1H-Pyrazole-3-carboxylic acid, 4,5-dihydro-5-oxo-1-(4-sulfophenyl)-, monosodium salt 52126-51-9 EINECS 257-677-2 Sodium hydrogen 4,5-dihydro-5-oxo-1-(4-sulphonatophenyl)-1H-pyrazole-3-carboxylate