Fischer reaction

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

ArSO3H + Cl2 → ArCl + ClSO3H

The method was once used extensively in the preparation of chlorinated anthraquinones such as 1-chloroanthraquinone and 2-anthraquinones. 1,5-Dichloroanthraquinone forms from the corresponding disulfonic acid. 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]

NaClO3 + 6 HCl → 3 Cl2 + NaCl + 3 H2O

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.
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