In organic chemistry, Keller's reagent is a mixture of anhydrous (glacial) acetic acid, concentrated sulfuric acid, and small amounts of ferric chloride, used to detect alkaloids. Keller's reagent can also be used to detect other kinds of alkaloids via reactions in which it produces products with a wide range of colors.[1][2][3] Cohn describes its use to detect the principal components of digitalis (note that they may not be alkaloids).[4] The reaction with this reagent is also known as the Keller–Kiliani reaction, after C. C. Keller and H. Kiliani, who both used it to study digitalis in the late 19th century.[5][6]It can be used for digitoxin's quantitative analysis.[7]Another method of visualizing the Keller-Kiliani reaction is to treat the test solution with ferric chloride-containing glacial acetic acid, followed by the addition of concentrated sulfuric acid, which sinks to the bottom (like in the brown ring test for nitrates). A brown ring in the interface indicates the presence of cardenolides.[8][better source needed]
List of color changes with various compounds
edit- Digoxin: olive-brown without red traces[9]
- Digitoxin: green, then blue[7]
- Digoxigenin: greenish-yellow[9]
- Vindolicine: bright blue[2]
- Uleine: yellow-brown[1]
- Hunteria eburnea alkaloid J (C39H46N4O2): pale red, later blue violet[3]
See also
editReferences
edit- ^ a b Ondetti, Miguel A.; Deulofeu, Venancio (1961), "Alkaloids from Aspidosperma australe Müll. Argov.: The structure of olivacine and u-alkaloid C (Guatambuine)", Tetrahedron, 15 (1–4): 160–166, doi:10.1016/0040-4020(61)80020-3. An extract of heartwood reacts with the reagent to produce a yellow-brown color.
- ^ a b Svoboda, Gordon H.; Gorman, Marvin; Neuss, Norbert; Barnes, Albert J. Jr. (1961), "Alkaloids of Vinca rosea Linn. (Catharanthus roseus G. Don.) VIII. Preparation and characterization of new minor alkaloids", Journal of Pharmaceutical Sciences, 50 (5): 409–413, doi:10.1002/jps.2600500508. Certain compounds "can be detected by means of a bright blue color formed with Keller's reagent".
- ^ a b Renner, Ulrich (1963), Hunteria Alkaloid J and the Extraction Thereof from Hunteria Eburnia, U.S. Patent 3,108,095. "With Keller's reagent there is first a pale red, later a blue violet color."
- ^ Cohn, Alfred Isaac (1909), Tests and reagents chemical and microscopical known by their authors' names, together with an index of subjects, J. Wiley & Sons, p. 154.
- ^ Keller, C. C. (1895), "Keller's reagent", Berichte der Deutschen Pharmazeutischen Gesellschaft, 5: 277.
- ^ Kiliani, H. (1896), "Ueber den Nachweis der Digitalis-Glycoside und ihrer Spaltungsprodukte durch eisenhaltige Schwefelsäure", Archiv der Pharmazie (in German), 234 (3–4): 273–277, doi:10.1002/ardp.18962340310, S2CID 84449886.
- ^ a b James, Arthur E.; Laquer, Fritz O.; McIntyre, Joseph D. (1947-01-01). "A photoelectric Colorimetric Assay for Digitoxin by Comparison with a Standard Powder*†". Journal of the American Pharmaceutical Association (Scientific Ed.). 36 (1): 1–4. doi:10.1002/jps.3030360102. ISSN 0095-9553. PMID 20285818.
- ^ "GYLCOSIDES Presented by BAHADUR SINGH HOD - ppt download". slideplayer.com. Retrieved 2024-11-18.
- ^ a b Smith, Sydney (1930-01-01). "LXXII.—Digoxin, a new digitalis glucoside". Journal of the Chemical Society (Resumed): 508–510. doi:10.1039/JR9300000508. ISSN 0368-1769.