gallic acid (HO)3C6H2COOH
Gallic acid (HO)3C6H2COOH, also known as 3,4,5-trihydroxybenzoic acid, is an acid occurring plants, including oak galls, sumach, and tea. It is obtained from tannins by hydrolysis. Gallic acid is used in ink, dyes, and as a mild antiseptic and astringent. On heating it gives pyrogallol, a photographic developer.