In organic chemistry hydroxyanthraquinones refers to compounds with the formula C<sub>12</sub>H<sub>8âÂÂn</sub>(OH)<sub>n</sub>(CO)<sub>2</sub> where n âÂÂ¥ 1. Almost all hydroxyanthraquinones are derivative of 9,10-anthraquinone.
One peculiarity of the hydroxyanthraquinones is the relative obscurity of the monohydroxy derivatives. Most hydroxyanthraquinones have two or more hydroxy groups.
Dihydroxyanthraquinones have the formula . The dyes alizarin (1,2-Dihydroxyanthraquinone) and quinizarin are prominent examples.
Trihydroxyanthraquinones have the formula . 1,2,4-Trihydroxyanthraquinone, commonly called purpurin, is a naturally occurring red/yellow dye.
Tetrahydroxyanthraquinones have the formula . The dye quinalizarin (1,2,5,8-tetrahydroxyanthraquinone is one example.
Hexahydroxyanthraquinones have the formula .1,2,3,5,6,7-hexahydroxy-9,10-anthraquinone (rufigallol) occurs in nature.