45 research outputs found
Continuous-flow liquid-phase dehydrogenation of 1,4-cyclohexanedione in a structured multichannel reactor
ChemInform Abstract: Unexpected Formation of a 1,2-Dichloroacenaphthylene in a Friedel-Crafts Reaction with Chloral Hydrate.
Internationale Entwicklungslinien im Recht der Auslandsüberweisung : eine vergleichende Darstellung der Regelungen des UNCITRAL-Modellgesetzes, des amerikanischen Art. 4 A UCC, der EU-Richtlinie über grenzüberschreitende Überweisungen und der deutschen Rechtslage /
Unexpected formation of a 1,2-dichloroacenaphthylene in a friedel-crafts reaction with chloral hydrate
An unprecedented rearrangement was encountered during an attempted alkylation of an electron-rich naphthalene with chloral hydrate. The reaction produced a dichlorinated acenaphthylene and presumably involves the intermediate formation of a chloronium ion which is opened to produce the five-membered ring of the final product
Reinfektion nach zweizeitigen Wechsel bei periprothetischer Hüftinfektion. Welche Faktoren spielen ein Rolle?
Impact Tests and Computed Tomography Scans of Prismatic Battery Cells
Recently, the use of prismatic cells in electric vehicles has increased significantly. Unlike the cylindrical or pouch format, the prismatic cell format has not been sufficiently investigated. In this study, quasi-static mechanical tests are performed on prismatic cells. The tests include a cylindrical and a hemispherical impactor that mechanically load the cells in all three spatial directions. In both in-plane directions, a cell stack consisting of three cells is tested to capture the influence and loading of the outer cells of a cell stack. It is found out that, in the in-plane tests, short-circuiting occurs first in the outer cells and subsequently in the middle cell, which is targeted by the impactor. This result can also be supported by computed tomography scans. The results illustrate that, when evaluating the crash safety of battery cells, several cells should always be tested in order to capture the different loading of the cells
Kinetic and Scale-up Investigations of a Michael Addition in Microreactors
Microreactors are an efficient tool
for process development and
intensification. However, the scale-up from lab studies to small-scale
commercial production is challenging, since a change in the channel
dimensions requires good knowledge of heat and mass transfer phenomena.
In this work, complete process development for an exothermic Michael
addition is presented. In a systematic scale-up approach, kinetic
studies and experimental characterization of the employed reactors
provide key parameters for detailed reactor modelling. The residence
time distribution, reactant mixing, and removal of reaction heat are
taken into account. It is exemplarily shown how preliminary experiments
can be the basis for the prediction of scale-up effects and the development
of a continuous production process. Plug flow behavior and short mixing
times could be confirmed for all investigated flow reactors. Furthermore,
interactions of reaction kinetics and the formation of hot spots in
the reactor channel were investigated. For the examined reaction,
the simulations predicted the product yield under production conditions
in good accuracy
Verbesserung der Gewinnungstechnik im Floez Zollverein 7/8 durch Einsatz einer Gleithobelanlage 9.30 v der GEW Luenen
SIGLEDEGerman
Fast and Efficient Acquisition of Kinetic Data in Microreactors Using In-Line Raman Analysis
This study demonstrates
that a microreactor setup with fast in-line
reaction monitoring by Raman spectroscopy can be a highly efficient
laboratory tool for kinetic studies and process development. Using
a coaxial probe and commercial spectrometer to perform real-time measurements
in the microchannel prevents the need for reaction quenching, sampling,
and time-consuming off-line analysis methods such as GC or HPLC. A
specially designed, temperature-controlled aluminum plate microreactor
was developed and tested in the exothermic synthesis of 3-piperidino
propionic acid ethyl ester by Michael addition. In-line measurements
through a fused quartz screen in the reactor channel, which had an
increasing cross-sectional area, allowed time-series kinetic data
to be collected over nearly the full range of reaction conversions.
An optimum flow rate range in which nearly ideal plug flow behavior
can be assumed was identified. Furthermore, a time gradient was applied
to the reactant flow rates, and the product concentration was simultaneously
and repeatedly measured at various locations in the reactor channel.
With this approach, the experiment duration and material consumption
are significantly reduced relative to those of conventional steady-state
experiments. Two hundred data points with residence times ranging
from 0.3 to 49 s were collected in less than 1 h. Thus, this method
can be used for the high-throughput screening of reaction parameters
in a microreactor