Chromatographic study of anionic complexes

Summary In this paper the variation of diffusion, through filter paper strips by the ascending method, of citrate complexes of Cu²⁺, Ni²⁺, Co²⁺ and Fe³⁺ has been studied using 50%, 55% and 60% ethanol as solvents. The R_f value is found to be less with higher concentrations of ethanol used. It has been noted that with 50% ethanol the R_f value increases with the addition of citrate and finally tends to become constant with high concentrations of citrate ions. In 55% ethanol the R_f value becomes constant at a later stage. In 60% ethanol it is noted that the R_f value does not change with small additions of citrate, but on increasing its concentration the R_f value begins to diminish.Part II see Z. analyt. Chem. 165, 81 (1959).     

Microdetermination of calcium, strontium and barium using the ring-oven method

Summary The ring-oven technique is recommended for the identification and determination of Ca, Sr and Ba in the micro scale. The elements are first converted into their nitrates and Ca is washed out by a mixture of absolute alcohol and ether. Sr is then separated from Ba as soluble diethyldithiocarbamidate in alcohol-ether. The rings obtained are developed by rhodizonate (Sr, Ba) and pyrogallol (Ca). Quantitative determinations are possible by comparison with standard rings. 0.60 g of Ca, 1.31 g of Sr and 8.24 g of Ba can be determined with an error lower than 6%.

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Zusammenfassung Zur Trennung und Bestimmung von Ca, Sr und Ba im Mikromaßstab wird die Ringofen-Technik empfohlen. Die drei Elemente werden dabei zunächst in die Nitrate übergeführt und Ca mit Äther-Alkohol ausgewaschen. Sr und Ba werden anschließend mit Diäthyldithiocarbamidat behandelt und Sr mit Äther-Alkohol abgetrennt. Die Identifizierung erfolgt mit Pyrogallol (Ca) bzw. Rhodizonat (Sr, Ba). Durch Vergleich mit Standardproben ist eine quantitative Bestimmung möglich. Hierbei können noch 0,60 g Ca, 1,31 g Sr und 8,24 g Ba mit einem Fehler < 6% erfaßt werden.

     

An efficient synthesis of pyrroles by a one-pot, three-component condensation of a carbonyl compound, an amine and a nitroalkene in a molten ammonium salt

A one-pot, three-component condensation of a carbonyl compound, an amine and a nitroalkene leading to an efficient synthesis of alkyl-substituted pyrroles has been carried out in molten tetrabutylammonium bromide. Neither a catalyst nor an organic solvent is required for this reaction and the molten ammonium salt is recyclable.     

Microdetermination of scandium,yttrium and lanthanum: Use of Chrome Azurol S as a chromogenic reagent

Summary Optimum conditions for the spectrophotometric determination of scandium, yttrium and lanthanum using Chrome Azurol S as a chromogenic reagent are described. The studies include the determination of the range for adherence toBeer's law, p_H range of stability of the chelates, sensitivity and the influence of foreign ions.

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Zusammenfassung Eine Arbeitsweise für die spektrophotometrische Bestimmung von So, Y und La mit Chromazurol S als Farbreagens wurde angegeben. Die Gültigkeit des Beerschen Gesetzes, die Stabilität der Chelate in Abhängigkeit vom P_h, die Empfindlichkeit der Reaktion und der Einfluß von Fremdionen wurden untersucht.

     

Spontaneous formation of vesicles and chiral self-assemblies of sodium N-(4-dodecyloxybenzoyl)-L-valinate in water

A novel N-acylamino acid surfactant, sodium N-(4-dodecyloxybenzoyl)-L-valinate (SDLV), has been synthesized. The aggregation behavior of the surfactant in aqueous solution has been studied by surface tension, fluorescence probe, microscopy, and dynamic light scattering (DLS) techniques. The amphiphile has a very low critical aggregation concentration (cac). These studies have suggested formation of large bilayer structures in water. The mean apparent hydrodynamic radius, RH, of the self-assemblies in dilute aqueous solution obtained from DLS measurements confirmed formation of large aggregates. The FT-IR spectra of the amphiphile have indicated strong intermolecular amide hydrogen bonding in the self-assemblies in aqueous solution. The microenvironment of the fluorescence probes is highly nonpolar and viscous in nature. The circular dichroism (CD) spectra of SDLV were recorded in water and in a 1:1 water-methanol mixture. The CD spectra have indicated the presence of chiral aggregates in aqueous solution above the cac. The microstructure of the aggregates has been studied by use of optical and transmission electron microscopy. Both types of micrographs have shown the presence of a variety of morphologies including giant spherical vesicles, tubules, twisted ribbons, and helical strands in aqueous solutions.     

Chromatographic study of anionic complexes

Summary In this paper the variation of diffusion, through a filter paper strip by the ascending method, of cuprioxalate complex has been studied. Various mixtures of Cu+^2üC₂O ₄ ^2– ions have been investigated. It has been noted that till there is a precipitation, the R_f values tend to decrease and finally reach nearly to zero, when the oxalate precipitates completely. With redissolution of the precipitate to form the complex anion, R_f values increase again to a maximum and then have a slight tendency to diminish. No tailing occurs in the chromatograms in cases where the copper has passed into the anion.     

Palladium-catalyzed site-selective arylation of symmetric dichlorobenzaldehyde to non-symmetric diaryl benzaldehyde via Suzuki coupling

Arylation of 2,6-dichlorobenzaldehyde by aryl boronic acids via site-selective Suzuki coupling catalyzed by PdCl₂ supported on 4 Å molecular sieves produces 2-aryl-6-chlorobenzaldehyde which on subsequent coupling with a different aryl boronic acid in the presence of Pd(OAc)₂–NHC ligand leads to non-symmetric diaryl benzaldehyde in good overall yield.