Industrial Applications of Flash Chemistry

Flash chemistry is expected to produce a paradigm shift not only in laboratory chemical synthesis but also in the industrial production of chemicals and drugs. Microflow systems are essential for conducting extremely fast reactions in flash chemistry, and it is often assumed that microflow systems can be used only in laboratory synthesis and in small-scale productions. It is often considered that large-scale productions cannot be carried out using microflow systems. However, this is not true. Microflow systems can be used for production on a relatively large scale. For example, some pilot plants on tons per year scale have already been constructed based on microflow technology. 

Flash Chemistry Fast Organic Synthesis in Microsystems Jun-ichi Yoshida 2008 John Wiley Sons, Ltd. ISBN 978-0-470-03586-3 

Both the scaling-up and numbering-up approaches are important for increasing the production volume in microflow processes. The number of reactors should be as low as possible, and the size of the reactor structure should be as large as possible, to the extent that the efficiency and selectivity of a reaction are acceptable. Flexibility is important in the designing of microflow processes and reactors based on flash chemistry in industrial production. The key points for the scaling-up and numbering-up approaches are  

Less effort and time are needed to increase the production volume. It is difficult to operate a large number of systems in parallel. Minimum numbering-up as far as the production volume is acceptable. 

Recently, microchemical plants have emerged as an important new trend in the chemical industry, and they are expected to produce a revolutionary change in achieving a more compact and knowledge-intensive industry that can produce chemicals in a much faster and more controlled manner. This trend has been accelerated by the increase in concern over the global environment that aims at saving natural resources and energy. Some examples are presented in this chapter to illustrate the benefits of flash chemistry from the viewpoint of the industrial production of chemical substances. 

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There are many other approaches to industrial applications of flash chemistry, although available information is limited. Let us briefly touch on some examples. The Kolbe-Schmitt synthesis serves as a useful standard method to introduce a carboxyl group into phenols (Scheme 10.6). The Kolbe-Schmitt synthesis has been widely used in industry, and there are many variants of this transformation. Microflow systems can be used for conducting the Kolbe-Schmitt synthesis under aqueous high-pressure conditions.A decrease in reaction times by an order of magnitude (a few tens of seconds instead of minutes) and increase in space-time yields by orders of magnitude can be attained using a microflow system. For example, a microflow system composed of five parallel capillaries (inner volume 9 ml) has a productivity of 555 g/h, whereas the productivity of a macrobatch reactor (IL flask) is 28 g/h. 

In conclusion, several attempts at industrial applications of flash chemistry have already been made to meet the demands of the pharmaceutical and chemical industries, although more progress is urgently needed in the scaling-up and numbering-up of microflow reactors and continuous operation of microchemical plants under commercial conditions. It is also important to note that flash chemistry is expected to serve as a powerful means of green sustainable synthesis. 

This example illustrates the utility of millimeter-sized tube reactors in industrial production, which opens various possibilities for the application of flash chemistry in industry. 

The following chapters provide more details of flash chemistry and its applications in laboratory synthesis and industrial production. 

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