Study of the antagonistic extraction of palladium(II) with 1-phenyl-3-methyl-4-propionylpyrazolone-5-one and an organic amine

The extraction mechanism of palladium (II) with the acidic chelating extrac tant 1-phenyl-3-methyl-4-propionylpyrazolone-5-one (HPMPP) and the tertiary amine (R1R2R3N) has been studied by spectrophotometry. A noticeable antago nistic extraction effect was observed in the extraction system under the gi ven conditions. To understand this phenomenon, a preliminary work was perfo rmed to explain the mechanism of this reaction. According to the theory of the corresponding solutions (TCS), the association reaction between HPHBP a nd R1R2R3N was represented and discussed in the organic phase. An associate d species HPMPP . NR1R2R3 formed through hydrogen bonding in chloroform med ium might be the main reason why an antagonistic extraction effect occurs. The association constant between HPMPP and R1R2R3N was calculated to be 2.2 +/-0.1.