Abstract

Reaction Networks in Flow – "End-to-end” after Activating the “Drop-in”

Volker Hessel, Professor, University of Adelaide

Flow chemistry is based on chemical intensification and therefore novel process windows through high-temperature, high-pressure and high-concentration processing are widely established. Even non-classical means of activation have been explored such as photocatalysis, microwave, ultrasound, and more. The next big step is on the process design and here specifically on process integration. While that is a “mandatory standard” in plant design up to a chempark level, the compact and miniature nature of flow chemistry offers new chances even with such classical approach. Flow cascades, denoting reaction networks in flow, are inspired by the strategies used by nature to solve problems of molecule assembly. Traditional “stop-and-go” synthetic protocols conduct individual transformations as stepwise processes punctuated by the isolation and purification of intermediates at each stage. On the contrary, a continuous series of highly regulated catalytic cascades could, as in nature, enable the rapid conversion of simple starting materials to complex molecular scaffolds. Own investigations so far are mainly targeting non-catalytic reactions, yet with full integration of continuous separation. We performed, for the first time, a life-cycle assessment of such multi-step reaction networks in flow, pointing at issues how to improve environmental friendliness. As an outlook and already realized in “stop-and-go” batch fashion, the integration of transformation-specific enzymes and homogeneous catalysts would allow for mediating efficient synthesis analogous to ‘biochemical assembly lines’. As counterpart of nature’s signaling pathway, the implementation of artificial intelligence would allow even further going data exploitation for process optimization and more.