3,3'-Dibromothymolsulfonphthalein 76-59-5 Bromothymol blue Bromthymol Blue Dibromothymolsulfophthalein NSC7819 Phenol, 4,4'-(3H-2,1-benzoxathiol-3-ylidene)bis[2-bromo-3-methyl-6-(1-methylethyl)-, S,S-dioxide Thymol, 6,6'-(3H-2,1-benzoxathiol-3-ylidene)bis[2-bromo-, S,S-dioxide