Purification Fast Chemical Reactions

Enzymes, as you probably know, are proteins that can make chemical reactions happen in a more selective and faster way. At the end of each reaction cycle the enzymes remain unchanged so they act as catalysts. Since they occur in the living world we call them biocatalysts. Aside from proteins, ribonucleic acids and their fragments can act as catalysts and are called ribozymes, by analogy to enzymes. Enzymes are extracted from living tissues, for example, milk, saliva, liver, muscle have to be stored under carefully maintained conditions and, once outside living tissue, lose their activity fast. Isolation and purification of enzymes and assaying their activity have been major operations in biochemical and biomedical laboratories. Today,... 

For routine syntheses of labelled compounds, automated procedures have been developed which enable fast, safe, reproducible and reliable production. Automation has found broad application for the synthesis of radiopharmaceuticals. All steps must be as efficient as possible. For that purpose, target positioning and cooling, irradiation, removal of the target after irradiation, addition of chemicals, temperature and reaction time, purification of the product and dispensing are remotely controlled. Automation may be aided by computers and robotics may be apphed. 

The simultaneous absorption of two gases that react with the solvent at different rates has been studied by Ouwerkerk. The specific system which he selected for analysis was the selective absorption of HjS in the presence of CO2 into amine solutions. This operation is a feature of several commercially important gas purification processes. Bench scale experiments were conducted to collect the necessary pi sico-chemical data. An absorption rate equation was developed for H2S based on the assumption of instantaneous reaction. For CO2 it was found that the rate of absorption into diisopropanolamine (DIPA) solution at low CO2 partial pressures can best be correlated on the l is of a fast pseudo-first-order reaction. A computer program was developed which took into account the competition between H2S and CC>2 when absorbed simultaneously, and the computer predictions were verified by experiments in a pilot scale absorber. Finally, the methodology was employed successfully to design a large commercial plant absorber. 

Microfluidic devices allow for processing small volumes (10" to rnS) of fluid within channels and are compatible with continuous flow mode of operation (Fernandes, 2010). Hence, the use of microscale devices in preparation of ionic liquids is potentially as green as chemical synthesis can be as reagents are quantitatively converted into the final product, no solvents are needed for synthesis or purification and absolutely no waste is generated (Ehrfeld et al, 2000). Wikns et al. (2009) repwrted that less than 1 % of impurities, mostly unreacted starting material, are present in ionic fiquids synthesized within microfluidic devices. Hu et al. (2010) showed that microchannel reaction system is also suitable for the kinetic study of fast reactions with high heat release and/ or a viscous system, such as alkylation of imidazolium species. 

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