Synthesis of Synthetic Lubricants by Trimerization of 1‐Decene and 1‐Dodecene with Homogeneous Chromium Catalysts

The Cr‐catalyzed trimerization of 1‐decene and 1‐dodecene is a highly selective method to synthesize C₃₀ and C₃₆ olefins. After hydrogenation, these products display very attractive viscosity indices (VI's). Due to the high trimer selectivity of the reaction no additional work‐up is needed to separate C₂₀, C₂₄ or C₄₀₊ oligomers from the product prior to a potential use of these products in synthetic lubricants for automotive applications.     

Chemical Recycling of Polyolefinic Waste to Light Olefins by Catalytic Pyrolysis

Catalytic pyrolysis of post-industrial and post-consumer waste is studied in an auger-type reactor at pilot scale by applying two different zeolites and an amorphous silica-alumina catalyst in-situ at 400–550 °C. Contrary to thermal pyrolysis, of polyolefin-rich waste, high gaseous pyrolysis product yields of approx. 85 wt % are achieved with C₂–C₄ olefin contents of up to 67 wt %. After deactivation by coke deposition catalyst regeneration is proved feasible for maintaining the gaseous product yield and composition. Waste feedstocks with significant nitrogen and halogen heteroatom content are not suitable for in-situ catalytic pyrolysis.     

Einfache Darstellung von 4-Oxo-tetrahydropyrimidinen

Convenient Synthesis of 4-Oxo-tetrahydropyrimidines Enamino-nitriles as 6 or 11 yield 4-oxo-pyrimidines ( 2 ; 2a ; 10 ; 12a – c ) on treatment with cyclohexanone in basic media. Analogous compounds are obtained using acetone, butyraldehyde, benzaldehyde or substituted benzaldehydes.     

Vergleich verschiedener Ansätze zur nachhaltigen Olefinproduktion nach dem MtO- und FT-Verfahren

Olefins are an irreplaceable part of modern organic chemistry. According to the current state of the art, mostly crude oil is used as raw material, which is separated in a refinery. The naphtha fraction is then fed into a steam cracker, in which the hydrocarbons are cracked to the desired olefins. In this short communication, two alternative production processes are compared as a basis for alternative routes to the production of olefins.     

Development and Characterization of a 96-Well Exposure System for Safety Assessment of Nanomaterials

In this study, a 96-well exposure system for safety assessment of nanomaterials is developed and characterized using an air–liquid interface lung epithelial model. This system is designed for sequential nebulization. Distribution studies verify the reproducible distribution over all 96 wells, with lower insert-to-insert variability compared to non-sequential application. With a first set of chemicals (TritonX), drugs (Bortezomib), and nanomaterials (silver nanoparticles and (non-)fluorescent crystalline nanocellulose), sequential exposure studies are performed with human lung epithelial cells followed by quantification of the deposited mass and of cell viability. The developed exposure system offers for the first time the possibility of exposing an air–liquid interface model in a 96-well format, resulting in high-throughput rates, combined with the feature for sequential dosing. This exposure system allows the possibility of creating dose-response curves resulting in the generation of more reliable cell-based assay data for many types of applications, such as safety analysis. In addition to chemicals and drugs, nanomaterials with spherical shapes, but also morphologically more complex nanostructures can be exposed sequentially with high efficiency. This allows new perspectives on in vivo-like and animal-free approaches for chemical and pharmaceutical safety assessment, in line with the 3R principle of replacing and reducing animal experiments.     

Elektrocyclische Synthese von aromatischen Aldehyden aus kettenförmigen Polymethinfarbstoffen

Electrocyclic Synthesis of Aromatic Aldehydes from Chain-shaped Polymethine Dyes Chain-shaped heptamethines form benzaldehyde by an electrocyclic reaction whereas nonamethines give cinnamic aldehyde. The Eyring parameters and the yields of the reaction are determined in dependence on the concentration of hydrogen ions.