is contained in various natural essential oils—for example, clove oil. In medicine it is used externally in cases of skin diseases as an antiseptic and fungicidal agent; its sodium salt is used as an expectorant. In addition, the sodium salt is used in the preservation of foodstuffs. The esters of benzoic acid (from methyl to amyl), which have a strong odor, are used in the perfume industry. Various derivatives of benzoic acid— for example, chlorobenzoic and nitrobenzoic acids—are used in the synthesis of dyes.