Iron chloride test

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The iron chloride test describes two different detection methods that are carried out with iron (III) chloride solution.

  • In the detection of acetic acid and acetates aqueous after addition of ferric chloride solution is performed to a sample containing acetic acid or acetate, an intense red coloration which is based on the forming complex ([Fe 3 O (H 2 O) 3 (CH 3 COO) 6 ] + ) can be traced back. When the complex is heated, red-brown iron (III) acetate is formed. To distinguish between acetic and propionic acid , the sample solution can also be mixed with a little amyl alcohol : If acetic acid is present, the lower, aqueous phase turns red. If it is propionic acid, the upper, alcoholic phase turns red, while the lower remains colorless.
  • Phenols and enols show intense color reactions with iron (III) salt solutions, in which the color can go from yellow to blue and purple, green or even black. This reaction is used in the production of the deep black iron gall ink .

Oximes and hydroxamic acids can also be detected as red complexes with iron (III) chloride solution.

Individual evidence

  1. ↑ Günther Harsch, Rebekka Heimann: The Estercyclus - an experimental project for training resource-conscious thinking and acting. (PDF; 2.6 MB) Chem. Sch. 41 (1994) supplement, p. 7.
  2. ↑ Kurt Eger, Reinhard Troschütz, Hermann J. Roth: drug analysis . 5th edition. Deutscher Apotheker Verlag Stuttgart, Stuttgart 2006, ISBN 3-7692-3761-7 , p. 114 .
  3. ↑ Experiment: Detection of phenol with iron (III) chloride at Prof. Blum's educational server for chemistry.