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.
Genista tinctoria, Linn. {Dyer's broom, Dyer's greenweed; Genet, Genestrole, Trentanel, Fr.; Ginster, Ger.) is found in the pastures, thickets, and waste places throughout Central and Southern Europe, across Russian Asia to the Baikal, and northward to Southern Sweden. It is frequent in the greater part of England, but rare in Ireland and Scotland. The fact that it contains a yellow colouring matter is recorded by numerous writers, and the following embody the principal references to the dyeing and general properties of the plant: Bancroft ("Philosophy of Permanent Colours," 1813, 2, 108); Gmelin ("Handbook of Chemistry," 16, 517); Berthollet ("On Dyeing," 1824, 2, 242); Gonfreville ("L'Artdela Teinturedes Laines," 501); Leuchs ("Farben u. Farbekunde," 1846, 2, 309), and Schützenberger ("Traite des Matieres Colorantes," 1867, 4, 422).
To isolate the colouring matters, a hot aqueous extract of the plant is treated with lead acetate solution, and the pale yellow viscous precipitate is collected and decomposed by means of boiling dilute sulphuric acid. The clear liquid decanted from the lead sulphate deposits on cooling a dull yellow powder; this is filtered off, dissolved in a little alcohol, and the solution poured into a large volume of ether, causing the separation of a dark-coloured resinous impurity. The clear liquid is evaporated, yielding a yellow crystalline residue, which consists of two substances. To separate these, advantage is taken of the fact that, with sulphuric acid in the presence of acetic acid, one only of these compounds gives an insoluble sulphate. This is collected and decomposed with water and the product crystallised from dilute alcohol. It is obtained as yellow needles, and was found to be identical with the luteolin of weld (Reseda luteola) (Perkin and Newbury, Chem. Soc. Trans., 1899, 75, 830).
Genistein, C14H10O5, the second colouring matter of dyer's broom, is present in the mother liquors obtained during the purification of the luteolin, and also in considerable quantity in the filtrate from the lead precipitate, from which it is most readily isolated. To the boiling liquid ammonia is added, causing the separation of a lemonyellow precipitate, which is collected and decomposed with boiling dilute sulphuric acid. The clear liquid is extracted with ether, and the extract evaporated, leaving a brownish crystalline mass. It is purified by crystallisation from acetic acid, and by conversion into the acetyl derivative.
Genistein crystallises in long colourless needles; melting-point 291-293° (Perkin and Horsfall, Chem. Soc. Trans., 1900, 77, 1312); soluble in alkalis with a pale yellow coloration. Alcoholic ferric chloride gives a dull-red violet coloration, and alcoholic basic lead acetate a lemon-yellow precipitate.
Triacetylgenistein, C14H7O5(C2H3O)3, colourless needles, melting-point, 197-201°; and tetrabromgenistein, C14H6Br4O5, colourless needles, melting-point above 290°, have been described.
On digestion with boiling 50 per cent, potassium hydroxide, genistein gives phloroglucinol and p-hydroxyphenylacetic acid.
By methylation with methyl iodide in the usual manner, genistein dimethyl ether and methylgenistein dimethyl ether are produced.
Genistein dimethyl ether, C14H8O3(OCH3)2, forms colourless leaflets, melts at 137-139°, and gives the monacetyl compound, C14H7O3(C2H3O)(OCH3)2, minute colourless needles, melting-point 202-204°. When decomposed with alcoholic potash, it forms methoxyphenylacetic acid and phloroglucinol-monomethyl ether (identified by means of its disazobenzene derivative).
Methylgenistein dimethyl ether,
CH3.C14H7O3(OCH3)2, melts at 202°; and the acetyl derivative,
CH3.C14H6O3(C2H3O)(OCH3) 2,
forms colourless needles, melting-point 212-214°. With alcoholic potash it gives methoxyphenylacetic acid and probably methylphloroglucinol-monomethyl ether.
Genistein diethyl ether, C14H8O3(OC2H5)2, forms colourless needles, melting-point 132-134°; whereas acetylgenistein diethyl ether, C14H7O3(C2H30)(OC2H5)2, melts at 168-170°. Alcoholic potash gives p-ethoxyphenylacetic acid.
According to Perkin and Horsfall, genistein is most probably a trihydroxyphenylketocumaran.
Genistein is a feeble colouring matter, and upon woollen cloth gives, with chromium mordant, a pale greenish-yellow; with aluminium mordant, a very pale yellow; and with iron mordant, a chocolate- brown shade.
Dyeing Properties of Dyer's Broom.
-In this respect there is a close resemblance between dyer's broom and weld. The dyeing power of the former is distinctly the weaker of the two; otherwise the only point of difference worthy of mention is that shown by the iron mordant, which, in the case of dyer's broom, gives a duller and more drab-coloured shade. Luteolin is also present in the Digitalis purpurea (digito-flavone), (Fleischer and Fromm, Ber., 1899, 32, 1184; v. Kostanecki and Diller, ibid.) 1901, 34, 3577), and in the flowers of Antirrhinum majus (Wheldaleand Bassett, Biochem. Jour., loc. cit.).
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