Coloriasto

11.1.25

Cotton Flowers
(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.

Among the various portions of the cotton plant which have been industrially employed must be included the flowers which constitute one of the numerous Indian dyestuffs. According to Watt ("Dictionary of the Economic Products of India") they are thus used in the Manipur district. Gossypetin was first isolated in small quantity from the flowers of the ordinary Indian cotton plant, G. herbaceum (Perkin, Chem. Soc. Trans., 1899, 75, 826), and has been more completely studied at a later period (ibid., 1913, 103, 650). For its preparation a concentrated alcoholic extract of the flowers is treated with hot water and the mixture digested when boiling with addition of hydrochloric acid for three hours. After removal of tar by filtration the hot liquid on cooling deposits a brownish-yellow powder, which contains a mixture of quercetin and gossypetin. These colouring matters are separated by a fractional crystallisation of their mixed acetyl derivatives from acetic anhydride, acetylgossypetin being in these circumstances the least soluble. The acetyl compound is finally hydrolysed by sulphuric acid in the presence of acetic acid in the ordinary manner.

[---]

Gossypitone, C₁₅H₈O₈, the name assigned to this substance, consists of microscopic needles of a dull red colour, which are difficultly soluble in the usual solvents. It dissolves in dilute alkalis with a pure blue coloration and its solution in concentrated sulphuric acid is dull brown. Sodium hydrogen sulphite solution reconverts it into gossypetin. Gossypitone possesses strong dyeing properties, and gives the following shades on mordanted woollen cloth:
Chromium. Dull-brown.
Aluminium. Orange-brown.
Tin. Orange-red.
Iron. Deep olive.

* This compound, more recently synthesised by Neirenstein (Chem. Soc. Trans., 1915, 107, 872), is described as melting at 354-355°, and its hexamethyl ether at 145-147°.These, it is interesting to note, are identical with those given in these circumstances by gossypetin itself, and it is accordingly evident that during the dyeing operation oxidation of the latter to gossypitone takes place. Until a definite knowledge of the tetrahydroxybenzene nucleus in gossypetin has been obtained the position of the hydroxyl groups in this portion of the molecule can only be conjectured. Existing as it does side by side with quercetin it seems natural to consider that gossypetin is a hydroxyquercetin. Again, should gossypitone be a p-quinone, the constitution of gossypetin will be the same as that which Neirenstein and Wheldale have suggested (Her., 1911, 48, 3487) for the flavonol described earlier (1) which they obtained from quercetone, but the descriptions of the two compounds are not in agreement.*

[---]

Quercimeritrin, C₂₁H₂₀O₁₂, 3H₂O, melting-point 247-249°, consists of small, glistening, bright yellow plates, insoluble in cold and fairly readily soluble in boiling water. Its alkaline solutions possess a deep yellow tint; with aqueous lead acetate it gives a bright red precipitate, and with ferric chloride an olive-green coloration. Octa-acetylquercimeritrin, needles, C₂₁H₁₂O₁₀(C₂H₃O)₈, melting-point 214-216°, is sparingly soluble in alcohol, whereas monopotassium quercimeritrin, a yellow powder, can be obtained by means of alcoholic potassium acetate. By hydrolysis with dilute sulphuric acid quercimeritrin yields quercetin and glucose according to the following equation: C₂₁H₂₀O₁₂ + H₂O = C₁₅H₁₀O₇ + C₆H₁₂O₆ and is thus analogous to quercitrin which in this manner is converted into quercetin and rhamnose.

On wool mordanted with aluminium, tin, chromium, and iron, quercimeritrin gives the following shades:
Aluminium. Orange-yellow.
Tin. Bright orange.
Chromium. Reddish-brown.
Iron. Olive-brown.
and these results are interesting, because with the exception of the iron mordanted pattern, which is of a rather browner character, the colours thus produced closely resemble those which are given by quercetin itself when dyed in a similar manner. They are widely different from those given by rutin and quercitrin, and mainly as a result of this property there can be little doubt that quercimeritrin is to be represented by one of the two following formulæ: [KUVA PUUTTUU]

Quercimeritrin is also present in the flowers of the Primus emarginata? (Finnemore, Pharm. Jour., 1910, (iv.), 31, 604).

[---]

Acetyl-gossypitrin, C₂₁H₁₁O₁₃(C₂H₃O)₉, colourless needles, melting-point 226-228°, is almost insoluble in alcohol.

When hydrolysed with dilute sulphuric acid gossypitrin yields gossypetin and dextrose according to the equation C₂₁H₂₀O₁₃ + H₂O = C₁₅H₁₀O₈ + C₆H₁₂O₆

The shades given by this glucoside on mordanted wool are as follows:
Chromium. Reddish-brown.
Aluminium. Dull yellow.
Tin. Bright orange.
Iron. Dark olive-brown.

Gossypitrin reacts, like gossypetin itself, with benzoquinone, and yields in this way a quinone to which the name Gossypitrone, C₂₁H₁₈O₁₃, has been assigned. This consists of maroon coloured needles, which possess no definite melting-point, although fusion of the product occurs about 255-259°. By the action of warm dilute sulphurous acid solution it is reconverted into gossypitrin, and the same change appears to occur in the dyeing process, for the shades produced are identical with those yielded by this latter glucoside. It is considered probable that the sugar group of gossypitrin is attached to its tetrahydroxybenzene nucleus, though until the exact nature of this has been decided, its position is necessarily uncertain.

Isoquercitrin, C₂₁H₂₀O₁₂, 2H₂O, crystallises from dilute alcohol in pale yellow needles, melting at 217-219°. It is sparingly soluble in water, and dissolves in alkaline solutions with a deep yellow tint, but its most interesting property is the fact that with aqueous lead acetate solution it gives a bright yellow precipitate entirely distinct from the deep red deposit which is produced in this manner from the isomeric quercimeritrin.

Again, though more readily susceptible to hydrolysis than the latter glucoside, it yields identical products: C₂₁H₂₀O₁₂+H₂O=C₁₅H₁₀O₇+C₆H₁₂O₆

Dyeing experiments with isoquercitrin give shades entirely distinct from those given by quercimeritrin, and these, although slightly paler, resemble those yielded by quercitrin.
Chromium. Brownish-yellow.
Aluminium. Golden-yellow.
Tin. Lemon-yellow.
Iron. Brownish-olive.

The properties of this substance indicate that its sugar group is riot attached as in quercimeritrin to the phloroglucinol nucleus of quercetin. Indeed it is probably constituted similarly to quercitrin (loc. cit.), which, however, contains a rhamnose in the place of the glucose residue. Three formulæ are possible for isoquercitrin, which may be briefly expressed by the statement that the position of the sugar residue in respect to the quercetin group is at one or other of the points in the following which are marked with an asterisk: [KUVA PUUTTUU]

The aqueous extract of the Egyptian cotton flowers employed in this investigation gave by hydrolysis with acid []86 per cent, of crude colouring matter, and in this approximately 10 per cent, of gossypetin was present. Dyeing experiments with the flowers in the usual way gave the following shades:
Chromium. Reddish-brown.
Aluminium. Green-yellow.
Tin. Orange-brown.
Iron. Olive-brown.
and these though duller were somewhat similar in character to those given by quercimeritrin. In comparison with the shades similarly produced from other natural dyes, they most nearly resemble those of the so-called "Patent Bark," a preparation of quercitron bark in which quercetin and no quercitrin is present.

Among the types of cotton flowers there are (a) red, (b) pink, (c) yellow, and (d) white flowered plants. In the offspring of a cross between (a) and (c) there occurs in the second and subsequent generations red and yellow plants which breed pure, whereas in the off-spring of a cross between (a) and (d) all four forms occur which breed pure. As a supplementary investigation to that of the Egyptian flowers the petals derived from such pure plants occurring among the offspring of one or other of these crosses have been examined (Perkin, Chem. Soc. Trans., 1916, 109, 145), (cp. Leake, Proc. Roy. Soc., 1911, (B), 83, 147).

The types were as follows: red flowered, G. arboreum (Linn.); pink, G. sanguineum (Harsk); yellow and white, two varieties of G. neglectum (Tod), usually now treated as one species but originally described as G. neglectum and G. rossrum. As a result it has been found that the red flowers of G. arboreum contain isoquercitrin, quercimeritrin and gossypitrin in this case being absent, whereas in the yellow flowers of G. neglectum, gossypitrin and isoquerdtrin were present, and quercimeritrin appeared to be absent. On the other hand, the white flowers of G. neglectum and the pink flowers of G. sanguineum gave but traces of colouring matter too small for complete identification, though the respective products obtained resembled in their properties apigenin and quercetin. An examination of the ordinary Indian cotton flower, G. herbaceum, available only in small amount, gave the same results as the G. neglectum.

Gossypetin is also present in the flowers of the Hibiscus sabdariffa or "red sorrel" of the West Indies, a small shrub which is widely cultivated throughout the hotter parts of India and Ceylon (Perkin, Chem. Soc. Trans., 1909, 95, 1855). The stems yield the "Rozelle hemp" of commerce, and this is obtained by retting the twigs as soon as the plant is in flower. The yellow flowers are just capable of dyeing yellow but are not used at all in India for this purpose; on the other hand, the red calyces are employed for dyeing in an obscure degree in two remote parts of the country (Burkill, Agricultural Ledger, Calcutta, 1908, No. 2, 13).

5.1.25

Other Sources of Myricetin.
(CHAPTER VII. Flavonol Group.)

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

Other Sources of Myricetin.
(CHAPTER VII. Flavonol Group.)

Sicilian sumach, the leaves of the Rhus coriaria (Linn.), contain myricetin, probably as glucoside (Perkin and Allen, ibid.) 69, 1299). The colouring matter also exists in Venetian sumach, R. colinus, and this is interesting, because the wood of this tree constitutes "young fustic" and contains fisetin. Among other plants myricetin has been isolated from the Myrica gale (Linn.), the leaves of Pistacia lentiscus (Linn.), the leaves of the logwood tree, Haematoxylon campechianum (Linn.), and it is found in conjunction with quercetin in the leaves of the Coriaria myrtifolia (Linn.) and the R. metopium (Linn.).

Everest (Royal Soc. Proc.,1918, B., 90, 251 (has shown that in all probability myricetin as a glucoside accompanies the anthocyanin pigment Violanin; a glucoside of [KUVA PUUTTUU] in the flowers of the purple-black viola (Sutton's "Black Knight"), an observation which is of considerable interest in connection with the relationship which exists between the flavonols and anthocyans.

2.1.25

Myrica nagi
(CHAPTER VII. Flavonol Group.)

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

Myrica nagi (Thunb.). This is an evergreen tree belonging to the Myricaceæ met with in the sub-tropical Himalaya from the Ravi eastwards, also in the Khasia mountains, the Malay Islands, China, and Japan. It is the box-myrtle or yangma of China, and is synonymous with M. sapida (Wall.), M. rubra (Sieb. and Zucc.) and M. integrifolia (Roxb.). The bark is occasionally used as a tanning agent, and is said to have been exported from the North-West Provinces to other parts of India to the extent of about 50 tons per annum. In Bombay it is met with under the name of kaiphal, and in Japan as shibuki.

Myricetin, C₁₅H₁₀O₈, H₂O, the colouring matter, can be isolated from an aqueous extract of the plant by a similar method to that which is serviceable for the preparation of fisetin (see Young Fustic), but is more readily obtained in quantity from the Japanese commercial "shibuki" extract (Perkin and Hummel, Chem. Soc. Trans., 1896, 69, 1287; and Perkin, ibid., 1902, 81, 204).

The extract is treated with ten times its weight of hot water to remove tannin, and when cold the clear liquid is decanted off, the residue washed twice in a similar manner, and well drained. The product is extracted with boiling alcohol, and the solution evaporated until crystals commence to separate. On cooling these are collected (the filtrate A being reserved) and washed first with strong and then with dilute alcohol. A complete purification is best effected by converting the colouring matter into its acetyl derivative, and when pure hydrolysing this in the usual manner. Myricetin crystallises in yellow needles, melting at about 357°, and closely resembles quercetin in appearance. Dilute potassium hydroxide solution dissolves myricetin with a green coloration, which, on standing in air, becomes first blue, then violet, and eventually brown coloured. Alcoholic lead acetate gives an orange-red precipitate, and ferric chloride a brown-black coloration.

[---]

Myricetin dyes mordanted woollen cloth the following shades, which are practically identical with those given by quercetin:
Chromium. Red-brown.
Aluminium. Brown-orange.
Tin. Bright red-orange.
Iron. Olive-black.

[---]

Myricitrin, C₂₁H₂₂O₁₃, H₂O, or rather C₂₁H₂₀O₁₂, 2H₂O, the glucoside, is present in the alcoholic filtrate A, from the crude myricetin, from which it separates on standing. The crystals are collected, washed first with alcohol, then with dilute alcohol, crystallised from water, from alcohol, and finally from water. Myricitrin forms pale yellow, almost colourless leaflets, melting at 199-200°, and is soluble in alkalis with a pale yellow tint. Aqueous lead acetate gives an orange-yellow precipitate, and alcoholic ferric chloride a deep greenishblack coloration. In appearance it cannot be distinguished from quercitrin, and the shades given by the two substances on mordanted woollen cloth are practically identical.
Chromium. Full brown-yellow.
Aluminium. Full golden-yellow.
Tin. Lemon-yellow.
Iron. Brown-olive.

When hydrolysed with dilute sulphuric acid myricitrin yields rhamnose and myricetin, according to the equation C₂₁H₂₀O₁₂+H₂O=C₁₅H₁₀O₆+C₆H₁₂O₅, and is analogous to quercitrin which in a similar manner gives rhamnose and quercetin. In addition to myricetin the M. nagi contains a trace of a glucoside of second colouring matter, which is probably quercetin.

The dyeing properties of myrica bark are generally similar to those of other yellow mordant dyestuffs. On wool with chromium mordant it gives a deep olive-yellow, and with aluminium a dull yellow, similar to the colours obtained from quercitron bark, but much fuller; with tin mordant it gives a bright red-orange, redder in hue than that given by quercitron bark; with iron mordant it gives a dark greenish-olive like that obtained from quercitron bark, but again fuller.

On cotton with aluminium and iron mordants it dyes colours which are more similar to those obtained from old fustic than from quercitron bark. Some specimens of myrica bark are exceedingly rich in colouring matter, and a sample examined by Hummel and Perkin (J. Soc. Chem. Ind., 1895, 14, 458) possessed much stronger dyeing power than old fustic.

According to Satow (J. Ind. Eng. Chem., 1915, 7, 113) (Abst. Chem. Soc., 1911, 149), the colouring matter of the M. rubra has the formula C₁₅H₁₀O₈, and is identical in some of its properties with myricetin. By fusion with sodium polysulphide and sulphur a product is obtained which dyes cotton a deep sepia colour, though if copper sulphate, manganese sulphate, or ferrous sulphate is added to the fused mass, substances possessing a bluish or bluish-grey colour are produced. By fusing myricetin with sulphur alone a brown-yellow compound is obtained. A yellow dye may also be obtained by nitrating myricetin sulphonic acid.

1.1.25

Jak-wood
(CHAPTER VII. Flavonol Group.)
(Osa artikkelista)

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

Jak-wood, or Jack-wood, is derived from the Artocarpus integrifolia (Linn.) which belongs to the Urticaceæ, and is cultivated throughout India, Burmah, and Ceylon, except in the north. It is largely used for carpentry, furniture, etc., and is stated to be imported to Europe for this purpose. The rasped wood is used by the natives of India and Java as a yellow dye in conjunction with alum, for the robes of the Burmese priests, also for dyeing silk and for general purposes.

An aqueous solution of the wood possesses the characteristic property that when it is treated with alkali and gently warmed, the yellow solution at first obtained assumes a beautiful blue tint.

Jack-wood (Perkin and Cope, Chem. Soc. Trans., 1895, 67, 937) is very similar to old fustic, and its dyeing properties are due to morin (see Old Fustic). Unlike old fustic, however, it contains no maclurin, but there is present a second substance, cyanomaclurin, which is devoid of tinctorial property. These compounds can be isolated from jack-wood by methods which are almost identical with those which have been applied to fustic itself, and their separation may be effected by means of lead acetate as this precipitates only the morin.

[---]

Jack-wood dyes shades very similar to those given by old fustic; that is, olive-yellow with chromium, dull yellow with aluminium, and a brighter yellow with tin mordant. On the other hand, the sample examined by Perkin and Cope possessed only about one-third of the dyeing power of old fustic.

30.12.24

Osage Orange
(CHAPTER VII. Flavonol Group.)

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

Though the wood of this tree has been used for many years in a desultory manner for dyeing by the Indians in the Red Valley region of Texas, America, its employment as a dyestuff has only recently engaged the attention of the United States Forest Service. As the -result of its examination by Kressmann (Journ. Amer. Leather Chemists Association, 1915, 347), it has been found that its dyeing properties are very similar to those given by old fustic, the shades which it produces being, however, slightly purer and somewhat less red in tint. A qualitative study of the aqueous extract showed that the dyeing principles present consisted as in old fustic of morin and maclurin, but that the unknown red constituent present in this latter was practically absent. Though apparently the tinctorial strength of distinct samples of the osage orange wood is somewhat variable, this is probably on the average quite equal to that of old fustic, and this wood can be satisfactorily employed not only for textile but also for leather dyeing.

Old Fustic
(CHAPTER VII. Flavonol Group.)
(Osa artikkelista)

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

Old fustic is the wood of a tree known as the Chlorophora tinctoria (Gaudich), previously called Morus tinctoria (Linn.), which occurs wild in different tropical regions. The tree frequently grows to a height of over 60 feet, is exported in the form of logs, sawn straight at both ends, and usually deprived of the bark. The best qualities of old fustic come from Cuba and the poorer from Jamaica and Brazil. It is at the present time used very largely, and, together with logwood, is the most important of the natural dyestuffs.

The colouring matters of old fustic were first investigated by Chevreul ("Leçons de chimie appliquee à la teinture," ii., 150), who described two substances, one sparingly soluble in water, called morin, and a second somewhat more readily soluble. Wagner (J. pr. Chem., (i.), 51, 82) termed the latter moritannic acid, and considered that it possessed 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 properties were quite distinct from those of morin, they gave it the name "Maclurin ".

Morin, C₁₅H₁₀O₇, 2H₂O. To isolate this colouring matter from old fustic a boiling extract of the rasped wood is treated with a little acetic acid and then with lead acetate solution. This causes the precipitation of the morin in the form of its yellow lead compound, whereas the main bulk of the maclurin remains in solution. The washed precipitate in the form of a thin cream is run into boiling dilute sulphuric acid, and the hot liquid, after decantation from the lead sulphate, is allowed to stand. Crystals of crude morin are gradually deposited, and a further quantity can be isolated from the acid solution by means of ether. During the preparation of commercial fustic extract, the solution on standing, or the concentrated extract itself, deposits, as a rule, a brownish-yellow powder, which consists principally of a mixture of morin and its calcium salt, and this forms the best source for the preparation of large quantities of the colouring matter. The product is digested with a little boiling dilute hydrochloric acid to decompose the calcium compound, extracted with hot alcohol, and the extract evaporated. Crystals of morin separate on standing, and a further quantity can be isolated by the cautious addition of a little boiling water to the mixture.

Crude morin can be partially purified by crystallisation from dilute alcohol or dilute acetic acid, but the product usually contains a trace of maclurin. To remove the latter the finely powdered substance is treated in the presence of a little boiling acetic acid with fuming hydrobromic acid (or hydrochloric acid), which precipitates the morin as halogen salt, whereas the maclurin remains in solution (Bablich and Perkin, Chem. Soc. Trans., 1896, 69, 792). The crystals are collected, washed with acetic acid, decomposed by water, and the regenerated morin crystallised from dilute alcohol.

Morin crystallises in colourless needles (Bablich and Perkin), readily soluble in boiling alcohol, soluble in alkaline solutions with a yellow colour. Lead acetate solution gives a bright orange-coloured precipitate and ferric chloride an olive-green coloration.

[---]

Morin dyes mordanted woollen cloth shades which, though of a slightly stronger character, closely resemble those given by kaempferol.
Morin
Chromium. - Olive-yellow.
Aluminium. - Yellow.
Tin. - Lemon yellow.
Iron. - Deep olive-brown.
Kaempferol
Chromium. - Brown-yellow.
Aluminium. - Yellow.
Tin. - Bright yellow.
Iron. - Deep olive-brown.
(Perkin and Wilkinson, Chem. Soc. Trans., 1902, 81, 590).

Maclurin, C₁₃H₁₀O₆. 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 dilute acetic acid (Perkin and Cope).

A description of maclurin and its derivatives will be found in the chapter devoted to benzophenone compounds.

Dyeing Properties of Old Fustic.

In silk and cotton dyeing fustic is employed to a comparatively limited extent, but in wool dyeing it is the most important natural yellow dyestuff. The olive-yellow or old-gold colours which fustic yields when used with chromium mordant and the greenish-olives obtained with the use of copper and iron mordants are all fast to light and milling, but the yellow colours yielded in conjunction with aluminium and tin possess only a moderate degree of fastness with respect to light. Fustic is chiefly employed in wool dyeing with potassium dichromate as the mordant, and it is for the most part used along with other dyestuffs, e.g. logwood, alizarin, etc., for the production of various compound colours, olive, brown, drab, etc.

Yellow Wallflower - Cheiranthus cheiri
(CHAPTER VII. Flavonol Group.)

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

The purplish-brown petals of the common garden wallflower are comparatively rich in colouring matter, though the shade given by these on alumina mordant possesses a greenish-olive-yellow tint, and is of a less pure character than that given by the variety known as "Cloth of Gold". A boiling aqueous extract of these latter flowers on treatment with sulphuric acid gradually deposits a yellow precipitate, and this is most readily purified by pouring the concentrated alcoholic solution into much ether. The main impurity is thus precipitated, whereas the colouring matter remains dissolved in the ether. By fractional crystallisation from alcohol two colouring matters can be isolated from this product, (a) sparingly soluble which consists of isorhamnetin (quercetin monomethyl ether) and (b) quercetin. The existence of isorhamnetin was first demonstrated by an examination of these flowers (Perkin and Hummel, Chem. Soc. Trans., 1896, 69, 1566).

29.12.24

Asbarg
(CHAPTER VII. Flavonol Group.)

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

Asbarg consists of the dried flowers and flowering stems of the Delphinium zalil, which is found in great quantity in Afghanistan. The dyestuff is collected and taken to Multan and other Punjab towns, from which it is conveyed all over India. It is much used in silk dyeing for the production of a sulphur-yellow colour known as "gandkaki," and, together with Datisca cannabina, to obtain a similar shade on alum-mordanted silk; it is also used in calico-printing. The flowers, which are bitter, are likewise employed medicinally as a febrifuge.

The colouring matters of asbarg are present entirely as glucosides, and are best isolated in the crude condition by digesting the boiling aqueous extract with a little sulphuric acid (Perkin and Pilgrim, Chem. Soc. Trans., 1898, 268). A brownish-yellow powder thus separates, which contains three substances: isorhamnetin, quercetin, and kaempferol.

Isorhamnetin, C₁₆H₁₂O₇, the sparingly soluble constituent, forms yellow needles, resembling rhamnetin in appearance. With lead acetate in alcoholic solution, an orange-red precipitate is formed, whilst ferric chloride gives a greenish-black coloration. Fused with alkali, phloroglucinol and protocatechuic acid are produced, and when air is aspirated through its alkaline solution, phloroglucinol and vanillic acid are obtained.

With acetic anhydride isorhamnetin gives a tetra-acetyl derivative, C₁₆H₈O₇(C₂H₃O)₄, colourless needles, melting-point 195-196°; and with methyl iodide a trimethyl ether, which is identical with quercetin tetramethyl ether. As, moreover, by the action of hydriodic acid wrhamnetin yields quercetin, its constitution can only be represented as follows: [KUVA PUUTTUU]

The dyeing properties of isorhamnetin are similar in character to those given by kaempferol. isoRhamnetin is also present in yellow wallflowers (Cheiranthus cheiri) (Perkin and Hummel), and in red clover flowers, Trifolium pratense (Power and Salway, Chem. Soc. Trans., 1910, 97, 245). A description of the more soluble colouring matters quercetin (quercitron bark) and kaempferol (Delphinium consolida) is given elsewhere.

In dyeing properties asbarg closely resembles quercitron bark, but yields with aluminium mordant a purer or less orange-yellow. It is, however, a much weaker dyestuff, having but 35 per cent, the dyeing power of quercitron bark. The colouring matter of the flowers, apart from the flowering stalks, is present to the extent of 3,47 per cent.

The stems and flowers of the D. saniculafolium give shades analogous to, though somewhat weaker than, those yielded by the D. zalil.

Rhamnus catharticus
(CHAPTER VII. Flavonol Group.)

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

The Rhamnus catharticus or Purging Buckthorn, indigenous to Great Britain, is a stiff many-branched shrub growing from five to ten feet high, the fruit of which consists of small berries, resembling when dry black pepper-corns. Formerly it was in great demand as a medicine, but has now fallen into disrepute. The juice of the berries admixed with lime and evaporated to dryness constitutes the pigment known as "sap" or "bladder green". According to Tschirch and Polacco (Arch. Pharm., 1900, 238, 459) the yellow tinctorial constituents yielded by the berries of this plant are quite distinct from those given by the berries of the various species of Rhamnus which constitute the Persian berry proper. Thus in addition to rhamno-emodine they isolated four yellow crystalline substances, rhamnocitrin, β-rhamnocitrin, rhamnochrysin, and rhamnolutin. Rhamnocitrin was considered to consist of the trihydroxy derivative of a dihydroxanthone [KUVA PUUTTUU] rhamnolutin of a tetrahydroxyflavone isomeric with luteolin and fisetin, and rhamnochrysin an oxidation product of rhamnocitrin, whereas β-rhamnocitrin was distinct from rhamnetin and indeed contains no methoxy groups.

Valiaschko and Krasowski (J. Russ. Phys. Chem. Soc., 1908, 40, 1502) and Krasowski (ibid., 1510) criticised this paper of Tschirch and Polacco, and could not isolate the compounds described by these latter authors. On the other hand, quercetin, rhamnetin, and xanthorhamnin, the glucoside of rhamnetin, were found to exist in these berries, and it seemed likely that the rhamnolutin of Tschirch and Polacco was rhamnetin and their rhamnochrysin a mixture of quercetin and emodine.

Oesch and Perkin (Chem. Soc. Trans., 1914, 105, 2350) also isolated rhamnetin from these berries, together with a small amount of quercetin, and considered that the former represents the β-rhamnocitrin of Tschirch and Polacco. The main colouring matter present, however, is kaempferol, C₁₅H₁₀O₆, the trihydroxyflavonol which can be obtained from the flowers of the Delphinium salil and D. consolida, and this is to be regarded as the so-called "rhamnolutin".

A fourth compound, evidently the rhamnocitrin of these latter authors, possessed the formula C₁₆H₁₂O₆, rather than C₁₅H₁₀O₅ which they assigned to it. This crystallised in yellow leaflets, melting-point 221-222°, and its acetyl derivative at 200-201°, and these melting-points are practically the same as those given by Tschirch and Polacco. It contains one methoxy group, by the action of hydriodic acid yields kaempferol, and is evidently a kaempferol monomethyl ether. It bears considerable resemblance to kaempferide, a monomethyl ether of kaempferol present in Galanga root, Alpinia officinarum (Jahresber., 1881, 14, 2385), which, however, melts at 227-229°, and its acetyl derivative at 193-195°, and though there is thus strong probability that the two compounds are not identical, Oesch and Perkin suggest that further work on this point is desirable.

Persian Berries
(CHAPTER VII. Flavonol Group.)

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

Persian berries are the seed-bearing fruit of various species of Rhamnus, growing wild or cultivated in France, Spain, Italy, the Levant, and Persia. The Persian berry proper is obtained from R. amygdalinus, R. oleoides, and R. saxatilis, and is imported from Smyrna and Aleppo. Its size is about that of a pea, colour yellowishgreen, surface much shrivelled, hard, and divisible along well-marked depressions forming a cross, into four parts, each containing a triangular seed; its taste is intensely bitter.

Avignon or French berries, the product of R. infectorius (Linn.) and R. alaternus (Linn.), are smaller in size than the foregoing and contain only two seeds.

Spanish, Italian, and Hungarian berries are respectively the products of R. saxatilis, R. infectorius (Linn.), and R. cathartica (Linn.). These are similar in quality to the Avignon berries. Other qualities come from the Morea, Wallachia, and Bessarabia.

All of these botanical varieties do not contain entirely the same constituents, but, on the other hand, there is every reason to suppose that the colouring constituents of those to which the term Persian berry proper is applied are identical in each case.

Gelatly (Edinburgh New Phil. Jour., 7, 252) was the first to isolate from Persian berries (R. tinctoria, Wald. et Kit.) the glucoside xanthorhamnin, C₄₅H₅₆O₂₈, which on hydrolysis with acid gave a sugar and a colouring matter rhamnetin. Hlasiwetz (Annalen, 112, 107) considered that xanthorhamnin was identical with quercitrin, and rhamnetin with quercetin, but Schützenberger and Berteche (Bull. Soc. Ind. Mulhouse, 35, 456) denied this, and assigned to rhamnetin the formula C₁₂H₁₀O₅. Xanthorhamnin, which Schützenberger (Jahres., 1868, 774) termed α-rhamnegin was considered to possess the formula C₂₄H₃₂O₁₄. The presence of a second glucoside, β-rhamnegin, was also detected by this chemist, and from this by hydrolysis fi-rhamnetin was derived. Liebermann and Hörmann (Annalen, 196, 313) also investigated Persian berries, devised a method for the preparation of xanthorhamnin and rhamnetin, and prepared various derivatives of the latter.

It is now known that Persian berries contain the glucosides of three colouring matters, namely rhamnetin, rhamnazin, and quercetin (Herzig, Monatsh., 6, 889; 9, 549; 12, 175; Perkin and Geldard, Chem. Soc. Trans., 1895, 67, 500).

To isolate these substances Persian berries are extracted with boiling water, the solution treated with a small quantity of sulphuric acid, and digested while boiling for one hour. The glucosides are thus hydrolysed and the crude colouring matters separate in the form of a greenish-yellow precipitate.

The product is extracted with boiling alcohol, which dissolves principally the quercetin, this being the most soluble of the three colouring matters. The residue now contains rhamnetin and rhamnazin, and the latter is removed from the former by two or three extractions with boiling acetic acid.

Rhamnetin, C₁₆H₁₂O₇, crystallises in yellow needles very sparingly soluble in acetic acid and alcohol. It dissolves in alkaline solutions with a pale yellow colour, and gives with alcoholic lead acetate an orange-red precipitate. When acetylated it forms tetra-acetylrhamnetin, C₁₆H₈O₇(C₂H₃O)₄ (Liebermann and Hörmann), colourless needles, melting-point 183-185°, and on bromination dibromrhamnetin is produced.

Rhamnetin sulphate, C₁₆H₁₂O₇.H₂SO₄ (Perkin and Pate, Chem. Soc. Trans., 1895, 67, 650), orange-red needles, and monopotassium rhamnetin, C₁₆H₁₁O₇K (Perkin and Wilson, ibid., 1903, 83, 136), orange-yellow needles, have been prepared.

Rhamnetin is in reality a quercetinmonomethyl ether (Herzig, loc. cit.}, for on digestion with hydriodic acid it is converted into quercetin, and when methylated with methyl iodide quercetintetramethyl ether is produced.

By the action of boiling potassium hydroxide solution, of boiling alcoholic potash, or by aspirating air through its alkaline solution, rhamnetin gives protocatechuic acid, and a syrupy phloroglucinol derivative. The latter, identified by means of its diazobenzene compound, consists of phloroglucinol monomethyl ether (Perkin and Allison, Chem. Soc. Trans., 1902, 81, 470), and consequently the constitution of rhamnetin is to be expressed as follows [KUVA PUUTTUU]

Rhamnetin is a strong dyestuff, and gives on mordanted woollen cloth shades which are practically identical with those produced by quercetin:
Chromium - Red-brown.
Aluminium - Brown-orange.
Tin - Bright Orange.
Iron - Deep olive.
(Perkin and Wilkinson, ibid., 1902, 81, 590).

Rhamnazin, C₁₇H₁₄O₇ (P. and G.), yellow needles, melting-point 214-215°, is moderately soluble in boiling toluene, a property which distinguishes it from both rhamnetin and quercetin. It dissolves in alkaline liquids to form orange-yellow solutions, and with alcoholic ferric chloride gives an olive-green coloration.

Acetylrhamnazin, C₁₇H₁₁O₇(C₂H₃O)₃, colourless needles, benzoylrhamnazin, C₁₇H₁₁O₇(C₇H₆O)₃, colourless needles, melting-point 204-205°, and dibromrhamnazin, C₁₇H₁₂Br₂O₇, yellow needles, have been prepared.

Rhamnazin is a quercetin dimethyl ether. Digested with boiling hydriodic acid, it is converted into quercetin, and by methylation in the ordinary manner gives quercetin tetramethyl ether. Boiling alcoholic potash hydrolyses rhamnazin with formation of vanillic acid and phloroglucinol monomethyl ether (Perkin and Allison, loc. cit.). It accordingly possesses the constitution [KUVA PUUTTUU]

Rhamnazin does not readily dye mordanted calico, but on mordanted wool gives shades resembling those which are produced by kaempferol-
Chromium - Golden-yellow
Aluminium - Orange-yellow
Tin. - Lemon-Yellow.
Iron - Olive-brown.
Only a small amount of this colouring matter is present in Persian berries.

Xanthorhamnin, C₂₃H₄₂O₂₀, is readily prepared by extracting powdered Persian berries with three times their weight of boiling 85 per cent, alcohol. On standing the dark brown filtered extract deposits a large quantity of the impure glucoside as a brown resinous mass. From the supernatant liquid on standing a purer xanthorhamnin separates in the form of a pale yellow cauliflower-like precipitate, and in such quantity as to congeal the whole liquid to a stiff paste. This is collected, repeatedly crystallised from alcohol, and finally from alcohol containing a little water and ether (Liebermann and Hörmann, loc. cit.}.

Xanthorhamnin consists of pale yellow needles readily soluble in water and hot alcohol, soluble in alkaline solutions with a yellow colour. With basic lead acetate it gives an orange precipitate. According to the work of Liebermann and Hörmann, xanthorhamnin, when hydrolysed with acid, gives rhamnetin and rhamnose, C₈H₆₆O₂₉ + 5H₂O = 4C₆H₁₄O₆ + 2C₁₂H₁₀O₅

More recently, however, Xanthorhamnin has been shown to possess the formula C₃₄H₄₂O₂₀, and that by means of its specific ferment rhamninase, contained by Persian berries, it is hydrolysed with formation of rhamnetin and a complex sugar rhamninose, C₁₈H₃₂O₁₄, C₂₄H₄₂O₂₆+H₂O=C₁₆H₁₂O₇+C₁₈H₃₂O₁₄

When rhamninose is digested with boiling dilute acids, it is converted into 2 molecules of rhamnose, and 1 molecule of galactose (C. and G. Tanret, Comptes rend., 1899, 129, 725), C₁₈H₂₂O₁₄+4H₂O=C₆H₁₂O₆+2C₆H₁₄O₆

No glucosides of rhamnazin or quercetin have been isolated as yet from Persian berries.

The action of the ferment rhamninase is readily demonstrated. If crushed Persian berries, contained in a muslin bag, are suspended in water heated to 40°, a yellow solution containing the glucosides is produced; this quickly becomes opaque and a heavy precipitate of the mixed colouring matters eventually separates. To within recent years this reaction was carried out on a commercial scale, and the product was placed on the market under the name of "rhamnétine". This reaction can be employed to distinguish between the dyeing properties of the glucosides contained in the berries, and the free colouring matters produced by their hydrolysis. Thus if Persian berries be added to a cold dye-bath, and this is slowly heated to boiling, the glucosides are hydrolysed by the ferment; but if, on the other hand, the berries be at once plunged into boiling water, the ferment is killed and a solution of the glucosides is obtained. In the former case wool mordanted with tin gives an orangered shade, whereas in the latter a pure yellow colour is produced.

Beyond the ordinary extract of Persian berries which is prepared in large quantity by extracting the berries with boiling water, and evaporating the solution under reduced pressure, no special commercial preparations are manufactured at the present time.

Dyeing Properties.

In wool dyeing Persian berries are little employed on account of their cost; moreover, they possess no special advantage over quercitron bark and old fustic. Persian berries, as a rule, give redder shades than quercitron bark, a fact which is to be explained as due to the hydrolysis of its glucosides by the ferment. The quercitrin of quercitron bark is not accompanied by such a specific ferment, and consequently the shades given by this dyestuff are of a yellower character. With tin mordant Persian berries give bright yellows and oranges, which are only fairly fast to light; but according to Hummel, the yellowish-olive produced with copper mordant is extremely fast, and is darkened rather than otherwise by exposure. Persian berries are still used to a considerable extent in calico-printing for the formation of yellow, orange, and green shades.

27.12.24

Prunus emarginata (?)
(CHAPTER VII. Flavonol Group.)

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

The bark of a spurious substitute for that of the Prunus serotina, probably P. emarginata, has been shown by Finnemore (Pharm. Journ., 1910, (iv.), 31, 604) to contain in addition to quercimeritrin (Perkin, Chem. Soc. Trans., 1909, 95, 243) a glucoside prunitrin, C₂₂H₂₄O₁₁, 4H₂O, fine needles, which when hydrolysed yields prunetin and glucose.

Prunetin, C₁₅H₉O₄.OCH₃, colourless needles, melting-point 242°, dissolves in alkalis with a slight yellow colour, and is sparingly soluble in all the usual solvents. Monacetylprunetin, C₁₆H₁₁O₅(C₂H₃O), pale yellow needles, melting-point 190°; diacetylprunetin, C₁₆H₁₀O₅(C₂H₃O)₂, melting-point 224-226°; benzoylprunetin, C₁₆H₁₀O₅(C₇H₅O)₂, needles, melting-point 215°; dimethylprunetin, C₁₅H₈O₃(OCH₃)₂, needles, melting- point 145°; and acetyldimethylprunetin, C₁₅H₇O₃(OCH₃)₂C₂H₃O, have been prepared.

Fused with caustic potash at 250°, prunetin gives phloroglucinol and p-hydroxyphenylacetic acid.

Prunetol, C₁₅H₁₀O₅, colourless needles, melting-point 290°, is formed by the demethylation of prunetin with hydriodic acid, and yields acetylprunetol, Cl5H7O5(C₂HO)₃, prunetol sulphate, C₁₅H₁₀O₅.H₂SO₄, yellow needles. On methylation with methyl iodide prunetol dimethyl ether, identical with prunetin monomethyl ether, and a sparingly soluble methyl ether, the acetyl derivative of which melts at about 186°, are produced (Finnemore, Chem. Soc. Trans., 1910, 98, 1102).

It is considered by this author that prunetin is closely related to scutellarein (Molisch and Goldschmiedt, loc. cit.) and may have the constitution [KUVA PUUTTUU]

26.12.24

Clover Flowers.
(CHAPTER VII. Flavonol Group.)

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

It has long been known that clover flowers dye a yellow colour on aluminium mordanted fabrics, and in the past they have been employed to a minor extent for dyeing purposes. Three varieties have been chemically examined, viz. those derived from the Trifolium pratense, the T. incarnatum, and the T. repens.

Trifolium pratense

The flowers known as the "common red clover," according to Power and Salway (Chem. Soc. Trans., 1910, 97, 231), contain in addition to isorhamnetin (quercetin monomethyl ether) and a glucoside of quercetin, melting-point 235°, numerous other phenolic substances, which, judging by their chemical properties, appear to be closely allied to the colouring matters of the flavone group. These are described below.

Pratol, C₁₅H₈O₂(OH).OCH₃, colourless needles, melting-point 253°, readily soluble in hot aqueous sodium carbonate and sodium hydroxide with a pale yellow coloration, yields the acetyl compound, C₁₅H₈O₂(OC₂H₃O).OCH₃, and is probably a hydroxymethoxyflavone.

A new yellow compound, C₁₈H₁₀O₇, thin yellow plates, melting point about 280°, is soluble in alkalis with a yellow colour, and its solution in sulphuric acid exhibits a brilliant green fluorescence. It contains a methoxy group and gives an acetyl compound, C₁₆H₆O₇(C₂H₃₀)_4l melting-point 145-147°.

Pratensol, C₁₇H₉O₂(OH)₃, is very readily soluble in alcohol, dissolves in alkali carbonates yielding yellow solutions, and its alcoholic solution gives with ferric chloride a greenish-black coloration. Triacetylpratensol, C₁₇H₉O₅(C₂H₃O)₃, colourless slender needles, melts at 189°.

A new phenolic substance, C₁₅H₇O₃(OH)₃, colourless needles, melting-point 225°, is soluble in alkali hydroxides, and gives with alcoholic ferric chloride a dark green coloration. The acetyl derivative, silky needles, has melting-point 209°.

The glucoside trifolin, C₂₂H₂₂O₁₁, H₂O, pale yellow needles, melts and decomposes at about 260°. It is soluble in alkalis with an intense yellow coloration, and dissolves in sulphuric acid, forming a yellow solution, which rapidly develops a brilliant green fluorescence. When hydrolysed it yields rhamnose and trifolitin, C₁₆H₁₀O₆, melting-point about 275°, readily soluble in alcohol,
C₂₂H₂₂O₁₁ = C₁₆H₁₀O₆ + C₆H₁₂O₅

* Both in its melting-point and that of its acetyl derivative there is a marked resemblance between trifolitin and kaempferol.Alkalis dissolve trifolitin with an intense yellow colour, alcoholic ferric chloride gives a dark green coloration, and alcoholic lead acetate an orange-yellow lead salt. It contains no methoxy group, and is unaltered when heated for several hours with 30 per cent, aqueous potassium hydroxide. It does not appear to belong to the flavone group, and differs from the flavone compounds by the fact that it does not give an oxonium salt with sulphuric acid, and only with difficulty a potassium compound by means of alcoholic potassium acetate. It may possibly consist of a tetrahydroxyphenylnaphthoquinone. The acetyl compound when rapidly heated melted at 116°, re-solidified at a higher temperature, and finally melted at 182°.*

The glucoside isotrifolin, C₂₂H₂₂O₁₁, isomeric with trifolin, consists of pale yellow needles, melting-point about 250°, and when hydrolysed yields similarly to the latter trifolitin, C₁₆H₁₀O₆, melting-point 275°. Though in general behaviour it is very similar to trifolin, it is much more soluble in alcohol, and does not appear to be identical with this glucoside.

In addition to these compounds the flowers contain salicylic acid, coumaric acid, myricyl alcohol, C₃₁H₆₃OH, heptacosane, C₂₇H₅₆, hentriacontane, C₃₁H₆₄, sitosterol, C₂₇H₄₆O, trifolianol, C₂₁H₃₄O₂(OH)₂, palmitic, stcaric, linolic, oleic, linolenic, and isolinotenic acids.

Trifolium incarnatum.

A considerable difference is exhibited between the constituents of the "carnation or crimson clover flowers" and those of the T. pratense or "common red clover".

According to Rogerson (Chem. Soc. Trans., 1910, 97, 1006) these flowers contain pratol, C₁₅H₈O₂(OH)(OCH₃), free quercetin, and a glucoside of quercetin, C₂₁H₂₀O₁₂, 3H₂O, to which the name incarnatrin is applied. This latter crystallises in yellow prismatic needles, melting-point 242-245°, dissolves in sulphuric acid with formation of a green fluorescent solution, and when hydrolysed yields quercetin and glucose according to the equation
C₂₁H₂₀O₁₂+H₂O=C₁₅H₁₀O₇+C₅H₁₂O₆

Incarnatrin is not identical with the quercimeritrin of Perkin (Chem. Soc. Trans., 1909, 95, 2181).

In addition to these substances the flowers yield furfuraldehyde, benzoic and salicylic acids, a trace of p-coumaric acid, incarnatyl alcohol, C₃₄H₆₉OH, hentriacontane, C₃₁H₆₄, a phytosterol, C₂₇H₄₆O, and palmitic, stearic, oleic, linolenic, and isolinolenic acids.

Trifolium repens.

The flowers of the white clover, T. repens, according to Perkin and Phipps (Chem. Soc. Trans., 1904, 85, 58), owe their tinctorial property to quercetin which is present as glucoside.

Podophyllum emodi
(CHAPTER VII. Flavonol Group.)

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

P. emodi is a small herbaceous plant growing abundantly in Northern India. The root, or rather the rhizome, is employed medicinally in India as a powerful purgative, just, indeed, as the allied P. peltatum is used in Europe and America.

An examination of this root by Dunstan and Henry (Chem. Soc. Trans., 1898, 73, 209) has shown that in addition to podophyllotoxin, the active constituent, a considerable quantity of quercetin is present. According to Hummel this material in dyeing property compares favourably with quercitron bark, and should prove commercially valuable as a dyestuff at least to the native dyer.

Eucalyptus macrorhyncha
(CHAPTER VII. Flavonol Group.)

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

Eucalyptus macrorhyncha (F. v. M.), a fair-sized tree, is the "red stringy bark" of New South Wales, and the ordinary stringy bark tree of Victoria (Smith, Chem. Soc. Trans., 1898, 73, 697).

The leaves yield under favourable conditions a very large amount (10 per cent.) of a crystalline glucoside termed by Smith myrticolorin, which can be isolated in the crude condition by mere extraction with boiling water. The solution on cooling became semi-solid owing to the separation of crystals, and these can be purified by extraction with ether to remove chlorophyll and crystallisation first from alcohol and subsequently from water. It formed pale yellow needles, gave on hydrolysis quercetin and glucose, and at first appeared to be a new glucoside of quercetin. Though very similar to rutin its identity with this glucoside was unsuspected in that rutin by hydrolysis was presumed at that time to give quercetin and 2 molecules of rhamnose (Schunck, ibid., 1888, 53, 264). Schmidt in 1908 (Arch. Pharm., 246, 214), however, pointed out that rutin in this manner yields not only rhamnose but glucose, and the probability that myrticolorin as also viola quercitrin and osyritrin (loc. cit.} were identical with rutin was subsequently confirmed by Perkin (ibid., 1910, 97, 1776).

18.12.24

Thespasia macrophylla
(CHAPTER VII. Flavonol Group.)

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.

8.12.24

Heather or Calluna vulgaris
(CHAPTER VII. Flavonol Group.)

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.)

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.

2.12.24

Sophora japonica
(CHAPTER VII. Flavonol Group.)

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).

20.9.24

Thuya occidentalis
(CHAPTER VII. Flavonol Group.)

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.

1.7.24

Other sources of Quercetin.
(CHAPTER VII. Flavonol Group.)

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).

30.6.24

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

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 Bark
Commercial preparations: Flavin, Patent bark, Bark-liquor.
(CHAPTER VII. Flavonol Group.)

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.

7.5.24

Quercitron Bark
(CHAPTER VII. Flavonol Group.)
(Osa artikkelista)

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_{26_H38}O₂₀ 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.

4.5.24

Yellow Cedar
(CHAPTER VII. Flavonol Group.)

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.

11.4.24

Young Fustic
(CHAPTER VII. Flavonol Group.)

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.

Tilaa: Blogitekstit ( Atom )

11.1.25

5.1.25

2.1.25

1.1.25

30.12.24

Dyeing Properties of Old Fustic.

29.12.24

Dyeing Properties.

27.12.24

26.12.24

Trifolium pratense

Trifolium incarnatum.

Trifolium repens.

18.12.24

8.12.24

2.12.24

20.9.24

1.7.24

30.6.24

Quercitron BarkCommercial Preparations.

Flavin.

Patent bark.

Bark-liquor.

Application.

7.5.24

4.5.24

11.4.24

Dyeing Properties of Young Fustic.

Quercitron Bark
Commercial Preparations.