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.
This substance occurs, together with morin, in the wood of the tropical tree Chlorophora tinctoria (Gaudich), which comes into commerce as "Old Fustic".
The colouring matters of old fustic were first investigated by Chevreul ("Lemons de chimie applique a la teinture," ii., 150), who described two substances, one sparingly soluble in water, calledmorin, and a second somewhat more readily soluble. Wagner (Jour. f. pr. Chemie, (i), 51, 82) termed the latter moritannic acid) and considered that it had the same percentage composition as morin. Hlasiwetz and Pfaundler (Annalen, 127, 351), on the other hand, found that the so-called moritannic acid was not an acid, and as moreover its composition and properties were quite distinct from those of morin, they gave it the name "Maclurin".
When morin is precipitated from a hot aqueous extract of old fustic by means of lead acetate the solution contains maclurin. After removal of lead in the usual manner, the liquid is partially evaporated and extracted with ethyl acetate, which dissolves the colouring matter. The crude product is crystallised from hot water or dilute acetic acid (Perkin and Cope, Chem. Soc. Trans., 1895, 67, 943). A crude maclurin is also obtained during the preparation of fustic extract, partly in the form of its calcium salt, and this product may be purified with dilute hydrochloric acid and crystallised from water. In order to decolorise the crystals, acetic acid is added to a hot aqueous solution and a little lead acetate in such quantity that no precipitate is formed, and the solution is then treated with sulphuretted hydrogen. The clear liquid thus obtained is much less strongly coloured, and after repeating the operation two or three times, the maclurin, which crystallises out on standing, possesses only a pale yellow tint.
Maclurin, to which the composition C13H10O6 was assigned by Hlasiwetz and Pfaundler (Jahresber., 1864, 558), consists, when pure, of almost colourless needles, which contain one molecule of water of crystallisation; the anhydrous compound melts at 200°C. (Wagner, Jahresber., 1850,529). The colouring matter is somewhat soluble in boiling water, is soluble in aqueous alkalis, forming pale yellow solutions, whilst with ferric chloride its aqueous solutions give a greenish-black coloration, and with aqueous lead acetate a yellow precipitate, which is soluble in acetic acid. When boiled with potassium hydroxide maclurin yields phloroglucinol and protocatechuic acid.
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Patent Fustin.
Under the name "patent fustin" a colouring matter has been placed on the market, which consists chiefly of diazobenzene-maclurin (C. S. Bedford, 1887; Eng. Pat. 12667). To prepare this substance, old fustic is extracted with boiling water, the solution is decanted from the precipitate of morin and its calcium salt which separates on cooling, and is neutralised with the necessary quantity of sodium carbonate. Diazobenzene sulphate is then added until a precipitate no longer forms, and this is collected and washed with water. It is sold in the form of a paste, and dyes chrome mordanted wool an orange-brown shade.
Diazobenzene-maclurin (Bedford and Perkin, Chem. Soc. Trans., 1895, 67, 933; ibid., 1897, 71, 186), which crystallises in salmon-red prismatic needles, melting-point 270°C. (decomp.), has the following constitution: [KUVA PUUTTUU]
It dyes wool and silk direct from a weakly acid bath, in shades of orange, and on mordants gives colours varying from orange-red on aluminium and orange-brown on chromium, to olive on iron. The dyeings are fairly fast to washing.
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Dyeing Properties of Maclurin.
With aluminium mordant maclurin gives a pale yellow, with chromium a yellow-green, and with iron a weak grey colour may be obtained.
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