Synonyms: 2-Anthraquinonesulfonicacid, 3,4-dihydroxy- (6CI); 1,2-Dihydroxy-3-sulfoanthraquinone; 1,2-Dihydroxy-3-sulfonate-9,10-anthraquinone;1,2-Dihydroxyanthraquinone-3-sulfonic acid;3,4-Dihydroxy-2-anthraquinonesulfonic acid;3,4-Dihydroxy-9,10-anthraquinone-2-sulfonic acid;3,4-Dihydroxy-9,10-dioxo-2-anthracenesulfonic acid; 3-Alizarinsulfonic acid; 9,10-Dihydro-3,4-dihydroxy-9,10-dioxo-2-anthracenesulfonicacid; Alizarin Red S free acid; PIN 077