p-[4,5-dihydro-4-[3-[5-hydroxy-3-methyl-1-(4-sulphophenyl)-1H-pyrazol-4-yl]but-2-enylidene]-3-methyl-5-oxo-1H-pyrazol-1-yl]benzenesulphonic acid

4-[[4,5-Dihydro-4-[3-[5-hydroxy-3-methyl-1-(4-sulfophenyl)-1H-pyrazol-4-yl]-2-buten-1-ylidene]-3-methyl-5-oxo-1H-pyrazol]-1-yl]benzenesulfonic acid