Why use MRT?

The idea behind MRT & Continuous Flow Chemistry

For centuries now the traditional method for solution-phase synthesis is to mix several compounds in a flask or reactor and to stir this mixture while the container is cooled or heated. After the lapse of a certain time this process is stopped and the product can be isolated from the mixture. Only recently, in the past two decades Microreactor Technology as a new concept in chemical engineering has rapidly evolved and demonstrated numerous advantages for chemical synthesis. The simple transfer into a continuous flow process solves multiple intrinsic problems of the batch procedure.

The reactants are supplied in separate solutions and pumped into micro-sized channels through a mixing chamber. Modern engineering permits complex channel structures for highest conversion quality. The reaction time of classical synthesis is converted into the path length of the micro channels the reaction mixture has to run through. Product samples may be collected continuously without having to stop the flow.

Schematic representation of a microreactor system and a picture of
the reactor that is part of Sigma-Aldrich's Microreactor Explorer Kit 19979.

Advantages of MRT & Flow Chemistry

• Superior heat exchange because of the high surface to volume ratio. This allows excellent control over reaction temperature. (please follow the link to learn more)
• Better mixing quality. Instant realization of a 1:1 mixture by laminar mixing regime in microlayers. (please follow the link to learn more)
• Instant removal of the material out of the reaction zone
• Improved safety
• Enhanced kinetic control
• Topmost reproducibility
• Scale-independent synthesis: numbering up of reactors replaces scale-up. No further process development required.
• Energy costs savings – perform reactions at the optimum temperature. No need to cool or heat more than is really necessary for the reaction.
• Labile intermediates can be fed directly into a second microreactor for instant conversion into the final product. (please follow the link to learn more)

Please click here for a graphical presentation of the most important chemistry and performance benefits of continuous flow synthesis.

Requirements of MRT

• Starting materials and products have to be in solution or liquid form.
• Introduction or formation of gas requires system adaptations.
• The reagents have to be compatible with the reactor materials.
• Fast reactions should be preferred.

Recommended literature for further reading:

1. ChemFiles Vol. 5 No. 7 "Microreactor Technology"
2. "Greener Approaches to Organic Synthesis Using Microreactor Technology": Mason, B.P.; Price, K.E.; Steinbacher, J.L.; Bogdan, A.R.; McQuade, D.T. Chem. Rev. 2007, 107, tbd.
3. "Microreactor Synthesis of beta-Peptides": Flögel, O; Codée, J.D.C.; Seebach, D.; Seeberger, P.H. Angew. Chem. Int. Ed. 2006, 45, 7000.
4. "Continuous Chemistry in Microreaction Systems for Practical Use": Müller, G; Gaupp, T.; Wahl, F; Wille, G. Chimia 2006, 60, 618.
5. "Chemistry in Microstructured Reactors": Jaehnisch, K.; Hessel, V.; Loewe, H.; Baerns, M. Angew. Chem. Int. Ed. 2004, 43, 406.
6. "Nitration Reactions in Microreactors": Panke, G.; Schwalbe, T.; Stirner, W.; Taghavi-Moghadam, S.; Wille, G. Synthesis 2003, 18, 2827.

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Sigma-Aldrich uses microreactors
Sigma-Aldrich MRE kit 19979
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