In organic chemistry hydroxyanthraquinones refers to compounds with the formula C12H8-n(OH)n(CO)2 where n ≥ 1. Almost all hydroxyanthraquinones are derivative of 9,10-anthraquinone.

Isomers

One peculiarity of the hydroxyanthraquinones is the relative obscurity of the monohydroxy derivatives. Most hydroxyanthraquinones have two or more hydroxy groups.

Dihydroxy

Dihydroxyanthraquinones have the formula C12H6(OH)2(CO)2. The dyes alizarin (1,2-Dihydroxyanthraquinone) and quinizarin are prominent examples.

Trihydroxy

Trihydroxyanthraquinones have the formula C12H5(OH)3(CO)2. 1,2,4-Trihydroxyanthraquinone, commonly called purpurin, is a naturally occurring red/yellow dye.

Tetrahydroxy

Tetrahydroxyanthraquinones have the formula C12H4(OH)4(CO)2. The dye quinalizarin (1,2,5,8-tetrahydroxyanthraquinone is one example.

Hexahydroxy

Dihydroxyanthraquinones have the formula C12H2(OH)6(CO)2.1,2,3,5,6,7-hexahydroxy-9,10-anthraquinone (rufigallol) occurs in nature.