Quercitron extract

This forms either dark brown, shining lumps or a more or less dense brown liquid. Under the names of flavine and quercetin, products are sold which are obtained by chemical processes from quercitron bark and represent the more or less pure colouring matter in the form of yellow or brown powder or paste. 

In addition to the general tests already indicated, the following are made in this case. 

Qualitative Tests.—The solution of quercitron extract is yellow and gives a pale, yellowish-brown precipitate with acids and turns brown with alkalies. Stannous chloride gives a yellow precipitate, ferric chloride an olive green precipitate, alum a light, yellow precipitate and a filtrate with greenish fluorescence, and copper acetate a greenish-yellow precipitate. With chloride of lime the solution becomes decolorised and yields a yellow precipitate. 

As regards flavine and quercetin, these dissolve more or less completely in ammonia and in alkalies to golden yellow solutions, and the ammoniacal solution turns brown in the air their alcoholic solution is coloured brownish- 

A good flavine should have a colouring power about sixteen times as great as that of quercitron bark. 

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Pit charcoal Pitch, wood Pyroligneous acid Quebracho extract Quercitron extract Rosin, produced by distillation of pine gum or pine wood... 

USE Has been used as textile dye. Flavine yellow shade Is prepared by extracting quercitron bark with high pressure steam and consists mainly of quercitrin Tisdale, Con. Textile J, 57, 44 (1941). 

The most important yellow dye in ancient and medieval times was weld, a flavone derivative extracted from the seeds, stems, and leaves of Reseda luteola, commonly known as dyer s rocket. Weld is resistant to atmospheric oxidation, rendering it quite lightfast and hence extremely popular and useful. In combination with the blue dye woad it was used to produce the Lincoln green made famous by Robin Hood and his merry men. Quercitron, a flavonol derivative, is much more susceptible to degradation by light and hence was not as important [23]. 

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