Keller's reagent

Keller's reagent can refer to either of two different mixtures of acids.

In metallurgy, Keller's reagent is a mixture of nitric acid, hydrochloric acid, and hydrofluoric acid, used to etch aluminum alloys to reveal their grain boundaries and orientations.^[1] It is also sometimes called Dix–Keller reagent, after E. H. Dix, Jr., and Fred Keller of the Aluminum Corporation of America, who pioneered the use of this technique in the late 1920s and early 1930s.^[2][3]

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.^[4][5][6] Cohn describes its use to detect the principal components of digitalis.^[7] 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.^[8][9]

References

1. Vander Voort, George F. (1999), Metallography, Principles and Practice, ASM International, p. 197, ISBN 978-0-87170-672-0.
2. Mondolfo, Lucio F. (2007), Metallography of Aluminum Alloys, Read Books, p. 169, ISBN 978-1-4067-3672-4.
3. Dix, E.H., Jr.; Keller, Fred (1929), "Keller's reagent", Mining and Metallurgy, 9: 327, ISSN 0096-7289.
4. 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.
5. 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".
6. 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."
7. 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.
8. Keller, C. C. (1895), "Keller's reagent", Berichte der Deutschen Pharmazeutischen Gesellschaft, 5: 277.
9. 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.