Semmler-Wolff reaction
The Semmler-Wolff reaction , named after the German chemists Friedrich Wilhelm Semmler and Ludwig Wolff , is a name reaction from the field of organic chemistry and was first described in 1892 by Friedrich-Wilhelm Semmler. The reaction was examined in more detail by Ludwig Wolff in 1902. The Semmler-Wolff reaction enables the preparation of aromatic amines from cyclic α, β-unsaturated ketooximes .
Overview reaction
In the Semmler-Wolff reaction, cyclic α, β-unsaturated ketooximes are converted into aromatic amines using acetic anhydride saturated with hydrochloric acid . The reaction is a rearrangement reaction, whereby an aromatic system is formed through a proton rearrangement.
Reaction mechanism
The following reaction mechanism is described in the literature and is explained using cyclohexenone oxime as an example :
Cyclhexenone oxime ( 1 ) and acetic anhydride ( 2 ) react with elimination of acetic acid to form the nitroso compound 3 and an acetyl cation ( 4 ) and further to compound 5 . Hydrochloric acid causes protonation of the nitrogen and - with the breaking of the C – N double bond - a proton rearrangement to nitrogen. Subsequent deprotonation and the associated shift of electrons lead to the cleavage of the acetate anion, which produces the aromaticity of the amine ( 6 ) by deprotonation .
Individual evidence
- ↑ Fr. W. Semmler: About the conversion of tanacetoxime into cymidine In: Ber. German Chem. Ges. 25, 1892, pp. 3352-3354, doi: 10.1002 / cber.189202502200 .
- ↑ Ludwig Wolff: Condensationsproducte der Tetronsäure In: Justus Liebigs Ann. Chem. 322, 1902, pp. 351-391, doi: 10.1002 / jlac.19023220304 .
- ↑ G. Schroeter, A. Gluschke, S. Götzky, J. Huang, G. Irmisch, E. Laves, O. Schrader and G. Stier: Oxime rearrangements in the tetralone series. In: Ber. German Chem. Ges. 63, 1930, pp. 1308-1329, doi: 10.1002 / cber.19300630605 .
- ^ Zerong Wang: Comprehensive Organic Name Reactions and Reagents , Wiley, 2009, ISBN 978-0-471-70450-8 , pp. 2552-2555.