Green and Sustainable Chemical Synthesis Using Flow Microreactors

• Published in: ChemSusChem Vol. 4; no. 3; pp. 331 - 340
• Main Authors: Yoshida, Jun-ichi, Kim, Heejin, Nagaki, Aiichiro
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 21.03.2011; WILEY‐VCH Verlag
• Subjects: Chemical Phenomena; flow reactions; green chemistry; Green Chemistry Technology - instrumentation; Green Chemistry Technology - methods; Microfluidic Analytical Techniques - instrumentation; Microfluidic Analytical Techniques - methods; microreactors; protecting groups; synthetic methods
• ISSN: 1864-5631; 1864-564X
• DOI: 10.1002/cssc.201000271

Several features that allow flow microreactors contribute to green and sustainable chemical synthesis are presented: (1) For extremely fast reactions, kinetics often cannot be used because of the lack of homogeneity of the reaction environment when they are conducted in batch macroreactors. Better controllability, by virtue of fast mixing based on short diffusion paths in microreactors, however, leads to a higher selectivity of the products, based on kinetics considerations. Therefore, less waste is produced. (2) Reactions involving highly unstable intermediates usually require very low temperatures when they are conducted in macrobatch reactors. By virtue of short residence times, flow microreactors enable performing such reactions at ambient temperatures, avoiding cryogenic conditions and minimizing the energy required for cooling. (3) By virtue of the precise residence time control, flow microreactors allow to avoid the use of auxiliary substances such as protecting groups, enabling highly atom‐ and step‐economical straightforward syntheses. The development of several test plants based on microreaction technology has proved that flow microreactor synthesis can be applied to the green and sustainable production of chemical substances on industrial scales. (4) Microreactor technology enables on‐demand and on‐site synthesis, which leads to less energy for transportation and easy recycling of substances. Flow microreactors can contribute to green and sustainable chemical synthesis and production by improving product selectivity and so giving less waste, avoiding energy‐consuming cryogenic cooling, and protecting‐group‐free synthesis to improve atom and step economy. Microreactors also enable on‐demand and on‐site synthesis, which leads to less energy for transportation and easy recycling of substances.