Lemon flavin

Preparation. Lemon flavin, a khaki dyestuff obtained from the bark of an oak species (Quercus tinctoria Mich.), provides an excellent source of the sugar. The main constituent of the lemon flavin is the rhamnoside quercitrin, which after hydrolysis, yields the aglycon (quercetin) and L-rhamnose. The lemon flavin is hydrolyzed in boiling dilute acid, and after neutralization of the solution and treatment with a considerable proportion of decolorizing carbon, the sugar crystallizes from the evaporated solution.237... 

The main constituent of the lemon flavin is the rhamnoside quercitrin (Chapter X). This glycoside yields after hydrolysis the aglycon (quercetin) and L-rhamnose. 

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