Thespasia macrophylla(CHAPTER VII. Flavonol 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.

Thespasia macrophylla, Blume (T. lampas, Dabz.). This is a small bush common to the tropical jungles of India, Burma, and Ceylon. In Watt's "Dictionary of the Economic Products of India" there is no mention of the use of this plant as a dyestuff, but, on the other hand, the capsules and flowers of the allied T. populnea (Soland) are stated to give a yellow dye.

According to Perkin (Chem. Soc. Trans., 1909, 95, 1859) tne flowers of the T. macrophylla yield quercetin and some quantity of protocatechuic acid.

With mordanted woollen cloth the flowers produce fairly good shades, but are in no way superior to the better-known Indian natural yellow dyestuffs.

Heather or Calluna vulgaris(CHAPTER VII. Flavonol 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.

In former times the common heath or heather, until recently named Erica vulgaris, was used as a dyestuff for producing a yellow colour on - woollen goods (Crookes, "Dyeing and Calico Printing," 1874, p. 511). Although now almost superseded it was until recently employed in the home industries of outlying districts, such as the Highlands of Scotland. Bancroft ("Philosophy of Permanent Colours," 1813, 2, 1 08) states that all five species of the erica or heather found in Great Britain are, he believes, capable of giving yellows much like those obtained from dyer's brown. According, however, to the experiments of the late J. J. Hummel the E. tetralix (bell heather) and E. cinerea contain only traces of yellow colouring matter. Leuchs (Farben u. Färbekunde, 2, 320) refers to the tanning property of heather, and notes that the effect resembles in character that given by oak bark. H. R. Procter found it to contain 6.4 per cent, of tannin. The colouring matter was isolated by Perkin and Newbury (Chem. Soc. Trans., 1899, 75, 837) from an aqueous extract of the green portion of the plant, in which it appears only to reside, by precipitation with lead acetate in the usual manner. It proved to be identical with the quercetin of quercitron bark. The dyeing properties of heather, though distinctly weaker, are so similar in character to those given by quercitron bark as to require no special description. Experiment showed that 36 parts of the heather were necessary to obtain as good a result as that given by 10 parts of quercitron bark.

Onion Skins(CHAPTER VII. Flavonol 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.

The outer dry skins of the bulb of the onion, Allium cepa (Linn.), were formerly employed for dyeing purposes. According to Leuchs (Farben und Färbekunde, 1825, 1, 434), "the outer skins of onion bulbs which are of a brownish-orange colour have long been used in Germany for dyeing Easter eggs yellow, and in conjunction with alum for dyeing woollen, linen, and cotton materials. The colour is fast and particularly brilliant. From Kurrer's observations onion skins are very suitable for dyeing cotton, on which they give a cinnamon-brown with acetate of alumina, a fawn with alumina and iron, a grey with iron salts, and a variety of shades with other additions."

The colouring matter was extracted by boiling the skins with distilled water for one hour, and the yellow extract on keeping gradually deposited the impure dye as a pale olive precipitate. The average yield was 1.3 per cent. This was extracted with alcohol, the concentrated extract treated with ether and the ethereal solution washed, until a tarry precipitate no longer separated. On extracting the ethereal solution with dilute alkali the whole of the colouring matter was removed, and on neutralising the alkaline liquid a yellow precipitate was thrown down, which was purified by crystallisation from dilute alcohol. The acetyl compound melted at 190-191°, and there could be no doubt as to the identity of this colouring matter with quercetin (Perkin and Hummel, Chem. Soc. Trans., 1896, 69, 1295). Attempts to isolate a quercetin glucoside from onion skins have hitherto failed, and it seems that such a compound is absent at least in the outer dry material.

Sophora japonica(CHAPTER VII. Flavonol 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.

Sophora japonica (Linn.). This is a large and beautiful tree, not unlike an acacia, belonging to the Leguminosæ, which grows abundantly throughout China.

The undeveloped flower-buds constitute an important yellow dyestuff employed by the Chinese for colouring the silken vestments of the mandarins. For this purpose the buds are collected and dried rapidly, either in the sun or by artificial means, usually with the addition of a little chalk. The method of dyeing consists in simply boiling for one to one and a half hours in a decoction of the flower-buds silk which has been previously mordanted by steeping overnight in a.decoction of alum. Less frequently it is employed in the dyeing of cotton and wool. Its price appears to be about 305. a cwt.

This dyestuff has been studied by many chemists, especially by Schunck (Chem. Soc. Trans., 1888, 53, 262; 1895, 67, 30), who has proved that the glucoside which it contains, formerly called sophorin (Forster, Ber., 1882, 15, 214), is in reality identical with rutin, the quercetin glucoside first isolated from rue (Ruta graveolens, Linn.) by Weiss (Chem. Zentr., 1842, 903). (Cf. also Stein, J. pr. Chem., (i.), 58, 399; 85, 351; 88, 280; Schunck, Manchester Memoirs, 1858, 2 Ser., 15, 122.) The glucoside is readily isolated by extracting the flower buds with boiling water. The liquid on cooling deposits crystals of rutin, which can be purified by recrystallisation from water or dilute alcohol.

When applied to wool the Sophora japonica buds give colours somewhat like those obtained with quercitron bark, viz. a dull orange with chromium, a yellow of moderate brilliancy with aluminium, a bright yellow with tin, and a dark olive with iron. In dyeing power it seems to be equal if not slightly superior to quercitron bark, and is to be regarded as an excellent natural dyestuff, quite equal to those of similar character in general use (Hummel and Perkin, J. Soc. Chem. Ind., 1895, 458).

Thuya occidentalis(CHAPTER VII. Flavonol 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.

Thuya occidenlalis (Linn.). In 1858 Rochleder and Kawalier (Wien. akad. Ber., 29, 10) isolated from the green portions of the Thuya (Thuja) occidentalis a glucoside Thujin, which, when hydrolysed, gave a yellow colouring matter thujetin.

Thujin, C₂₀H₂₂O₁₂. The plant was extracted with alcohol, the extract when cold filtered from wax, and evaporated to a small bulk. The residue was diluted with water, a few drops of lead acetate solution added, the precipitated impurities removed, and the clear brown filtrate treated with lead acetate. The yellow lead compound was collected, extracted with dilute acetic acid, and basic lead acetate now added to the solution. The bright yellow precipitate was suspended in water, decomposed with sulphuretted hydrogen, the lead sulphide removed, the filtrate treated with carbon dioxide in order to free it from sulphuretted hydrogen and evaporated in vacua over sulphuric acid. Crystals gradually separated, and these were crystallised repeatedly from dilute alcohol until when treated with ammonia a green coloration was no longer produced.

Thujin is described by these authors as citron yellow microscopic prisms sparingly soluble in cold water. The alcoholic solution becomes yellow on treatment with alkalis, whereas with ferric chloride a dark green coloration is produced. When thujin is digested in alcoholic solution with dilute hydrochloric or sulphuric acid it is hydrolysed with formation of glucose and thujigenin, apparently an intermediate product, which readily takes up a molecule of water, with formation of thujetin
C₂₀H₂₂O₁₂ + H₂O = C₁₄H₁₂O₇(Thujigenin.) + C₆H₁₂O₆
C₁₄H₁₂O₇ (Thujigenin.) + H₂O = C₁₄H₁₄O₈ (Thujetin.)

Thujetin, C₁₄H₁₄O₈, forms yellow crystals, and is characterised by the fact that its alcoholic solution is coloured blue-green with ammonia, and green coloured by potassium hydroxide solution.

With lead acetate it gives a deep red precipitate. When thujetin is digested with boiling baryta water it is converted into thujetinic acid, C₂₈H₂₂O₁₃, which consists of yellow microscopic needles, sparingly soluble in water, readily soluble in alcohol.

Thujigenin, C₁₄H₁₂O₇, crystallises in fine yellow needles, soluble in alcoholic ammonia, with a blue-green coloration.

The quantity of thujin which is present in the plant is very small; thus, from 240 lbs. Rochleder and Kawalier were successful in isolating a few grams only.

Perkin (Chem. Soc. Trans., 1914, 105, 1408), who re-examined this subject and employed methods almost identical with those of Rochleder and Kawalier, found that the glucoside corresponding to thujin possessed the formula C₂₁H₂₀O₁₁, melted at 183-185°, and when hydrolysed gave rhamnose and quercetin and was identical with the quercitrln of quercitron bark. The plant also contained a small amount of quercetin, and this also, prepared by the hydrolysis of the glucoside which evidently corresponds to the thujetin of Rochleder and Kawalier, dissolved in alkaline solutions with a pale green tint, but failed to give the blue-green coloration with ammonia described by these authors. During a preliminary investigation of this plant (Chem. Soc. Trans., 1899, 75, 829), the sample then examined gave a trace of yellow colouring matter soluble in alkalis with a strong green coloration, the acetyl compound of which after frequent recrystallisation melted at 205-206°. It thus seems probable that the thujin of Rochleder and Kawalier consisted of quercitrin contaminated with a second glucoside, possibly that of myricetin. The quantity of this latter present in the plant may possibly vary according to its environment or with the season of the year.

Other sources of Quercetin.(CHAPTER VII. Flavonol 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.

See ONION SKINS, PERSIAN BERRIES, SOPHORA JAPONICA, PODOPHYLLUM EMODI, WHITE CLOVER (Trifolium repens), CUTCH (Acacia catechu and Uncaria gambier), and SUMACH, Osyris compressa, Osyris abysinnica, Ailanthus glandulosa, Rhus rhodanthema, Artostaphylos uva ursi. Quercetin has also been shown to exist probably as glucoside in tea leaves (Hlasiwetz and Malin, Jahres., 1867, 732);
in the flowers of the horse-chestnut (Rochleder, ibid., 1859, 523);
in the bark of the apple-tree (Rochleder, ibid., 1867, 731);
in Craetagus oxycantha (may blossom); and yellow wallflowers, Cheiranthus chieri (Perkin and Hummel, Chem. Soc. Trans., 1896, 69, 1568);
Rumex obtusifolius (seeds), (Perkin, ibid., 1897, 71, 1199);
Delphinium zalil (Asbarg), (Perkin and Pilgrin, ibid., 1898, 73, 381);
Prunus spinosa (flowers), (Perkin and Phipps, ibid., 1904, 85, 56),
Thespasia lampas (Perkin, ibid., 1909, 95, 1859),
the flowers of the Poinciana regia (Bengal), Woodfordia floribunda, and the common fuschia, F. macrostema globosa (Perkin and Shulman, Chem. Soc. Proc., 1914, 30, 177).

Quercitron Bark.Glucosides of Quercetin.Rutin.(CHAPTER VII. Flavonol 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.

Rutin was discovered by Weiss (Chem. Zentr., 1842, 305) in the leaves of a rue (Ruta graveolens, Linn.), and was subsequently isolated from capers (Capparis spinosa, Linn.) by Rochleder and Hlasiwetz (Ann. Chem. Pharm., 82, 196), and by Schunck (Manchester Memoirs, 1858, 2 Ser., 155, 122) from buckwheat (Fagopyrum esculentum, Moench.). Whereas Hlasiwetz (Ann. Chem. Pharm., 96, 123) came to the conclusion that rutin was identical with quercitrin, it was shown by Zwenger and Dronke (ibid, 123, 145) that this could not be the case, because on hydrolysis rutin gives quercetin and two molecules of sugar. Schunck (Chem. Soc. Trans., 1888, 53, 262; 67, 30) considered that the formula of rutin is C₂₇H₃₂O₁₆, 2H₂O, and that on hydrolysis it is converted into quercetin and 2 molecules of rhamnose, C₂₇H₃₂O₁₆+3H₂O=C₁₅H₁₀O₇+2C₆H₁₄O₆. Rutin, moreover, was identical with the sophorin, which Foerster (Ber., 15, 214) had isolated from the Sophora japonica.

It has been shown by Schmidt (Chem. Zentr., 1901, ii., 121) that by the hydrolysis of rutin glucose is also produced, the formula of this substance being therefore C₂₇H₃₀O₁₆.C₂₇H₃₀O₁₆ + 3H₂O = C₁₅H₁₀O₇ + C₆H₁₂O₆ + C₆H₁₄O₆

Rutin forms pale yellow glistening needles, sparingly soluble in water, and is said to melt above 190°. With alcoholic potassium acetate it gives a bright yellow monopotassium salt (Perkin, Chem. Soc. Trans., 1899, 75, 440).

According to Schmidt, violaquercitrin (violarutin) is identical with rutin (ibid.) 1908, 246, 274), and Perkin (ibid., 1910, 97, 1776) has shown that osyritin (Colpoon compressum, Berg.) (Osyris compressa) (ibid., 1902, 81, 477) and myrticolorin {Eucalyptus macrorhyncha, F. Muell.) (Smith, ibid., 1898, 73, 697) in reality consist of this substance (loc. cit.).

The dyeing properties of rutin are similar to, though weaker than those of quercitron bark. The following shades are given on mordanted woollen cloth:
Chromium. Brown-yellow.
Aluminium. Full golden-yellow.
Tin. Lemon-yellow.
Iron. Dull brown.

Quercitron BarkCommercial preparations: Flavin, Patent bark, Bark-liquor.(CHAPTER VII. Flavonol 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.

Quercitron Bark
Commercial Preparations.

Flavin.

This is the most important commercial preparation of quercitron bark; it seems to have been first imported into this country from America. The details of its manufacture have been guarded with much secrecy, and analyses of commercial samples show that different methods have been adopted by different makers. Some specimens consist essentially of quercitrin, and are known as yellow flavin, whilst others contain only quercetin, and are known as red flavin. The former have probably been prepared by merely extracting the bark with water and high-pressure steam, or, as it is said, with steam only at a temperature of 102-103°.

The best qualities of flavin are those in which the colouring matter is present as more or less pure quercitrin, and entirely free from woody fibre. Red flavin is prepared by rapidly extracting the powdery portion of rasped quercitron bark with ammonia or other alkali, and boiling the solution with sulphuric acid. The precipitate thus produced is ultimately collected, washed with cold water till free from acid, and finally dried. Flavin of this character has about sixteen times the tinctorial value of quercitron bark. It is not very soluble, but it yields with aluminium, and especially with tin mordants, much more brilliant colours than quercitron bark itself.

Patent bark.

Patent bark, or "commercial quercetin," is a preparation of quercitron bark analogous to the garancin made from madder. It is manufactured in a similar manner, viz. by boiling, for about two hours, 100 parts finely ground quercitron bark, 300 parts water, and 15 parts concentrated sulphuric acid. The product is collected on a filter, washed free from acid, and dried. The yield is about 85 per cent, of the bark employed, while its colouring power is much greater. It seems to have been first manufactured in 1855 by Leeshing.

Bark-liquor.

Bark-liquor is simply an aqueous extract of quercitron bark, and is sold with a specific gravity of 1.66-1.255.

Application.

Quercitron bark, patent bark, and bark extracts have been largely employed by the calico and woollen printer. The latter are used in the preparation of steam-yellows, olives, chocolates, etc., in conjunction with aluminium, tin, chromium, and iron mordants. The former at one time found employment in conjunction with garancin for the production of various compound shades, e.g. chocolate, dull red, orange, etc. Now they may be used in a similar manner along with alizarin. When used alone, quercitron bark and patent bark give, with aluminium mordant yellow, with tin orange, with chromium olive-yellow, with iron greenish-olive colours.

Flavin is chiefly serviceable in wool dyeing for the production, in single-bath, of bright yellow and orange, fast to milling, and was at one time largely used along with cochineal to obtain a bright scarlet. The mordant employed is stannous chloride and oxalic acid or cream of tartar.

On cotton all the quercitron colours are but moderately fast to light; on wool and silk the chromium, copper, and iron colours are fairly fast, whereas the aluminium and tin colours are only moderately so.

Quercitron Bark(CHAPTER VII. Flavonol Group.)(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 important yellow dyestuff, the latest addition to the somewhat meagre list of commercial natural colouring matters, was discovered and introduced by Bancroft in 1775. In his "Philosophy of Permanent Colours" he states (ii., 113): "Quercitron bark is one of the objects of a discovery of which the use and application for dyeing are exclusively vested in me, for a term of years by an Act of Parliament in the twenty-fifth year of his present Majesty's reign".

Quercitron bark is the inner bark of a species of oak known as Quercus discolor; Ait (Q. tinctoria), which is a native of the Middle and Southern States of America. The tree in the south is described as being from 60 to 80 feet high, with a trunk from 6 to 10 feet in diameter; but in the north it does not attain to this size. In order to obtain the dyestuff the epidermis or exterior blackish coat of bark is usually removed by shaving and the inner portion then detached and ground. The product may be separated into stringy fibres and a light fine powder, the latter of which contains the principal portion of the colouring matter.

Quercitron bark and its preparations are still used to a considerable extent, although not so much as was formerly the case. This is not only due to the introduction of the artificial colouring matters, but because it has been supplanted for many purposes by the less costly old fustic.

Quercetin, C₁₅H₁₀O₇;, the colouring matter of quercitron bark, has been the subject of numerous researches, and many of these unfortunately resulted in the publication of complicated and unsatisfactory formulæ. At an early stage it was ascertained that quercetin does not exist in the plant, at least to any extent in the free condition, but in the form of its glucoside quercitrin.

To prepare quercetin the following method devised by the late Sir W. H. Perkin, and employed by him for several years on the manufacturing scale, gives good resets. Quercitron bark dust is macerated with moderately strong salt solution to remove gummy substances, filtered, and then extracted with dilute ammonia. The cold ammoniacal liquid is treated with a slight excess of hydrochloric acid, causing the separation of certain impurities in the form of a brown flocculent precipitate. This is removed, and the pale yellow acid solution of the glucoside is boiled for about thirty minutes. The glucoside is thus hydrolysed and almost chemically pure quercetin separates in the form of pale yellow needles, which are collected while the mixture is still warm and washed with water. It is readily soluble in alcohol, and dissolves in alkaline solutions with a yellow colour. With aqueous lead acetate it gives a bright orange- red precipitate, and with alcoholic ferric chloride a dark green colour.

The most important of the early investigations of quercetin was carried out by Liebermann and Hamburger (Ber., 12, 1178), who assigned to it the formula C₂₄H₁₆O₁₁ and to quercitrin the formula C_26H38O₂₀ Herzig (Monatsh., 5, 72; 6, 863; 9, 537; 12, 172; 14, 53; 15, 697), who made an elaborate series of researches on this subject, at first adopted this formula. Subsequently it was ascertained that quercetin was in reality C₁₅H₁₀O₇, and this receivedsupport by the examination of its compounds with mineral acids (Perkin and Pate, Chem. Soc. Trans., 1895, 67, 647).

When quercetin is fused with alkali, it gives protocatechuic add and _{phloroglucinol}, and if its alkaline solution is oxidised with air, the same products are obtained. By the more gentle action of the alkali, Hlasiwetz and Pfaundler (Jahres., 1864, 561) obtained certain intermediate products of the hydrolysis, paradiscetin, C₁₅H₁₀O₆, yellow needles, quercetic acid, C₁₅H₁₀O₇, colourless needles, and quercimeric acid, C₈H₆O₅, H₂O, colourless crystals. Herzig and others who have reinvestigated this decomposition have been unable to obtain the substances of Hlasiwetz and Pfaundler, and if these compounds are in reality chemical individuals, it seems likely that their formation was due to the action of some special impurity contained in the alkali employed by these chemists.

[---]

Quercetin is a strong dyestuff, and gives with mordanted wool the following shades, which are almost identical with those produced by fisetin:
Chromium. Red-brown.
Aluminium. Brown-orange.
Tin. Bright orange.
Iron. Olive-black.

[---]

Quercitrin, the glucoside of quercetin, was first isolated from quercitron bark by Chevreul, and has been examined by numerous chemists. The method usually employed for the preparation of this substance is that devised by Zwenger and Dronke (Annalen, Suppl., 1, 267), and this was subsequently utilised by Liebermann and Hamburger (Ber., 12, 1179).

Quercitron bark is extracted with 5-6 times its weight of boiling 50 per cent, alcohol, the extract evaporated to one-half, and treated with a little acetic acid, followed by lead acetate solution. The precipitate is removed, sulphuretted hydrogen is passed through the filtrate, and after removal of lead sulphide the clear liquid is evaporated to dryness. The residue is dissolved in a little hot alcohol, the solution treated with water and the crude quercitrin which separates on cooling is purified by repeated crystallisation from water.

A very convenient source of quercitrin is yellow flavine (Perkin, private communication), which consists almost entirely of this substance, and is usually free from quercetin. A hot aqueous extract of this material gives, on cooling, a crystalline precipitate of the glucoside, and this by recrystallisation from water with the aid of animal charcoal is readily obtained pure.

[---]

It was formerly considered that the glucosides (colouring principles) were hydrolysed during the dyeing operation, and that the shades thus obtained were due not to the glucosides, but to the free colouring matters. This in certain cases is correct, especially when the plant contains an enzyme capable of effecting the hydrolysis; but on the other hand, in many cases the glucoside is itself the colouring matter and directly responsible for the dyeing effect. Quercitrin is an instance in point (Perkin, Chem. Soc. Trans., 1902, 81, 479), and gives upon mordanted fabrics shades which are distinct from those of quercetin itself.

Quercitrin.
Chromium - Full brown-yellow.
Aluminium - Full golden-yellow.
Tin - Lemon-yellow.
Iron - Deep olive.

Quercetin.
Chromium - Red-brown.
Aluminium - Brown-orange.
Tin - Bright orange..
Iron - Olive black.

Kaempferol.
Chromium - Brown-yellow.
Aluminium - Yellow.
Tin - Lemon-yellow..
Iron - Deep olive-brown.

In dyeing property quercitrin very closely resembles kaempferol, and, indeed, differs but little from morin (old fustic) and luteolin (weld) in this respect. It was thus probable, according to Perkin (loc. cit.), that the constitution of the glucoside is to be represented by one of the two following formulæ: [KUVA PUTTUU]

[---]

The colours given by quercitrin are somewhat faster than those derived from quercetin.

Yellow Cedar(CHAPTER VII. Flavonol 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.

The Rhodosphacra rhodanthema (Engl.) or yellow cedar, a tree growing to the height of 70 or 80 feet, is indigenous to the northern part of New South Wales.

The colouring matter of this dyewood is fisetin, which is readily isolated by the method described in connection with young fustic (Perkin, Chem. Soc. Trans., 1897, 71, 1194).

A second substance, C₃₆H₃₀O₁₆?, colourless needles, melting-point 215-217°, is also present in small amount, and may be identical with fustin, the glucoside of fisetin obtained from young fustic by Schmid (Ber., 1886, 19, 1755).

The shades given by the yellow cedar are slightly weaker and differ considerably from those given by young fustic (Rhus cotinus), although both contain the same colouring matter. Employing mordanted woollen cloth, the following distinctions are observed:
Young fustic - Chromium. Reddish-brown; Aluminium. Orange; Tin Orange-yellow; Iron. Brown-olive
Yellow cedar - Chromium Yellowish-brown; Aluminium. Brownish-yellow; Tin Golden-yellow; Iron Olive
and these may be due to varying amounts of the glucoside which is contained in both plants.

Young Fustic(CHAPTER VII. Flavonol 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.

Cotinus coggygria

Young fustic consists of the wood of the stem and larger branches of the Rhus cotinus (Linn.), a small tree which is a native of Southern Europe, and the West India Islands. It is a hard compact yellow wood, and is usually imported in small bundles or faggots. Within the last few years young fustic has almost disappeared from the market, not only on account of the artificial colouring matters, but because the shades it yields lack permanence, and the percentage of colouring matter it contains is small. The leaves of the R. cotinus constitute Venetian sumach, a tanning material which is employed to some extent in Italy and Southern Europe.

Fisetin, C₁₅H₁₀O₆, the colouring matter of young fustic, was first isolated by Chevreul ("Leçons de Chimie appliquee a la Teinture," A. ii., 150), who gave it the name "Fustin". Bolley (Schweiz. polyt. Zeitschr., 1864, 9, 22) considered that it was identical with quercetin, but Koch (Ber., 5, 285) maintained that fisetin was probably an aldehyde of quercetinic acid.

Schmid (Ber., 1886, 19, 1734), who carried out an exhaustive examination of this dyewood, obtained fisetin in a pure condition and proved that it was not identical with quercetin. He found that in addition to the free colouring matter, young fustic contains a glucoside of fisetin combined with tannic acid to which he gave the name of fustin tannide.

To prepare fisetin, Schmid (loc. cit.), and later Herzig (Monatsh., 12, 178), employed "cotinin" (v. infra), a commercial preparation of young fustic which is no longer on the market. According to Perkin and Pate (Chem. Soc. Trans., 1895, 67, 648), fisetin is readily isolated from the dyewood as follows:

Young fustic is extracted with boiling water, and the extract treated with lead acetate solution. The lead compound of the colouring matter is collected, made into a thin paste with water, and in a fine stream run into boiling dilute sulphuric acid. After removal of lead sulphate the dark-coloured filtrate, on cooling, deposits a semicrystalline brownish mass, which is collected and purified by crystallisation from dilute alcohol.

[---]

Fisetin is a strong colouring matter and gives shades which are almost identical with those produced by quercetin, rhamnetin, and myricetin. The colours given with wool mordanted with chromium, aluminium, and tin are, respectively, red-brown, brown-orange, and bright red-orange (Perkin and Hummel, Chem. Soc. Trans., 1896, 69, 1290).

The glucoside of fisetin, according to Schmid (loc. cit.), is prepared as follows: A boiling aqueous extract of young fustic is treated with lead acetate, the precipitate removed, the clear liquid freed from lead by means of sulphuretted hydrogen, and saturated with salt. The mixture is filtered, the filtrate extracted with ethyl acetate, and the extract evaporated. There is thus obtained a residue consisting of the crude fustin-tannide, which is purified by solution in water, precipitation with salt, and extraction with ethyl acetate.

Fustin tannide crystallises in long yellowish- white needles, which are easily soluble in water, alcohol, and ether. When heated it decomposes above 200°. If a solution of fustin tannide in hot acetic acid is treated with water, and allowed to stand for some time, colourless crystals of fustin are gradually deposited.

Fustin crystallises from water in yellowish-white needles, melting-point 218-219°, and when digested with boiling dilute sulphuric acid gives fisetin and a sugar, the nature of which has not been determined. The formula given to this glucoside C₅₈H₄₆O₂₃ by Schmid cannot be regarded as correct, in view of the fact that the true formula of fisetin is now known to be C₁₅H₁₀O₆.

Dyeing Properties of Young Fustic.

The colours derived from young fustic are all fugitive to light, hence this dyestuff has lost its importance. In silk dyeing it was formerly used for dyeing brown, the silk being mordanted with alum, and afterwards dyed with a decoction of young fustic, peachwood, and logwood. With the various metallic salts as mordants young fustic yields colours somewhat similar to those obtained from old fustic, the chromium colour is, however, much redder, being a reddish-brown, and the aluminium yellow is much duller; stannous chloride on the contrary gives an incomparably more brilliant orange, not unlike that obtainable from flavin or from Persian berries (Hummel).

Fisetin is present also as glucoside in the wood of the yellow cedar, Rhodosphacra rhodanthema, and in the wood of the Quebracho Colorado (loc. cit.).

The leaves of the R. cotinus contain myricetin.

Robinia pseud-acacia, Flowers (CHAPTER VII. Flavonol 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.

Robinin was first isolated from the flowers of the white Azalea by Zwengerand Dronke (Annalen, Supp., 1861, 1, 263), who considered that it was a glucoside of quercetin. Perkin (Chem. Soc. Trans., 1902, 81, 473) has shown that this is not the case.

To prepare the glucoside the flowers are exhausted with boiling alcohol, the solution concentrated by evaporation and poured into water. The mixture is extracted with ether, and the aqueous liquid distilled down to a small bulk. On standing, crystals of robinin separate, which are purified by crystallisation from water.

Robinin, according to Perkin, consists of pale yellow needles, sintering at 190 and melting at 196-197°, and when air-dried it possesses the formula C₂₃H₄₂O₂₀, 8H₂O.

Boiling dilute sulphuric acid hydrolyses robinin with formation of kaempferol, 2 molecules of rhamnose and 1 of glucose, according to the following equation:
C₂₃H₄₂O₂₀ + 4H₂O = C₁₅H₁₀O₆ + 2C₆H₁₄O₆ + C₆H₁₂O₆

Schmidt (Chem. Zentr., 1901, ii., 121), who examined robinin at almost the same time, also obtained by its hydrolysis a colouring matter C₁₅H₁₀O₆, the acetyl compound of which melts at 182-183° (evidently kaempferol), and Waljascko (J. Russ. Phys. Chem. Soc., 1904, 36, 421), again, no doubt, also unaware of the communication of Perkin, terms this colouring matter C₁₅H₁₆O₆, H₂O, robigenin. Robinin he considered to possess the formula C₃₃H₄₀O₁₉.7½H₂O, and the sugars that it yields by hydrolysis to consist of galactose (1 mol.) and rhamnose (2 mols.).

Robinin is a most interesting glucoside, and with the exception of xanthorhamnin is the only known substance of this class which yields three sugar nuclei. It is practically devoid of tinctorial property.

Interesting is the fact that whereas the bark of this plant contains acacetin, the monomethyl ether of the trihydroxyflavone, apigenin, its flowers yield the glucoside of the trihydroxyflavonol kaempferol. Whether the occurrence of distinct flavones in various portions of the same plant is exceptional or otherwise, has been little studied, and appears to have only been observed elsewhere in the cases of the yellow cedar (Rhodesphaera rhodanthema), the leaves of which contain quercetin and the stem fisetin, and the Venetian sumach, the stem of which contains fisetin and the leaves myricetin.

Delphinium consolida, Flowers (Kaempferol)(CHAPTER VII. Flavonol Group.)(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.

Delphinium consolida is a common European plant belonging to the Larkspur family; its name refers to its powers, real or imaginary, of healing or consolidating wounds. The blue flowers were examined by Perkin and Wilkinson (Chem. Soc. Trans., 1902, 81, 585) to determine if these yield the same colouring matters as those previously isolated from the flowers of the D. zalil (ibid., 1898, 73, 267). The presence of kaempferol only could, however, be detected. For its isolation an aqueous extract of the flowers was digested at the boiling-point with addition of sulphuric acid, and the brown resinous product which separated on keeping, extracted with alcohol and the extract evaporated to a small bulk. Addition of ether to this solution caused the precipitation of resinous impurity, and on evaporating the ethereal liquid a semi-crystalline residue of the crude colouring matter was obtained. The product was crystallised from dilute alcohol, converted into acetyl derivative, and this after purification retransformed into colouring matter in the usual manner. The yield was approximately 1 per cent.

[---]

Kaempferol possesses well-defined dyeing properties, and gives with mordanted woollen cloth the following shades which closely resemble those given by morin (loc. cit.):
Chromium. Brownish-yellow.
Aluminium. Yellow.
Tin. Lemon-yellow.
Iron. Deep olive-brown.

It is also present in the Impatiens balsamina (Chantili Pass), the Erythrina stricta (vernacular name "Kon kathet"), (Perkin and Shulman, Chem. Soc. Proc., 1914, 30, 177), the berries of the Rhamnus catharticus (loc. cit.), and together with quercetin, both apparently as glucosides, in the flowers of the Prunus spinosa (Perkin and Phipps, Chem. Soc. Trans., 1904, 85, 56). For the separation of the two colouring matters a fractional crystallisation from acetic acid was employed, kaempferol in these circumstances being the more sparingly soluble.

Galanga Root(CHAPTER VII. Flavonol Group.)(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.

Galanga root is the rhizome of Alpinia officinarum (Hance) and is a native of China. It is employed in the form of a decoction as a remedy for dyspepsia.

Galanga root was first examined by Brandes (Arch. Pharm., (2), 19, 52), who isolated from it a substance which he named kaempferide, but this, according to Jahns (Ber., 1881, 14, 2385), was a mixture of three substances, kaempferide, alpinin, and galangin. The subject was later examined by Gordin (Dissert., Berne, 1897), and by Ciamician and Silber (Ber., 1899, 32, 861) and Testoni (Gazzetta, 1900, 30, ii., 327), and it is now clearly demonstrated that galanga root contains kaempferide, galangin, and galangin monomethylether. According to Testoni, the alpinin of Jahns is a mixture of galangin and kaempferide.

Kaempferide, C₁₆H₁₂O₆, consists of yellow needles, melting-point 227-229°, soluble in alkaline solutions with a yellow colour. Sulphuric acid gives a blue fluorescent yellow solution.

[---]

Galangin, C₁₅H₁₀O₅, the second constituent of galanga root, crystallises in yellowish-white needles, melting-point 214-215°, soluble in alkaline solutions with a yellow colour. With acetic anhydride, it gives a triacetyl derivative, C₁₅H₇O₅(C₂H₃O)₃, melting-point 140-142° (Jahns), and by means of methyl iodide a dimethylether, C₁₅H₈O₃(OCH₃)₂, melting-point 142°.

[---]

[---] Galangin dyes with mordanted woollen cloth the following shades:
Chromium. Olive-yellow.
Aluminium. Yellow.
Tin. Lemon-yellow.
Iron. Deep olive.

[---]

CHAPTER VII. Flavonol Group.Introduction, Flavonol

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.

It is usual to subdivide the great family of yellow colours derived from flavone into two classes, flavone and flavonol, and the latter group is distinguished by the fact that the hydrogen in the γ-pyrone ring of these compounds is substituted by hydroxyl, whereas in the former it is not.

Flavonol) so designated by v. Kostanecki, was synthesised by v. Kostanecki and Szabranski (Ber., 1904, 37, 2819) in the following manner:

By the action of amyl nitrite and hydrochloric acid in alcoholic solution on flavanone, isonitrosoflavanone, melting-point 158-159°, is produced, and this by means of boiling dilute acids splits off hydroxylamine and is converted into flavonol.

Flavonol crystallises from alcohol in yellow needles, melting-point 167-170°. When warmed with aqueous sodium hydroxide it forms a yellow liquid, and on cooling the sodium salt separates in the form of yellow needles. Its solution in sulphuric acid exhibits an intense violet fluorescence. Acetylflavonol, colourless needles, melts at 110-111°.

According to Auwers and Müller (Ber., 1908, 41, 4233) benzylidenecoumaranones can be converted into flavonols. Thus benzylidene 4 methylcoumaranone dibromide when treated with potassium hydroxide gives 2 methylflavonol. The reaction may be thus expressed : [KUVA PUUTTUU]

The hydrolysis of flavonol into 0-hydroxybenzoylcarbinol and benzoic acid may be expressed by the following equations [KUVA PUUTTUU] and this reaction, which is typical of the behaviour in these circumstances of the whole series of these compounds, has in general been employed to ascertain their structure. It is best effected by digesting the fully methylated flavonols with boiling alcoholic potash for some hours, for owing to the occurrence of secondary reactions it cannot be satisfactorily carried out with the unmethylated compounds.

For the synthesis of numerous flavonols, many of which occur naturally, v. Kostanecki and his co-workers have employed as a general method that found serviceable for the preparation of flavonol itself, and many instances of this are given in the sequel. The flavonols, with the exception of morin, which curiously enough is colourless, are yellow crystalline substances, soluble in alkaline solutions with a yellow colour, and yield with ease in the presence of acetic acid orange crystalline oxonium salts. According to Perkin, whereas as a rule hydroxyflavones are not oxidised by air in alkaline solution and can be precipitated therefrom unchanged by acids, flavonols on the other hand are readily decomposed in this manner with the formation of water-soluble products.

Interesting is the fact that though certain colouring matters of this group do not possess two hydroxyls in the ortho-position relatively to one another, they are nevertheless strong dyestuffs, and of these the tetrahydroxyflavonol morin may be taken as an example [KUVA PUUTTUU]

That this peculiarity arises from the presence of the pyrone hydroxyl is evident if the structure of morin is compared with the lotoflavone of Dunstan and Henry (loc. cit.) the tinctorial properties of which are exceedingly feeble. It seemed possible that this dyeing effect was to be attributed to the fact that this compound contains the hydroxyl (i) in the peri-position to the chromophore and which is present in most of the natural dyes of this group. Such a suggestion, however, became untenable on the synthesis of resomorin by Bonifazi, v. Kostanecki, and Tambor (Ber., 1906, 39, 86), which dyes the same shades as morin but does not contain the peri-hydroxyl in question. Evidently therefore the tinctorial properties of these hydroxy flavonols can only be accounted for by their possession of the grouping [KUVA PUUTTUU] the effect of which is considerably strengthened by the presence of hydroxyls in other positions in the molecule, and this has received support from the observation of v. Kostanecki and Szabranski that flavonol itself dyes on aluminium mordant a pale yellow shade. Though ortho-hydroxyl groups are not essential to the dyeing property of hydroxyflavonols, their presence, at least in certain positions, has considerable influence, not only in deepening the tone, but also in reddening the shade. Thus, whereas morin dyes bright yellow shades, quercetin gives a brown-orange shade on aluminium mordant, and the effect of the pyrone hydroxyl is very evident on comparing quercetin with luteolin which gives in the same way only a bright yellow colour. A multiplication of hydroxyls does not effect any general alteration of shade given by these compounds, as is so well known to take place in the anthraquinone group, and this affords support to the theory of Watson previously mentioned.

The shades given by the flavonols are not so fast to light as those given by the flavone luteolin, and this may arise in part owing to the greater susceptibility of their salts (or lakes) to oxidation. In this respect they vary again among themselves, quercetin being a somewhat faster colour than fisetin, and morin than quercetin.

On the other hand, the character of the shade given by the natural dyestuff varies in tone, as to whether the colouring matter is present as glucoside or in the free condition. Thus in dyeing with quercitron bark, quercitrin and not quercetin is the dyestuff, whereas in old fustic no glucoside is present, and the tinctorial effect is due to morin itself. The shade again given by a glucoside is naturally dependent on the position of the sugar nucleus, and thus the quercetin glucoside, quercimeritrin (see Cotton Flowers) has quite distinct properties in this respect from quercitrin itself. Again, a glucoside may be almost devoid of tinctorial property, as in the case of the kaempferol glucoside robinin and the alizarin glucoside ruberythric acid. The idea formerly held that glucosides in general were not true dyestuffs, and that during the dyeing operation by the action of the mordant they were hydrolysed with production of the colour lake of the free colouring matter, is incorrect. This evidently arose from the fact that in certain of these dyestuffs, as, for instance, madder and Persian berries, the glucoside is accompanied by its specific enzyme, which in case the temperature of the dye-bath is gradually raised from the cold upwards, effects the hydrolysis of the glucoside before the dyeing operation has really commenced.

In the following pages the natural dyestuffs containing flavonols, or their glucosides, are as far as possible arranged as to the number of hydroxyls present in the colouring matter, commencing with those which contain least. As, however, in many plants more than one flavonol is present, it has obviously not been possible to adhere strictly to this method of classification.

Butea frondosa(CHAPTER VI. The Chalkone and Flavanone Groups.)(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.

The Butea frondosa, also called Dhak or Pulas, is a fine tree, 30-40 feet high, belonging to the order Leguminosæ. It is common throughout India and Burma, and is found in the North-West Himalaya, as far as the Jhelum River. The flowers, which in the dried condition are known as tísu, késú, kesuda or palás-képpúl, have a bright orange colour, and, although they are much larger, closely resemble in appearance the common gorseflower (Ulex europæus) with which, indeed, they are botanically allied. Large quantities of the flowers are collected in March and April, and employed by the natives to produce a yellow dye, much used during the "Holi" festival. The dyeing operation, which consists in steeping the material in a hot or cold decoction of the flowers, is virtually a process of staining, because the colour can be readily washed out. On the other hand, a more permanent result is sometimes produced either by first preparing the cloth with alum and wood ash or by adding these substances to the dye-bath.

From the Butea frondosa is also obtained the so-called "Butea gum" or "Bengal kino," employed by the natives for tanning leather, and the tree is of additional interest because in many parts of India the lac insect (Coccus lacca) is reared upon it. This latter, as is well known, causes the formation of stick lac, from which shellac and lac dye are prepared.

Butin, C₁₅H₁₂O₅. The flowers are extracted with water, and the extract digested boiling with a little sulphuric acid. A light viscous precipitate devoid of dyeing property separates, and this is removed while hot and the filtrate left over-night. The clear liquid is now decanted from a small quantity of tarry substance, and partially evaporated on the water-bath. A further quantity of a black viscous precipitate thus separates, and when this has been removed the filtrate, after some days, deposits crystals of the colouring principle. For purification the product is dissolved in a little alcohol, the mixture poured into ether, and the solution well washed with water. The liquid is evaporated, and the residue repeatedly crystallised from dilute alcohol (Perkin and Hummel, Chem. Soc. Trans., 1904, 85, 1459).

[---]

* This result has been criticised by Goschker and Tambor, who by the employment of mordanted calico obtained from butin very weak shades. It is, however, certain that by the use of mordanted wool a conversion of butin into butein occurs.Butin and butein dye mordanted woollen cloth identical shades, though as butin gives with an alcoholic lead acetate a practically colourless precipitate, it is not to be regarded as a colouring matter. In other words, butin is merely a colouring principle, and is converted during the dyeing operation by the action of the mordant into the colouring matter butein.*

The following shades are obtained: Chromium. Reddish-brown,
Aluminium. Brick-red
Tin. Full-yellow
Iron. Brownish-black,
and these are strikingly similar to those yielded by some of the hydroxybenzylidenecoumaranones artificially prepared by Friedlander and Rüdt (Ber., 1896, 29, 879) (see above).

The butea flowers contain but a trace of free butin or butein, and the glucoside present, which has not yet been isolated, is probably that of butin. This glucoside does not decompose readily during the dyeing process, hence the flowers do not dye mordanted cotton. In wool-dyeing, where acid-baths are employed, a better result is obtained, although in this case the shades possess but little strength. If the glucoside is first hydrolysed by boiling the flowers with dilute hydrochloric acid, or if sulphuric acid is employed, and the acid then neutralised with sodium carbonate, on evaporation a material is obtained which readily dyes by the usual methods. Such products give the following shades: with chromium, deep terra-cotta; with aluminium, a bright orange; with tin, bright yellow; and with iron, a brownish-olive. The chromium colour is characteristic, and is much redder in tint than that yielded by any known natural yellow dye.

Scoparin, Scutellarein(CHAPTER V. The Flavone Group.)(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.

Cytisus scoparius Jänönpapu, jänönvihma

Scoparin, the colouring matter of the Cytisus scoparius (Link.), has been investigated by Stenhouse (Annalen, 78, 15), by Hlasiwetz (Annalen, 138, 190), and by Goldschmiedt and Hemmelmayer (Monatsh., 14, 202).

[---]

Scutellarin. If the flowers and leaves of Scutellaria altissima are extracted with water the solution on keeping deposits crystals of scutellarin, C₂₁H₁₈O₁₂ (Molisch and Goldschmiedt, Monatsh., 1901, 22, 68; Goldschmiedt and Zerner, ibid.) 1910, 31, 439). It melts above 310, is sparingly soluble in the usual solvents, and the alcoholic solution gives with lead acetate a red precipitate, and with ferric chloride a green coloration passing into red on heating. With the haloid acids and sulphuric acid in the presence of acetic acid orange-red crystalline oxonium compounds separate, which are readily decomposed in contact with water.

[---]

Fukugi(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.

The Japanese dyestuff "fukugi" (botanical origin unknown) [EDIT: Garcinia subelliptica] has, at least until recently, been employed to a considerable extent in Japan as a mordant dyestuff. It consists of the wood of a tree which when ground forms an almost colourless powder, the extract of which is sold in the form of brittle rectangular cakes of a yellowish-brown colour.

Fukugetin, C₁₇H₁₂O₆, the colouring matter, forms minute canary-yellow prismatic needles melting at 288-290° (Perkin and Phipps, Chem. Soc. Trans., 1904, 85, 58). It dissolves in alkaline solutions with a yellow colour, and gives with alcoholic lead acetate an orange-yellow precipitate and with alcoholic ferric chloride a brown-black coloration.

Crystalline acetyl and benzoyl derivatives of this colouring matter could not be obtained, but the bromine compound, C₁₇H₁₀O₆Br₂, minute flat needles, melting-point 280°, is readily prepared by the action of bromine on fukugetin in the presence of acetic acid. Fukugetin dyes mordanted fabrics shades which are almost identical with those given by luteolin - Chromium. Dull orange-yellow,
Aluminium. Orange-yellow,
Tin. Bright yellow,
Iron. Olive brown,
and resembles this colouring matter in that its alkaline solution is not oxidised on exposure to air. By fusion with alkali fukugetin gives phloroglucinol and protocatechuic acid.

The dyeing properties of "fukugi" are analogous to those of weld. The similarity in shade indeed is so marked that except in point of strength for fukugi is a stronger dye than weld it is impossible to distinguish between them.

Dyer's Broom.(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.

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.).

Weld(CHAPTER V. The Flavone Group.)(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.

Weld is the dried herbaceous plant known as Reseda luteola formerly cultivated to a considerable extent in France, Germany, and Austria. Its cultivation in this country has nearly ceased, because not only is the quantity of colouring matter it contains very small, but the carriage of the plant, owing to its bulky nature, is expensive. A special interest, however, attaches to weld, for it is said to be the oldest European dyestuff known, and was used by the Gauls and other nations dwelling north of the Alps in the time of Julius Caesar.

The plant attains a height of about 3 feet, is pale brown in colour, and is sold in sheaves like straw. The colouring matter is disseminated throughout the entire plant, but the greater quantity occurs in the upper extremity and the seeds.

Luteolin, the main colouring matter of weld, was examined by Chevreul (J. Chim. Med, 6, 157; Annalen, 82, 53), who obtained it in a crude condition; its isolation in a state of chemical purity was first achieved by Moldenhauer (Annalen, 100, 180), who assigned to it the formula C₂₀H₁₄O₈. It was subsequently investigated by Schützenberger and Paraf (Bull. Soc. Chim., 1861, (i.), 18), who proposed the formula C₁₂H₈O₅ and purified it in a somewhat novel manner which is worthy of mention. Weld was exhausted with alcohol, the extract evaporated, and treated with water, which threw down a dirty greenish precipitate. This was collected, introduced with a little water into a sealed tube and heated to 250°. On cooling the sides of the tube were found to be coated with golden-yellow needles of luteolin, and the impurities had collected at the bottom of the tube to form a resinous cake.

Hlasiwetz suggested that luteolin had the formula C₁₅H₁₀O₆ and was isomeric with the paradiscetin, which he obtained during the fusion of quercetin with alkali (Annalen, 112, 107).

For the preparation of luteolin in quantity, Perkin (Chem. Soc. Trans., 1896, 69, 206, 799) employs weld extract.

300 gms. of the extract dissolved in 3 litres of water is treated with 100 c.c. of hydrochloric acid (33 per cent.), and the mixture is digested at the boiling temperature for some hours. A quantity of a black resinous substance separates, which is collected while hot, and the filtrate, which contains the colouring matter, is allowed to stand for twelve hours. A brown precipitate of impure luteolin is slowly deposited, and is collected, washed, and dissolved in a little hot alcohol. On pouring this solution into ether, the main bulk of the impurity is precipitated, and the ethereal liquid on evaporation yields a yellow residue, which is crystallised from dilute alcohol. The product in addition to luteolin contains apigenin (Chem. Soc. Trans., 1900, 77, 1315), and the latter can only be removed with certainty by the following method: -

The mixture dissolved in boiling glacial acetic acid is treated with a few drops of strong hydrochloric acid; this causes the almost immediate separation of luteolin as hydrochloride, whereas the apigenin remains in solution. The hydrochloride is collected, decomposed by water, and the luteolin crystallised from dilute alcohol.

[---]

It has already been stated that weld contains a second colouring matter, Apigenin (v. Parsley).

Dyeing Properties of Weld.

The importance of weld as a dyestuff in silk and wool dyeing has greatly diminished in consequence of its low colouring power compared with quercitron bark, flavin, and old fustic. This in one respect is unfortunate, because, of all the natural yellow colouring matters, it yields the purest and fastest shades. In conjunction with aluminium and tin mordants it gives very bright pure lemon-yellow colours, and these do not change to an olive or reddish tint as in the case with other vegetable yellows. With chromium and iron mordants weld gives yellowish and greenish olives respectively. For yellow, wool and silk are mordanted with alum and tartar in the usual manner and dyed subsequently in a decoction of weld with the addition of chalk to the dye-bath. Weld alumina yellow is to some extent still employed in this country for certain army cloths and braid. For silk dyeing, weld extract is manufactured in small quantity, and is used for the production of yellow and olive colours.

Lotus arabicus(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.

The L. arabicus (Linn.) is a leguminous plant, indigenous to Egypt and Northern Africa, and in the young condition is extremely poisonous. It has been investigated by Dunstan and Henry (Phil. Trans., 1901, 194, 515).

Lotusin, the active principle, can be isolated by extracting the dried plant with methyl alcohol. The extract is evaporated, the residue treated with water to remove chlorophyll and resin, and from the aqueous solution tannin and other impurities are precipitated by means of lead acetate. The nitrate, on evaporation, leaves a syrupy residue, from which crystals of lotusin slowly separate. In the pure condition lotusin, C₂₈H₃₁NO₁₆, forms yellow needles, and when hydrolysed by digestion with hydrochloric acid, or by means of an enzyme lotase, also found in the plant, yields dextrose, lotoflavin, and hydrocyanic acid, according to the following equation:
C₂₈H₃₁O₁₆N + 2H₂O = 2C₆H₁₂O₆ + C₁₅H₁₀O₆ + HCN

When warmed with alcoholic potash (20 per cent.) lotusin is gradually decomposed with production of ammonia and lotusinic acid:
C₂₈H₃₁O₁₆N + 2H₂O = C₂₈H₃₂O₁₈ + NH₃ (Lotusinic acid.)

This compound is monobasic, gives yellow crystalline salts, and is hydrolysed by dilute hydrochloric acid with formation of lotoflavin dextrose and heptogluconic acid:
C₂₈H₃₂O₁₈ + 2H2 = C₁₅H₁₀O₆; + C₆H₁₂O₆ + C₇H₁₄O₈

Lotoflavin, C₁₅H₁₀O₆, crystallises in yellow needles, soluble in alkaline solutions with a yellow colour. By fusion with alkali, phloroglucinol and β-resorcylic acid are produced.

With acetic anhydride lotoflavin gives a tetra-acetyl compound, C₁₅H₆O₆(C₂H₃O)₄, colourless needles, melting-point 176-178°, and when methylated by means of methyl iodide the trimethyl ether, C₁₅H₇O₃(OCH₃)₃, is obtained. This latter compound exists in two forms, viz. the a-form yellow rosettes, melting-point 125°, and the -form glistening needles, melting-point 175°, which are mutually convertible. Both varieties give by means of acetic anhydride the same monoacetyl-lotoflavin trimethyl ether, C₁₅H₆O₃(C₂H₃O)(OCH₃)₃, yellow needles, melting-point 147°.

According to Dunstan and Henry, lotoflavin is probably a tetrahydroxyflavone, possessing the formula [KUVA PUUTTUU]

The hydrolysis of the cyanogenetic glucoside lotusin, with formation of maltose, lotoflavin and hydrocyanic acid, may be expressed by the equation
C₂₈H₃₁NO₁₆ + H₂O = C₁₂H₂₂O₁₁ + C₁₅H₁₀O₆ + HCN

The following constitutions are respectively assigned to lotusin (1) and lotusinic acid (2): [KUVA]

Saponaria officinalis(CHAPTER V. The Flavone Group.)(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.

The epidermal cells of the leaves of certain flowering plants contain, dissolved in their cell sap, a substance which is coloured blue by iodine. The colour disappears on warming and returns on cooling, as is the case with starch. On this account the compound was regarded as an amorphous variety of starch by Sanio, its discoverer (Botanische Zeitung, 1857, 15, 420). Schenck (ibid., 1857, 15, 497, 455) doubted whether this substance was identical with starch, and the correctness of this view was confirmed by Nageli (Beitrage zur wissensch. Botanik, 1860, 2, 187). For the chemical examination of this substance the dried shoots of the S. officinalis were selected by Barger (Chem. Soc. Trans., 1906, 89, 1210) as the raw material, because this plant is relatively rich in the compound, and is grown on the Continent for pharmaceutical purposes, so that large quantities are easily obtainable.

[---]

Vitex littoralis(CHAPTER V. The Flavone Group.)(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.

Vitex littoralis = Vitex lucens

The Vitex littoralis (A. Cunn.) or "Puriri" is a large tree, 40-60 feet high, and 3-5 feet in diameter, which grows only in the northern portion of the North Island of New Zealand. The wood affords a very durable timber, and is chiefly used for house blocks, fencing posts, piles for bridges, railway sleepers, etc.

Vitexin, the main colouring matter, is present in the wood in the form of a glucoside which has not yet been isolated. It is prepared by digesting a purified extract of the dyestuff with boiling dilute hydrochloric acid, and by this means separates in the form of a yellow viscous mass. By extracting this crude product with boiling alcohol, a pale yellow crystalline powder remains undissolved, and this, owing to its sparing solubility, is most readily purified by acetylation, and the subsequent hydrolysis of the pure acetyl derivative (Perkin, Chem. Soc. Trans., 1898, 74, 1020).

[---]

[---] Vitexin is a somewhat feeble colouring matter, and dyes shades similar to those given by apigenin; these, employing woollen cloth mordanted with chromium, aluminium, and tin, are respectively greenish-yellow, pale bright yellow, and pale brown.

In addition to vitexin the wood of the Vitex littoralis contains (as glucoside) a small quantity of a second colouring matter, homovitexin. It was obtained as a pale yellow powder, melting-point 245-246°, and is distinguished from vitexin by its ready solubility in alcohol. Fused with alkali it gives phloroglucinol and p-hydroxybenzoic acid, and is possessed of feeble dyeing property. The analytical figures approximate to C₁₆H₁₆O₇ or C₁₈H₁₈O₈.

According to Barger (Chem. Soc. Trans., 1906, 89, 1120) the glucoside saponarin, which is present in Saponaria offirinalis (Linn.), yields on hydrolysis glucose, saponaretin, and a small quantity of vitexin. It is possible that saponaretin and homovitexin are identical.

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.

Chamomile Flowers(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.

Anthemis Nobilis. An examination of the flowers of Anthemis nobilis (Linn.) by Power and Browning (Chem. Soc. Trans., 1914, 105, 1833) has shown that these contain in addition to numerous other substances an apigenin glucoside, C₂₁H₂₀O₁₀.2H₂O, faintly yellow microscopic crystals melting at 178-180°. It dissolves in alkalis with a yellow colour and gives with aqueous ferric chloride a purplish-brown coloration. Dried at 125-130° it loses one molecule of water of crystallisation, but the second molecule cannot be eliminated without decomposing the substance. This is evident from the composition of the hexa-acetyl derivative, C₂₁H₁₄O₁₀(COCH₃)₆, colourless microscopic crystals, melting-point 144-146°, the molecule of water in question being eliminated in the process of acetylation.

By digestion with 5 per cent, aqueous sulphuric acid for three hours, this glucoside yields apigenin and dextrose according to the equation -
C₂₁H₂₀O₁₀, H₂O = C₁₅H₁₀O₅ + C₆H₁₂O₆