Flow Chemistry – A Key Enabling Technology for (Multistep) Organic Synthesis

TLDR

Flow chemistry has rapidly evolved over the past decade into a key enabling technology that improves synthetic efficiency through automation, process optimization, and integration with other technologies, bridging bench chemists and process engineers. This review examines two distinct aspects of modern flow chemistry that provide significant advantages over conventional batch processes. Flow chemistry achieves these advantages by harnessing diverse energy inputs—such as heat for supercritical conditions, microwave and inductive heating, and radiation for scalable photochemistry—and by enabling multistep synthesis with integrated purification or solvent‑switching reactors.

Abstract

Abstract Laboratory scaled flow‐through processes have seen an explosive development over the past decade and have become an enabling technology for improving synthetic efficiency through automation and process optimization. Practically, flow devices are a crucial link between bench chemists and process engineers. The present review focuses on two unique aspects of modern flow chemistry where substantial advantages over the corresponding batch processes have become evident. Flow chemistry being one out of several enabling technologies can ideally be combined with other enabling technologies such as energy input. This may be achieved in form of heat to create supercritical conditions. Here, indirect methods such as microwave irradiation and inductive heating have seen widespread applications. Also radiation can efficiently be used to carry out photochemical reactions in a highly practical and scalable manner. A second unique aspect of flow chemistry compared to batch chemistry is associated with the option to carry out multistep synthesis by designing a flow set‐up composed of several flow reactors. Besides their role as chemical reactors these can act as elements for purification or solvent switch.