What is flow chemistry?
“Flow chemistry”, sometimes referred to as “plug flow”, “microchemistry”, or “continuous flow chemistry” is the process of performing chemical reactions in a tube or pipe. Reactive components are pumped together at a mixing junction and flowed down a temperature controlled pipe or tube.
The major advantages of flow chemistry are faster reactions, cleaner products, safer reactions, quick reaction optimization, easy scale-up, and the integration of typically separate processes (such as synthesis, work-up, and analysis).
Syrris is the world’s longest established provider of lab scale flow chemistry systems. These systems are called Asia and Titan and allow easy access to the benefits of flow chemistry.
What are the benefits of flow chemistry
Flow reactors are easily pressurized (e.g. Asia systems can be pressurized to 300psi). This allows reactions to be heated 100-150ºC above their normal boiling point, therefore, creating reaction rates that are 1000s of times faster. This process is called superheating.
Flow reactors enable excellent reaction selectivity. The rapid diffusion mixing avoids the issues found in batch reactors. The high surface area to volume ratio (1000x greater than a batch reactor) enables almost instantaneous heating or cooling and therefore ultimate temperature control.
Flow chemistry allows only a small amount of hazardous intermediate to be formed at any instant. The high surface area also allows excellent control of exotherms.
Integrated synthesis, work-up, and analysis
Reaction products exiting a flow reactor can be flowed into a flow aqueous workup system or solid phase scavenger column. From there they can be analyzed either in line (e.g. FTIR) or a sample taken, using a sampler and diluter then and injected onto and LCMS.
Rapid reaction optimization
Flow Chemistry with automation enables the quick variation of reaction conditions on a very small scale e.g. 100 µL. Parameters such as reaction time, temperature, ratio of reagents, concentration and reagents themselves can all be rapidly varied. One reaction can follow another, separated by solvent, each cleaning out the previous reaction.
Scale-up issues are minimized due to maintaining excellent mixing and heat transfer. Higher flow rates and correspondingly larger reactors can be used to easily produce kilogram quantities.
Reaction conditions not possible using traditional batch chemistry methods
Flow chemistry facilitates reaction conditions not possible in batch such as a 5-second reaction at 250ºC. Multi-step procedures such as a rapid low-temperature deprotonation followed instantaneously by the addition of an electrophile high temperature are made easy.
This section provides information about the application of flow chemistry. Please use the navigation to the left to access more specialist flow chemistry information.
For information on Syrris flow chemistry products, click on Asia.
Examples of flow chemistry
Syrris has a range of resources that demonstrate a variety of flow chemistry application notes and reactions using Syrris’ flow chemistry systems. Syrris’ innovative microreactor-based systems include the modular Asia and Titan product ranges. Here are two examples shown below:
Oxidation of a primary alcohol
This paper describes reaction conditions for the oxidation of alcohols in continuous flow using a column reactor packed with polymer-supported tetra-N-alkylammonium perruthenate.
Steven V. Ley, Ian R. Baxendale, Jon Deeley, Charlotte M. Griffiths-Jones, Steen Saaby, Geoffrey K. Tranmer (University of Cambridge)