Coloriasto

30.3.25

Archil or Orchil.
CHAPTER XVI. Lichens, Lichen acids, and Colouring Matters Derived Therefrom.

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.

Archil or Orchil (Orseille, Fr.; Orseille, Ger.; Oricello, It.) appears in commerce in three forms: (1) as a pasty matter called archil; (2) as a mass of a drier character, named persio; and (3) as a reddish powder called cudbear. It is obtained from various lichens of the genus Roccella, growing on the rocky coasts of the Azores, the Canaries and Cape de Verd Isles, also of the Cape of Good Hope, Madeira, Corsica, Sardinia, etc., and from Ochrolechia tartarea, growing in Sweden and Norway. None of these lichens contains the colouring matters ready formed, but they contain certain colourless acids of the type of lecanoric acid, derivatives of orcin, into which they can be readily converted. Thus, lecanoric acid (1) gives first orsellinic acid (2) and subsequently orcin (3) according to the following scheme (see under LECANORIC ACID): [KUVA PUUTTUU]

Orcin itself, when acted upon by air and ammonia, changes into a purple substance called orcein, which is the name applied to the colouring matters of archil (Robiquet, Ann. Chim. Phys., [2], 47, 338).

Finely powdered orcin is placed in. a thin layer under a bell jar, together with a beaker containing strong ammonia solution. As soon as the substance has become brown coloured, it is removed and exposed to air for some time. It is then dissolved in very dilute ammonia solution, reprecipitated with acetic acid, and dried. According to Gerhardt and Laurent, orcein has the composition C₁₄H₇NO₆ (Ann. Chim. Phys., [3], 24, 315), but more recent researches indicate that it is a mixture of substances. Liebermann, for instance (Ber., 7, 247; 8, 1649), considers that by this reaction three colouring matters are produced, having respectively the formulæ (a) C₁₄H₁₃NO₄; () C₁₄H₁₂N₂O₃; and (c) C₁₄H₁₂N₂O₃.

Zulkowski and Peters (Monatsh., 11, 227) allowed orcin to remain in contact with ammonia for two months, and from the product isolated three substances:

(a) Red orcein, C₂₈H₂₄N2O₇, the main product, which appears to be formed according to the following equation:
4C₇H₈O₂ + 2NH₃ + 6O = C₂₈H₂₄N₂O₇ + 7H₂O
It is a brown crystalline powder, soluble in alcohol with a red colour, and in alkaline solutions with a blue-violet tint.

(b) A crystalline yellow compound, C₂₁H₁₉NO₅, which is accounted for as follows: 3C₇H₈O₂ + NH₃ + 3O = C₂₁H₁₉NO₅ +4H₂O

(c) An amorphous product similar to litmus.

These substances can be prepared much more rapidly by the addition of hydrogen peroxide to an ammoniacal solution of orcin.

There can be no doubt that this reaction proceeds in several stages, and that the character of the product varies according to the duration of the process. This is well known to manufacturers, whocan prepare at will a blue or a red orchil. The constitution of these colouring matters has not yet been determined, but in view of the circumstances by which they are produced, it is most probable that they are members either of the oxazine or oxazone groups.

Orchil was originally prepared from the lichens by means of stale urine, which supplied the necessary ammonia, but ammonia solution is now exclusively employed. The older methods have, however, been greatly improved, and in the place of barrels the operation is carried out in large horizontal or vertical cylinders fitted with stirrers, and suitable openings for the admission of air.

In such an apparatus the weed is digested with about three times its weight of ammonia solution at 60° for from three days to one week, the admission of air being regulated according to the judgment of the manufacturer. The first product of the reaction has a blue colour, and if the process be stopped at this point, there is formed the dyeware known as blue orchil. On the other hand, if the action of the air and ammonia is allowed to proceed further, red orchil is obtained. These orchil pastes when dried and finely ground constitute the product known as cudbear.

Bedford (Ger. Pat. 57612, 1889) blows air or oxygen through the ammoniacal mixture, which, especially in the latter case, materially shortens the process. The apparatus employed is erected vertically, and by an ingenious arrangement of projecting shelves, the edges of which are turned down, a considerable quantity of the air or oxygen is entrapped, and exerts therefore a more powerful oxidising effect.

Orchil liquor is prepared by extracting the lichens with boiling water, concentrating the extract to from 8-10° Tw., and submitting this to the action of air and ammonia; whereas orchil extract is produced by the extraction of orchil paste itself.

In former times archil and cudbear were frequently adulterated with magenta, certain azocolours, extracts of logwood, brazilwood, etc.; but as the importance of these dyestuffs has now very greatly diminished, such a contamination is at the present time of rare occurrence.

Archil and its preparations are substantive colouring matters, which dye well in a neutral bath, but have the useful property of behaving nearly as well under slightly acid or lightly alkaline conditions. Even colours of considerable intensity are produced from it without difficulty, but unfortunately these are not fast to light. Wool is dyed in a neutral bath, or with addition of a trace of sulphuric acid, and silk is dyed in the presence of soap solution, acetic acid being sometimes added. Archil is not applied to cotton.

Archil was at one time employed to a large extent for "bottoming" indigo, that is to say, the fabric was first dyed with archil and subsequently with indigo. The reverse process, known as "topping," has again been considerably in vogue. Cudbear and archil are also used to a limited extent in conjunction with other dyestuffs for the production of compound shades. White wines are sometimes coloured with archil, but its presence can be detected by precipitating with lead acetate and extracting with amyl alcohol, when a red colour indicates the presence of archil or magenta. The addition of a little hydrochloric acid changes the colour to yellow if magenta be present, but does not alter it if archil is the adulterant (Haas, Zeitsch. anal. Chem., 20, 869; J. Soc. Chem. Ind., 1, 119).

29.3.25

Barbatic acid
CHAPTER XVI. Lichens, Lichen acids, and Colouring Matters Derived Therefrom.

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

Barbatic acid, C₁₉H₂₀O₇, was first isolated from the lichen Usnea barbata by Stenhouse and Groves (Chem. Soc. Trans., 1880, 37, 405), in which it occurs in conjunction with usnic acid. Zopf (Annalen, 1897, 297, 271) found barbatic acid in the Usnea longissima, in the Electora ochroleuca (ibid., 1899, 306, 282), and in the Usnea dasypoga (ibid., 1902, 324, 39); Hesse (J. pr. Chem., 1898, ii., 57, 232) describes its presence in the Usnea longissima, Usnea barbata, and Usnea ceratina. Hesse (loc. cit.) originally considered that barbatic acid had the composition C₂₂H₂₄O₈, and described potassium barium and copper salts and an ethyl ester, melting-point 132°, which apparently established this formula, but in a later paper (J. pr. Chem., 1903, ii., 68, i) he adopted Stenhouse and Groves' formula, C₁₉H₂₀O₇. The sodium salt, C₁₉H₁₉O₇Na, 2H₂O, crystallises in straight-sided leaflets (compare also Zopf, 1902, 789). The action of acetic anhydride on barbatic acid leads to the formation of a compound which is probably the lactone of acetylbarbatic acid; this melts at 250° and on recrystallisation from acetic anhydride yields acetylbarbatic acid, C₁₉H₁₉(C₂H₃O)O₇, melting-point 172°. By the hydrolysis of barbatic acid with aqueous alkalis betorcinol and rhizoninic acid are formed. Barbatic acid crystallises in colourless needles, melting-point 184° (Hesse, J. pr. Chem., 1906, (2), 73, 113).

Atranorin
CHAPTER XVI. Lichens, Lichen acids, and Colouring Matters Derived Therefrom.
(Osa artikkelista)

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

Atranorin, C₁₉H₁₈O₈, is present in the lichens Evernia vulpina, E. prunastri, E.furfuracea, Lecanora atra, L. sordida, Parmelia perlata, P. physodes, P. tinctorium, Physcia stellaris, Xanthoria parietina, Cladonia rangiformis, Stereocaulan vesuvianum and others. It forms colourless prisms, melting-point 195-197° C. (Zopf), 187-188°C. (Hesse), easily soluble in hot chloroform, soluble in alkalis with a yellow colour.

According to Paternò, by heating with water to 150°, atranorin gives physciol (methyl-phloroglucinol) and atraric acid (betorcinolcarboxylic acid methyl ester), and these substances are also obtained when atranorin is heated with acetic acid in a sealed tube (Hesse).

[---]

Erythrin
CHAPTER XVI. Lichens, Lichen acids, and Colouring Matters Derived Therefrom.
(Osa artikkelista)

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

Erythrin, erythric acid, erythrinic acid, erythroiecanoric acid, C₂₀H₂₂O₁₀H₂O, is a constituent of most lichens from which archil is prepared. It was discovered by Heeren (Schweigger's Journ. f. Chem., 59, 513) in Rocella tinctoria (D.C.), from which lichen, and several others of the same genus, it may be extracted by boiling water, or better, with milk of lime (cf. also Kane, Stenhouse, and Hesse (loc. cit.); Schunck, Annalen, 61, 69; De Luynes, Ann. Chim. Phys., [4], 2, 385; Menschutkin, Bull. Soc. chim., [2], 2, 424).

The method adopted by Stenhouse to prepare this substance from the Rocella fuciformis is as follows (Annalen, 68, 72, and 149, 290): Three pounds of the lichen are macerated for twenty minutes in a milk of lime made by shaking ½ lb. of lime in 3 gallons of water, and the product filtered by means of a bag filter. The clear liquid, as it passes through, is immediately precipitated with hydrochloric acid, as prolonged contact with the lime decomposes part of the erythrin. The crude erythrin collected on bag filters is freed from acid and calcium chloride by stirring it up once or twice with a considerable quantity of water and again collecting.

[---]

Evernic Acid and Everninic acid
CHAPTER XVI. Lichens, Lichen acids, and Colouring Matters Derived Therefrom.
(Osa artikkelista)

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

Evernic acid, or lecanoric acid monomethyl ether, was first isolated by Stenhouse from the Evernia prunasti (Annalen, 68, 83), and has been found also by Hesse (Ber., 1897, 30, 366) to exist in the Ramalina pollinaria (compare also Zopf, Annalen, 1897, 297, 271).

The lichen is extracted with diluted milk of lime, the extract neutralised with acid, the precipitate collected, dried, and digested with a little boiling alcohol. The hot alcoholic liquid, treated with its own volume of water, deposits crystals of evernic acid (Stenhouse).

[---]

Lecanoric acid
CHAPTER XVI. Lichens, Lichen acids, and Colouring Matters Derived Therefrom.
(Osa artikkelista)

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

Lecanoric acid (Diorsellinic acid), C₁₆H₁₄O₇, H₂O, was first described by Schunck under the name of "lecanorin,"and was isolated by him from various species of the Lecanora and Variolaria lichens. It is also present in some quantity in the Rocella canariensis, R. portentosa, R. sinensis, and Parmelia perlata (loc. cit.), and, according to Hesse (Annalen, 139, 24), is best isolated by the following method, which is a modification of that originally devised by Schunck. The finely divided lichen is extracted with ether, the extract evaporated, and the greenish-white crystalline residue treated with lime water. The solution, when neutralised with acid, gives a precipitate of lecanoric acid, which is collected and crystallised from alcohol. In case the product is not quite pure it is treated with ether, which dissolves the acid, but not the impurity.

Lecanoric acid crystallises in colourless needles, melting-point 166° (Hesse, Ber., 37, 4693), the solutions of which possess an acid reaction. With alcoholic ferric chloride it gives a dark purple coloration, and with dilute calcium hypochlorite a blood-red liquid, which, according to Hesse, is characteristic, and can be used to distinguish this substance from the known lichen acids.

[---]

Orsellinic acid.
CHAPTER XVI. Lichens, Lichen acids, and Colouring Matters Derived Therefrom.
(Osa artikkelista)

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

Orsellinic acid, C₈H₈O₄, H₂O, was first prepared by Stenhouse (Annalen, 68, 61) by digesting lecanoric acid with boiling baryta water, and can also be produced from erythrin in a similar manner. According to Hesse (ibid., 139, 35), the solution of erythrin in baryta water is heated on the steam-bath until a sample of the product no longer yields a gelatinous precipitate when neutralised with hydrochloric acid. The liquid is then acidified, and the orsellinic acid, which separates on standing, is crystallised from alcohol or acetic acid.

Orsellinic acid crystallises from dilute acetic acid in needles with 1H₂O. When heated, it melts at 176° with evolution of carbon dioxide and formation of orcin, and is evidently an orcin carboxylic acid.

Ethyl orsellinate, C₁₀H₁₂O₄, colourless leaflets, melting-point 132°, is produced when erythrin is boiled for several hours with alcohol (Stenhouse, loc. cit.), and can be prepared in an identical manner from lecanoric acid (Schunck, Annalen, 54, 265).

Methyl orsellinate, C₉H₁₀O₄ (Schunck, loc. cit., and Stenhouse, loc. cit.), and isoamyl orsellinate, C₁₃H₁₈O₄ (Stenhouse; Hesse, Annalen, 139, 37), melting-point 76°, have also been obtained.

[---]

Lichens
CHAPTER XVI. Lichens, Lichen acids, and Colouring Matters Derived Therefrom.

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

Many species of lichens have been employed from the earliest times in medicine, dyeing, and as foodstuffs ("Mémoires sur 1'utilité des lichens," par Hoffmann, Amoreux et Willemet, Lyon, 1787). From about the year 1300, certain species have been utilised for the production of the purple dyestuff "archil" or "orchil," since, as shown by modern researches, they contain colourless principles, derivatives of orcin, which under the influence of ammonia and atmospheric oxygen yield the purple colouring matter known as orcein (v. archil). Under the name of Crottle or Crotal, with various descriptive prefixes, several species have been, and still are to a very limited extent, directly applied in dyeing buff and brown colours on homespun yarn in the Highlands of Scotland, Wales, etc. Those lichens, e.g. Iceland moss (Cetraria islandica, Ach.), which serve as foodstuffs, contain a starch-like substance termed lichenin, which is capable of conversion into glucose.

Our earlier chemical knowledge of the constituents of many of these lichens is mainly due to the work of Knop, Rochleder, Heldt, Schunck, Schmidt, Stenhouse, Stenhouse and Groves, and Weppen, whereas for the later very numerous investigations we are chiefly indebted to the chemists Oswald Hesse and Wilhelm Zopf. As a result, a very large number of new compounds have been isolated and described, the constitutions of which in most cases, however, are as yet undecided. On the other hand, considerable advance has been made as regards the exact structure of some of the more common constituents, viz. atranorin (atranoric acid), barbatic acid, evernic acid, erythrin (erythric acid), lecanoric acid, and ramalic acid, and the chemistry of these substances is dealt with under their special headings.

As the work of Hesse (H.) is mainly to be found in the Journal für praktische Chemie, and that of Zopf (Z.) in the Annalen, to avoid frequent repetition the year only of the papers published in the journals is noted below.

Trachylia tigillaris, Fr. (Acolium tigillare; Calicium tigillare, Cyphelium tigillare), rhizocarpic acid, C₂₈H₂₀O₇ (H.), melting-point 177-178°, and acolic acid (H. 1900).

Acarospora chlorophana, rhizocarpic acid, pleosidic acid, C₁₇H₂₈O₄, melting-point 131-132° (Z. 1903).

Alectoria implexa, Nyl. (A. cana), zeorin, salazinic acid (Z. 1898). A. ochroleuca, usnic acid, C₁₈H₁₆O₇, and barbatic acid (Z. 1899). A. sarmentosa, usnic acid (Z. 1900). A. jubata, var. implexa, salazinic acid, alectoric acid, C₂₈H₂₄O₁₅, melting-point 186°. A. articulata d-usnic acid, usnaric acid, C₂₈H₂₂O₁₅, melting-point 240-260°. A. canariensis, d-usnic acid, usnaric acid (H. 1902). A. implexa, atranorin (H. 1906).

Anaptychia ciliaris, atranoric acid (atranorin). A. speciosa, atranorin, zeorin, C₅₂H₈₈O₄ (Z. 1895 1897).

Aspicilia calcarea, erythric acid, oxalic acid, aspicilin, melting-point 178.5° (H. 1900). A. gibbosa, aspicilic acid, melting-point 150° (H. 1904).

Baeomyces roseus, an acid, melting-point 180° (H. 1898).

Biatora lucida, rhizocarpic acid, C₂₈H₂₀O₇, atranorin (Z. 1897; H. 1907); no usnic acid (cf. Knop, 1843). B. mollis, diffusic acid (Z. 1905). B. Lightfootii, l-usnic acid (Z. 1906). B. grandulosa, gyrophoric acid, C₁₆H₁₄O₇ (Z. 1906).

Blastenia arenaria (Callopisma erythrocarpa), phytosterol, blasterin, melting-point 170° (H. 1898). B. arenaria, atranorin, gyrophoric acid, C₁₆JH₁₄O₇ (H. 1898). B. Jungermanni, parietin (Z. 1906).

Calydum crysoctphalum, vulpic acid (H. 1898; Z. 1895). C. chlorinum or chlorellum, vulpic acid (Z. 1895); pulvic acid and traces of leprarin, C₁₉H₈O₉ (Kassner, Arch. Pharm., 239, 44; H. 1900). C. flavum, chyrsocetraric acid, C₁₉H₁₄O₆ (H. 1900). C. Stenhammari, calycin, C₁₈H₁₂O₅ (Z. 1895).

Callopisma flavovirescens, chrysophanic acid, physcion, C₁₈H₁₂O₅ (H. 1902). C. vitellinum, calycin (Z. 1895); callopismic acid and mannitol (Z. 1897).

Rhizocarpon oreites, A. Zahlbr. (Catocarpus oreites), rhizocarpic acid, C₂₈H₂₀O₇, psoromic (parellic) acid, C₂₁H₁₆O₉ (Z. 1905).

Cetraria cucullata (Platysma cucullatum), protolichesteric acid, C₁₈H₃₂O₅ (Z. 1902). C. chlorphylla, protolichesteric acid and atranorin (Z. 1902). C. complicata, protocetraric acid, C₃₀H₂₂O₁₅, l-usnic acid, and atranorin.

Cetraria islandica contains starch not deposited in granules, but uniformly distributed among the cells (lichenin). The lichenin, which is convertible into sugar, is present in such large quantity that this lichen can be used for food (Schmidt, Annalen, 51, 29). There is also said to be present cetraric acid, lichenstearic acid (Knop and Schaedermann, Annalen, 55, 114), protocetraric acid, and proto-#- lichesteric acid (Z. 1902; H. 1903 and 1904), α-lichenostearic acid, C₁₈H₃₀O₅ (melting-point 122-123°), β-lichenostearic acid, C₁₈H₃₀O₅ (melting-point 121°), γ-lichenostearic acid, C₁₈H₃₀O₅ or C₁₉H₃₂O₅ (melting-point 121-122°), paralichenostearic acid, C₂₀H₃₄O₅, dilichenostearic acid, C₃₆H₆₀O₁₀, and cetraric acid, C₂₆H₂₀O₁₂ (H. 1898).

C. nivalis, usnic acid (Z. 1904). C. stuppea, protolichesteric acid (Z. 1904). C. aculeata or Cornicularia aculeata, protolichesteric acid (Z. 1 904); lichenin and lichenic (fumaric) acid. C. pinastri, pinastric acid, C₁₀H₈O₃ (Z. 1895). C. glauca (Platysma glaurum), lichenin (Berzelius). C. juniperina, chrysocetraric acid, C₁₉H₁₄O₆, usnic and vulpic acids (H. 1898). C. pinastri, chrysocetraric, usnic and vulpic acids (H. 1898; Z. 1899). C.fahlunensis, cetraric acid (Z. 1898).

Candelaria concolor, callopismic acid or ethyl-pulvic acid, C₂₀H₁₆O_5, dipulvic acid, C₃₂H₂₂O₅ (Z.); calycin, and stictaurin, C₁₈H₁₂O₅ (H.; Z. 1899). According to Hesse, 1898, dipulvic acid is a mixture of calycin and pulvic anhydride. C. vitellina, stictaurin (Z. 1899), calycin and pulvic anhydride (Z. 1899).

Cladina silvatica, usnic acid and cetraric acid (Z. 1898). C. alpestris, usnic acid (Z. 1898). C. rangiferina, cetraric acid and atranorin (Z. 1898) and usnic acid (H. 1898). C. pyxidata, parellic acid (H. 1898). C. coccifera, cocellic acid, C₂₂H₂₀C₇ (H. 1898). C. uncialis, d-usnic and thamnolic acids, C₂₀H₁₈O₁₁ (Z. 1902).

Cladonia amaurocraea, usnic acid (Z. 1898). C. alcicornis, usnic acid (H. 1902). C. deformis, usnic acid (Z. 1900). C. cyanipes usnic acid (Z. 1900). C. Floerkeana, cocellic and thamnolic acids (H. 1900). C. rangiformis, atranorin, rangiformic acid C₂₀H₃₃O₅.OMe (H. 1898). C. uncinata (no usnic acid, see Knop, Annalen, 1844, 49, 120); but uncinatic acid, C₂₃H₂₈O₉ (H. 1900). (7. destricta (C. uncialis), usnic acid and starch (Knop, ibid., 119); l-usnic acid (Salkowski, Annalen, 1901, 319, 391). C. incrassata, l-usnicacid (S.). C. glauca, squamatic acid (Z. 1902). C. strepsilis, thamnolic acid and strepsilin (Z. 1903). C. thamnolis, thamnolic acid, C₂₀H₁₈O₁₁, and strepsilin. C. destricta, l-usnic acid (Z. 1903); l-usnic and squamatic acids and cladestin (H. 1904). C. macilenta, usnic acid and starch (Knop, loc. cit.); rhizonic acid (Z. 1903). C. squamosa, var. ventricosa, squamatic acid (Z. 1904). C. squamosa, var. denticollis, squamatic acid (Z. 1907). C. fimbriata, var. simplex, fumaroprotocetraric acid and fimbriatic acid (Z. 1907). C. fimbriata, var. cornuto-radiata, fumaroprotocetraric acid (Z. 1907). C. pityrea, var. cladomorpha, fumaroprotocetraric acid (Z. 1907). C. silvatica, var. condensata, l-usnic acid (Z. 1907). C. verticillata, var. subcervicornis, fumaroprotocetraric acid (Z. 1907), atranorin and cervicornin. C. chlorophœa, fumaroprotocetraric acid. C. gracilis, var. chordalis, fumaroprotocetraric acid (Z. 1907). C. crispata, var. gracilescens, squamatic acid (Z. 1907). C. coccifera, cocellic acid, C₂₀H₂₂O₇ (H. 1895). C. incrassata, l-usnic acid (Z. 1905). C. rangiferina usnic acid (Rochleder and Heldt, Annalen, 48, 2); lichenin (Schmidt, ibid., 51, 29); cladonic acid (β-usnic acid), C₁₈H₁₈O₇ (Stenhouse, ibid. 155, 58); d-usnic acid (no l-usnic) and silvatic acid, CO₂Me.C₁₈H₂₄O₃.COOH (H. 1907); atranorin and fumaroprotocetraric acid (Z. 1906). C. rangiferina, var. vulgaris, atranorin and protocetraric acid (H. 1898). C. rangiferina, var. silvatica, d-usnic acid (Z. 1906); usnic and protocetraric acids (H. 1898). C. pyxidata, lichenin (Schmidt, Annalen, 51, 29); emulsin (Hérissey, J. Pharm. Chim., 1898, [vi.], 7, 577).

Cornicularia aculeata, rangiformic acid (H. 1902).

Chiodecton sanguineum (C. rubrocinctum), chiodectonic acid, C₁₄H₁₈O₅

Cyphelium trichiale, var. candelare, calycin (Z. 1906).

Darbishirella gracillima, parellic acid (H. 1898).

Dendographa leucophœa, protocetraric acid (H. 1898); erythrin and orcinol (Ronceray, Bull. Soc. chim., 1904, [iii.], 31, 1097).

Dimelaena oreina, zeorin and usnic acid (Z. 1897).

Diploicia canescens (Catolechia canescens), diploicin, melting-point 225, catolechin, melting-point 214-215°, and atranorin (Z. 1904).

Diploschistes scruposa, diploschistessic acid, C₁₅H₁₆O₇ (Z. 1906).

Endorcarpon miniatum (a) vulgare, phytosterol and an acid (H. 1898).

Evernia divaricata, divaricatic acid, C₂₁H₂₂O₆.OMe (H. 1900), and usnic acid (Z. 1897); no usnic acid (H.). E. furfuracea, usnic acid (Rochleder and Heldt, Annalen, 48, 9); no usnic acid, but erythric acid (Z. 1897), or rather olivetoric acid, C₂₇H₃₆O₈ (Z. 1900) physodic acid, physodylic acid, C₂₃H2₂₆O₈, and fureverninic acid (H. 1907); atranorin, evernuric acid, C₂₂H₂₄O₈, and furevernic acid, but no erythric or olivetoric acids (H. 1906); emulsin (Hérissey, J. Pharm. Chim., 1898, [v.], 7577). E. prunastri, evernic acid, atranorin (Z. 1897); evernic acid, usnic acid and atranorin and chrysocetraric acid (H. Annalen, 1895), C₁₉H₁₄O₆. E. thamnodes, divaricatic acid, usnic acid (Z. 1897; H. 1900). E. vulpina, vulpic acid and atranorin (H.). E. illyrica (Dalmatia), divaricatic acid and atranorin (Z. 1904). E. ochroleuca, usnic acid (Knop, Annalen, 49, 122).

Everniopsis Trulla, salazinic acid and atranorin (Z. 1897).

Gasparrinia medians (Physcia medians) calycin, rhizocarpic acid (H. 1898); pulvic lactone (H. 1903). G. sympagea, parietin (Z. 1905). G. elegans (Physcia elegans), physcion (H. 1898). G. murorum, physcion (H. 1898). G. decipiens, physcion (H. 1898). G. cirrhochroa, chrysophanic acid (Z. 1897).

Graphis scripta, salazinic acid (H. 1900).

Gyalolehia aurella, calycin (Z. 1895), callopismic acid (Z. l897)> stictaurin (Z. 1899).

Umbilicaria pustulata (Hoffm.). (Gyrophora pustulata), gyrophoric acid, C₃₆H₃₆O₁₅ (Stenhouse, Annalen, 70, 218), C₁₆H₁₄O₇ (H.). G. hirsuta, gyrophoric acid (Z. 1898). G. deusta, gyrophoric acid (Z. 1898). G. polyphylla, umbilicaric acid, C₂₅H₂₂O₁₀ (Z. 1898); umbilicaric acid and gyrophoric acid (H. 1898, 1901). G. hyperborea, umbilicaric acid (Z. 1898). G. deusta, umbilicaric acid (Z. 1898). G. vellea, gyrophoric acid and gyrophorin, melting-point 189° (Z. 1899). G. spodochroa, var. depressa, gyrophoric acid (Z. 1900). G.polyrrhiza, umbilicaric acid, lecanoric acid, gyrophoric acid (Z. 1905).

Hæmatomma ventosum, divaricatic acid, C₂₂H₂₆O₇, melting-point 149° (Z. 1898); -usnic acid, divaricatic acid, and an acid resembling alectoric acid (H. 1900). H. coccineum, var. leiphæmum, leiphaemin, melting-point 193°, atranorin, zeorin (Z. 1902). H. coccineum, var. abortivum, coccic acid, C₁₂H₁₆O₁₀, 3H₂O, melting-point 262-264°, atranorin, haematomin, C₁₀H₁₆O or C₂₀H₃₂O₂, melting-point 143-144°, and haematommidin, melting-point 194-196° (Z. 1903); no zeorin (H. 1907). H. coccineum, var. (?) lecanoric acid, (H. 1907). H. coccineum, var. (?) (from Wildbad), coccic acid, atranorin, zeorin, hydrohaematommin, C₁₀H₁₈O, melting-point 101° (H. 1906). H. coccineum, l-usnic acid, zeorin, atranorin, porphyrillic acid, hymenorhodin, and leiphaemin (Z. 1906). H. leiphæmum, atranorin, zeorin, leiphaemin, leiphaemic acid, C₃₂H₄₆O₅, melting-point 114-115°(Z. 1903). H. porphyrium, atranorin, zeorin, porphyrilic acid, leiphaemin, hymenorhodin (Z. 1906).

Pertusaria dealbata, Nyl. f. corallina, Cromb. (Isidium corallinum) ("white crottle"), calcium oxalate (Braconnot, Ann. Chim. Phys., [ii.], 28, 319).

Lecanora atra, atranoric acid (atranorin), C₁₉H₁₈O₈, and a yellow crystalline substance (Paternò and Oghaloro, Gazz. chim. ital., 1877, 7). Hesse (Ber., 10, 1324) considers the atranoric acid to be hydrocarbonusnic acid, and the yellow substance to be cladonic acid. Obtained from certain districts it contains lecanorol (Z. 1897), C₂₇H₃₀O₉, H₂O. L. varia, psoromic acid and l-usnic acid (Z. 1905). L. grumosa, atranorin and lecanorol (Z. 1897). L. cenisea, atranorin and roccellic acid, C₁₇H₃₂O₄ (cf. Schunck and Hesse, Roccella tinctoria}. L. sordida, atranorin, zeoric acid (Z. 1897). L. sordida, var. glaucoma, atranorin and parellic acid (H. 1898). L. sordida, var. Swartzii, atranorin, thiophanic acid, C₁₂H₆O₁₂.H₂O, melting-point 242°, roccellic acid, lecasteric acid, C₁₀H₂₀O₄, melting-point 116°, and lecasteride, C₁₀H₈O₃, melting-point 105° (H. 1898). L. campestris, atranorin (Z. 1897). L. badia, stereocaulic acid (Z. 1897). L. effusa, atarnorin and usnic acid (Z. 1897). L. subfusca, atranorin (Z. 1897); (H. 1900). L. epunora, zeorin and lepanorin, melting-point 131° 132° (Z. 1900), L. glaucoma (L. sordida a-glaucoma) (from Tyrol), atranorin, thiophanic acid, roccellic acid (Z. 1903). L. sulphurea, usnic acid (Z. 1903). L. parella ("light erottle"), parellic acid, lecanoric acid (Schunck, Annalen, 54, 257, 274; 41, 161). L. tartarea (Linn.) (Patellaria tartarea, Parmelia tartarea), erythric acid, synonymous with Nees. v. Esenbeck's "remarkable resin" (Brandes' Archiv. Apoth., 16, 135), with Heeren's erythrin, and with Kane's erythrilin (Schweiggers, J. Ch. Phys., 59, 313). Schunck found crustaceous lichens belonging to Lecanora, etc., collected on the basalt rocks of the Vogelsberg in Upper Hessia to contain lecanoric and erythric acids (Annalen, 41, 157). In a specimen from Norway, Stenhouse (ibid., 70, 218) found gyrophoric acid. L. ventosa, usnic acid (Knop, ibid. 49, 122).

Rhizocarpon geographicum, Dl. (Lecidea geographical], usnic acid (Knop, loc. tit.). Lecidea Candida (Psora Candida), calcium oxalate (Braconnot, Ann. Chim. Phys., [ii.], 28, 319). L. cineroatra, lecidic acid, C₂₂H₂₇O₄.COOMe, melting-point 147°, and lecidol, melting-point 93° (H. 1898). L. sudetica, salazinic acid (Z. 1899). L. confluens, confluetin, melting-point 147-148° (Z. 1899). L. grisella, gyrophoric acid (H. 1900). L. agloeotera (L. armeniaca, var. lutescens), roccellic and cetraric acids (Z. 1904).

Lepraria latebrarum, leprarin, melting-point 155°, roccellic acid (Z. 1897), and atranorin (Z. 1900); d-usnic, hydroroccellic, lepraric, and talebraic acids (melting-point 208°), and atranorin (H. 1903). L. flava, calycin, pinastric acid, calyciarin (Z. 1905). L. xanthina (from Vorarlberg), physcion (H. 1906). L. latebrarum (Baden- Baden), atranorin, leprariaic acid, oxyroccellic acid, and neobraic acid (H. 1906). L. candelaris, calycin (Z. 1906). L. chlorina, calycin (Z. 1895).

Lepra candelaris (Lepraria flava), calycin, C₁₈H₁₁O₄.OH, melting-point 240-242° (H. 1898).

Leprantha impolita (Arthonia pruinosd), lecanoric acid, lepranthin, C₂₅H₄₀O₁₀, melting-point 183°, lepranthaic acid, C₂₀H₃₂O₂, melting-point 111-112° (Z. 1904).

Mycoblastus sanguinarius, caperatic acid and atranorin (Z. 1899).

Menegazzia pertusa (Parmelia pertusa), atranorin and farinacic acid (capraric and pysodic acids absent) (H. 1907).

Nephroma arcticum, zeorin, nephrin, and d-usnic acid (Z. 1909). N. antarcticum, zeorin and d-usnic acid (Z. 1909). N. parile, zeorin and mannitol (Z. 1909). N. resupinatum, mannitol (Z. 1909). N. lævigatum, mannitol (Z. 1909). Nephromium lævigatum, usnic acid and nephrin, C₂₀H₃₂, H₂O, melting-point 168° (H. 1898). N. tommentosum, usnic acid and nephrin (H. 1898). N. lusitanicum, nephrin and nephromin, C₁₀H₁₂O₆, melting-point 196° (H. 1898).

Ochrolechia androgyna (Lecanora subtartarea), gyrophoric acid and calyciarin (Z. 1905). O. pallescens, var. parella (from Auvergne), parellic acid and ochrolechiasic acid, C₂₂H₁₄O₉, melting-point 282° (H. 1906); but no lecanoric acid (see Schunck, Annalen, 1845, 54, 274) (Z. 1898). O. tartarea, gyrophoric acid (Z. 1898).

Pannaria lanuginosa, hydroxyroccellic acid, C₁₇H₃₂O₅ melting-point 1284°, and pannaric acid, C₉H₈O₄, melting-point 224° (H. 1901).

Parmelia aleurities, atranorin (Z. 1897). P. tiliacea, atranorin and parmelialic acid, melting-point 165° (Z. 1897); the latter is in reality lecanoric acid (H. 1898 and 1900). P. perlata, atranorin and haematommic acid (Z. 1897); usnic acid, lecanoric acid, and perlatin (H. 1900); imbricaric acid (Z. 1902); no lecanoric acid (H. 1903); atranorin and perlatic acid, C₂₇H₂₇O₉.OMe, 2H₂O (H. 1904). P. perlata from certain sources: (a) atranorin, (b) atranorin, usnic, and vulpic acids, (c) atranorin and lecanoric acid, (d) atranorin and perlatin C₁₉H₁₄O₅(OMe)₂ (H. 1898). P. saxatilis, var. sulcata, atranorin and stereocaulic acid (Z. 1897); protocetraric acid only (H. 1900), not protocetraric but pannatic acid (H. 1904); usnic acid (Schmidt, Annalen, 51, 29). P. saxatilis, var. panniformis) atranorin, protocetraric acid, and usnetic acid, C₂₄H₂₆O₈ (not C₉H₁₀O₃), melting-point 192° (H. 1900). P. saxatilis retiruga, atranorin, protocetraric acid, and saxatic acid, C₂₅H₄₀O₈, melting-point 115° (H. 1903). P. physodes (or P. ceratophylla, var. physodes) is known as "dark crottle," and is employed for dyeing a brown colour on homespun woollen yarn. Contains physodin and two colourless substances (Gerding, Brandes, Arch. Pharm., [ii.], 87, i), ceratophyllin (H. Annalen, 119, 365); atranorin, physodalic acid, and physodalin (Z. 1897 and 1898); evernuric acid, physodylic acid, capraric acid, and atranorin (H. 1907). P. parietina, chrysophanic acid (Rochleder and Heldt); identical with Thomson's (Edin. New Phil. Jour., 37, 187) parietin, also (H. 1895) physcion, C₁₆H₁₂O₅, physcianin, c₁₀H₁₂O₄, melting-point 143°, and physciol, C₇H₈O₃, melting-point 107°. A variety of P. parietina growing on sandstone rock and not on trees like that of Rochleder and Heldt, contained vulpic acid (chrysopicrin), (Stein, J. pr. Chem., [i.], 93, 366). P. caperata ("stone crottle"), emulsin (Hérissey, J. Pharm., [vi.], 7, 577); capraric acid, C₂₂H₁₈O₈(COOH)₂, melting-point 240°, usnic acid, caperatic acid, COOMe, C₁₈H₃₃O₂(COOH)₂, melting-point 132°, and caperin, C₃₆H₆₀O₃, melting-point 243 (H. 1898), P. caperata from Castanea vesca, usnic, capraric and caperatic acids (H. 1904). P. conspersa, usnic acid, zeorin, and atranorin (Z. 1898); usnic acid and salazinic acid (H. 1898); d-usnic acid and conspersaic acid, melting-point 252° (H. 1903). P. acetabulum, atranorin (Z. 1898); atranorin and salazinic acid (H. 1901). P. excrescens, zeorin and atranorin (Z. 1898). P. perlata, var. exrescens, atranorin (Z. 1898). P. Nilgherrensis, atranorin (Z. 1898). P. perforata, zeorin and atranorin (Z. 1898); lecanoric acid (H. 1900). P. olivetorum, atranorin (Z. 1898); lecanoric acid, but no erythric acid (H. 1900); olivetoric acid, C₂₇H₃₄O₈, melting-point 141-142° (Z. 1902); atranorin, olivetorin, melting-point 143°, and olivetoric acid, C₂₁H₂₆O₇ (H. 1903). P. pertusa, physodalic acid (Z. 1898). P. fuliginosa, atranorin and lecanoric acid (H. 1898). P. fuliginosa, var. ferruginascens, lecanoric acid (Z. 1899). P. pulverulenta, unknown acid (H. 1898). P. ciliaris, everninic acid and atranorin (?) (H. 1898). P. omphalodes (P. saxattilis, var. omphalodes}. Under the name of "black crottle" this lichen is employed for dyeing a brown colour in the outer Hebrides (Lewis and Harris); contains stereocaulic acid (Z. 1899). P. tiliacea, var. scortea, lecanoric acid (Z. 1899). P. verruculifera, lecanoric acid (Z. 1899). P. glomellifera, glomelliferin, melting-point 143-144° (Z. 1899 and 1902). P. incurva, usnic acid (Z. 1900). P. Borreri, lecanoric acid (Z. 1900). P. sorediata, diffusin (Z. 1900); lecanoric acid (H. 1900). P. tinctorum, atranorin (H. 1900). P. tinctorum (E. Africa), atranorin and lecanoric acid (H. 1906). P. tinctorum (Madras cinchona bark), atranorin and lecanoric acid (H. 1904). P. glabra, lecanoric acid (H. 1902). P. lacarnensis, imbricaric acid (Z. 1902). P. sinuosa, d-usnic and usnaric acids (Z. 1902).

Parmelia cetrata (Java cinchona bark), cetrataic acid, C₂₉H₂₄O₂₅, melting-point 178-180° (H. 1903). P. olivacca, oliveacein, C₁₇H₃₂O₆.H₂O, melting-point 156°, and oliveaceic acid, C₁₆H₁₉O₅.OMe, melting-point 138° (H. 1903). P. revoluta, atranorin and gyrophoric acid (Z. 1905). P. pilosella, atranorin and pilosellic acid, melting-point 245 (Z. 1905). P. Moûgeotti, d-usnic acid (H. 1906).

Peltigera apthosa, peltigerin, C₂₁H₂₀O₈ (or C₁₆H₁₆O₆ ), melting-point 170-180°, and mannitol (Z. 1909). P. malacea, peltigerin, zeorin, and mannitol (Z. 1909). P. horizontalis, peltigerin, zeorin, and mannitol (Z. 1909). P. polydactyla, peltigerin, mannitol, polydactylin, melting-point 178-180°, and peltidactylin, melting-point 237-240°. P. venosa, peltigerin. P. scabrosa, peltigerin. P. propagulifera, peltigerin and zeorin. P. lepidophora, peltigerin. P. praetextata, mannitol. P. rufescens, mannitol. P. spuria, mannitol. P. canina, caninin (Z. 1909); emulsin (Hérissey, J. Pharm. Chim., [vi.], 7, 577).

Pertusaria amara (P. communis β-variolosa, Variolaria amara), emulsin (Hérissey, loc. cit.); cetraric acid, pertusaric acid, C₂₄H₃₈O₆, melting-point 103°, pertusarin, C₃₀H₅₀O₂, melting-point 235°, pertusarene, C₃₀H₁₀₀, melting-point 286°, and pertusaridin (H. 1898); salazinic acid and picrolichenin (Z. 1900); orbiculatic acid, C₂₂H₃₆O₇ (H. 1901). P. lactea, lecanoric acid and variolaric acid, melting-point 285° (Z. 1902). P. lactea (sterile Auvergne), lecanoric acid and ochrolechiasic acid (H. 1906). P. corralina (P. ocellata β-coralline), ocellatic acid, C₂₀H₁₅O₁₁.OMe, melting-point 208° (H. 1901). P. rupestris (P. communis β-areolata) areolatin, C₁₁H₇O₆. OMe, melting-point 270°, areolin, melting-point 243°, and gyrophoric acid, C₁₆H₁₄O₇ (H. 1903). P. glomerata (Wildbad), porin, C₄₂H₆₇O₉OMe, melting-point 166°, and porinic acid 2[C₁₁H₁₂O₄], H₂O, melting-point 218° (H. 1903). P. Wulfenii (P. stilfurea, P. sulphurella, P. fallax), thiophanic acid (Z. 1904). P. lutescens, thiophanic acid (Z. 1904).

Placodium gypsaceum, squamaric acid and usnic acid (Z. 1898); parellic acid, but no usnic acid (H. 1901). P. chrysoleǔucǔm, usnic acid (Z. 1898). P. saxicolum, var. vulgare, usnic acid and zeorin (Paternó, Atti. R. Accad. Lincei, 1876, [ii.], 3); zeorin, but no atranorin (H. 1898), -usnic acid (H. 1900). P. saxicolum, var. compactum, atranorin (H. 1901). P. melanaspis, atranorin (Z. 1898). P. Lagascoe, psoromic and usnic acids (Z. 1897).

Placodium crassum, atranorin (trace), l-usnic acid (H. 1901). P. circinatum (a) radiosum, salazinic acid (H. 1902).

Physcia ciliaris, emulsin (Hérissey, J. Pharm. Chim., [vi.], 7, 577). P. endococdna, zeorin and atranorin (Z. 1895), rhodophyscin and endococcin (Z. 1905). P. caesia, zeorin and atranorin (Z. 1895); atranorin and zeorin (H. 1902). P. stellaris, f. adscendens, atranorin (Z. 1895). P. parietina, atranorin and placodin, melting-point 245° (H. 1899). P. medians, vulpic acid and calycin (Z. 1895), calycin and callopismic acid (Z. 1897). P. pulverulenta, var. β-pityrea, atranorin (Z. 1895).

Physcia tenella, atranorin (Z. 1895). P. aipolia, atranorin (Z. 1895).

Cetraria glauca (Platysma glaucum), atranorin and caperatic acid (Z. 1899). Cetraria cucullata (P. cucullatum), lichenostearic acid and usnic acid (Z. 1899). P. diffusum, diffusin, melting-point 135-136°, and usnic acid (Z. 1899).

Pleopsidium chlorophanum, rhizocarpic acid (Z. 1895).

Pseudevernia ericetorum, atranorin, physodalin (Z. 1905).

Psora ostreata, lecanoric acid (Z. 1899).

Pulveraria chlorina, calycin, vulpic acid, and lepraric acid, melting- point 228° (H. 1898). P. latebrarum, atranorin, parellic acid, latebride, melting-point 128°, and pulverin, melting-point 262° (H. 1898). P. farinosa, oxyroccellic acid, and pulveraric acid, melting-point 234° (H. 1898).

Raphiospora flavovirescens, rhizocarpic acid (Z. 1895).

Ramalina calicaris, var. fastigiata, contains large quantities of starch (lichenin) and a small quantity of saccharic acid (Berzelius, Scherer's Annalen, 3, 97), usnic acid (Rochleder and Heldt, ibid., 48, 9). R. calicaris, var. fraxinea, lichenin and usnic acid (Rochleder and Heldt, loc. cit.); a-usnic acid (Hesse, Annalen, 117, 297). R. ceruchis) usnic acid and usnaric acid (H. 1898). R. armorica, atranorin, armoricaic acid, melting-point 240-260°, armoric acid, C₁₈H₁₈O₇, H₂O, melting-point 226-228° (H. 1907). R. cuspidata, cuspidatic acid, C₁₆H₂₀O₁₀, melting-point 218° (H. 1900). R. farinacea, d-usnic acid and ramalic acid, melting-point 240-245° (H. 1903). R. subfarinacea, d-usnic acid and salazinic acid (Z. 1907). R. minuscula, d-usnic acid (Z. 1907). R. Kullensis, d-usnic acid, kullensisic acid, C₂₂H₁₈O₁₂ (Z. 1907). R. obtusata, d- usnic acid, ramalinellic acid, melting-point 169°, and obtusatic acid (Z. 1907). R. Landroënsis, d-usnic acid and landroënsin (Z. 1907). R. pollinaria, ramalic acid, C₁₈H₁₃O₃OMe, and evernic acid (Z. 1897); usnic acid, atranorin, evernic acid, and ramalic acid (H. 1898). R. fastigiata, emulsin (Hérissey, J. Pharm. Chim., 1898, [vi]. 5, 577). R. fraxinea, emulsin (Hérissey, ibid.}. R. polymorpha, usnic acid (Z. 1897). R. scopulorum (see Thomson, Annalen, 53, 252), d-usnic acid, scopuloric acid, C₁₉H₁₆O₉, melting-point 260° (Z. 1907). R. thrausta, usnic acid (Z. 1900). R. yemensis, d-usnic acid (H. 1902).

Reinkella birellina, roccellic and oxyroccellic acids (H. 1898).

Rhizocarpon geographicum f. contiguum, parellic acid, rhizonic acid, C₁₉H₂₀O₇, melting-point 185°, rhizocarpic acid, C₂₈H₂₂O₇ (H., Ber., 1898, 31, 663), rhizonic acid is OMe.C₁₇H₁₄O₂(OH)2COOH (H.).

R. geographicum f. lecanorinum, rhizocarpic acid (Z. 1895); parellic acid, rhizocarpinic acid, melting-point 156°, rhizocarpic acid, COOH.C₂₄H₁₆O₃.COOEt, melting-point 177-178°. Parellic acid, COOMe.C₁₇H₁₁O₃(COOH)₂, melting-point 262-265°, is the same as Zopfs psoromic acid, and the squamaric acid and zeoric acid of other writers (H.). R. geographicum f. geronticum, parellic and rhizocarpic acids, but not rhizocarpinic acid (H., 1909).

Rhizoplaca opaca (Lecanora chrysoleuca, β-opaca, Parmelia rubina, β-opaca, Squamaria chrysoleuca β-opaca), usnic acid, placiodilic acid (previously termed placiodïlin), rhizoplacic acid, C₂₁H₄₀O₅, melting- point 94-95° (Z. 1905), usnic acid and placiodilic acid, C₁₇H₁₈O₇, melting-point, 156-157° (Z. 1906).

Roccella fuciformis (R. tinctoria, var. fuciformis]. This wellknown "orchella weed" is imported from Angola, Zanzibar, Madagascar, Ceylon, and Lima for the purpose of manufacturing archil and cudbear. It contains erythric acid (Heeren's erythrin, Kane's erythrilin) and roccellic acid (Schunck, Pharm. J., [iii.], 39, 164; Annalen, 61, 64; Kane, Trans. Roy. Soc., 1840, 273; Heeren and Schweiggers, J. Pharm. Chim., 59, 346). Stenhouse (Annalen, 149, 288) examined a Lima weed in 1848, and found it to contain lecanoric acid, but this was probably R. tinctoria and not identical with the R. fuciformis examined by him in 1869, and in which he found erythric acid. Cf. Hesse (Annalen, 117, 329, and 139, 22) who found Lima weed to contain erythric acid, but not lecanoric acid. Stenhouse considers the R. Montagnei from Angola, in which he found erythric acid to be identical with R. tinctoria, var. fuciformis, examined by Schunck. A stunted variety of R. fuciformis, examined by Menschutkin and Lamparter, contained β-erythrin. In a better growing specimen erythrin was obtained (Lamparter, Annalen, 134, 243). A variety of R. fuciformis, probably from the west coast of Africa, contained erythric acid and a bkter substance picroroccellin (Stenhouse and Groves, ibid.) 185, 14). More recently Hesse (1898) has found the weed to contain erythric acid and oxyroccellic acid.

Roccella Montagnei, erythric acid and oxyroccellic acid (H. 1898); orcinol (Ronceray, Bull. Soc. Chim., 1904, [iii.], 1097). R.fruticosa, erythric acid (erythrin) (H., Ber., 1904, 37, 4693). R. phycopsis (Crete), erythrin, oxyroccellic acid, oxalic acid, and erythritol (H. 1906). R. peruensis (R. fructectosa and R. cacticola], erythrin, oxyroccellic and roccellic acids (H. 1898), erythrin, erythritol and oxalic acid (H. 1906). R. portentosa, lecanoric acid (H. 1898). R. decipiens, lecanoric acid (H. 1898). R. sinensis, lecanoric acid (H. 1898).

Roccella tinctoria. - This lichen, used largely for the manufacture of orchil and cudbear, is imported from the Cape of Good Hope, the Cape Verde Islands, and Chile (Valparaiso weed). Formerly it seems to have been imported also from Lima (Stenhouse). It contains lecanoric acid (Stenhouse's α- and β-orsellic acid) and roccellinin. The latter is, however, probably a decomposition product of the former (Stenhouse, Annalen, 68, 55; 149, 288; Phil. Mag., [iii.], 32, 300). According to Hesse (1898) it contains erythrin, oxyroccellic acid, roccellic acid, and lecanoric acid, whereas Ronceray (Bull. Soc. Chim., 1904, [iii.], 31, 1097) detected in this lichen the presence of lecanoric acid and orcinol (cf. Hesse, Ber., 1904, 37, 4693).

Roccellaria intricata, zeorin and roccellaric acid, melting-point 110° (H. 1898).

Squamaria elegans (Gasparrinia elegans) chrysophanic acid (Thomson, Phil. Mag., [iii.], 25, 39); physcion (H.).

Solorina crocea, soloric acid, melting-point 199-201° (Z. 1895).

Spharophorus fragilis, sphaerophorin, melting-point 138-139°, and fragilin (Z. 1898), sphaerophorin (C₁₄H₁₆O₄)_n, or C₂₈H₃₄O₈, sphaerophoric acid, melting-point 206-207°, and fragilin (Z. 1905).

Sphyridium placophyllum, atranorin (Z. 1898).

Stereocaulon alpinum, atranorin, and stereocaulic acid, melting-point 200-201° (Z. 1895). S. coralloides, atranorin and psoromic acid (Z. 1895), usnetic acid, atranorin, and an acid not psoromic acid. Zopfs stereocaulic acid from S. alpinum is usnetic acid (H. 1900). S. incrustatum, atranorin and psoromic acid (Z. 1895). 5. vesuvianum, psoromic acid (Z. 1895). S. denudatum, var. genuinum, atranorin (Z. 1895). 5. tomentosum, atranorin (Z. 1895). S. pileafum, atranorin and stereocaulic acid (Z. 1895 and 1899). S. condensatum, atranorin (Z. 1895). S. paschale, atranorin (Z. 1895). S. virgatum f. primaria, atranorin (Z. 1895). S. ramulosum, atranorin (Z. 1895). S. salazinum, salazinic acid, which blackens at 260-262° (H. 1900).

Sticta fuliginosa, trimethylamine (Z. 1897). S. aurata, stictaurin, a derivative of pulvic acid (Z. 1899). Stictaurin has the formula C₁₈H₁₂O₅ (H. 1900). S. desfontainii, calycin and ethyl-pulvic acid (H. 1900). S. pulmonaria, stictaic acid, C₁₈H₁₁O₈(OMe), melting-point 264°, stictinic acid (Knop and Schnedermann, J. pr. Chem., 1846, 39, 365), and not protocetraric acid (H. 1900). This lichen is known as "hazel crottle".

Stictina gilva, stictinin, melting-point 160-161° (Z. 1905).

Thamnolia vermicularis, thamnolic acid, melting-point 202-204° (Z., Chem. Zentr., 1893, [ii.], 54). According to Hesse this has the formula C₁₉H₁₅O₁₀.OMe (1898 and 1900).

Thallædema candidum, probably lecanoric acid (H. 1898).

Thalloschistes flavicans, parietin (Z. 1905) (Brittany); physcion and acromelin (H. 1907).

Tornabenia chrysophthalma, physcion (H. 1907). T. flavicans, var. crocca, physcion (H. 1907). T. flavicans, var. acromela (Physcia acromela}, acromelin, C₁₇H₂₀O₉ melting-point, 242°, and acromelidin, C₁₇H₂₀O₂, melting-point 162° (H. 1907). T.flavicans, var. cinerascens, physcion and acromelin (H. 1907).

Umbilicaria pustulata (Gyrophora pustulatd), gyrophoric acid, C₁₈H₁₈O₇ (?), (Stenhouse, Annalen, 70, 218; Z. 1898; H. 1898).

Urceolaria lichens, collected from the basalt rock of the Vogelsberg in Upper Hessia, contain lecanoric and erythric acids (Schunck, Mem. Chem. Soc., 1, 71).

Urceolaria scruposa, var. vulgaris, atranorin and lecanoric acid (H. 1898, 1904, 1907); patellaric acid (Z. 1902). U. cretacea (U. scruposa, var. gypsacea), lecanoric acid, but no atranorin, zeorin, or parmelialic acid (H. 1898; cf. Zopf, 1897).

Usnea barbata {Lichen barbatus, Parmelia barbata) usnic acid (Rochleder and Heldt, Annalen, 48, 8; Stenhouse, ibid., 155, 51), and lichenin (Berzelius, Scherer's Annalen, 3, 205; Hesse, Annalen, 137, 241; Ber., 10, 1324), usnic and barbatic acids (H. 1898); emulsin (Hèrissey, J. Pharm. Chim., [vi.], 7, 577). U. barbata f. dasypoga, usnic acid and usnaric acid, C₃₀H₂₂O₁₅, melting-point 240-260° (H. 1898), d-usnic, usnaric, and alectoric acids (H. 1900); barbatic, usnic, and usnaric acids, but no alectoric acid (Z. 1902); alectoric acid (H. 1903). U. barbata, var. ceratina, usnic acid, C₁₈H₁₆O₇, melting-point 195-196°, and barbatin (H., Annalen, 1895, 284, 157). U. barbata α-florida, d-usnic, usnaric, and parellic acids, and usnarin (H. 1902). U. ceratina, usnic acid, barbatic acid and barbatin (H. 1898). U. ceratina (Black Forest), barbatic and usnic acids (Z. 1902), d-usnic acid, barbatic acid, and barbatin (H. 1903), (Java cinchona bark), d-usnic, usnaric, and parellic acids and ceratin (H. 1903). U. ceratina β-hirta (Bolivian), d-usnic, usnaric, p'icatic, and barbatic acids (H. 1903). U. barbata (β) hirta, d-usnic, usnaric, and barbatic acids, and usnarin (H. 1902), atranorin (H. 1906). U. barbata (β) hirta (St. Thomas), d-usnic and usnaric acids, and santhomic acid, C₁₁H₁₄O₄, melting-point 166° (H. 1902). U. hirta, usnic acid (Knop, Annalen, 49, 103), usnic acid, alectoric acid, hirtic acid, melting-point 98°, and hirtellic acid (melting-point 215° decomp.), (Z. 1903). U. cornuta, d-usnic and usnaric acids (Z. 1902). U. longissima, barbatic and usnic acids (Z. 1897; H. 1898). U. longissima (from Amani), ramalic acid, d-usnic acid, and dirhizonic acid, C₁₈H₁₆O₅(OMe)₂, melting-point 189° (H. 1906). U. florida, usnic acid (Knop, Annalen, 49, 103); usnic acid and hirtellic acid (Z. 1904). U. schraderi, d-usnic acid and usnaric acid (Z. 1905). U. microcarpa, d-usnic acid and usnaric acid (Z. 1905). U. articulata, var. intestiniformis (Indian cinchona bark), d-usnic acid, barbatic acid, and articulatic acid, C₁₈H₁₆O₁₀ (?), (H. 1907). U. plicata, d-usnic acid, usnaric acid, usnarin, and plicatic acid, C₂₀H₃₃O₈(OMe), melting-point 133° (H. 1900). U. scrŭposa, atranorin and lecanoric acid (Z. 1902).

Pertusaria dealbata, Nyl. (Variolaria dealbata, Lichen dealbatus), variolarin (Robiquet, Annalen, 42, 236; 58, 320). Schunck found crustaceous Variolaria collected on the basalt rocks of the Vogelsberg in Upper Hessia, to contain lecanoric and erythric acids.

Xanthoria parietina (Parmelia parietina, Physria parietina), atranorin and physcion (H. 1898). X. lychnea, physcion (H. 1898). X. candelaria (X. controversa, X. lychnea, var. pygmxa X. parietina, var. lychnea), parietin, melting-point 202° (Z. 1904).

7.3.25

Purple of the Ancients
(CHAPTER XV. Indole Group.)

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

Kappaleita lisätty luettavuuden helpottamiseksi. // Paragraphs added to help reading online.

The ancients derived their purple from certain molluscs or seasnails, the Purpura hoeinastoma, known to Pliny as Buccinum, and from the Murex brandaris, called by Pliny Purpura. At Athens and Pompeii, large quantities of the shells have been discovered lying in heaps close to ancient dyeworks. These molluscs are to be ound throughout the whole of the Mediterranean, and indeed, in the sea in numerous parts of the world varieties exist which may be employed for dyeing purposes. Two sorts of purple, known as Tyrian and Byzantium purple, were recognised by the ancients, the former possessing a redder tint than the latter.

From the observations of Cole (Phil. Trans., 1685), Reaumur (Mem. de 1'Acad. Royale des Sciences, 1711) and Bancroft ("Philosophy of Permanent Colours," i, 120, 1813), it appears that the colour-producing secretion, which resembles pus in appearance and consistence, is contained in a small whitish cyst or vein, placed transversely under, but in immediate contact with the shell, and near the head of the animal. This pus-like matter, either diluted with water or undiluted, on being applied to bits of white linen or calico, and exposed to sunlight, rapidly changes its colour, passing from yellow, through light green, deep green, and "watchet blue," to purplish-red or crimson.

To produce this change of colour the light of the sun is essential. It is effected more rapidly by the direct action of the sun's rays than by that of diffused light, but it does not take place in moonlight or in artificial light. If the linen or other fabric to which the secretion has been applied is kept in the dark, it remains unchanged, but when exposed to the sun it becomes purple, even after the lapse of years, though a little more slowly than at first. The metamorphosis which the change of colour indicates is not sensibly promoted by heat. It proceeds in a vacuum and in hydrogen or nitrogen gas as speedily as in air on exposure to light.

The colour produced is remarkably stable, resisting the action of soap, alkalis, and most acids, being destroyed only by nitric acid and chlorine (see also Bizis, Journ. de Ch. Med., 1835, 10, 99, and A. and G. de Negri, Gazz. chim. ital., 1875, 437). Schunck (Chem. Soc. Trans., 1879, 35, 591) who examined the Purpura capillus, which he procured from the rocks at Hastings, finds that the colouring matter (punicin) is quite insoluble in water, alcohol, or ether, sparingly soluble in boiling benzene or boiling glacial acetic acid, and readily soluble in boiling aniline, giving a solution which is at first green, but as it approaches saturation becomes purplish-blue. At this point it shows a broad, well-defined absorption band, beginning near C and extending beyond D; but as the solution cools, depositing the substance contained in it, the colour changes to green, and the band becomes gradually narrower, until it occupies the space midway between C and D, and then disappears.

The colouring matter as deposited from the solution in aniline is seen, under the microscope, to consist of star-shaped groups of irregular crystalline needles, which, when very thin, show by transmitted light a purple colour. Punicin is soluble in oil of vitriol, giving a dirty purple colour, and showing a broad ill-defined absorption-band between D and E, the green and blue of the spectrum being much darkened. On heating the solution slightly, or allowing it to stand for some time, the colour changes to a bright bluish-green and it now shows an absorption-band in the red. Punicin is also sparingly dissolved by a hot alkaline solution of stannous oxide, and the solution on exposure to air becomes covered with a blue pellicle. Punicin may be sublimed, giving crystals which show by reflected light a semi-metallic lustre, like that of sublimed indigo-blue (Schunck, loc. cit.). Witt (Technologic der Gespinnstfasern, 1888) expressed the opinion that the colouring matter yielded by these molluscs was an admixture of indigotin with a red colouring matter not so fast to light.

Friedlander (Annalen, 351, 390; Ber., 1906, 39, 1060) has examined the dye yielded by the Murex brandaris and Murex trunculus which he obtained from the zoological station at Trieste. Letellier (Comptes rend., 1891, 109, 82) had observed that, in addition to the colouring principle, organic sulphur compounds were also present in these glands, and it suggested itself, therefore, to Friedlander as possible that the "purple of the ancients" might in reality consist of the thioindigotin which he had lately discovered.

To isolate the colouring matter the glands of the molluscs were spread out as thinly as possible upon filter paper, which was then exposed to the sunlight for half an hour. The highly coloured product was now immersed in diluted hydrochloric acid (1:1), the mixture evaporated to dryness on the water-bath, the residue extracted with hot water, and washed with alcohol and ether. In this manner a product consisting only of cellulose and the pure colouring matter was obtained, and the latter could be readily removed by extraction with boiling anisole, from which it separates in the crystalline condition. Finally, it was recrystallised from nitrobenzene. It consists of dark violet crystals which possess a coppery lustre, dissolves in hot, high-boiling solvents with a blue-violet colour, yields a sublimate on heating, and in numerous respects resembles the colouring matters of the indigo group. Analysis indicated the absence of sulphur, although nitrogen was found to be present. The absorption spectrum is similar to that given by indigotin; but, on the other hand, it is distinguished from this latter colouring matter by its sparing solubility, and by giving with cold concentrated sulphuric acid a reddish-violet coloration. With fuming sulphuric acid it yields a soluble blue sulphonic acid, and when reduced in alkaline solution forms a pale yellow liquid, from which, when exposed to air, it separates as a reddish-violet precipitate. In a later paper by the same author (Ber., 1909, 42, 765) some slight modifications of the method for the isolation of the dye from the Murex brandaris are given, and it is shown that in this manner about 12,000 molluscs are required for the preparation of 1.4 grams of the substance. This colouring matter contains bromine, and by a comparison with the synthetic dye, there can be no doubt that it is in reality 6:6'-dibromoindigotin.

Further investigation has indicated that in addition to this dibromindigotin another dye of a bluer shade, also containing bromine, but possessing a greater solubility in organic solvents, is produced from the Murex brandaris. It contains more carbon and less bromine than dibromindigotin, but its constitution is as yet undetermined (Friedlander, Chem. Zeit., 1911, 640).

6.3.25

Woad.
(CHAPTER XV. Indole Group.)

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

This commercial product is a dark clay-like preparation made from the leaves of the woad-plant, Isatis tinctoria (Linn.), an erect, herbaceous, biennial plant, belonging to the Cruciferæ, bearing yellow flowers, small flat elliptical pods, and large smooth lanceolate or spathulate leaves.

The term "woad" is derived from the Saxon "wad," which it has been suggested is derived from Woden, the Saxon God of War. It is synonymous with the Gallic glastum, with which, according to Pliny, the ancient Britons dyed their skin blue, in time of war and in connection with certain religious observances.

The plant is a native of Southern Europe, and from very early times has been employed in dyeing blue, for which purpose, previous to the introduction of indigo from India, it was largely cultivated in various parts of Europe - e.g. Thuringia, Languedoc, Piedmont, etc. Its cultivation has now declined almost to the vanishing-point.

In this country woad is now only grown, to a very small extent, in the fen lands of Lincolnshire and Huntingdon. The seed is sown in the early spring, March or April, and the young plants having been duly thinned and weeded, the leaves are ready for the first plucking in June, which, at intervals of five or six weeks, is repeated once or twice, or as often as fresh leaves shoot up.

The newly-gathered leaves are at once crushed or ground in edge-runner mills to a pulp, which is then placed in small heaps to drain, till sufficiently dry to cohere and be submitted to the "balling" process. This consists in working the pasty mass by hand into balls, 4-6 ins. in diameter. These are at once spread out on wicker-work trays Or "fleaks," and thoroughly dried in well-ventilated sheds. The balls are stored in a dry airy place till the whole crop has been gathered, and are then submitted to the so-called "couching" - i.e. a fermentation - process. For this purpose the balls are ground to a coarse powder, which is spread on the floor of the couching- house to a depth of 2 or 3 feet, and there reduced again to the consistency of a paste by frequent sprinkling with water and turning over with shovels. During this process, which lasts from twenty to forty days, the mass becomes heated and abundant offensive odours are given off. The operation needs to be conducted with some care and skill, so that the fermentation is neither so slow that a "heavy" product is obtained, nor so rapid as to give one which is "foxy". When the fermentation has subsided, and the stiff, pasty mass is sufficiently cooled, it is packed in casks ready for the market.

It has been calculated that 9 parts by weight of woad leaves yield 1 part of the prepared product.

Although woad was formerly used for the indigo contained in it, it is at present only employed for the purpose of exciting fermentation in the indigo-vat ordinarily used by the woollen dyer, which is therefore termed the "woad-vat".

According to Wendelstadt and Binz (Ber., 1906, 39, 1627) woad contains two distinct micro-organisms, one of which under suitable conditions appears to be able to reduce indigo.

Spurious woad was sometimes prepared from the leaves of the rhubarb, cabbage, etc., but these products were very inferior to the true woad.

The colouring principle of woad leaves, considered by Schunck to be identical with that present in the Indigoferæ, is now known to be a distinct substance. This has not been isolated in a pure condition, but in its general reactions resembles indoxylic acid (see INDIGO, NATURAL).

Other Literature. - Chevreul, J. Pharm. Chim., 1808, 66, 369; 1817, 350; Ann. Chim. Phys., 68, 284; Gilbert, Annalen, 41, 245; 42, 315; Trommsdorff, J. Pharm. China., 19, 93; Paris, Mus. Hist. Nat. Ann., 18, 251.

Lonchocarpus cyanescens.
(CHAPTER XV. Indole Group.)

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

The Lonchocarpus cyanescens (Benth.), a leguminous plant of the sub-order Paplionaceae, is a woody-climber from 10 to 14 feet long. The young leaves contain an indigo-yielding principle, and on this account the plant is employed by the tribes of Sierra Leone and the interior and those of Western Soudan as the source of a blue dye. In the former country the young leaves are collected along with some more matured ones, roughly pounded, and dried in the sun. In this state it is sent into the market as "Gara," and sold to the dyers. The natives of Western Soudan employ the young and tender buds, which are collected, pounded when quite raw, made into balls, and dried in the sun. For dyeing purposes the "Gara" is covered with water, treated with potash and the bark of the Morinda citrifolia (Linn.) and allowed to ferment for some days. The cloth to be dyed is thrown into the vat, left there for some time, and dried in the sun. An examination of "Gara" by Perkin indicated the presence of approximately 0,62 per cent, of indigotin (J. Soc. Chem. Ind., 1907, 389). Apparently also this plant is utilised in Northern Nigeria as a dyestuff in the form of a similar preparation to that described above, and for the manufacture of a crude indigo. A sample of this Nigerian leaf product contained approximately 0,65 per cent, of indigotin, whereas in the indigo the presence of 21,47 Per cent, of indigotin and 1,33 per cent, of indirubin was detected (Perkin, J. Soc. Chem. Ind., 1909, 353). The botanical examination of the former, and also of plant debris contained in the latter, by V. H. Blackman, indicated that they were derived from the L. cyanescens, or some closely related form. Rawson and Knecht (J. Soc. Dyers, 1888, 66) have described similar leaf and crude indigo products, which had been sent to this country by Sir T. Goldie, Governor of the Royal Niger Co., and these respectively contained 0,52 per cent, of indigotin and 39,12 per cent, of indigotin, together with 4,75 per cent, of indirubin. A more recent examination of the leaf fragments in Rawson and Knecht's samples has shown that these possess the same structure as those of the L. cyanescens (Perkin, loc. cit.), and it thus appears evident that in Western Africa this plant is extensively employed for dyeing and the preparation of indigo. There is reason to presume that the indigo yielding principle present in the young leaves of the L. cyanescens gradually disappears when these reach maturity, as samples of the latter examined in this country were devoid of indigo-producing property. The L. cyanescens is probably identical with the "Taroom akkar" described by Bancroft ("Philosophy of Permanent Colours," 1813, i., 189 and 191).

The Properties and Syntheses of Indigotin. (Natural Indigo.)
(CHAPTER XV. Indole Group.)

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

The history of the determination of the constitution of indigotin and of the many syntheses which have been devised for its preparation, leading as they have done to the successful manufacture of the artificial product, constitutes without doubt one of the most interesting chapters in the annals of synthetical organic chemistry. This has been dealt with so fully in other manuals that a brief resume of the main features of the subject will only be given here, and to avoid detail the main reactions are only expressed by constitutional formulæ.

Whereas early work had proved the benzenoid character of indigotin, by the production from it of aniline, anthranilic acid, picric acid and nitrosalicylic acid and isatin, the commencement of a systematic attack on the problem of its structure first dates from the work of Baeyer and Knop (Annalen, 1865, 141, 1).

That isatin, C₈H₅NO₂, was simply related to indigotin, at that time expressed as C₈H₅NO, appeared probable, and with the hope of reconverting isatin into the latter, its behaviour on reduction was studied by these chemists. The results obtained, though unsuccessful at first in their immediate object, proved to be of considerable importance, and indeed form the basis from which much of our present knowledge of the subject has been derived.

When reduced isatin gives dioxindol (i), oxindol (2), and these substances are now known to respectively consist of the inner anhydrides of α-amino-phenylglycollic (3) and ο-amino-phenylacetic acids (4) [KUVA PUUTTUU]

By further reduction indole is obtained, and to this, which was subsequently synthesised by Baeyer and Emmerling (Ber., 1869, 2, 680), by fusing 0-nitro-cinnamic acid with potash and iron filings the formula [KUVA PUUTTUU] was assigned (Ber., 1870, 3, 517).

The same chemists again by heating isatin with phosphorus oxychloride and acetyl chloride under pressure obtained indigotin.

In 1879 Baeyer and Sinda (Ber., 1878, 11, 584) converted oxindole into isatin according to the following scheme: [KUVA PUUTTUU] and such a series of reactions formed the coping-stone of the first artificial synthesis of indigotin.

Isatin is the inner anhydride of ο-amino-phenylglyoxylic acid (isatinic acid) and such a constitution was predicted for it by Kekule in 1869 (Ber., 2, 748). Isatin, which possesses acid properties and is capable of forming metallic compounds, may exist as pointed out by Baeyer in two modifications. These are known as pseudo-isatin (lactamisatin) and isatin (lactimisatin).

A synthesis of isatin from 0-nitro-benzoyl chloride was announced by Claisen and Shadwell in 1879 (Ber., 12, 350), and the reactions involved may be expressed by the following formulæ [KUVA PUUTTUU]

The fact that indole can be prepared from 0-nitro-cinnamic acid (loc. cit.) and that indole is closely related to indigotin, as indeed was shown by Nencki (Ber., 1875, 8, 727), who prepared indigotin by the action of osonised air upon an aqueous suspension of indole, led Baeyer to experiment on the synthesis of indigo from this same acid (Ber., 1880, 13, 254). This object he eventually accomplished by the two methods given below [KUVA PUUTTUU]

The former method is exceptionally interesting, in that it provided the basis for the first attempt to manufacture indigo on a commercial scale, and though this was hardly successful, the 0-nitrophenylpropiolic acid obtained by this method was of some service to the dyeing industry, as a means for obtaining indigo prints on calico.

Baeyer, again, in 1882 (Ber., 15, 50) announced a further synthesis employing ο-nitro-phenylpropiolic acid which was important in connection with the constitution of indigotin. When boiled with water ο-nitro-phenylpropiolic acid yields ο-nitro-phenylacetylene and from the copper compound of this by oxidation with ferricyanide, dinitro-diphenylacetylene is obtained. With fuming sulphuric acid this forms diisatogen, a compound which on reduction gives indigotin.

ο-Nitro-phenylpropiolic acid, on the other hand, by the action of sulphuric acid (Baeyer, Ber., 1881, 17, 1741) is transformed into its isomer isatogenic acid. Reducing agents convert this into ethyl indoxylate which by heating gives indoxyl and this latter when oxidised readily passes into indigotin.

Indoxyl reacts with aldehydes and ketones to form the so-called indogenides. Thus with benzaldehyde the indogenide of benzaldehyde (benzylidene pseudo-indoxyl) is produced (Baeyer, Ber., 16, 2188).

In a similar way indoxyl condenses with isatin to form indirubin a colouring matter present in natural indigo (loc. cit.), and which is to be regarded as the indogenide of isatin.

Baeyer in 1883 reviewing the facts here enumerated was enabled to deduce the following constitution of indigotin - which is now accepted as correct. The main arguments he employed in support of this formula are as follows:
1. Indigotin contains two imido groups.
2. As a result of its formation from diphenylacetylene the carbon atoms of indigotin must be arranged in a similar manner to those present in this substance -
C₆H₅.C.C.C.C.C₆H₅
3. Indigotin is only formed from compounds in which the carbon atoms adjacent to the benzene ring are united with oxygen.
4. The properties of indigotin point to the fact that it is closely related to indirubin.

As a result indigotin is to be regarded as the a-indogenide of pseudo-isatin, indirubin itself being the β-indogenide. Owing, however, to the lack of activity of the α-oxygen atom in isatin, indigotin cannot, like indirubin, be directly prepared from indoxyl and isatin.

In 1882 (Ber., 15, 2856) Baeyer and Drewsen synthesised indigotin by the action of acetone on ο-nitro-benzaldehyde in the presence of alkali.

When the acetone is replaced by acetaldehyde ο-nitro-phenyl-lactic aldehyde is obtained, whereas with pyroracemic acid ο-nitrocinnamyl- formic acid is produced.

These compounds under the influence of alkali are transformed into indigotin.

Heumann in 1890 (Ber., 23, 2043) devised the synthesis of indigotin from phenylglycocoll (phenylglycine). This on fusion with alkali is transformed into indoxyl which passes readily by oxidation into indigotin.

The yield by this method is extremely small, but this can be improved by employing in the place of phenylglycine, phenylglycine ο-carboxylic acid (Heumann, ibid., 3431).

This important reaction forms the basis of the first economical synthesis of indigo, the large scale manufacturing operations of which were perfected by the Badische Anilin und Soda Fabrik in 1897. For the preparation of phenylglycine ο-carboxylic acid, naphthalene is employed as the starting-point, and the procedure involved will be evident from the following formula: [kuva puuttuu]

An improved method for the production of phenylglycine ocarboxylic acid from anthranilic acid has subsequently been adopted, the reagents employed being formaldehyde, bisulphite, and potassium cyanide.

Phenylglycine can be prepared directly from aniline by the same method.

More recently it has been recognised that the unsatisfactory yield of indigo by the original process of Heumann is due to the presence of water in the alkali fusion. By the replacement of the sodium hydroxide with sodium amide the destructive action of the water is avoided and the fusion can be successfully carried out at a lower temperature. The manufacture of indigo by such a method has been more recently adopted by the firm of Meister Lucius & Brüning at Höchst.

Interesting is also the fact that by treatment with fuming sulphuric acid phenylglycine is converted into indigotin disulphonic acid.

Of other indigo syntheses that of Sandmeyer, at one time employed on the manufacturing scale, is of importance. The startingpoint in this method is thio-carbanilide obtained by the action of carbon disulphide on aniline. This compound by the action of potassium cyanide and lead carbonate forms hydrocyano-carbodiphenylimide, which on treatment with ammonium sulphide gives the thio-amide. The latter by heating with sulphuric acid is converted into isatin anilide and from this by reduction with sulphuretted hydrogen in acid solution thio-isatin is obtained. By the action of dilute alkalis thio-isatin readily passes into indigotin.

Commercial Natural Indigos. (Natural Indigo.)
(CHAPTER XV. Indole Group.)

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

When natural indigo was at its zenith very numerous varieties of this dyestuff were placed on the market, but more recently, owing to its severe competition with the artificial colouring matter, many of these are now rarely met with. From Asia came the indigos of Bengal, Oudh, Madras, Java, Manilla; from Africa those of Egypt and Senegal; and from America those of Guatemala, Caracas, Mexico, Brazil, South Carolina, and the Antilles.

The best varieties are the Bengal, Java, and Guatemala, although in England the Bengal is now mainly employed. Java indigo, formerly largely esteemed for the manufacture of indigo extract, chiefly because of its general purity, at the present time appears to find its market chiefly in the East.

A good quality of natural indigo has a deep violet-blue colour; it acquires a coppery lustre when rubbed with the finger-nail; it is light, porous, adhering to the tongue, and can be readily broken and ground. Low qualities, which contain much extractive and mineral matter, are dull and greyish in appearance, heavy, tough, and hard, and do not become bronzy by rubbing with the finger-nail.

Efficiency of the Process. (Natural Indigo.)
(CHAPTER XV. Indole Group.)

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

The actual yield of indigotin from the plant during the manufacture is not discussed by Rawson (loc. cit.), but this author considers that if the suggestions enumerated in his report are adopted, there is little or no room for a remunerative alteration of the process. Bergtheil, on the other hand, considers that under the conditions he describes (1906, 12) the efficiency is represented by an 82 per cent, yield, or that if to this be added the 5 per cent, believed by Rawson to be retained by the extracted plant, 87 per cent, is thus accounted for. The quantity of indigo estimated refers to the precipitate present in the vat after oxidation, and from this must be, therefore, deducted the indigo (10 20 per cent.) lost by the "running off" of the "seeth" water, so that the actual yield of dry colouring matter may thus represent from 62-72 percent, of the theoretical quantity. Recent experiments, however, indicate that by adding aluminoferric to the oxidation a more perfect settlement of the indigo is to be anticipated (ibid., 1909).

Bloxam (Dalsingh Serai Report, and J. Soc. Chem. Ind., 1906, 25, 735), who examined the daily output of indigo (as pressed cake) from the Pembarandah factory, found that the first cuttings of the plant (Moorhun mahai) represented an approximate value of 0,1495 per cent, of indigotin from the plant, whereas the second cuttings gave a value of but 0,1526. Assigning to the plant the low value of 0,3 per cent., a considerable and serious loss is thus apparent. Moreover, the estimation of the results given by the "isatin" method of leaf estimation, and of the finished cake by the "tetrasulphonate" process (loc. cit.), both of which have been standardised with extreme care, point to a loss during the manufacture much greater than has hitherto been acknowledged (Report to Government of India, 1908).

Apart from the retention of indoxyl by the residual plant in the steeping vat, and the mechanical carrying over of indigo by the "seeth" water, the deficiency of colouring matter is chiefly to be attributed to the conversion of indoxyl into products other than indigotin. Rawson (loc. cit.) has pointed out that if the fermented liquid is allowed to stand before oxidation a considerably decreased yield of indigo is ultimately observed. Thus, on the large scale, by standing for six hours a loss of 16,1 per cent, was apparent. Perkin and Bloxam (loc. cit.) have found as a result of their experiments with pure indican, that this alteration or "decay" of indoxyl takes place not only in this manner during the fermentation process, but they consider that the indoxyl from the moment of its production by the hydrolysis of indican until its final conversion into indigotin is continually suffering this alteration. This peculiar reaction is, according to these authors, considerably inhibited by the presence of acid.

The Estimation of Indican in the Leaves of Indigo Plants. (Natural Indigo.)
(CHAPTER XV. Indole Group.)

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

Although some indication of the indigo-yielding capacity of the plant can He obtained by ordinary steeping experiments, this method was found by Rawson ("Cultivation and Manufacture of Indigo," loc. cit.) to possess several drawbacks, and numerous experiments were therefore carried out by him on the quantitative formation of indigo from the leaf extract by the simultaneous action of acids and oxidising agents. As regards the latter, ferric chloride, potassium chlorate, and hydrogen peroxide were tried, but persulphuric acid gave much the best results.

Persulphate Method.

20 grams of leaves are extracted for two minutes with 250 c.c. of boiling water, the solution is strained through muslin, and the residues squeezed and washed with boiling water. The solution is treated with 5 c.c. of 20 per cent, hydrochloric acid, and 40 c.c. of a 5 per cent, solution of ammonium persulphate. The persulphate is not added all at once; at first 2 c.c. are added, after half an hour 2 c.c. more, and again 2 c.c. after another half an hour. After two hours the remainder of the ammonium persulphate is added, and when the mixture has stood for a further period of an hour, the indigo is collected and estimated by permanganate in the usual manner. Bergtheil and Briggs (J. Soc. Chem. Ind., 1906, 734) point out, however, that this process of Rawson's requires modification, as the addition of the reagents at such a high temperature involves a loss of indigotin. The main features of a modification of the process devised by these latter authors are the addition of acid to the cooled extract, and a determination of the course of the reaction, after addition of small amounts of persulphate, by filtration of a portion of the mixture and the addition to the filtrate of a trace of the oxidising agent.

Orchardson, Wood, and Bloxam (ibid.., 1907, 40; cf. also Bloxam and Leake, "Research Work on Indigo," Dalsingh, Serai, 1905), who employ sulphuric acid and persulphate, arrived independently at the same conclusion. To 200 c.c. of the leaf extracts these authors add 100 c.c. of a mixture of equal parts of 2 per cent, ammonium persulphate, and 4 per cent, sulphuric acid, and the mixture is kept at 60 for one hour. A comparison of their methods with that of Bergtheil and Briggs indicated an identical result in each case, and an increase of 20 25 per cent of pure colouring matter in comparison with that yielded by Rawson's original process.

The Isatin Method.

Beyerinck (Proc. K. Akad. Wetensch., 1899, 120), in discussing indican, suggested the possibility that by warming its solution with isatin and acid a quantitative yield of indirubin might be produced. Orchardson, Wood, and Bloxam (loc. cit.) have employed this reaction for the estimation of the leaf, and have devised the following method for this purpose:

250 c.c. of extract, equivalent to 5 grams of the leaf, is treated with 0,1 gram of isatin, and the mixture boiled for five minutes to expel air, carbon dioxide being passed through the flask. 20 c.c. of hydrochloric acid is then added by means of a tap funnel, and the whole kept boiling for thirty minutes. The precipitate is collected on a tared filter, washed with hot 1 per cent, soda to remove brown compounds, then with 4 per cent, acetic acid and dried. An aliquot portion of the crystalline product is sulphonated, and analysed by the titanous chloride method, adopting the modifications employed by Bloxam (loc. cit.). The indirubin thus obtained is usually almost pure (98,5 per cent.), so that for an approximate estimation the latter part of the process is unnecessary. Gaunt, Thomas, and Bloxam (ibid., 1907, 26, 56) have examined the process in greater detail, and point out that by its employment pure indican gives quantitative figures (cf. also Perkin and Bloxam, Chem. Soc. Trans., 1907, 91, 90). On the other hand, this method gives considerably higher figures, both with pure indican (15 per cent.) and the leaf extract (25 percent.), than those which are obtained by the persulphate process (Orchardson, Wood, and Bloxam; and Gaunt, Thomas, and Bloxam, loc. cit.). The unsatisfactory figures in the latter cases arise from a further oxidation of the indigo by the persulphate. That this isatin method does not appear to be affected by other plant constituents was shown by the successful estimation of indican, purposely added to an extract of the leaves of the Tephrosia purpurea (Pers.), a plant in which this glucoside is absent.

Tilaa: Blogitekstit ( Atom )