Abstract 3-Pyrazolidinone compounds having a solubility of at least 12 grams/liter in an aqueous medium of pH 9 of the formula: ##STR1## wherein R is a mononuclear phenyl group having substituents in the 3, 4, or 5 positions with a total of no more than 4 non-metallic atoms with an atomic number greater than 1 and the total mass of the substituents being less than that of benzene, Q is an aqueous-solubilizing group of the formula: ##STR2## wherein R 1 and R 2 are independently a hydrogen, or alkyl group or together with the included nitrogen form a 5 or 6 membered heterocyclic ring composed of carbon, nitrogen and no more than one atom from the group of sulfur and oxygen, the total number of atoms in R 1 and R 2 having an atomic number greater than 1 being equal to or less than 6.