A New Entry for Short and Regioselective Synthesis of [1,2,4]Triazolo[4,3‐b][1,2,4]‐triazin‐7(1H)‐ones

Reaction of benzenediazonium chloride with active [1,2,4]triazin‐3‐ylthio‐methylene compounds 3 afforded the azo coupling products 5 , which yielded [1,2,4]triazolo[4,3‐b][1,2,4]triazin‐7(1H)‐ones 8 upon treatment with sodium ethoxide in ethanol. The latter products 8 were characterized on the basis of alternate synthesis and spectral data. The mechanism of formation of 8 and the regiochemistry of the studied reactions are discussed.     

Darstellung und Atropisomerie von 1‐(2‐Aryl)‐piperidin‐2‐onen

Preparation and Atropisomerism of 1‐(2‐Aryl)‐piperidin‐2‐ones Course and rate of the dehydrogenation of N‐tertiary piperidines dependent on their substitution in 4‐position and on the hydroxy bearing neighbor group were examined, using mercury(II)‐EDTA and the model amino alcohols 1a 1e, 3a 3f, 8a 8f and 10a 10f . The results showed that increasing size of 4‐substituents and neighbor groups too decreased the rate of reaction. The products from the 2‐substituted benzylic alcohols, the 2‐piperidones 7a 7g, 9a 9g and 11a 11g demonstrated atropisomerism. In the case of chiral neighbor groups diastereomeric mixtures were formed.     

Beziehungen zwischen algistatischer Aktivität und physikalisch‐chemischen Eigenschaften von 5‐Amino‐1‐aryl‐1H‐tetrazolen

A series of 20 5‐amino‐1‐aryl‐1H‐tetrazoles was synthesized by diazotation of corresponding 1‐amino‐3‐aryl‐guanidines and tested for growth‐inhibiting activity against autotrophic Chlorella vulgaris cultures. In the used tests the different algae growth was quantified by photometric measurements at 680 nm. From obtained dosage‐effectivity relationships the reciprocal values of isoeffective concentrations c ₅₀ were derived and defined as activity parameters A in QSAR (quantitative structure‐activity relationship) studies. It could be shown that the algistatitic activity (log A) of the tested heterocycles strongly depends on hydrophobicity described by their octan‐1‐ol/water partition coefficients (log P). The calculated linear relationships between log A and log P can be significantly improved by separate treatment of meta‐/para‐ and ortho‐substituted compounds or using an indicator variable to describe the lower activity of ortho‐substituted 5‐ami‐no‐1‐aryl‐1H‐tetrazoles in common regression equations. The results are discussed and compared with analogous QSAR found for earlier tested series of N‐heterocycles and compounds with urea structure.     

Nucleophile Substitution in der 1,3,5-Triazinreihe. IX. Kinetik und Mechanismus der Reaktion von Cyanurchlorid mit 4′-substituierten 4-Aminoazobenzenen

Nucleophilic Substitutions in 1,3,5-Triazines. VII. The Kinetic and ¦ Mechanism of Cyanuric Chloride with 4′-Substituted 4-Aminoazobenzens The kinetic and mechanism of cyanuric chloride reaction with 4′-substituted 4-aminoazobenzens in dioxan-water was studied by conductometry. An addition-elimination mechanism with a monomolecular elimination of chlorine ion at low water concentrations or a nucleophilic attack of 4-aminoazobenzens at high water concentration as low step has been supported by experimental data.     

Dielektrische Erwärmung von Zeolithen mittels Radiowellen – Selektivität,thermo‐chromatographischer Puls und Trocknen mit Wasser

Dielectric heating with radio‐frequency energy can be applied for a wide spectrum of dry or moist zeolites. It is possible to homogeneously heat packed beds in technical scale. The energy absorption strongly varies with the zeolite type enabling selective heating of layered arrangements containing different zeolites. The specific effect of water interacting with the structural cations allows establishing pronounced temperature gradients within a packed bed with varying water content. For distinct materials such as zeolite NaY, a coupled water‐temperature pulse moving through the packed bed can be established. Potential applications for such a so‐called thermo‐chromatographic pulse range from adsorptive catalytic off‐gas cleaning to thermal regeneration of zeolites in the context of gas drying.     

Absorption von CO2 mittels wässriger Natronlauge – Experimente und Simulationen mit dem Ansatz der Hydrodynamischen Analogien

An approach for the simulation of separation processes in packed columns is based on hydrodynamic analogy between complex flow pattern in real equipment units and geometrically simplified model flow and is known as the Hydrodynamic Analogy (HA) approach. In this work, the HA approach was applied to reactive absorption of CO₂ in aqueous sodium hydroxide solution under turbulent gas flow conditions. An extensive experimental study was carried out to measure the CO₂ concentration profiles along the column height. These data provided a basis for a successful validation of the HA approach.     

Inline‐Bestimmung der CO2‐Beladung von wässrigem Diglykolamin in Abhängigkeit von Viskosität und Temperatur

The solvents CO₂ loading is an important factor when evaluating the efficiency of an absorption/desorption process. There is almost no possibility to measure the CO₂ loading inline. Therefore experiments were made to determine a correlation between the CO₂ loading and the solvents viscosity as well as the solvents temperature. The correlation was verified using control tests and values from the literature. An overall maximum relative error under 10 % could be observed. Simultaneously investigations were made to understand if the solvents electrical conductivity and pH value are suitable for a similar correlation.     

Zur physikalisch‐chemischen Charakterisierung von 5‐Amino‐1‐aryl‐1H‐tetrazolen: Charakterisierung von Wasserlöslichkeiten und ihre Beziehungen zu Octan‐1‐ol/Wasser‐Verteilungskoeffizienten

The aqueous solubilities (logS) of a set of 27 5‐amino‐1‐aryl‐1H‐tetrazoles with known biological activity were determined photometrically and correlated with their octan‐1‐ol/water partition coefficients (logP). The otained linear relationship between logS and logP can be significantly improved by a melting point term, an electronic term and several indicator variables describing the deviating solubility behaviour of compounds with hydrogen bonding groups and the dependence on substituent position. The calculated moreparameter equations allow the reliable prediction of aqueous solubilities for 5‐amino‐1‐aryl‐1H‐tetrazoles not yet synthesized or investigated.     

Katalysatorrecycling in der homogenkatalysierten Kreuzmetathese von Ölsäuremethylester und 4‐Octen

The recycling of homogeneous metathesis catalysts is a big challenge in alkene metathesis. Within this contribution the recycling of these catalysts is investigated in the cross metathesis of methyl oleate and 4‐octene as model reaction. Fluid‐fluid separation technique and temperature dependent solvent systems allow the separation of the homogeneously solved catalysts from the metathesis products. The catalyst phase was successfully recycled in multiple recycling runs only with minor loss of yield.     

Synthese von porösen Voll‐ und Core‐Shell‐Glaskugeln zur Trennung von chiralen Anästhetika

For the separation of chiral anesthetic gases suitable support materials for the selectors are necessary. Due to the controlled texture properties porous glass shows a high potential for such applications. In this study porous glass beads with particle diameters of 40 – 400 µm and 2 – 4 mm could be obtained via a special fluidized‐bed reactor and the method of ionotropic gelation. Furthermore, the first core‐shell beads on the basis of porous glasses could be synthesized via the combination of an ion‐exchange induced phase separation and a selective leaching step. The new materials are characterized by a defined mesoporous shell and a non‐porous glass core.