Benzenesulfonic acid, 2-[(5-bromo-4-hydroxy-3-methylphenyl)(3-bromo-5-methyl-4-oxo-2,5-cyclohexadien-1-ylidene)methyl]- Bromocresol purple NSC6244 o-Toluenesulfonic acid, .alpha.-(5-bromo-4-hydroxy-m-tolyl)-.alpha.-(3-bromo-5-methyl-4-oxo-2,5-cyclohexadien-1-ylidene)-