The Hitchhiker’s Guide to Flow Chemistry

Abstract

Flow chemistry involves the use of channels or tubing to conduct a reaction in a continuous stream rather than in a flask. Flow equipment provides chemists with unique control over reaction parameters enhancing reactivity or in some cases enabling new reactions. This relatively young technology has received a remarkable amount of attention in the past decade with many reports on what can be done in flow. Until recently, however, the question, "Should we do this in flow?" has merely been an afterthought. This review introduces readers to the basic principles and fundamentals of flow chemistry and critically discusses recent flow chemistry accounts.

Energy Optimization of Gas–Liquid Dispersion in Micronozzles Assisted by Design of Experiment

“…Gaseous reagents are prone to be atom economic [8]; however, they are often used in large stoichiometric excess because of insufficient interfacial mixing [9]. This can lead to extended reaction times and, consequently, prohibitively slow processes, which underlines the importance of gas-liquid mixing [10].…”

Selective C(sp3)−H Aerobic Oxidation Enabled by Decatungstate Photocatalysis in Flow

“…However, direct use of the simple, green, and effective oxidant molecular oxygen is discouraged because of its associated safety hazards and limited solubility in organic solvents, which often leads to mass‐transfer limitations. In the past few years, continuous‐flow microreactor technology has been hailed as an enabling technology to overcome such limitations, as well as providing means to scale operationally complex transformations, for example, multiphase reactions,22 hazardous processes,23 and photochemical transformations,24 among others 25. As described below, we present a simple, selective, and synthetically useful decatungstate‐photocatalytic aerobic oxidation of C(sp 3 )−H bonds using continuous‐flow technology to overcome mass‐ and photon‐transfer limitations and safety hazards (Scheme 1 c).…”

Efficient kinetic experiments in continuous flow microreactors

“…They provide the benefits of ease of process automation, higher heat and mass transfer rates and a more straightforward incorporation of inline analysis tools compared to traditional batch setups. [6][7][8][9][10][11] Continuous flow systems have been used for complex chemical synthesis, [12][13][14][15] gas-phase reactions, [16][17][18][19] photochemistry, [20][21][22][23] electrochemistry, 24,25 and reaction optimization [26][27][28] but their robustness for reaction kinetics is hindered by the need to take steady state measurements. [29][30][31][32] Recent studies have shown that transient flow data could be used to quickly generate kinetic data.…”