4-(2,4-dihydroxy-phenylazo)-naphthalene-1-sulfonic acid

4-[(2Z)-2-(2-羟基-4-氧代-1-环己-2,5-二烯亚基)肼基]苯磺酸

3-[2-(2-hydroxy-4-oxocyclohexa-2,5-dien-1-ylidene)hydrazinyl]benzenesulfonic acid