- Pyrogallol or benzene-1,2,3-triol is a benzenetriol. It is a white crystalline powder and a powerful reducing agent. It was first prepared by Scheele 1786 by heating gallic acid. An alternate preparation is heating para-chlorophenoldisulphonic acid with potassium hydroxide.
- When in alkaline solution, it absorbs oxygen from the air, turning purple from a colourless solution. It can be used in this way to calculate the amount of oxygen in air, notably via the use of the Orsat apparatus.
- One can find its uses in hair dying, dying of suturing materials and for oxygen absorption in gas analysis. It also has antiseptic properties. Pyrogallol was also used as a developing agent in black-and-white developers, but its use is largely historical except for special purpose applications.
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