The molecule is an arenesulfonic acid that is 2,5-dichloro-4-(pyrazol-1-yl)benzene-1-sulfonic acid in which the pyrazole ring is substituted by methyl, (4-sulfophenyl)diazenyl and hydroxy groups at positions 3, 4, and 5 respctively. The disodium salt is the biological stain 'lissamine fast yellow'. It has a role as an allergen, a food colouring and a histological dye. It is a member of azobenzenes, a member of pyrazoles, a dichlorobenzene, a heteroaryl hydroxy compound and an arenesulfonic acid. It is a conjugate acid of a lissamine fast yellow(2-).
2,5-dichloro-4-[5-methyl-3-oxo-4-[(4-sulfophenyl)diazenyl]-1H-pyrazol-2-yl]benzenesulfonic acid