Liquid-liquid extraction of ruthenium(III) thiocyanate with hexamethylphosphoramide: Direct spectrophotometric determination in the organic phase

Summary Ru(III)-thiocyanate has been extracted with hexamethylphosphoramide (HMPA) in methyl isobutyl ketone (MIBK). Thus the extractability, sensitivity and selectivity are improved over the simple binary Ru(III) thiocyanate system in spectrophotometric determination of ruthenium in the organic phase. The maximum colour develops on the steam bath, at the acidity range of 1.5–2.5M with HCl and ammonium thiocyanate concentration range of 0.25–0.5M. The colour is completely extractable in MIBK when 1.5–3.0 ml HMPA is used and show maximum absorbance at 570 nm. The colour system obeys Beer's law for 0.7–13 g Ru/ml and the optimum concentration range is 2–13 g/ml. The molar absorptivity and sensitivity are 69401-mole^–1 cm^–1 and 0.0145 g/cm² respectively. The percent relative error is 2.72%. The method is very simple and does not require oxidation and subsequent distillation. The method can be applied in the presence of osmium.

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Flüssig-flüssig-Extraktion von Ruthenium(III)thiocyanat mit Hexamethylpbosphoratnid: spektrophotometrische Bestimmung in der organischen Phase

Zusammenfassung Ru(III)thiocyanat wurde mit Hexamethylphosphoramid (HMPA) in Methylisobutylketon (MIBK) extrahiert. Die Extrahierbarkeit, Empfindlichkeit und Selektivität wurden im Vergleich zum binären Ru(III)-thiocyanatsystem durch spektrophotometrische Bestimmung in der organischen Phase verbessert. Das Farbmaximum entwickelt sich auf dem Wasserbad in 1,5 bis 2,5M Salzsäure bei einer Ammoniumthiocyanat-Konzentration von 0,25–0,5 Mol/l. Mit 1,5–3,0 ml HMPA läßt sich die Färbung vollständig in MIBK extrahieren und zeigt ein Absorptionsmaximum bei 570 nm. Die gefärbte Lösung entspricht dem Beerschen Gesetz für 0,7–13 g Ru/ml; das Konzentrationsoptimum liegt zwischen 2 und 13 g/ml Die molare Absorptivität und Empfindlichkeit betragen 69401·mol^–1·cm^–1 bzw. 0,0145g/cm². Die Methode ist sehr empfindlich; Oxydation und nachfolgende Destillation sind überflüssig. Bei Anwesenheit von Osmium ist dieses vorher zu entfernen.

     

Analytical applications of liquid-liquid phase equilibria: analysis of binary mixtures of chemically similar components

A new, simple and rapid method based on the principle of liquid-liquid phase equilibria has been developed for the analysis of binary mixtures of chemically similar organic compounds. The method does not require elaborate instrumentation and can be used to analyse mixtures of members of homologous series. The application of the method has been illustrated by analysing binary mixtures of n-hexane and n-octane; the maximum uncertainty in this analysis is ~2%.     

N,N'-diphenyldithiomalonamide as a gravimetric reagent for nickel and cobalt

N,N'-Diphenyldithiomalonamide, (C₆H₆. NH. CS)₂CH₂, is found to be a very suitable gravimetric reagent for nickel(II) and cobalt(II). The complexes, of composition Ni(C₁₅H₁₃N₂S₂)₂ and Co(C₁₅H₁₃N₂S₂)₃, are stable and can be weighed after drying at 110°. Separation from base metals has been studied, and the structural interpretation is supported by DTA, TG, infrared and NMR data.     

Studies on mixed ligand complexes involving ligands of biological importance [Ni(II), Zn(II) or Cd(II)-1,10-phenanthroline — or 2,2′-bipyridyl-histidine]

The formation of mixed ligand complexes of the title metal ions with 1,10-phenanthroline (Phen) or 2,2-bipyridyl (Bipy) in presence of histidine (His) has been studied pH-metrically. The stepwise formation of 111 mixed ligand complexes has been inferred from the potentiometric titration curves. Initially, a 11 metal—Phen or—Bipy complex is formed in the lower buffer region and then the addition ofHis takes place resulting in 111 ternary complex formation. The formation constants (K _MAL ) of the resulting mixed ligand complexes have been calculated at 30±1°C (=0.1 KNO₃) and the values have been found to be higher than the formation constants of 12 and lower than those of 11 metal—His complexes. The order of stability in terms of metal ions follows the order, Ni(II)>Zn(II)>Cd(II).With 2 Figures     

Excited singlet (S1)-state interactions of Nile red with aromatic amines

Both steady-state (SS) and time-resolved (TR) studies show that the fluorescence of the dye Nile red (NR) is quenched by various aromatic amines (ArA). Bimolecular quenching constants (kq) from both SS and TR measurements are observed to match well, indicating that the interaction is dynamic in nature. The quenching interaction in the present systems has been attributed to electron transfer (ET) from ArA to excited NR, based on the variations in the kq values with the oxidation potentials of the amines. The kq values calculated within the framework of Marcus' outer-sphere ET theory at different free-energy changes (deltaG0) of the ET reactions match well with the experimental ones, supporting the ET mechanism in the systems studied. The reorganization energy (lambda) estimated from the correlation of the experimental and the calculated kq values is quite similar to the solvent reorganization energy (lambda(s)), calculated on the basis of the solvent dielectric continuum model along with the assumption that the reactants are the effective spheres. Although a modest error is involved in this lambda(s) calculation, the similarity in lambda and lambda(s) values suggests that the solvent reorganization plays a dominant role in governing the ET dynamics in the present systems.     

Nanocrystalline Manganese Iron Oxide as a Charge Storage Electrode

Phase pure nanocrystalline manganese iron oxide [(Mn_0.37Fe_0.63)₂O₃] was synthesized by combustion technique based on propellant chemistry principle employing citric acid as fuel. The synthesized powder was characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), BET, BJH analysis and electrochemical studies for possible application as a charge storage electrode. The average crystallite size was found to be 18.6 nm from XRD analysis. BET analysis yielded the surface area and specific pore volume of the powder to be 22.96 m² g^?1 and 0.0098 cm³ g^?1 respectively. The specific capacitance from cyclic voltammetric studies at scan rate 5 mV s^?1 was found to be about 30 F g^?1 cm^?2 while from charge discharge studies was found to be 27±1 F g^?1 cm^?2. In addition, the material showed appreciable stability during charge‐discharge cycling.