Some colour reactions of adrenine and allied bases / by A.J. Ewins.

  • Ewins, Arthur James.
Date:
1910
Catalogue details

Licence: Attribution 4.0 International (CC BY 4.0)

Credit: Some colour reactions of adrenine and allied bases / by A.J. Ewins. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    The Frankel-Alters Reaction. This new characteristic reaction for adrenine was recently described by Frankel and Allers (loc. cit.) and is brought about by heating to just below boiling a dilute solution of the base with an equal volume of a N/1000 solution of potassium biiodate and a few drops of dilute phos- phoric acid. There is thus produced a rose red colour which with the more concentrated solutions of adrenine (1—50,000) assumes on standing a distinct violet tint. The reaction was stated to be obtainable with a dilution of 1—300,000. The production of the colour is in the opinion of the authors probably due to the formation of an iodo- or iodoso- compound since “ at no stage of the reaction can free iodine be detected.” This last statement is not strictly accurate as the following experiment shows. To 5 c.c. of a solution of adrenine (1—1000) were added 4 c.c. of a N/100 solution of potassium biiodate and 1 c.c. of a 1 °/o solution of phosphoric acid and the mixture allowed to stand at the laboratory temperature. After a few seconds a few drops of the solution (which had already become distinctly yellow) gave with a few drops of starch solution a distinct purple colour. At the end of five minutes on repeating the test a distinct blue coloration was obtained. At the end of one hour the solution had assumed the characteristic reddish violet colour normally produced on heating and free iodine could no longer be de- tected. This is in agreement with a statement in a note very recently published by L. Krauss1 who calls attention to the fact that this (Frankel-Allers) reaction was first described by him2. He employed free iodic acid in place of the biiodate phosphoric acid mixture. He states that free iodine is momentarily set free in the reaction, as may be demonstrated by shaking the mixture with chloroform, which on separating shows a pink colour due to iodine in solution, and also by mixing a few drops of a solution of iodic acid (1—20) with a solution of adrenine and adding a little starch solution when the characteristic blue colour is at once obtained. With the catechol bases of the types of dihydroxyphenylethylamine and of aminoaceto-catechol it is still more easy to show that iodine is set free during the course of the reaction. On standing at the 1 Krause. Biochem. Ztschr. xxii. 131. 1909.