Fischer phenylhydrazine synthesis

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The Fischer phenylhydrazine synthesis , named after its discoverer Emil Fischer, is a name reaction from organic chemistry and was first published in 1875. The reaction describes the synthesis of phenylhydrazine from aniline .

Overview reaction

Aniline reacts to phenylhydrazine using sodium nitrite in hydrochloric acid and sodium sulfite :

Fischer phenylhydrazine synthesis overview

Reaction mechanism

The mechanism is described in the literature:

Fischer phenylhydrazine synthesis mechanism

First, a diazotization reaction takes place in which aniline ( 1 ), using a sodium nitrite / hydrochloric acid mixture , is converted to the diazonium ion 3 via the intermediate stage of the diazohydroxide 2 . 3 reacts with a sulfite ion to form 2-phenyldiazene sulfonate ( 4 ). With the addition of water and subsequent splitting off of the hydrogen sulfate anion , this is reduced to phenyldiazene ( 5 ). By further reaction with sulfite ions and water, 5 is converted to phenylhydrazine ( 6 ) with elimination of the sulfate anion .

Individual evidence

  1. Fischer, E. (1876), Ueber aromatic hydrazine compounds. In: Reports of the German Chemical Society 9 (1), pp. 880-891, doi: 10.1002 / cber.187600901263 .
  2. Fischer, E. (1878), About the hydrazine compounds; First treatise. In: Justus Liebigs Annalen der Chemie , 190: 67–183. doi: 10.1002 / jlac.18781900104 .
  3. ^ Z. Wang: Comprehensive organic name reactions and reagents Volume 1 . John Wiley, Hoboken (NJ) 2009, ISBN 978-0-470-28662-3 , pp. 1080-1082 .