High-speed synthetic chemistry

High-speed synthetic chemistry is a modern way to perform chemical synthesis. While the traditional way to perform reactions takes several hours or even days under reflux conditions, dedicated synthesis reactors can significantly reduce reaction times down to a few minutes. This works due to rapid superheating of the reaction mixtures to temperatures far above the boiling point of the used solvent(s).

Instrumentation

A conventionally heated sealed tube reactor for performing high-speed synthetic chemistry is equipped with a heating coil, a contact temperature sensor for accurate temperature control, a magnetic stirrer for optimum homogenization of the reaction mixture and with a pressure piston which allows reactions at elevated pressures (Figure 1).

Cheme of the cavity
Figure 1. Scheme of the cavity of a conventionally heated reactor for high-speed synthetic chemistry.

Theory: Microwave Chemistry Without Microwaves

Microwave reactors have been well known to accelerate chemical reactions for more than 25 years. But also conventionally heated closed vessel reactors can significantly increase the efficiency in chemical laboratories. The Arrhenius law in general states an approximate duplication of the reaction rate with a temperature increase of 10 °C. This is true for any system, independent of the heat source. It is just important to employ closed vessel systems, which allow reaching temperatures far above the boiling point of the used solvent(s).

By using silicon carbide vessels in monomode microwave reactors it has already been shown that virtually conventionally heated closed vessel systems provide similar results to purely microwave heated experiments.[1] Also with the above mentioned conventionally heated synthesis reactor, it could be shown that the outcome of a chemical reaction is independent of the heat source as long as the reaction time at a defined temperature is similar.[2]

References

[1] D. Obermayer, B. Gutmann, C. O. Kappe, Angew. Chem. Int. Ed. 2009, 48, 8321.
[2] Anton Paar application report D91IA002EN.

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