3-Carbethoxy-1-(2-sulfophenyl)-2-pyrazolin-5-one

3-ethyl 4,5-dihydro-5-oxo-1-(2-sulphophenyl)-1H-pyrazole-3-carboxylate

4,5-Dihydro-5-oxo-1-(2-sulfophenyl)-1H-pyrazole-3-carboxylic acid 3-ethyl ester