345trihydroxybenzoic

345trihydroxybenzoic acid, more commonly known as gallic acid, is a naturally occurring polyphenolic carboxylic acid. It is the 3,4,5-trihydroxy derivative of benzoic acid and serves as a building block for many plant polyphenols and tannins.

Chemical structure and properties: The molecule consists of a benzene ring bearing a carboxyl group and three hydroxyl groups at the 3-, 4-, and 5-positions. Its formula is C7H6O5. The carboxyl group provides acidity, while the phenolic OH groups confer antioxidant activity and enable the formation of esters with alcohols. Gallic acid is moderately soluble in water and more soluble in hot water, with higher solubility in many organic solvents. It can participate in standard phenol-reactivity tests and serves as a common analytical standard.

Occurrence and sources: Gallic acid occurs widely in nature, particularly as a constituent of gallotannins found in gallnuts, certain barks, and leaves. It is released by hydrolysis or during the processing of tannin-rich materials. It is also found in tea, wine, grapes, and various fruits and plants as a degradation or hydrolysis product of larger polyphenols.

Uses and applications: Gallic acid is used as a precursor to gallic acid esters (gallates), which are employed as antioxidants in fats, oils, and cosmetics. Esters such as propyl gallate and other gallates are widely used to stabilize food products and personal care formulations. The compound is also utilized in analytical chemistry as a reference standard and in the Folin–Ciocalteu method for estimating total phenolic content.

Safety and handling: Gallic acid is a relatively common chemical with low to moderate toxicity. It can be an irritant to skin and eyes; appropriate PPE and handling procedures should be followed in laboratory or industrial settings.