Robinia pseud-acacia(CHAPTER V. The Flavone 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.

Acacetin, C₁₆H₁₂O₅, the colouring matter of the leaves of the Robinia pseud-acacia (Linn.) (common or false acacia, North American locust), forms almost colourless needles, soluble in alkalis with a pale yellow coloration (Perkin, Chem. Soc. Trans., 1900, 71, 430.

To prepare it a boiling aqueous decoction of the leaves is treated with basic lead acetate solution, and the pale yellow precipitate is suspended in water and decomposed with boiling dilute sulphuric acid. From the clear liquid the colouring matter is removed by extraction with ether and purified by crystallisation from dilute alcohol.

Acacetin forms a diacetyl derivative, C₁₆H₁₀O₅(C₂H₃O)₂, colourless needles, melting-point 195-198°, and when fused with alkali gives phloroglucinol and p-hydroxybenzoic acid. Digested with boiling hydriodic acid it yields apigenin and one molecule of methyl iodide, and is consequently an apigenin monomethylether. Acacetin is very probably identical with von Gerichten's apigenin methyl ether (Ber., 1900, 33, 2908) - the acetyl derivative of which melts at 198-200°.

Interesting is the fact that the flowers of the Robinia pseud-acacia contain robinin, a glucoside of the trihydroxy flavonol kaempferol - which contains one more hydroxyl than apigenin. This is referred to later.