Safety assessment in development and operation of modular continuous-flow processes

Abstract

Improved safety is one of the main drivers for microreactor application in chemical process development and small-scale production.

Improved Reactor Productivity for the Safe Photo‐Oxidation of Citronellol Under Visible Light LED Irradiation

“…However, it is noteworthy that the potential of singlet oxygen has not been fully exploited since there are a number of limiting factors that hinder the wider implementation of this ideal terminal oxidant to production scale. The main restrictions of this process has been recognized as light penetration in reaction medium, gas‐liquid mass transfer limitation, and safety issues . To our knowledge, there are only two counterexamples where photo‐oxidation is used at large scale, i. e. for the synthesis of artemisinin and rose oxide 4 .…”

“…In the past few years, to increase the safety of liquid phase oxidation and G/L reaction, continuous‐flow reactors with channel dimensions in the millimeter region have been studied. The handling of a highly reactive intermediate (hydroperoxide), working within an explosive regime (O 2 and organic solvent) can be addressed through the usage of continuous flow reactors ,,. Furthermore, photochemistry in continuous‐flow microreactors is now widely recognized as an enabling combination in order to provide major process assets arising from a much‐improved light penetration, heat and mass transfer and particularly the safe handling of oxygen.…”

Equipment and Separation Units for Flow Chemistry Applications and Process Development

“…Strongly exothermic reactions are governed by their kinetics (i.e., reaction time) and heat release in relation to the transferred heat. While the hydraulic diameter scales for constant heat transfer with the volume flow rate to the power of 1/7 to 2/7 , further safety aspects must be considered, such as sufficient residence time, pressure buildup and control, or flow split of one of the reagents , .…”

Continuous‐Flow retro‐Diels–Alder Reaction: A Process Window for Designing Heterocyclic Scaffolds

“…Our interest in CF processes can be explained, at least in part, by the number of potential advantages that CF processes have over traditional batch chemistry. These include the ease of scale‐up, high reproducibility, excellent heat transfer and mixing, as well as the inherently greater safety resulting from the small reactor volumes . Moreover, the accurate tuning of residence times can further broaden the versatility of CF processes .…”