Liquid phase oxidation chemistry in continuous-flow microreactors

Abstract

Continuous-flow liquid phase oxidation chemistry in microreactors receives a lot of attention as the reactor provides enhanced heat and mass transfer characteristics, safe use of hazardous oxidants, high interfacial areas, and scale-up potential. In this review, an up-to-date overview of both technological and chemical aspects of liquid phase oxidation chemistry in continuous-flow microreactors is given. A description of mass and heat transfer phenomena is provided and fundamental principles are deduced which can be used to make a judicious choice for a suitable reactor. In addition, the safety aspects of continuous-flow technology are discussed. Next, oxidation chemistry in flow is discussed, including the use of oxygen, hydrogen peroxide, ozone and other oxidants in flow. Finally, the scale-up potential for continuous-flow reactors is described.

Chemical reaction engineering, process design and scale-up issues at the frontier of synthesis: Flow chemistry

“…The safety issues connected with liquid phase oxidation reactions have been reviewed recently [150,151]. Oxidising reactants typically used are oxygen, ozone or peroxides, which are usually mixed with organic solvents.…”

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).…”

Overcoming the Gas–Liquid Mass Transfer of Oxygen by Coupling Photosynthetic Water Oxidation with Biocatalytic Oxyfunctionalization

“…To improve O 2 mass transfer, various reactor concepts with different modes of gaseous reactant supply have been proposed 2a. Examples include the utilization of bubble columns, gas‐permeable membranes, segmented flow microreactors, or falling film microreactors 7a, 8…”