Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008)
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Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008)
Jun-lchiYOSHIDAFLASH CHEMISTRYFast Organic Synthesis in Microsystems4 WILEY ™ —— —1IntroductionWe tend to think that what we usually do is appropriate Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) e. This is often true in our daily life. However, it is not necessarily true in the field of science. For example, we usually run reactions in a centimeter size flask in an organic chemistry laboratory. Why? The reason is probably, that the sizes of the flasks are similar to the size of our hands. H Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) owever, the sizes of the flasks are not necessarily appropriate from a molecular-level viewpoint. Flasks are often too big for the control of moleculaJun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008)
r reactions. Scientifically, smaller reactors such as microreactors provide a much better molecular environment for reactions. What about reaction timJun-lchiYOSHIDAFLASH CHEMISTRYFast Organic Synthesis in Microsystems4 WILEY ™ —— —1IntroductionWe tend to think that what we usually do is appropriate Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) erval of minutes to hours is acceptable and convenient for human beings. In such a range of time, we can recognize how the reaction proceeds. We start a reaction, wait for a while, and stop it in this range of time. If reactions are too fast, it is difficult to determine how the reaction proceeds, b Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) ecause the reaction is complete too soon after it is started. Therefore, we have chosen reactions that complete in a range of minutes to hours. AnotheJun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008)
r reason is that we are able to conduct only such reactions that require minutes to hours for completion in a controlled way. In other words, in laborJun-lchiYOSHIDAFLASH CHEMISTRYFast Organic Synthesis in Microsystems4 WILEY ™ —— —1IntroductionWe tend to think that what we usually do is appropriate Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) significant amounts of unexpected compounds are obtained as byproducts. In addition, extremely fast reactions sometimes lead to explosions. However, we should keep in mind that such limitations of reactionFlash Chemistry: Fast Organic Synthesis in Microsystems Jun-ichi Yoshida © 2008 John Wiley & S Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) ons. Lid. ISBN: 978-0-470-03586-32INTRODUCTIONtime for chemical synthesis are only applicable for flask chemistry that we usually do in a laboratory.1Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008)
.1FLASK CHEMISTRYBased on conventional flask chemistry, organic synthesis has witnessed a steady march in rhe progress of our understanding of factorsJun-lchiYOSHIDAFLASH CHEMISTRYFast Organic Synthesis in Microsystems4 WILEY ™ —— —1IntroductionWe tend to think that what we usually do is appropriate Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) ynthesis has been extended to various fields of science and technology, such as materials, pharmacy, and medicine. Conventional organic synthesis, however, has been a rather time-consuming task; chemists have been using slow reactions because fast reactions are difficult to control and often give si Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) gnificant amounts of undesired by-products, as stated above. Reaction times in conventional organic synthesis usually range from minutes to hours. TheJun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008)
rapid progress in science and technology based on organic compounds means the demand to produce desired compounds in a highly time-efficient way has Jun-lchiYOSHIDAFLASH CHEMISTRYFast Organic Synthesis in Microsystems4 WILEY ™ —— —1IntroductionWe tend to think that what we usually do is appropriate Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) sirable. For this purpose, flash chemistry, where much faster reactions are conducted in a controlled and selective way to produce desired products, is greatly needed.We are still running chemical reactions using much of the same apparatus that was used in rhe eighteenth and nineteenth centuries (Fi Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) gure 1.1). The sizes of the flasks are determined not by any scientificFigure 1.1 Ugo Schiff (1834-1915) (provided by the University of Florence)FLASHJun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008)
CHEMISTRYreasons but probably by the size of our hands. It is not necessary to use reactors of flask size for studies of chemical reactions and synthJun-lchiYOSHIDAFLASH CHEMISTRYFast Organic Synthesis in Microsystems4 WILEY ™ —— —1IntroductionWe tend to think that what we usually do is appropriate Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) actions in a highly controlled and selective way to synthesize desired compounds. There should be many fast reactions that we have not yet explored because of the constraints of the reaction environment. Such constraints should be removed to further develop the efficiency and utility of organic synt Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) hesis. In order to do this, we need microflow systems as a new environment for chemical reactions.1.2FLASH CHEMISTRYThe word ‘flash’ is not new in theJun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008)
history of chemistry. Flash chromatography1’1 is one of rhe fundamental techniques for separating organic compounds in laboratory synthesis. In fact,Jun-lchiYOSHIDAFLASH CHEMISTRYFast Organic Synthesis in Microsystems4 WILEY ™ —— —1IntroductionWe tend to think that what we usually do is appropriate Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) s, flash vacuum pyrolysis1’1 is also a well-known technique that has been available for many years. Flash laser photolysis131 is widely used for mechanistic studies because it serves as a powerful method for generating reactive species in a very short period of time. However, flash laser photolysis Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) does not seem to be suitable for chemical synthesis because it is rather difficult to produce a large amount of compounds using this technique. In theJun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008)
‘flash chemistry’ proposed here, a substrate undergoes extremely fast reactions to give a desired product very quickly in a highly selective manner. Jun-lchiYOSHIDAFLASH CHEMISTRYFast Organic Synthesis in Microsystems4 WILEY ™ —— —1IntroductionWe tend to think that what we usually do is appropriate Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) a continuous flow system, it is fairly easy to make a larger quantity of compounds than one can expect from the size of the reactor. In any case, the word ‘flash’ is very common in chemistry, hut the term ‘flash chemistry’ is uncommon.It is important to propose new words for the developments in new Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) fields of science and technology; as Wittgenstein wrote in his book:141 ‘A new word is like a fresh seed thrown on the ground of the discussion’. A JJun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008)
apanese poet,Toson Shimazaki, also wrote in the preface of his collection of poems:151 ‘A new word leads to a new life’. Therefore, it seems useful anJun-lchiYOSHIDAFLASH CHEMISTRYFast Organic Synthesis in Microsystems4 WILEY ™ —— —1IntroductionWe tend to think that what we usually do is appropriate Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) in the range of 10 13-10 12 s (see Chapter 2), while reaction rimes range from minutes to hours (1 o2—lo'* s) in a flask (Figure 1.3). The size of molecules is in the range of 10-n,-10_s m, whereas the size of a flask ranges from 10-2 to io"m. So, there is a rough correlation between rhe reaction ri Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) me and rhe size of the reaction environment, as shown in Figure 1.3. In flash chemistry, we use a reactor, the size of which ranges from 10-6 to 10“3mJun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008)
. T hetimeFigure 1.3 rime-space relationship for chemical reactionsREFERENCES5reaction time ranges from 10 ' to 1 s. Therefore, it is easy to understaJun-lchiYOSHIDAFLASH CHEMISTRYFast Organic Synthesis in Microsystems4 WILEY ™ —— —1IntroductionWe tend to think that what we usually do is appropriate Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) k chemistry.This book provides an outline of the concept of flash chemistry for conducting extremely fast reactions in a highly controlled manner using microflow systems. In the following chapters, we will discuss the background, the principles, and applications of flash chemistry.REFERENCES11] w. c Jun ichi yoshida flash chemistry fast organic synthesis in microsystems wiley (2008) . Still, M. Kahn, A. Mitra, y. Org. Ghent. 1978, 43, 2923-2925.Jun-lchiYOSHIDAFLASH CHEMISTRYFast Organic Synthesis in Microsystems4 WILEY ™ —— —1IntroductionWe tend to think that what we usually do is appropriateJun-lchiYOSHIDAFLASH CHEMISTRYFast Organic Synthesis in Microsystems4 WILEY ™ —— —1IntroductionWe tend to think that what we usually do is appropriateGọi ngay
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