Kino.(CHAPTER XIV. Coumarane 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
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Bombay, Calcutta, and Madras
1918

Kaikki kuvat (kemialliset kaavat) puuttuvat // None of the illustrations (of chemical formulas) included.

Kino consists of the dried astringent juice of various trees, and though now practically obsolete, came into commerce in the form of small semi-opaque reddish-brown fragments. There are numerous varieties of this material, of which the following are the best known:

Malabar kino (Pterocarpus marsupium), African or Senegal kino (Pterocarpus erinaceus), West Indian kino (Coccoloba uvifera), Bengal kino (Butea frondosa), and Australian kino (Eucalyptus spec). Among these, Malabar kino, at one time medicinally employed in Europe owing no doubt to its astringent properties, appears to have been the most frequently examined, though as the results obtained by distinct workers have not always been in agreement, it is probable that material experimented with has in certain cases consisted of some other variety.

When distilled Malabar kino evolves catechol (Eissfeld, Annalen, 1854, 92, 101), and by fusion with potassium hydroxide, phloroglucinol and protocatechuic acid are obtained.

According to Etti (Ber., 1878, 11, 1879) when kino is digested with dilute hydrochloric acid, and the liquid extracted with ether, a substance kinoin, C₁₄H₁₂O₆, crystallising in colourless prisms, can be isolated. This compound is readily soluble in hot water, and when heated with hydrochloric acid to 130° yields catechol, gallic acid, and methyl chloride, and at 120° is converted into an amorphous red compound, C₂₈H₂₂O₁₁, the so-called kino red. Kino red is itself present in kino and forms a red resinous powder sparingly soluble in water, and the solution thus obtained gives a dull green coloration with ferric chloride.

Perkin (Chem. Soc. Trans., 1902, 81, 1173) obtained in a similar way from a sample of kino (botanical origin uncertain) a small amount of crystalline substance, which he regarded as kinoin, and which possessed yellow dyeing properties with aluminium mordanted calico.

White, however (Pharm. J., 1903, (ix.), 16, 676), was unable to obtain kinoin from Malabar kino, and again, Simonsen (Chem. Soc. Trans., 1911, 99, 1532), who submitted material of undoubted botanical authenticity to critical examination, could only isolate a small amount of catechol by Etti's method. From kino itself Simonsen, by the action of methyl sulphate and potassium hydroxide, obtained the trimethyl ether, C₁₅H₁₁O₄OMe)₃ a colourless amorphous powder which could not be crystallised. That kino thus contains three hydroxyl groups was confirmed by an examination of the acetyl derivative, an amorphous brown powder of the formula C₁₅H₁₁O₄(OAc)₃

By oxidation with permanganate, kino methyl ether yields veratric acid, whereas by fusion with alkali, kino itself gives protocatechuic acid. By neither of these decompositions could the formation of phloroglucinol or a phloroglucinol derivative be detected, and the statement of Eissfeld that he obtained phloroglucinol from kino appears, therefore, to be incorrect. Smith (Roy. Soc. N.S. Wales, 1895, 30, and 1896, 135) isolated from Australian kinos derived from Eucalyptus hemiploia (F. and M.) and E. calophylla (R. Br.), by means of ether, a substance aromadendrin, melting-point 216°, to which the formula C₂₉H₂₆O₁₂ was assigned. This crystallises from water in colourless needles resembling catechin in appearance, soluble in alkalis with a yellow colour, and gave with lead acetate a yellow coloured precipitate, and with ferric chloride a purple-brown coloration. When heated in glycerol solution, or above its melting-point, aromadendrin gives kino yellow, a yellow resinous substance almost insoluble in cold water. It is, however, easily soluble in alcohol, and this solution possesses great staining power and dyes wool and skin a bright yellow colour.