A trihydroxyanthraquinone or trihydroxyanthracenedione is any of several isomeric organic compounds with formula C
14H
8O
5, formally derived from anthraquinone by replacing three hydrogen atoms by hydroxyl groups. They include several historically important dyes.[1][2] The isomers may differ in the parent anthraquinone isomer and/or of the three hydroxyl groups.
In general there are 56 ways of choosing three out of the 8 hydrogens. However, if the underlying core is symmetrical, some of these choices will give identical molecules.
Due to the symmetry of the 9,10-anthraquinone core, there are only 14 isomers.[3]