(m-aminobenzenesulfonic acid), colorless crystals that decompose without fusion upon heating. It is poorly soluble in cold water and insoluble in alcohol. Conversion into m-aminophenol upon fusion with NaOH at 280°C is an important property of metanilic acid.
Metanilic acid is prepared industrially from nitrobenzene by sulfonation and subsequent reduction. It is used in the manufacture of synthetic dyes-for example, azo dyes.