Abstract: A novel acyclic β-diketone type quadridentate chelating agent,bis-(1'- phenyl-3'- methyl-5' oxopyrazol-4'- yl)phthaldione(BPMOPP,H₂A) was synthesized from 1-phenyl-3-methylpyrazolone and o-phthalyl chloride. The valency behaviour of cerium ion and the synergistic extraction of cerium by BPMOPP and 1, 10-phenathroline from aqueous hydrochloric acid or hydrochloric acid and sodium formate buffer solution have been investigated. By using the slope analysis method the solid mixed ligand synergic adduct showed a constitution of CeA·HA·phen with an extraction equilibrium constant k_s.e=1.21×10^-2. All the compounds obtained have been characterized by elemental analvsis, UV, IR,¹H NMR. and TG-DTA measurements. The molar conductivity of the complexes in chloroform was 0.1～0.2S·cm²/mol indicating that they are nonelectrolytes.

Key words: bis-acylpyrazolone, phenathroline, cerium, synergistic extraction