Wenker synthesis

Wenker synthesis
Named after Henry Wenker
Reaction type Ring forming reaction
Identifiers
Organic Chemistry Portal wenker-synthesis

The Wenker synthesis is an organic reaction converting a beta amino alcohol to an aziridine with the aid of sulfuric acid.[1]

The original Wenker synthesis of aziridine itself takes place in two steps. In the first step ethanolamine is reacted with sulfuric acid at high temperatures (250 °C) to form the sulfate mono-ester. This salt is then reacted with sodium hydroxide in the second step forming aziridine. The base abstracts an amine proton enabling it to displace the sulfate group. A modification of this reaction involving lower reaction temperatures (140–180 °C) and therefore reduced charring increases the yield of the intermediate.[2]

The Wenker synthesis protocol using trans-2-aminocyclooctanol, available from reaction of ammonia with the epoxide of cyclooctene, gives a mixture of cyclooctenimine (the Wenker aziridine product) and cyclooctanone (a competing Hofmann elimination product).[3]

References

  1. ↑ Wenker, Henry (1935). "The Preparation of Ethylene Imine from Monoethanolamine". Journal of the American Chemical Society. 57 (1): 2328–28. doi:10.1021/ja01314a504.
  2. ↑ Leighton, Philip A.; Perkins, William A.; Renquist, Melvin L. (1947). "A Modification of Wenker's Method of Preparing Ethyleneimine". J. Am. Chem. Soc. 69 (6): 1540. doi:10.1021/ja01198a512.
  3. ↑ Kashelikar, D. V.; Fanta, Paul E. (1960). "Chemistry of Ethylenimine. VII. Cycloöctenimine or 9-Azabicyclo[6.1.0]nonane". J. Am. Chem. Soc. 82 (18): 4927–30. doi:10.1021/ja01503a044.
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