New Interfaces for Coupling TLC with TOF SIMS

JPC – Journal of Planar Chromatography – Modern TLC - Two interfaces have been tested for coupling thin-layer chromatography (TLC) with time-of-flight secondary-ion mass spectrometry...     

Preparation and NMR spectra of substituted 2-phenyl-5,5-dialkylimidazolinones

Eighteen substituted 2-phenyl-5,5-dialkylimidazolinones 2 have been prepared by cyclizations of substituted 2-(N-benzoylamino)alkanamides 1. The cyclization of methylamides 1 proceeds at room temperature whereas primary amides are cyclized on boiling. The ¹H and ¹³C nmr spectra of the imidazolinones are presented and the changes in their spectra connected with their protonation in hexadeuteriodimethyl sulfoxide-trifluoroacetic acid mixtures are discussed.     

Stationary-phase effects in gradient high-performance liquid chromatography

The type of the stationary phase for reversed-phase liquid chromatography significantly affects the sample polarity range that can be covered using gradients of organic solvents in water. The polarity range available for gradient separations of samples containing compounds differing in the lipophilic parts of the molecules can be characterized by "gradient lipophilic capacity", Pl, based on the retention of standard compounds with a repeat lipophilic structural unit, such as a methylene group. The gradient lipophilic capacity is also suitable to characterize the separation possibilities of the columns in non-aqueous reversed-phase gradient elution of strongly non-polar compounds, such as triacylglycerols. In the same way, the suitability of various columns for reversed-phase gradient separations of oligomers can be characterized by "gradient oligomer capacity", as demonstrated in the example of oligo(ethylene glycols). To enable a comparison of the properties of stationary phases independent of column efficiency and dimensions, the gradient lipophilic capacity or the gradient oligomer capacity should be normalized for a "standard" column plate number, gradient range and volume (in column hold-up volume units). The gradient lipophilic capacity or the gradient oligomer capacity and the number of compounds that can be resolved during a gradient run decrease as the initial concentration of the strong solvent in the mobile phase increases and (or) the gradient time decreases. These quantities can be used to select a suitable column and to adjust the optimum gradient profile (the initial composition of the mobile phase and the gradient steepness) with respect to the time of analysis and the number of oligomers or other compounds with regular repeat structural groups that can be resolved during the gradient run.     

A Cleavage of O-Hydroxy and p-Hydroxy-1-Aminobenzylphosphonates in a Basic Medium

Abstract

As part of our studies mto the synthesis of benzylic aminophosphonates we have found, that hydroxybenzyl(amino)osphonates underwent a cleavage in strong basic conditions to form aldehydes, amines and phosphorous acid, in high yield.     

Der heutige Stand der Technik von Viskose-, Azetat- und Gelatinefilmen und ähnlichen Gebilden

Ohne Zusammenfassung     

Studies on pyrrolidinones. Synthesis of 2-(5-oxo-2-pyrrolidinyl)-1,3,4-oxadiazoles and 2-(5-oxo-2-pyrrolidinyl)benzimidazoles

The condensation of pyroglutamic acids with 1,2-phenylenediamine leads to 2-(5-oxo-2-pyrrolidinyl)benzimidazoles and the cyclization of disilylated diacylhydrazines derived from the same acids gives 2-(5-oxo-2-pyrrolidinyl)-1,3,4-oxadiazoles. These compounds show weak antifungal activity.     

Numerical modeling of unsteady flow in steam turbine stage

This work deals with numerical solution of unsteady flow in turbine stage. We use models of compressible single-phase flow of air and two-phase flow of wet steam. Presented numerical methods are based on different stator-rotor matching algorithms, as well as different numerical schemes. Numerical results achieved by both methods and flow models are discussed.     

Numerical Solution of Turbine Cascade Flow by Two Equations,EARSM and Bypass Transition Turbulence Models

This work deals with numerical solution of transonic flow in turbine cascades. We compare results achieved by SST, TNT and EARSM turbulence models and we also present results achieved by two equations turbulence model with an algebraic bypass transition model. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

A SIMPLE ONE-STEP SYNTHESIS OF MONOESTERS OF AMINOPHOSPHONIC

Abstract

Alkyl monoesters of N-substituted aminophosphonic acids have been prepared by heating of the corresponding dialkyl aminophosphonates oxalate salts in water. The formed monoesters were separated as crystalline solids from the aqueous reaction mixture.