Letter | Published:

Colour Reactions of Certain Phenols with Ehrlich's Reagent


THE use of Ehrlich's reagent (1 per cent p-dimethylaminobenzaldehyde in N hydrochloric acid, for the detection of indoles, pyrroles and related nitrogen-containing compounds has been a long-established analytical procedure1,2,3. Spraying this reagent on paper chromatograms containing indole compounds produces purple, blue, and red spots. However, certain phenols have been reported1 to produce similar colours under the conditions of the Ehrlich test.

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  1. 1

    Morton, Avery A., “The Chemistry of Heterocyclic Compounds”, 68 (McGraw-Hill Book Co., Inc., New York, 1946).

  2. 2

    Block, R. J., Durrum, E. L., and Zweig, G., “A Manual of Paper Chromatography and Paper Electrophoresis”, 2nd Edition (Academic Press, Inc., New York, 1958).

  3. 3

    Sen, S. P., and Leopold, A. C., Physiol. Plantarum, 7, 98 (1954).

  4. 4

    Flaig, W., and Breyhan, Th., Z. für Pflanzenernähn., Dung., Bodenk., 75, 132 (1956) (Chem. Abs., 51, 6061, 1957).

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