The Production of Anthocyanins and Anthocyanidins. 



449 



■ yon 



OH 



> 



OH 



CI 



O OH 



> 



OH 



HO AAc yOB. 



-H 2 0. ^/^/ 

 O C 



C— OH 



H | 

 H 



II. 



In this connection an examination of the properties of cyanin chloride and 

 cyanidin chloride* is of interest. Cyanidin chloride when heated for a 

 short time in dilute alcohol to ca. 80° becomes decolorised — the decolorised 

 substance has properties resembling those of a yellow flavonol pigment, 

 soluble in ether, colourless in acid solution, extracted from it by ether ; 

 yellow in alkaline solution, and alkalis withdraw it from its solution in ether. 

 The decolorised cyanidin chloride, however, on boiling with acids, returns to the 

 red form. It is possible that these changes may be represented by the change 

 from I to II above being a reversible reaction. The fact that a decolorised 

 solution of cyanidin chloride on concentration regains its colour also 

 harmonises with the above. 



Quite similar properties are observed in the case of cyanin chloride, save 

 that heat is not required for decolorisation, nor for return of the red pigment 

 on acidification. Extraction of the decolorised solution with ether was not 

 tried by Willstatter and Everest, but alkalis on the decolorised solution 

 gave a yellow coloration. Most probably the general character of the groups 

 in the molecule would have their effect on the readiness with which this 

 change took place, and hence this decolorisation. Such a change might 

 perhaps explain the observation of Keeble, Armstrong, and Jones (loc. cit.), 

 that in the case of polyanthus mere boiling with acid was sufficient to 

 produce the red pigment. 



As he learns that recent developments in the work of Prof. Willstatter 

 and his collaborators have caused them to commence a series of investigations 

 dealing with the relation between the yellow pigments and the anthocyans 

 the author proposes to discontinue these investigations for the present. 



* "Willstatter and Everest, loc. cit. 



