NOTES ON TWO IMPORTANT ALKALOIDAL REACTIONS. 



By H. C. FULLER. 



During the systematic analysis of a large number of pharma- 

 ceutical products it has been apparent from time to time that certain 

 of the standard reactions employed as a means of identification of 

 alkaloids can not be relied upon absolutely and in all circumstances. 

 The tests in question are the Vitali color reaction given by atropin 

 and the oxidation reaction of sulphuric acid and potassium bichro- 

 mate on strychnin. When the ingredients of certain medicines were 

 separated, and tests subsequently applied in order to establish the 

 identity of the unknown substances, residues were found to give 

 a purple color with alcoholic potash very characteristic of atropin, 

 yet neither atropin nor belladonna extract had been added to the 

 preparation, and in other instances on treating a residue with sul- 

 phuric acid and potassium bichromate a characteristic purple color 

 was obtained, yet neither strychnin nor nux vomica was found. 

 These facts become especially important in forensic work where, in 

 many instances, the analyst has a comparatively small sample at his 

 disposal, and often the proportion of alkaloidal substances is not 

 large. 



Allen a says in connection with Vitali's reaction: 



The violet reaction is almost peculiar to atropin and its isomers. Out of some 60 

 alkaloids examined none others were found to give a violet coloration. Strychnin 

 gives a red, brucin a greenish, and homatropin a yellow color when similarly treated, 



while Menegazzi 6 holds that strychnin acts similarly to atropin. 



Beckmann states that on evaporating veratrin with nitric acid 

 a yellow residue is left which on the addition of alcoholic potash gives 

 a violet color that quickly changes to a cherry red and gradually 

 becomes brown. 



Allen, commenting on the sulphuric-acid bichromate test, states 

 that "colocynth resin gives a very similar reaction to strychnin, but 

 is readily detected by agitating the acidulated solution with benzene 

 or ether." 



The similarity of the action of the alkaloids of gelsemium and of 

 berberin has been mentioned in the literature from time to time. 



In order to determine which of the drug extracts in common use 

 yield substances responding to the reactions in question, a series of 



a Comiuerical organic analysis, 1907, vol. 3, pt. 2, p. 268. 

 6 Ber. d. chem. Ges., 1894, 27 (4):275. 

 c Archiv. phann., 1886, 224; :481. 

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