Rumex ecklonianus, Rumex nepalensis(CHAPTER I. The Anthraquinone Group.)

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.

RUMEX ECKLONIANUS.

Rumex ecklonianus (Meisner) is a herb indigenous to South Africa which possesses medicinal properties of a mild -purgative nature. Tutin and Clewer (Chem. Soc. Trans., 1910, 97, 6) examined the over-ground portion of the plant, and found it to contain chrysophanic acid, emodin, emodin mono-methyl ether and kaempferol.

RUMEX NEPALENSIS.

According to Hesse, the root of Rumex nepalensis (Wall), does not contain chrysophanic acid, but there is present in addition to two other substances, one he termed rumicin, which is isomeric with it.

Rumicin, C₁₅H₁₀O₄, golden-yellow leaflets, melts at 186-188°, and is soluble in caustic potash solution with a purple-red coloration. With hydriodic acid it yields chrysophanohydranthrone.

Nepalin, C₁₇H₁₄O₄, orange needles, melts at 136°, is insoluble in alkali carbonates, but dissolves in caustic potash, forming a purple solution. Diacetyl-nepalin, C₁₇H₁₂O₄(C₂H₃O)₂, crystallises in brownish- red rhombohedra, melting-point 181°.

Nepodin, the main constituent of the root C₁₈H₁₆O₄, greenish-yellow prisms, melting-point 158°, is distinguished from the preceding compounds by its solubility in solutions of the alkali carbonates. The diacetyl compound forms pale yellow rhombohedra which darken at 180°, and melt with decomposition at 198°.