Rhubarb, Emodin(CHAPTER I. The Anthraquinone Group.)(Osa artikkelista)

The Natural Organic Colouring Matters
By
Arthur George Perkin, F.R.S., F.R.S.E., F.I.C., professor of colour chemistry and dyeing in the University of Leeds
and
Arthur Ernest Everest, D.Sc., Ph.D., F.I.C., of the Wilton Research Laboratories; Late head of the Department of Coal-tar Colour Chemistry; Technical College, Huddersfield
Longmans, Green and Co.
39 Paternoster Row, London
Fourth Avenue & 30th Street, New York
Bombay, Calcutta, and Madras
1918

Kaikki kuvat (kemialliset kaavat) puuttuvat // None of the illustrations (of chemical formulas) included.

EMODIN, C₁₅H₁₀O₅.

Emodin, the second important constituent of rhubarb root, is now known as frangula-emodin not only on account of its existence (in the form of glucoside) in the bark of the Rhamnus frangula, but to distinguish it from the isomeric aloe-emodin which can be obtained from rhubarb and other sources.

It was first isolated from rhubarb root by Warren de la Rue and Müller (Trans. Chem. Soc., 1857, 10, 300), who extracted the washed root with benzene, and treated the crude mixture of emodin and chrysophanic acid thus isolated with sodium carbonate solution, in which, in the cold, emodin only is soluble.

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Emodin is contained as the glucoside frangulin in the bark of the Rhamnus frangula, the glucoside polygonin in the root of the Polygonum cuspidatum, and it has also been isolated from the R. purshianos and R. cuilludica (Tschirch and Pool, Arch. Pharm., 1908, 246, 315) and R. cathartica (Tschirch and Polacco, Arch. Pharm., 1900, 238, 459).