Cover Picture: Green and Sustainable Chemical Synthesis Using Flow Microreactors / Continuous Synthesis of tert‐Butyl Peroxypivalate using a Single‐Channel Microreactor Equipped with Orifices as Emulsification Units / Heterogeneous Catalytic Hydrogenation Reactions in Continuous‐Flow Reactors (ChemSusChem 3/2011)

The front cover showcases the use of flow microreactors for green and sustainable chemical synthesis, described in the Concept paper by Jun-ichi Yoshida et al. (Kyoto University) on page 331. In microreactors, fast mixing based on short diffusion paths leads to a higher product selectivity and, hence, less waste. Short residence times enable flow microreactors to perform reactions that involve highly unstable intermediates at ambient temperatures, avoiding cryogenic conditions and minimizing the energy required for cooling. Precise residence time control avoids the use of auxiliary substances such as protecting groups, enabling straightforward syntheses with good atom economy and fewer reaction steps. Finally, microreactor synthesis enables on-demand and on-site synthesis, requiring less energy for transportation and easy recycling of substances. This Concept paper, and the paper on the synthesis of tert-butyl peroxypivalate in a single-channel microreactor from the groups of Hessel and Schouten (p. 392), was invited to demonstrate the sustainable chemistry merits of using flow reactors. The editorial office acknowledges Prof. C. Oliver Kappe for his efforts in promoting the use of flow chemistry to achieve sustainability, by inviting these contributions and by enriching this issue with an excellent Review on catalytic hydrogenation in flow reactors (p. 300).