ABSTRACT
The extraction of lanthanides from an aqueous acetatechloride medium into cyclohexane solutions of trifluoroacetylacetone, hexafluoroacetylacctone, 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione and tri-n-butyl phosphate was studied. The extraction properties of other fluorinated aliphatic beta-diketones and fluoroorganophosphates were also investigated. The efficiency of the extraction of the lanthanides, the composition of the complexes transferred to the organic phase and the extraction and stability constants for the synergic reactions were determined. Synergic extraction, as a technique for the preparation of lanthanide species, was evaluated for compatibility with subsequent gas chromatography. The lanthanides were found to be rapidly and quantitatively transferred into organic phases containing mixtures of fluorinated aliphatic beta-diketones and TBP. The resulting mixed complexes that contained fully fluorinated beta-diketones had a distinct stoichiometry and were thermodynamically more stable dan similar mixed complexes of partially fluorinated beta-diketones. These properties of the synergic systems allow precise control of the formation of anhydrous complexes in the organic phase and are compatible with the use of these systems for gas chromatography.
ABSTRACT
The thallium-indium alloys were dissolved in sulphuric acid (1 + 1). In this medium thallium remained in the univalent state and could be determined directly, without a separation, by an oxidation-reduction titration with potassium bromate. The indium was determined directly with an EDTA titration. Ascorbic acid was added to maintain the thallium in the univalent state, which did not interfere. Ascorbic acid also masked any interfering tervalent thallium by effectively reducing it to the univalent state. Sharp end-points were obtained for both titrations, which were carried out in the temperature range of 50-95 degrees . The method offers excellent precision and accuracy.
ABSTRACT
The conditions for the spectrophotofluorometric determination of terbium and europium, in solutions of potassium carbonate, have been established. The apparent excitation and fluorescence wavelengths used, respectively, are 245 mmu and 550 mmu for terbium and 400 mmu and 620 mmu for europium. The fluorescence varies linearly with the concentration of terbium and europium in the range 0.3-70 mug, of terbium/ml and 4-800 mug of europium/ml. Large amounts of gadolinium, lutetium and yttrium do not interfere. Cerium(IV) interferes seriously.
ABSTRACT
The ultraviolet and visible spectra of copper dimethyl-glyoxime exhibit significant shifts as the solvent medium is varied; no such changes were observed for nickel dimethylglyoxime and nickel ethylmethylglyoxime. The observed variations in the metal-to-ligand charge transfer bands for copper dimethylglyoxime are attributed to slight changes in the nature of the Cu-N bonds; the absence of such changes in the corresponding band in nickel dimethylglyoxime is taken to indicate an insignificant variation in the Ni-N bonds of the two chelates of nickel in different solvents. The presence of small amounts of n-butylamine changed the spectra of copper dimethylglyoxime very significantly while 100-fold excesses of n-butylamine did not alter the spectra of the chelates of nickel. These changes in the spectra of copper dimethylglyoxime were used to establish the assignment of the metal-to-ligand charge transfer band. Finally, in agreement with other investigators, it is concluded that the difference in solubility between copper dimethylglyoxime and nickel dimethylglyoxime in polar solvents is due to the greater tendency of copper dimethylglyoxime to complex with solvent molecules. The higher solubility of nickel ethylmethyl-glyoxime in organic solvents is attributed to stronger crystal forces in both nickel dimethylglyoxime and copper dimethylglyoxime. The stronger forces in copper dimethylglyoxime are due to the well-established Cu-O bonds, and the stronger forces in nickel dimethylglyoxime are attributed to Ni-Ni interactions.
