Willoughbv - . F. Meek and John B. Entrikin Centenary College Shreveport, Louisiana
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Quinhydrone Test for Amines
The
T h e ouinhvdrone test nronosed " Krollerl was not found satisfactory for general use because the colors produced by low molecular weight amines were too intense for accurate classification. Also, higher amines-above pentyl-gave false or no color. The following modification of the procedure was devised and adopted because of its usefulness in classification. Place 6 ml of water in a 6-in. test tube and add one drop (or 15-20 mg) of the amine. If the amine dissolves, add 6 ml more water to the tube. If the amine does not dissolve in the first 6 ml of water, add 6 ml of ethanol. Shake the mixture and add one drop of a 2.5% solution of quinhydrone in methanol. Shake the A
Presented at the ACE Southwest Regional Meeting, December 8, 1962. 'KROI.LER, E.,Suddeul. Apoth. 9tg, 90, 724 (1950); C.A., 45, 1464 (1951).
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tube and allow it to stand for two minutes. Aliphatic amines produce a color with only one drop of reagent: violet for primary; rose for secondary; and yellow for tertiary amines. Aryl amines generally do not develop a color with only one drop of the reagent, hence, if no color develops, add five more drops of the reagent. Shake the tube and allow it to stand for two minutes. For aryl amines, the colors generally produced are: rose-red for primary; amber for secondary; and yellow for tertiary amines. The following aryl amines were properly classified by the reagent: aniline, p-bromoaniline, p-tohidine, otoluidine, 2-naphthylamine, N-methylaniline, N-butylaniline, N-propylanilime, N-ethylauiline, N,N-dimethylaniline, N,Ndiethylanilme, N,N-dimethyl-1-naphthylamine. The following aryl amines were not properly classified by this test: diphenylamine, 3-nitroaniline, 2,5-dichloroaniline, and phenylenediamine.
