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The distribution of copper(II) and zinc(II) chelates with three β-diketones, acetylacetone (AA), trifluoroacetylacetone (TFA), and hexafluoroacetylacetone (HFA) between carbon tetrachloride and aqueous sodium perchlorate solutions at 0.1m, 1m, and 3m has been determined at 25°C as a function of the concentration of the dissociated chelate anions. The stability constants for the metal chelates in the aqueous phase and the two phasedistribution constants for the uncharged complexes have been determined by a graphic analysis of the distribution data. The distribution was also measured when the carbon tetrachloride phase was added with tributylphosphate (TBP) or trioctylphosphine oxide (TOPO) and the adduct-formation constants of the uncharged chelate with these ligands have been determined by a graphic analysis of the increase in the distribution ratio as a function of the ligand concentration. The results are as follows: (i) Copper(II) forms first and second complexes with these chelating ligands in the aqueous phase, whereas zinc (II) forms the third complex (except with HFA) besides the first and the second ones; the complexes are more stable in the ligand order of AA>TFA>HFA. (ii) The stability constants of the copper(II) complexes are much higher than those of the corresponding zinc(II) complexes. (iii) The distribution constant of the uncharged copper(II) complex is higher than that of the corresponding zinc(II) complex. (iv) No remarkable relation has been found among the distribution constants of the chelating acid and those of the uncharged metal chelates. (v) The adducts of the metal chelates are more stable in the ligand order of HFA>TFA>AA. The zinc(II) complex forms more stable adducts than does the corresponding copper(II) complex, and TOPO forms more stable adducts than does TBP. (vi) Changes in the concentration of the background salt alter the stability constants of the metal chelates and the distribution constants of the uncharged chelate (salting-out); the effects are, however, very complicated. On the basis of these results, the distribution constants of the uncharged chelates were discussed from the standpoint of the interactions of the central metal ions in the complexes with the water molecules, and a qualitative relationship between these interactions and the stabilities of the adduct chelate complexes was pointed out.

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Aqueous solutions containing sodium hydroxide and sodium perchlorate at various mixing ratios, 1 m Na-(OH, ClO4), were equilibrated with several organic solvents containing 2-thenoyltrifluoroacetone (TTA) at 25°. From the measurements of the hydrogen-ion concentration of the aqueous phase, the (KD+l)Ka−1 values, where KD is the distribution constant and Ka is the acid dissociation constant of TTA, were obtained; they were, 107.17(hexane), 107.74 (CCl4), 108.01 (C6H6) and 108.17 (CHCl3). From the values of KD obtained in another study, the value of Ka was determined to be 10−6.28. However, a much lower value than that expected was obtained for the MIBK system; this was due to the extraction of sodium (I) with TTA. The extraction was also confirmed by the distribution experiments of sodium (I). The extraction constant, Kex=[NaA]org/[Na+] [A−] (where A− is the TTA anion), was found from these results to be 100.86 in 1 M NaClO4 and 100.79 at an infinite dilution.