Chemistry:Fischer reaction

From HandWiki

In organic chemistry, the Fischer reaction is the conversion of an aryl sulfonic acid to an aryl chloride using chlorine:[1]

ArSO
3
H + Cl
2
→ ArCl + ClSO
3
H

The method was once used extensively in the preparation of chlorinated anthraquinones such as 1-chloroanthraquinone and 2-anthraquinones. 1,5-Dichloroanthraquinone ({{{2}}}) forms from the Anthraquinone-1,5-disulfonic acid ({{{2}}}). Illustrating some scope for this reaction, 1-chloroanthraquinone-2-carboxylic acid forms from the sulfonic-carboxylic acid.

Chlorine can be generated in situ from sodium chlorate and hydrochloric acid:[2]

NaClO
3
+ 6 HCl → 3 Cl
2
+ NaCl + 3 H
2
O

The acidity of this mixture means that sodium sulfonate salts can be used in situ, since they are readily protonated.

References

  1. Bien, Hans-Samuel; Stawitz, Josef; Wunderlich, Klaus (2000). "Anthraquinone Dyes and Intermediates". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a02_355. ISBN 3527306730. 
  2. W. J. Scott. C. F. H. Allen (1938). "α-Chloroanthraquinone". Organic Syntheses 18: 15. doi:10.15227/orgsyn.018.0015.