Synthese von Dithiocarbamidsäureestern des Pyrazols

Synthesis of Pyrazolyldithiocarbonates The reaction of 3-amino-pyrazole 1 with carbondisulfide and alkylating agents in basic conditions to yield different dithiocarbonates 2 – 8 was studied. The dithiocarbonates 2a react with isocyanates to form 1-acyl-5-acylamino-pyrazoles 9 – 10 . Acyl migrations were observed depending on the reaction temperature and the isocyanates. The results obtained enable us to correct some confusions in the literature about thioureas of pyrazoles.     

Mehrdimensionale selektive Umbenetzungsagglomeration – Bestimmung der Reinheit von Graphitagglomeraten

The spherical agglomeration offers the possibility of a separation by two particle properties. The first separation property is the wetting behavior of the solids in relation to the suspension and binding liquid followed by a size separation. The aim of this work is to gravimetrically determine the purity of the resulting graphite agglomerates in a mixture with quartz sand and to correlate this with the wetting properties. The quality of these results is investigated by means of micro X-ray tomography (µ-CT). It has been shown that quartz cannot be wetted with paraffin oil and thus purities of 99.5 % to 99.9 % can be achieved, which was confirmed by the µ-CT results. An influence of the quartz sand particle size could not be verified in the investigated range.     

ACHEMA Pulse – Erfahrungen aus der Sicht von Studierenden

Alle drei Jahre öffnet die ACHEMA in Frankfurt ihre Tore für internationale Besucher und Aussteller aus der Prozessindustrie für chemische Technik, Verfahrenstechnik und Biotechnologie. Die diesjährige Pandemielage führte zur Verschiebung der Präsenzveranstaltung auf 2022. Als Ersatz wurde die ACHEMA Pulse angeboten. Die interaktive Online-Veranstaltung beinhaltete digitale Unternehmens- und Produktprofile und ermöglichte die persönliche Kontaktaufnahme via Chat-, Audio- oder Videofunktion. Zudem wurden an zwei Live-Tagen zahlreiche Fachvorträge, Workshops oder Produktvorführungen angeboten. Hier wird von persönlichen Erfahrungen bei der ACHEMA Pulse berichtet.     

Synthese von Heterocyclen durch C?C-Knüpfung. I. Edelmetall-katalysierte Cyclisierung von Acrylsäure-diallylamid

Synthesis of Heterocycles by C C-Bond Formation. I. Noble Metal Catalyzed Cyclization of Acrylic Acid Diallyl Amide The action of PdCl₂ on acrylic acid diallyl amide 1 leads, by ring closure between the acryloyl group and one of the allyl groups, to a mixture of the five-membered heterocycles 2, 3, 4, 5 and 6 . Additionally, some 7 and 8 is formed by ring closure involving both allyl groups. The latter reaction is predominant on catalysis by RhCl₃, resulting in the formation of 7 besides some 2, 4 and an isomer 14 . With more RhCl₃, quantitative elimination of allyl groups from N-allyl acid amides is observed.     

Entwicklung von Echtzeitmodellen für Kreislaufprozesse der chemischen Absorption

The focus of this paper is the development of fast solvable dynamic mathematical models (real-time models). Real-time models represent a part of model-based tools that can be used to prevent and eliminate emergency situations in industry. In this paper, the development of real-time models is illustrated for chemical absorption, using rigorous dynamic rate-based models. An approach to develop the real-time models is explained in detail and the outcome is presented in the form of mathematical equation systems. The results are shown for the chemical absorption of CO₂ by aqueous monoethanolamine solutions.     

Systematische Entwicklung von Verfahren zur Kornvergrößerung durch Agglomerieren

Systematic Development of Processes for the Size Enlargement by Agglomeration Size enlargement by agglomeration, the technical application of a natural phenomenon, includes the uncontrolled, unwanted, and desired adhesion of solid particles. Latest since the fundamental publications of RUMPF in 1958, it has been recognized as one of the unit operations of mechanical process technology. In spite of its long history and the meanwhile wide distribution of applications, a systematic approach to the development of new processes is not normally used. Although a large interdisciplinary pool of knowledge exists, processes for new applications are almost exclusively based on empirical similarity. Methods for the systematic development of new technologies for the size enlargement by agglomeration and the selection of peripheral systems are discussed. Special considerations related to desired, unwanted or uncontrolled agglomeration in particle engineering are also mentioned.     

Bestimmung des Δg0-faktors von einigen anisotropen kohlenstoffmaterialien

For some graphitizable materials it is shown that after elimination of the skin effect, the ESR-line remains symetrically not only for d = δ but also for d <δ. For carefully prepared carbon samples the ESR-measurements allow the determination of the Δg-factor as well as the corrected Δg₀-factor. A marked increase of the Δg-factor during the heat treatment of anthracene, phenanthrene and pyrene in the temperature range 1700–2400°C is observed. It is shown, that the Δg₀-factor is a direct measure for the orientation degree (S) of the investigated material. An attempt is made to explain the shape of the observed ESR lines.     

Zur heterogenkatalytischen Oxydation und Ammoxydation von Isobuten. IV. Über die Beeinflussung der heterogenkatalytischen Oxydation von Isobuten zu Methacrolein durch n-Buten

On the Heterogeneous-Catalytic Oxidation and Ammoxidation of Isobutene. IV. Influence of n-Butene on the Heterogeneous-Catalytic Oxidation of Isobutene to Methacroleine The influence of n-butenes 2 on the oxidation of isobutenes 1 to methacroleine 3 has been investigated in presence of a catalyst containing Bi, Mo, P, Fe, Mg, Mn, Si and O. Addition of 2 to the gas mixture increase the selectivity and yield of 3 . This fact can be correlated by decrease of oxygen partial pressure in consequence of the dehydrogenation of 2 to butadiene 4 .     

Untersuchungen zur intramolekularen C?C-Verknüpfung von Dienen durch Basenkatalyse. III. [1] Cyclisierung von Diallylaminen

Attempts to Intramolecular C C-Connexions of Dienes by Base-catalysis. III. Cyclization of Diallyl Amines Diallyl alkyl amines 1 are isomerized to the corresponding dipropenyl alkyl amines with potassium on alumina catalyst. The trans, trans-isomers are thermodynamically prefered. If the alkyl group in the diallyl alkyl amines is replaced by an electron-attracting group a cyclization to tetrahydropyridines takes place. The base-catalysed isomerization of diallyl ether 3 does not give a cyclic product. Diallyl sulfide 4 can be isomerized to 5-methyl thiacyclohexen-(2) 4a .     

Umsatz- und Selektivitätsverhalten von Dicobaltoctacarbonyl und Cyclopentadienylcobaltdicarbonyl auf Silicagel-, Alumosilicagel- und Aluminiumoxid-Trägern bei der Hydroformylierung von Hex-1-en

Conversion and Selectivity in Hydroformylation of Hex-1-en with Silica-Gel-, Silica-Alumina-Gel and Alumina-Oxide- Supported Dicobalt Octacarbonyl and Cyclopentadienylcobalt Dicarbonyl The catalytic influence of silica-gel-, silica-alumina-gel- and alumina-oxide-supported Co₂(CO)₈ and CpCo(CO)₂ on the conversion and selectivity in hydroformylation of hex-1-en has been studied at 353 K under 120 bar syngas pressure in acetonitrile. The support systems were prepared by impregnation of SiO₂ (Grace), SiO₂/4% Al₂O₃ (Kali Chemie), SiO₂/11% Al₂O₃ (Kali Chemie) and Al₂O₃ (Kali Chemie) using Co₂(CO)₈ and CpCo(CO)₂ solutions in pentane, dichlormethane and 2-chlorpropane. The results are discussed with regard to some measured relevant support characteristics. The turn over numbers especially those of silica-gel- and silica-alumina-gel supported Co₂(CO)₈ and CpCo(CO)₂ show positive effects in relation to a heterogeneous catalytic process within these reactions.     

Rücklaufmengen und Verwertungswege von Altbatterien aus Elektromobilen in Deutschland

Electro-mobility is considered a key technology for reducing CO₂ emissions in road traffic. However, an aspect that is little addressed in the discussion about the advantages of electro-mobility for the reduction of greenhouse gas emission is the high ecological footprint of the manufacturing of electric vehicles, especially due to the resource-intensive traction battery. In addition to the provision of renewable electricity for vehicle charging, efficient recycling of the battery materials and the longest possible use of the battery systems and components are prerequisites for the sustainable design of electro-mobility. This article provides an overview of the circular value chain of obsolete traction batteries from electric vehicles. Based on a system-dynamics and a discrete-event simulation approach, future return quantities of obsolete traction batteries are estimated on the basis of current diffusion scenarios, and various utilization options from 2nd-life concepts to alternative recycling processes are presented and discussed.     

Acylierung von tautomeriefähigen C-Amino-azolen mit Amidin- bzw. Guanidinstruktur

Acylation of Tautomerizable C-Amino-Azoles with Amidine or Guanidine Structure Amino-azoles can react with electrophiles to give different regioisomers. Stable ringacylated isomers were isolated at low temperatures and under neutral conditions. Acyl migrations are obtained at higher temperatures and under basic conditions to form the thermodynamic stable isomers. The different isomers can be characterized by mean of ¹H-NMR, ¹³C-NMR, IR and mass spectrometry. The results obtained enable us to correct some confusions in the literature about the regioselectivity of the acylation of amino-azoles.