The molecule is an arenesulfonic acid that is 5-chloro-2-(pyrazol-1-yl)benzene-1-sulfonic acid in which the pyrazole ring is substituted by methyl, 4-(tosyloxy)phenyldiazenyl and hydroxy groups at positions 3, 4, and 5 respctively. The monosodium salt is the biological stain 'Milling yellow 3G'. It has a role as a histological dye. It is an arenesulfonic acid, a member of azobenzenes, a heteroaryl hydroxy compound, a member of pyrazoles, a tosylate ester and a member of monochlorobenzenes. It is a conjugate acid of a Milling yellow 3G(1-).
5-chloro-2-[5-methyl-4-[[4-(4-methylphenyl)sulfonyloxyphenyl]diazenyl]-3-oxo-1H-pyrazol-2-yl]benzenesulfonic acid