SYNTHESIS, POTENTIOMETRIC TITRATIONS, AND ULTRAVIOLET ABSORPTION SPECTRA OF 3-OXO-2-PHENYL-4, 4-DISUBSTITUTED-5-PYRAZOLONES AND 3-HYDROXY-2-PHENYL-4-MONOSUBSTITUTED-5-PYRAZOLONES

Abstract

A number of 3-oxo-2-phenyl-4,4-disubstituted-5-pyrazolones and 3-hydroxy-2-phenyl-4-monosubstituted-5-pyrazolones have been prepared by reacting ethyl di- and monosubstituted malonates with phenylhydrazine in the presence of sodium ethylate. The evidence of an oxo group in position 3 in the disubstituted pyrazolones has been obtained by hydrolyzing 4,4-dibenzyl-3-imino-2-phenyl-5-pyrazolone and identifying the product of the reaction with 4,4-dibenzyl-3-oxo-2-phenyl-5-pyrazolone prepared from dibenzylmalonic ester and phenylhydrazine. A study of the ultraviolet absorption spectra of the pyrazolones has been made and their ionization constants have been determined by potentiometric titrations.