Parallelization and Performance Optimization

Lindborg H, Eide V, Unger S, Henriksen ST, Jakobsen HA (2004) Parallelization and performance optimization of a dynamic PDE ractor model for practical applications. Computers and Chemical Engineering 28 1585-1597... 

Today, multi-parallel synthesis lies at the forefront of organic and medicinal chemistry, and plays a major role in lead discovery and lead optimization programs in the pharmaceutical industry. The first solid-phase domino reactions were developed by Tietze and coworkers [6] using a domino Knoevenagel/hetero-Diels-Alder and a domino Knoevenagel/ene protocol. Reaction of solid-phase bound 1,3-dicarbonyl compounds such as 10-22 with aldehydes and enol ethers in the presence of piperidinium acetate led to the 1-oxa-1,3-butadiene 10-23, which underwent an intermolecular hetero-Diels-Alder reaction with the enol ethers to give the resin-bound products 10-24. Solvolysis with NaOMe afforded the desired dihydro-pyranes, 10-25 with over 90 % purity. Ene reactions have also been performed in a similar manner [7]. 

Synthesis of the orthogonally diprotected homospermidine 91 and the monoprotected homospermidine 92 was performed on SynPhase Crowns with a carbonate handle. The optimization of the reactions was aided by rapid handling of Crowns and performing reactions in parallel. 

Kleiner et al. [23] theoretically and experimentally investigated forced air-cooling, which employs microchannel parallel plate fin heat sinks and tubes. Optimization was performed and design trade-off was studied. Tube sizes were observed to have a significant impact on optimum heat sink design. Air-cooled heat sinks are used for micro channel heat sinks with heat loads less than 100 W/cm. ... 

Karonis, N., de Supinski. B., Foster, I.. Gropp, W., Lusk, E., Bresnahan,, 1. (20()()) Exploiting hierarchy in parallel computer networks to optimize collective operation performance In Proc. International Parallel and Distributed Processing Symposium. 

The pyrolysis process for waste recycling is frequently done at larger scale than analytical pyrolysis. However, analytical pyrolysis studies are performed independently for the understanding and the optimization of such processes [10,16-19]. Also, model mixtures can be used in parallel with real samples. For example, the comparison of thermal degradation products from real municipal waste plastic and model mixed plastics can help understand the compounds generated in waste incinerators. In one such study [20], analytical pyrolysis of real municipal plastic waste obtained from Sapporo, Japan and model mixed plastics was carried out at 430 °C in atmospheric pressure by batch operation. The chlorinated hydrocarbons found in degradation liquid products of poly(ethylene)/poly(propylene)/ poly(styrene)/poly(vinyl chloride) and other polymeric mixtures were monitored. It was determined that the presence of poly(ethylene terephthalate), in addition to chlorinated plastics in the waste, facilitates... 

DMH is an intermediate in peroxide chemistry and could be used for synthesis in the field of lubricant or polyester. So far research has mainly focused on the development of different catalysts and the comparison of their performance [1]. Despite intensive optimization of catalysts and reaction conditions, selectivity to DMH is still low, because molecular oxygen in the gas-phase causes deep oxidation. Beside the development of catalysts and the optimization of reaction conditions, the mode of gas-solid contact and the reactor configurations are important issues as well. As in any parallel-series network with valuable intermediate products, the design of the reactor has a strong influence on the selectivity towards DMH. In principle, modes of contact which maintain a low oxygen concentration in the reactor favour the desired reaction and thus improve selectivity. Obviously, the requirement of a low oxygen concentration in the gas phase can be met by using a redox-type operation in which a... 

The first requirement is mainly important for the assessment of chemical reactions. In the overwhelming majority of chemical processes, not only the chemical conversion into the single desired product takes place. Instead, the desired reaction is accompanied by numerous parallel and consecutive reactions. Under the defined operating conditions resulting from the optimization work, the effect of these simultaneous reactions on yield and selectivity has been minimized by the choice of mode of operation (continuous, batch or semibatch) and of process parameters, such as pressure, temperature, concentration, pH-value, mass flow rates etc. A performance of the safety tests under conditions deviating fi-om those chosen for the plant process would inadvertently favour those secondary reactions in a different manner. Values for the gross value of heat output and reaction rate obtained this way would not be suitable for any process safety evaluation. Modem reaction calorimeters, like those commercially available today, enable the conduction of experiments with sufficient similarity to actual plant conditions. 

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