Sanderswood.CHAPTER XVIII. Colouring Matters of Unknown Constitution. The Insoluble Red Woods(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.

This dyestuff, known also as Red Sanderswood, Santalwood, or Sandelwood, is the product of the Pterocarpus santalinus (Linn.), a papilionaceous tree growing in tropical Asia. It is, or was, imported from the East Indies, Ceylon, the coasts of Coromandel and Malabar, Golconda, Madagascar, etc. It comes into commerce in the form of hard heavy billets of a dull red colour. In the state of powder it gives off a faint aromatic odour like that of orris root, specially noticeable when it is heated or boiled with water. It yields to alcohol about 19,6 per cent, of extract, mainly consisting of colouring matter which is sparingly soluble even in boiling water, though readily in alcohol.

The resinous colouring matter was first isolated from Sanderswood by Pelletier (Ann. chim. phys., 1832, (2), 51, 193), who termed it sandel red, and assigned to it the formula Q H10O5. Meier (Arch. Pharm., 1848, 55, 285; 56, 41) named the colouring matter he obtained santalic acid or santalin, and though he did not analyse it, considered it to be a purer form of Pelletier's "sandel red". Meier extracted the wood with ether, evaporated the solution, and washed the residue with water. The impure product was dissolved in alcohol, the colouring matter precipitated by means of lead acetate, and the lead salt was collected and well washed with alcohol. In alcoholic suspension this lead compound was now decomposed by dilute sulphuric acid, and the clear liquid, after removal of the lead sulphate, was evaporated to crystallisation. Thus obtained, the santalin consisted of minute red crystals, melting-point 104°, insoluble in water but very soluble in alcohol. Sulphuric acid dissolved it with a dark red tint and caustic alkalis with a purple colour. Somewhat later Weyermann and Haffely (Annalen, 1850, 74, 226) suggested for santalin the formula C₁₅H₁₄O₅, though Franchimont and Sicherer again (Ber., 1879, 12, 14) considered the formula C₁₇H₁₆O₆ preferable. These latter authors who adopted a process very similar to that devised by Meier, could not obtain santalin in a crystalline condition, though this melted at 104-105°. Fused with caustic potash the amorphous product gave acetic acid, resorcinol, and probably also protocatechuic acid and catechol, and when heated with hydrochloric acid at 180° methyl chloride was evolved. Nitric acid gave oxalic acid and a yellow bitter substance, probably picric or styphnic acid, and when oxidised with permanganate, a crystalline substance having a strong odour of vanillin together with oxalic and acetic acids was produced. Weidel (Zeitsch. fur Chem., 1870, 6, 83) extracted the wood with boiling dilute alkali, neutralised the solution with hydrochloric acid and collected and dried the voluminous brickred precipitate. By long-continued extraction with ether he obtained from this two crystalline substances, santal, 2C₈H₆O₃, 3H₂O, which is colourless, and a bright red compound, C₁₄H₁₂O₄.

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O'Neill and Perkin point out that the dyeing property of sanderswood seems to be due rather to deoxysantalin than to santalin, and although sanderswood is specially rich in colouring matter, it is astonishing how little of this comes into play during the dyeing process. Proof of this is obtained by dyeing wool with 60 per cent, of sanderswood and at the end of the operation employing the residual wood twice for dyeing fresh material. The first pattern possessed the usual colour, the second was pale pink, and the third was practically undyed, indicating that all the colouring matter soluble in water had then been removed. The woody matter, however, now yielded to alcohol 13,8 per cent, of extract compared with the 19,4 per cent. originally present, and this consisted of a dark red resinous mass and contained much santalin. Even, therefore, if it be presumed that all the soluble matter removed from the wood in the dye-bath is colouring matter (and this is improbable), it is evident that the larger proportion present therein, owing to its insoluble nature, remains undissolved and takes no part in the operation. Attempts to isolate Weidel's compounds (loc. cit.) from sanderswood were unsuccessful.

In addition to colouring matter, sanderswood contains two neutral compounds, Ptero-carpin and Homo-ptero-carpin, which were first isolated by Cazeneuve and Hugonueng (Comptes rendus, 1874; civ., 1722). These authors extracted a dried mixture of the wood and slaked lime with ether, and the product which remained on evaporating the ether was crystallised, first from alcohol and then fractionally so from carbon disulphide.

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