Peter Mühl

LIQUID-LIQUID EXTRACTION OF METAL IONS WITH AMIDO PODANDS

Abstract The extraction properties of ami do podands 1 - 3_ have been investigated. The ether dicarboxylic acid diamide i shows a clear preference for the extration of rare earth metal ions Yb(III)-, La(III) and the alkaline-earth metal ions Ca(II), Sr(II) as well. Due to the presence of the carboxylic group the ether dicarboxylic acid monoamide, 2. extracts the ions of the 3d-elements Cu(II), Co(II) and Zn(II), too. High distribution ratios have been obtained mainly for soft and medium-hard transition metal ions with the N-alkyl imino diacetic acid diamide 3_. Under the experimentally chosen conditions, alkali metal ions such as Na(I) and K(I) are practically not extracted by the investigated amido podands.

LIQUID-LIQUID EXTRACTION OF STRONTIUM WITH AMIDO PODANDS

Abstract The extraction of strontium picrate with various open-chain ether dicarboxylie acid diamides, ether dicarboxylie monoamido acids and N-alkyl imino diacetic diamides has been investigated. The influence of pH, diluents and counter anions on the extraction equilibrium was studied. The extraction results are discussed in relation to the structure of the investigated amido podands and compared with crown compounds and open-chain structure analogous. The performed investigations show clearly the amido group is decisive for the extraction properties.

Liquid-liquid extraction of alkaline earth and alkali metal ions with acylpyrazolones

Abstract The extraction of calcium, magnesium and lithium with 1-phenyl-3-methyl-4-stearoylpyrazol-5-one and with 1-phenyl-3-methyl-4-lauroylpyrazol-5-one was studied and separation factors were determined. A good separation of alkaline earth metal ions from lithium chloride can be achieved. 1-Phenyl-3-methyl-4-benzoylpyrazol-5-one in the presence of trioctylphosphine oxide is also suitable as an extractant for lithium whereas other alkali metals are extracted to only a minor extent. The distribution constant of this ligand was obtained for the investigated system. From the extraction data, stability constants of the formed complexes were determined.

Modellierung von Extraktionsgleichgewichten auf der Grundlage des Marquardt-Verfahrens

Abstract ( Modelling of liquid-liquid extraction equilibria on the basis of the Marquardt algorithm. ) Graphical methods are inadequate for detailed evaluation of liquid-liquid extraction data in complicated systems. Computerized evaluation can be used to estimate not only the extraction constants but also the model which gives the best description of the system studied. The Marquardt algorithm is particularly suitable for use with personal computers. The computer analysis of data is discussed; its application to the extraction of silver nitrate with 1,5-bis( n -hexylthio)pentane in benzene is given as an example.

LIQUID-LIQUID EXTRACTION STUDIES OF METAL IONS WITH DITHIACROWN COMPOUNDS

ABSTRACT The extraction properties of dibenzo-1, 10-dithia-[18]crown-6 compounds have been investigated. Especially thiophilic metals are effectively extracted. The extraction of Ag(I), Pd(II) and Au(III) is much greater than that of Hg(II) or Cu(I). Alkali and alkaline earth metals are not extracted. The experimental results show the coordination of metal ions with sulfur is decisive for the extraction. The variation of the subetituents at the macrocyclic ring from CH3- t o CH2Cl-groups influences the extraction power considerably. In contrast, the substitution on the benzo groups shows a less strong effect. The influence of diluents and counter anions on extraction are comparable with results in known crown ether systems. Synergistic extraction is observed for silver and mixtures of dithiacrown compounds and HDEHP, n-caprylic acid or TBP.

Extraktionsverhalten methylsubstituierter chinolin-8-ole gegenüber kupfer

Abstract Extraction behavior of methyl-substituted 8-quinolinols towards copper). The distribution of 2-, 5-, and 7-methyl-8-quinolinols and the extraction of their copper chelates are reported for the chloroform/water system. The stability constants for the copper complexes were calculated. From the acidity and distribution constants of the isomeric 8-quinolinols and the stability and extraction constants of the copper chelates, 7-methyl-8-quinolinol provides the highest complex stability and is the best extractant of the series.

Extraktion von alkali- und erdalkalimetallionen mit (sym-dibenzo-14-krone-4-oxy)- und (sym-dibenzo-16-krone-5-oxy)-carbonsäuren

Abstract (Extraction of alkali on alkaline earth metal ions with (sym-dibenzo-14-crown-4-oxy)- and (sym-dibenzo-16-crown-5-oxy)-carboxylic acids.) The extraction of lithium, sodium, potassium, calcium and some other metal ions with dibenzo-4-crown-4-oxy- and dibenzo-16-crown-5-oxycarboxylic acids containing the groups -CH 2 COOH, -(CH 2 ) 2 COOH, -(CH 2 ) 3 COOH, -CH(C 2 H 5 )COOH and -CH(C 4 H 9 )COOH was studied. The extraction increases as a function of the lipophilic character of the carboxylic acid group. Calcium, barium and strontium ions are better extracted than Li + , Na + and K + ; there are only small differences among the alkaline earth metal ions. Evaluated from the extraction data, the composition of the extracted species was 1:1 (metal/ligand) for Li + , and 1:2 for CaCa 2+ ; Na + and K + favour the formation of 1:2 complexes with dibenzo-14-crown-4-derivatives bbut 1:1 complexes with dibenzo-16-crown-5-oxy-carboxylic acids. The dependence of the distribution ratio on pH does not provide unequivocal evidence for the composition of the extracted compounds.

Synthese und extraktionseigenschaften von 2-(sym-dibenzo-14-krone-4-oxy)essigsäure bzw. -n-hexansäure

Abstract ( Synthesis and extraction behaviour of 2-(sym-dibenzo-14-crown-4-oxy)-acetic and -hexanoic acid ) An improved synthesis for carboxylic acid derivatives of dibenzo-14-crown-4- using sodium amide is described. The reagents were studied for the extraction of alkali and alkaline earth metal ions. The dependence of the metal distribution on pH and ligand concentration is used to evaluate the composition of the extracted species. (2-sym-Dibenzo-14-crown-4-oxy)hexanoic acid is a very good extractant for alkaline earth metal ions but is also if interest for lithium.

Liquid—liquid extraction of transition metals with acylthioacetamides

Abstract The extraction behaviour of acylthioacetamides, R 1 —CO—CH 2 —CS—NR 2 R 3 , was studied for a series of transition metals. The highest distribution ratios were obtained with benzoylthioacetanilide. Complexes with acylthioacetamides which were completely substituted on the amide group were extracted slowly. The ranking of the extraction characteristics is related to the different pK a values of the compounds used. Polymerization and solvation reactions can be excluded at metal concentrations of ⩽ 10 -3 mol dm -3 and extractant concentrations of ⩽10 -1 mol dm -3 , respectively. Decreasing extractability, Cu(II) > Zn(II) > Ni(II) > Co(II) > Cd(II), corresponds to the stability constants of the extracted metal chelates. Iron(III) cannot be extracted at pH ⩽3; Hg(II), Pd(II), and Au(III) are extracted readily over a reasonably wide pH range. The different extraction constants for zinc(II) and cadmium(II) permit an effective separation of these ions with benzoylthioacetanilide.