William F. Wagner

Rare-earth trishexafluoroacetylacetonates and related compounds☆

Abstract Rare-earth trishexafluoroacetylacetonates, Ln(hfac)3·nH2O, have been prepared and characterized by chemical analyses, infra-red spectra, and X-ray powder diffraction patterns. Two series of hydrates exist: Ln(hfac)3·3H2O (Ln = LaNd) and Ln(hfac)3·2H2O (Ln = LaLu). No evidence for a lower hydrate was found. A mixed ligand chelate, Ln(hfac)2CF3CO2·2H2O, is a byproduct of the tris chelate preparations. Several series of salts were also prepared, including NH4Ln (hfac)4·nH2O (n = 0 and 1 for Ln = LaNd; n = 0 for Ln = SmLu), pyHLn(hfac)4·nH2O (n = 0 and 1 for Ln = LnNd; n = 0 for Ln = SmLu), and (pyH)2Ln(hfac)5 (Ln = LaNd). Ln(hfac)3·3H2O. NH4Ln(hfac)4·H2O, and pyHLn(hfac)4·H2O are reversibly converted with great ease to Ln(hfac)3·2H2O, NH4Ln(hfac)4, and pyHLn(hfac)4, respectively. Most of the chelates studied are probably eight-co-ordinate, including Ln(hfac)3·3H2O, NH4Ln(hfac)4·H2O, and pyHLn(hfac)4·H2O, but (pyH)2Ln(hfac)5 may be ten-co-ordinate.

Characteristics of the solvates of the rare-earth acetylacetonates

Abstract Chemical analyses, X-ray diffraction patterns, vapour-pressure studies and cryoscopic molecular weight determinations of nine rare-earth acetylacetonates prepared by conventional methods show that only two hydrates are formed: the monohydrate and the trihydrate. None of the conventional methods of preparation and drying yielded the anhydrous rare-earth acetylacetonates. Vapour pressure studies showed the formation of a solvate containing two moles of methanol per mole of chelate. Values of Δ H for the decomposition of the methanol disolvate indicate that the bond energy between the chelate and methanol is equivalent to strong hydrogen bonding. Solubility and cryoscopic molecular weight studies show that the chelates dissolve in benzene to form the monobasic compounds which polymerize, especially upon heating.

Extraction of the lanthanides with acetylacetone

Abstract Acetylacetone extracts the lanthanides from aqueous solution at pH values between four and six. The solubility and extractability of the rare earth acetylacetonates vary with the ionic radii of the central metal ions. Extraction of the lanthanides with acetylacetone is enhanced by the decrease in basicity of the central metal ion. While separations based on differences in the pH 1 2 values of these chelates would be at best fractional, the variations in solubility and in the partition coefficients of these chelates make separations possible.

ACETYLACETONE ADDUCTS OF RARE EARTH TRIS-THENOYLTRIFLUOROACETONATES IN SYNERGISTIC SOLVENT EXTRACTION.

The synergistic effect of acetylacetone (Hacac) in the extraction of rare earth thenoyltrifluoroacetonates (Mtta3) was attributed to the formation of the species Mtta3 · Hacac. The adduct was isolated and identified by chemical analyses and i.r. spectra.

Some adducts of rare earth acetylacetonates

Abstract Several previously unreported adducts of rare earth acetylacetonates have been prepared and characterized by chemical analyses (including Karl Fischer titrations for water), i.r. spectra, and X-ray powder diffraction patterns. These adducts include compounds with methanol, ethanol, propanol, butanol, dioxane, pyridine, 2- and 4- methylpyridine, 2,4- and 2,6-dimethylpyridine, acetone, benzene, and acetylacetoneimine. Most of the adducts contain one or more moles of water per mole of chelate. It is concluded that when water and an organic donor are both present, only the water is coordinated to the rare earth ion and that the organic donor molecules are hydrogen-bonded or held in the crystal by lattice forces.

Synergistic solvent extraction of rare earths by mixtures of thenoyltrifluoroacetone and acetylacetone

Abstract The synergistic extraction of the thenoyltrifluoroacetonates of neodymium, samarium, gadolinium, dysprosium, and erbium by acetylacetone was studied using mixtures of the two β-diketones. The synergistic shift of the extraction curves decreases the separability of the rare earth chelates.

Countercurrent extraction of the rare-earth acetylacetonates☆

Abstract The countercurrent distribution behaviour of the rare-earth acetylacetonates in different solvent systems has been studied. Solubilities of the chelates in various solvents were determined in order to obtain data on the partition coefficients. The hydrated rare-earth acetylacetonates hydrolyze upon dissolving in benzene. Excess acetylacetone prevents hydrolysis and lowers the solubility of the chelates in the organic phase. A four-component system using acetylacetone, chloroform, methanol and water was developed. The acetylacetone in the chloroform phase suppressed hydrolysis and the methanol in the aqueous phase increased the solubilities of the chelates by a factor of ten over the solubilities in the water-acetylacetone system.

Electrochemical studies of potassium ferrate(VI)

The electrochemical reduction of potassium ferrate(VI) in 6N-KOH occurs in three steps, at approximately +0.3, −0.7, and −1.4 V vs. Hg/HgO, 6N-KOH. The first reduction appears as a voltammetric wave on a platinum electrode and the second two are observed as polarographic waves with a dropping mercury electrode. Controlled potential coulometric, voltammetric, and chronopotentiometric studies indicate the reduction proceeds stepwise first to iron(III), then to iron(II) and finally to iron(0).

A simple tantalum strip atomizer for the flameless atomic absorption determination of trace metals in water

ZusammenfassungDie elektrische Erhitzung des Tantalstreifens wird mit Hilfe einer preisgünstigen Energiequelle (Powerstat/Transformator) vorgenommen, die leicht anstelle des Brenners in den üblichen Geräten untergebracht werden kann. Das Verfahren wurde zur Bestimmung von Ag, Cd, Pb und Zn in Leitungswasser sowie von Zink neben Albumin angewendet.SummaryA simple and efficient tantalum strip atomizer is described suitable for use in the atomic absorption determination of trace elements in water. The cell operates with an inexpensive Powerstat-transformer unit to provide the necessary electrothermal heat for atomization. It can be easily fitted in the place of the burner in atomic absorption instruments. The atomizer has been used to determine Ag, Cd, Pb, and Zn in tap water samples and Zn in the presence of albumin.