dark brown powder
Also know nas pyrogallol and 1,2,3-trihydroxy-benzene,C6H3(OH)3 is white,lustrous crystals that turn gray on exposure to light. It is soluble in water,alcohol,and ether. A solution of pyrogallol acquires a brown color on exposure to air. This absorption of oxygen and change of color take place rapidly when the solution is made alkaline. Derivation is by heating gallic acid in an autoclave with three times its weight of water.
Uses are as a protective colloid in preparation of metallic colloidal solutions, photography, dyes, intermediates, synthetic drugs, medicine (antibacterial), process engraving, laboratory reagent, gas analysis (an oxygen absorber), reducing agent, and antioxidant in lubricating oils.
It is recrystallised from aqueous alkaline solution (Na2CO3 or NaOH) by precipitation on acidification, filter it off and dry in a vacuum. [Suk Collect Czech Chem Commun 31 3127 1966, Beilstein 19 H 407, 19 II 417, 19 III/IV 599, 19/10 V 226.]