450 



Mr. A. E. Everest. 



Experimental. - 



Quercitrin. — Reduction carried out in 2N HC1 by zinc (fine granulated). 



(1) Hot, yielded rapidly a red solution. 



(2) Cold, gave red coloration but very slowly. 



(3) Cold, alcoholic HC1 and Na Hg : rapidly gave red pigment. 



(4) Cold, electrolysis in 2N sulphuric acid, lead electrodes : very slow pro- 

 duction of red. 



(5) The best method, however, of obtaining the red pigment from quercitrin 

 is by the action of magnesium (ribbon or turnings) on a solution of the 

 substance in a mixture of 5 vols, absolute alcohol and 1 vol. concentrated 

 hydrochloric acid. 2STot only does this go very readily, but the acidity of the 

 solution — so essential in working with these compounds — is preserved as the 

 magnesium practically ceases to react before the solution becomes neutral. 

 This method was of no value when working with crude plant extracts, as 

 alcoholic extracts contained so much extraneous matter that the results were 

 masked. 



In every case pigment, when shaken with amyl alcohol, went quantitatively 

 into the alcohol, solution red with tinge of violet ; shaken with sodium acetate 

 solution, pigment remained quantitatively in alcohol, turned violet ; shaken 

 with sodium carbonate solution, pigment descended quantitatively into 

 aqueous layer with green colour ; prepared by method (5) and purified from 

 remaining quercitrin, solution gave blue solution in sodium carbonate. 

 The red pigment was not extracted from aqueous acid by any other 

 organic solvent. 



Yellow Wallflovjer. — Petals from a few flowers crushed in mortar with fine 

 sand and cold 2N HC1, then filtered, gave a faintly yellow extract which with 

 ammonia became deep yellow. To one portion of acid extract a small 

 quantity of zinc was added, whilst a second portion was kept for comparison, 

 to show that no red developed without the reduction. In a few minutes the 

 portion containing zinc became pink and the colour rapidly deepened to red. 

 Blank portion remained unchanged. The pigment produced by reduction 

 remained quantitatively in the aqueous layer when shaken with amyl alcohol, 

 but if the layer was separated, then boiled to hydrolyse the pigment, and then 

 again shaken with amyl alcohol, the red pigment then went quantitatively 

 into the alcoholic layer with production of a red solution. This reacted in 

 every way as an anthocyanidin. Electrolysis also produced the anthocyanin 

 and only that, no trace of anthocyanidin was produced by reduction in the 

 cold. 



Reduction in hot solution produced anthocyanidin and no anthocyanin. 



