Heterogeneous Catalytic Acylation of Benzo Crown Ether Using Acetic Anhydride

Benzo-15-crown-5 macrocycle has been acetylated using acetic anhydride and a series of cation exchanged clays. This acetylating method has great advantages such as the significant reduction of the formation of by-products, lower price and the possibility of environmental friendly process. Yields as high as 80% for the acetylated compound are reached in short times.     

On Parabolic Trigonometry in a Degenerate Minkowski Plane

A Minkowski plane is considered having a parabola as indicatrix curve and taking for its center the vertex of the parabola causing by this a degeneration of the Minkowski geometry. After a short discussion of the concept of the length and angle, the trigonometrical functions of this geometry has been calculated and their basic properties explained. A two-parameter pseudogroup of generalized rotations has been found as an analogon of the Lorentz transformation group in special relativity. The theory has applications to thermodynamics.     

Gaschromatographische Bestimmung von Methoxyacetaldehyd neben Formaldehyd, Acetaldehyd und Glykolmethyl?ther

Zusammenfassung Eine gaschromatographische Methode zur Bestimmung von Formaldehyd, Acetaldehyd, Methoxyacetaldehyd und GlykolmethylÄther nebeneinander wurde entwickelt. Die Methode leistet gute Dienste bei der Kontrolle der ersten Stufe der Synthese von d-Cycloserin. Das Studium des Einflusses der verschiedenen Parameter auf die Ausbeute und der bei der heterogenen Katalyse verlaufenden Nebenreaktionen wird ermöglicht.

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Summary A gas-chromatographic method has been worked out for the determination of formaldehyde, acetaldehyde, methoxy acetaldehyde and glycolmethyl ether in presence of each other. It can be advantageously used for controlling the first stage of the synthesis of d-cycloserine. It also permits an investigation of the influence of the different parameters on the yield and an examination of the side-reactions involved in the heterogenous catalysis.

     

Modulation spectroscopy of gold: Comparative studies

An apparatus has been constructed to investigate the modulated optical properties of thin films. We report here the piezo- (PR), thermo- (TR) and electroreflectance (ER) spectra for a thin gold film, 800 Å thick. The experimental results show that the PR and TR spectra are similar to each other but quite different from the ER one. A new interpretation of ER is given in which this phenomenon is assumed to be due to a surface current related to a change in the electron density. The agreement between the theoretical and experimental results is encouraging.     

Comparison of trace analytical results obtained with different hollow cathode discharge lamps

Summary Detection limit and sensitivity of trace analysis of powdered samples have been tested using hollow cathod discharge lamps made in our laboratory. We found some special problems for trace analysis with hollow cathode excitation; such problems are the energy tuning and the pressure dependence of spectral lines. Results obtained with improved hollow cathode discharge lamp and with water cooled hollow cathode discharge lamp are compared to each other.

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Vergleich spurenanalytischer, mit verschiedenen Hohlkathodenlampen erzielter, Ergebnisse

Zusammenfassung In Pulveranalysenergebnissen wurde die mit den von uns entwickelten Entladungsröhren erzielten Nachweisgrenzen sowie die Veränderung des Nachweisvermögens geprüft. Es wurde experimentell nachgewiesen, daß bei der Hohlkathodenentladung auch spezielle spurenanalytische Probleme entstehen, wie die Energieabstimmung und die Druckabhängigkeit der Spektrallinien. Die Ergebnisse der modifizierten und die der wassergekühlten Hohlkathodenentladung wurden zusammengestellt und verglichen.

     

Mössbauer study of the substituent effect in mixed ligand complexes of europium (III)

A series of europium (III) mixed ligand complexes containing phenanthroline, benzoic acid and their derivatives, respectively, as ligands, were investigated by Mössbauer spectroscopy. The substituents changed the electron density on the donor atoms of the ligands by their electrophilic or nucleophilic nature and changed the stereochemistry of the coordination sphere by their different space requirement. Both effects were reflected in the isomer shift values. The basicity changes on the donor atoms due to the substituents were characterized by the Hammett 6 values of latters. The correlation betweenEu isomer shifts and the Hammett 6 values of the corresponding substituents on the ligands of otherwise analogous europium (III) compounds indicated the binding mode in the complexes /1/.     

Gas chromatography-mass spectrometry-Fourier transform infrared spectrometry and high-performance liquid chromatographic characterization of mononitro- and dinitro-isomers from the nitration of N,N-dimethyldiphenylacetamide

Gas chromatographic retention data, Fourier transform infrared and mass spectrometric (electron impact, electron attachment and methane chemical ionization) profiles are reported for the products of mono- and dinitration of N,N-dimethyldiphenylacetamide. Differentiations of analytical importance among isomers could be gathered by the study which led to their complete identification.