Fenridazon [iso]

1-(4-chlorophenyl)-6-methyl-4-oxo-pyridazine-3-carboxylate

1-(4-chlorophenyl)-6-Methyl-4-oxo-1,4-dihydropyridazine-3-carboxylate

1-(4-Chlorophenyl)-1,4-dihydro-6-methyl-4-oxo-3-pyridazinecarboxylic acid