View Article Online / Journal Homepage / Table of Contents for this issue 2350 OESCH AND PERKIN: CCXVII1.-The Colouring Mattem OJ Rhamnus catharticus. By JOSEFOESCH and ARTHURGEORGE PERKIN. ACCORDINGto the work of Tschirch and Polacco (Arch. Yharm., 1900, 238, 459), tlie yellow, tinctorial constituents yielded by the berries of Bhamnus catharticus (Hungarian berries) are quite dis- tinct from those given by tlhe berries of the various species of Rhamnus which constitute the Persian berry proper, and now well known to consist of rhamnetin, rhamnazin, and quercetin. Thus, according to these authors, in addition to rhamnoemodin and certain other allied non-tinctorial compounds, with which the pre- sent paper is not concerned, there could be isolated from the berries of R. catharticus four hitherto unknown yellow, crystalline substances, to which the names rhamnocitrin, P-rhamncrcitrin, rhamnochrysin, and rhamnblutin were assigned. Although the constitution of these compounds was not ascertained, it appeared likely that rhamnocitrin, Cl3HI0O5, was the triliydroxy-derivative of the dihydroxanthone, 0 and rhamnolutin a new tetrahydroxyflavone isomeric with luteolin and fisetin. Again, rhamnochrysin, CI3Hl0O7, was probably an oxidation product of rhamnocitrin, whereas the latter and P-rhamnocitrin, C13H1006, closely resembled the P-rhamnetin which Published on 01 January 1914. Downloaded by UNIVERSITY OF NEBRASKA 17/10/2015 17:18:40. Schutzenberger describes as obtainable from Persian berries. 8-Rhamnocitrin is quite distinct from rhamnetin, C,,H,,O,, and, indeed, in all these compounds methoxy-groups were absent. It is somewhat remarkable that Tschirch and Polacco were un- aware that the true formula of rhamnetin is C16H120, (Herzig, Mosaartsh., 1888, 9, 548; 1891, 12, 172), and that the so-called P-rhamnetin is with little doubt quercetin (T., 1895, 67, 502). Valiaschka and Krasowski (J. Buss. Yhys. C’hent. SOC.,1908, 40, 1502), and Krasowskj * (ibid., 1510), on tlie other hand, strongly criticise this work of Tschirch and Polacco, and contend that from the botanical relationship existing between the Persian berries and those of R. catharticus, and the similarity of their dyeing properties, it is only to be anticipated that the same colour- * For R translation of this paper, which is written in ttre Russian language, we arc iodelrted to the kindiiess of Mr. T. 11. Pop. View Article Online THE COLOURING MATTERS OF RHAMNUS CATHARTICUS 2351 ing matters will be yielded by both. As a matter of fact, the compounds of Tschirch and Polacco could not be isolated, although the presence of rhamnetin and quercetin was easily detected. Rhamnolutin is possibly rhamnetin, as the melting point of the acetyl derivative, 183--184O, would appear to suggest, whereas rhamnocitrin is exactly like quercetin and rhamnetin in its re- actions. Again, instead of rhamnochrysin, a mixture of quercetin and emodin was obtained. Further, xanthorhamnin, the glucoside of rhamnetin, is present in these berries. At the outset of this work we were unaware of Krasowski’s paper, our object being chiefly the study of the rhamnocitrin of Tschirch and Polacco, for although flavone derivatives are ex- tremely common throughout nature, the closely allied xanthone group of which this compound was apparently a member appears to be but poorly represented. Having, however, soon satisfied our- selves as to the nature and properties of this compound, a study of the other colouring matters which can be obtained from the berries has been carried out, with the results given in this paper. As it seemed possible that the divergent results of these former workers might have been occasioned in the one case or the other by the accidental use of berries not derived from R. catha?*ticus, special pains have been taken to ensure the botanical authenticity of the material here employed. EXP E RIME NT AL. Four kilos. of the berries were extracted with eight litres of boiling water for three hours, the mixture was filtered, and the residue washed with 1.5 litres of hot water. Experiments were first carried out on the substances removed from this extract by Published on 01 January 1914. Downloaded by UNIVERSITY OF NEBRASKA 17/10/2015 17:18:40. agitation with ether, but this eventually proved to be unnecessary, and fortunately so, for not only did the mixture separate from the ether with difficulty, but very little colouring matter was removed thereby. The small quantity of the produccs isolated in this manner, however, closely resembled in property those described by Tschirch and Polacco. It was found better at once to hydrolyse the glucosides present in the aqueous solution, and for this purpose sulphuric acid to the extent of 1.5 per cent. was added, and the mixture boiled for two hours. A granular precipitate gradually separated, which in- creased in quantity on cooling, and this was collected and washed, and, when dry, consisted of 352 grams of a dark brown powder. In order to remove a trace of plant wax which was present, it was extracted with a little boiling benzene, only a minute amount of yellow coIouring matter being removed thereby. 702 View Article Online 2352 OESCH AND PERKIN: The product in the finely powdered condition was now thoroughly extracted with boiling ether, and t’he extract evaporated, whereby a yellow, crystalline residue (A), weighing 102 grams, remained. The residue insoluble in ether, which possessed a dark brownish- black tint, was practically free from colouring matter, and was possibly largely a phlobaphen produced from a phobatannin by the action of the boiling acid. The crystalline residue (A) was now exhausted with boiling toluene, leaving 82.5 grams (B)undissolved, and on cooling overnight, 8 grams of yellow crystals (C) separated from the solution. These were extracted with 200 C.C. of 50 per cent. alcohol, the residue (D)being twice crystallised from toluene, and then from methyl alcohol, until the melting point was constant. Found, C = 63-77; H = 4.19. C,,H,,O, requires- C = 64.00 ; H = 4.00 per cent. It consisted of pale yellow leaflets, soluble in alkali with a yellow colour, and began to sintier at 210°, finally melting at 221-222O. With lead acetate it gave a yellow precipitate, and its solution in sulphuric acid possessed a deep green flkorescence. The amount obtained was exceedingly small. The acetyl compound, prepared in the usual manner, crystallised from alcohol in colourless needles, melting at 200-201°. The melting of this compound, and that of its acetyl compound, are practically the same as those given by Tschirch and Polacco for rhamnocitrin and acetylrhamnocitrin respectively, and the fact that its sulphuric acid solution is strongly fluorescent left no doubt as to ita identity. Tschirch and Polacco adopted the formula Cl3HlOO5 (C = 63.44 ; H = 4-06), and, curiously enough, tested for the presence of a methoxy-group, with a negative result. Feeling far from certain on this point, experiments were carried out by Published on 01 January 1914. Downloaded by UNIVERSITY OF NEBRASKA 17/10/2015 17:18:40. Zeisel’s method, with the result that this statement was found to be incorrect.* Found, Me = 4-92. C15H90,*OMerequires Me= 5-00 per cent. * Manuiiig and Nierensteiu (Bey., 1913, 46, 3983) have stated that whcii acetic anhydride is employed in conjunction with Zeisel’s niethod, a prdcedure firat suggested as beneficial by Herzig (Monntsh., 1888, 9, 514), crroneous results art: obtained, because hydriodic acid and acetic anhydride aione give ill this way a weighable amount of silver iodide. Goldschmiedt (Ber., 1914, 47, 389) has pointed out that in the case of the ordinary apparatus, where bulbs containing amorphous phosphorus are employed, and when pure acetic anhydride is used, this statement of Manning and Nierenstein is incorrect. On tlie otlier hand, Goldschmiedt suggests as possible that the results of these authors had been obtained with tlie apparatus of I’erkin or of Hesse iii.which thesc bulbs are absent. Frequent practice with the former siiggrsted as improb ible that such an error occurred, but experiments were carried out with this apparatus employing pure acetic auhydride with “Zeisel View Article Online THE COLOURING MATTERS OF RHAMNUS CATHARTICUS. 2353 The product from the action of the hydriodic acid, which was evidently preseut in the form of an oxonium salt, was poured into sodium hydrogen sulphite solution, the yellow precipitate collected, crystallised from dilute alcohol, and traces of iodine still present were removed by means of potassium iodide solution. Finally, it was crystallised from acetic acid, and obtained in yellow- needles, melting at 274O, which gave with sulphuric acid a fluorescent solu- tion. The acetyl compound, prepared in the usual. manner and crystallised fro’m methyl alcohol, formed colourless needles, which melted at about 116O, gradually solidified as the temperature rose, and finally melted at 182O. Again all the properties of this colour- ing matter were identical with those of kaempferol, and from these results there could be no doubt that rhamnocitrin is not, as sug- gested by Tschirch and Polacco, an hydroxydihydroxanthone, but is in reality a monomethyl ether of kaempferol. The only substance of this constitution at present known is the kaempferide of Galanga root, A Zpinia oficinarurn, first isolated by Jahns (Ber., 1881, 14, 2385), who found its melting point to be 221-22207 and that of its acetyl derivative 188-189O. According, however, to the later work of Ciamician and Silber (Ber., 1899, 32, 861), and Testoni (Gazzetta, 1900, 30, ii, 327), kaempferide and acetylkaempferide melt, re- spectively, at 227-229O and 193-195O, and although in general respect rhamnocitrin very closely resembles kaempferide, it would appear, more especially from the difference in the melting point of their acetyl derivatives, that they are distinct compounds. In order to compare the two compounds, an ethereal extract of Galanga root was obtained by purchase, but this proved to be of no service, in that but a trace of kaempferide was present, and Published on 01 January 1914.