Extraction chemistry of palladium I. Study on the mechanism of synergisticextraction of palladium (II) with 1-phenyl-3-methyl-4-dichloroacetopyrazolone-5-one and diphenyl sulfoxide

1-Phenyl-3-melhyl-4-dichloroacetopyrazol-5-one (HPMDCP), which is an acidic chelating P-diketone extractant, was synthesized by acylation reaction in dioxane medium. The behavior of synergistic extraction of palladium (II) wi th HPMDCP and diphenyl sulfoxide (DPSO) has been studied. The results show that an antagonistic effect was observed under the given conditions. To und erstand this phenomenon, a preliminary work was performed to explain the me chanism of this reaction. According to the theory of the corresponding solu tions (TCS), the association reaction between HPMDCP and DPSO in the organi c phase was discussed. The results show that the associate species HPMDCP.D PSO formed in chloroform medium is the main reason why an antagonistic extr action effect occurs. The association constant between HPMDCP and DPSO in t he extraction process was calculated to be 4.2.