The molecule is a dihydroxyanthraquinone that is 1,2-dihydroxyanthraquinone compound carrying an additional sulfo substituent at the 3-position. The monosodium salt is the biological stain 'alizarin red S'. It has a role as a histological dye. It is a dihydroxyanthraquinone and an organosulfonic acid. It is a conjugate acid of a 3,4-dihydroxy-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate.
3,4-dihydroxy-9,10-dioxoanthracene-2-sulfonic acid