345Trihydroxybenzene

3,4,5-Trihydroxybenzene, also known as pyrogallol or pyrogallic acid, is an organic compound with the chemical formula C6H3(OH)3. It is a benzene ring substituted with three hydroxyl groups at positions 3, 4, and 5. Pyrogallol is a white crystalline solid that is soluble in water, alcohol, and ether.

Historically, pyrogallol was first prepared by heating gallic acid. Its name derives from its preparation from gallic acid. It is a strong reducing agent and readily undergoes oxidation, particularly in alkaline solutions. This property makes it useful in various applications, including as a photographic developer, a hair dye component, and an oxygen scavenger in analytical chemistry. It has also been used in analytical methods for determining oxygen content in gases.

Pyrogallol can be synthesized through several methods, including the decarboxylation of gallic acid, as mentioned, or through various multi-step organic synthesis routes. It occurs naturally in certain plants, such as the inner bark of the Acacia genus and in gallnuts. In biological contexts, it and its derivatives can act as antioxidants due to their ability to scavenge free radicals. However, pyrogallol can also exhibit toxicity, and its handling requires appropriate precautions. Its reactivity and reducing properties are central to its chemical behavior and applications.