1,4-Dimethyl-5-hydroxybenzenesulfonphthalein 125-31-5 2,5-Xylenol, 4,4'-(3H-2,1-benzoxathiol-3-ylidene)di-, S,S-dioxide NSC10471 Phenol, 4,4'-(3H-2,1-benzoxathiol-3-ylidene)bis[2,5-dimethyl-, S,S-dioxide Xylenol Blue p-Xylenesulfonephthalein p-Xylenol Blue p-Xylenolsulfonephthalein p-Xylenolsulfonphthalein p-Xylenolsulfophthalein