4-(3,4-dimethyl-5-oxo-4,5-dihydro-pyrazol-1-yl)-benzenesulfonic acid, 3,4-Dimethyl-1-(4-sulfophenyl)pyrazol-5(4H)-one, p-(4,5-dihydro-3,4-dimethyl-5-oxo-1H-pyrazol-1-yl)benzenesulfonic acid, 3,4-Dimethyl-1-(4-sulfophenyl)pyrazol-5-one, 4-(3,4-Dimethyl-5-oxo-4,5-dihydro-pyrazol-1-yl)-benzolsulfonsaeure, 3,4-Dimethyl-1-(4-sulfo-phenyl)-pyrazol-5-on, 4-(3,4-dimethyl-5-oxo-4,5-dihydro-1h-pyrazol-1-yl)benzenesulfonic acid, 4-(3,4-dimethyl-5-oxo-2,5-dihydro-pyrazol-1-yl)-benzenesulfonic acid