2 62 SCHUNCTL ON TEE SUPPOSED IDENTITY XXII1.-On the Supposed Identity of Rutin and Quercitrin. By EDWARD SCHCNCK Ph.D. F.R.S. RUTIN a crystalline yellow colouring matter was discovered by Weiss (Planrm. Centr. 1842 903) who obtained it by treating the leaves of Rzcta graveoZeus with alcohol or acetic acid and described some of its properties. It was next examined by Borntrager (Annnlen 53 385) who confirmed the statements of his pre-decessor and also analysed the substance and its lead compound. Rocbleder and Hlasiwetz (AnnaZen 82 197) obtained from the capers of commerce the flower-buds of Cupparis spinosa a colourin OF RUTlN AND QUERCITRIN. 263 matter having the properties of rutin and the same composition as that given by Borntrager and in 1858 (Jlanchester Nemoirs 2 Ser., 15 122) I showed that the same substance could be easily procured from the leaves of common buckwheat Polygonurn Fugopyrum.I n a second investigation undertaken by himself Hlasiwetz (Annalefi 96, 123) found that by the action of strong acids rutin is decomposed, yielding quercetin and sugar and the quantities of the two latter formed by its decomposition being very nearly those required in accordance with the then accepted formula of quercitrin he con-cluded that quercitrin and rutin were identical. This conclusion seems to have been generally adopted by compilers of handbooks and dictionaries. Afew years later however Zwenger and Dronke (AiznaZeiz 123,145) endeavoured again to prove that the t w o bodies were really distinct, and that though they were very similar in many respects they differed with regard to some of their properiies as well as in composition.The conclusion they arrived at was that whereas quercitrin was a corn-pound of 1 mol. of quercetin with 1 mol. of sugar (dextrose?) minus water rutin contained 1 mol. of quercetin and 2 mols. of another kind of sugar. This conclusion is an approximation to what I believe to be the truth. If however it had been known a t the time that the sugar formed by the decomposition of quercetin is isodulcite, C6H1406 and not glucose and that rutin yields the same kind of sugar as quercitrin the subject would have again been involved in the obscurity which the authors had attempted to remove. Among the earlier memoirs on the subject there is one by Stein (J.yr. Chem. 58 399; 85 351; 88 280) who obtained from so-called Chinese yellow berries the unexpanded flower-buds of Xoplzora juponica a colouring matter which he considered to be identical with rutin from rue. Foerstm (Ber. 15 214) however who has recently examined this substance supposes it to be distinct and has accor-dingly named it sophorin. The properties of quercitrin and of its products of decomposition having of late years been minutely studied and its composition accurately ascertained by Liebermann and Hamburger and others and rutin so far as I know not having been anew examined it seemed to me that i t might be interesting again to compare the two substances, and if they were found to be distinct to ascertain wherein the differ-ence consists.The quercitrin which I used was prepared in the usual way from quercitron bark. The rutin was obtained from Polygonuyn fago-yyvi~nz leaves and though it had been kept for many years had undergone no change and seemed quite pure. The yellow colouring matter from buckwheat leaves has the sam 264 SCBUNCK ON THE SUPPOSED 1L)ENTITY properties as the rutin from garden rue but the latter contains some impurity which is not easily removed a fact already pointed out by Zwenger and Dronke. Rutin even after numerous crystallisations, retains a faint greenish tinge and may be described as being of a pale primrose-yellow whereas the colour of quercitrin inclines more to lemon-yellow. I n the following table the reactions in which the two substances show a marked difference are placed side by side ; the reactions in which no difference could be observed are omitted.@cercetin. Soluble in 280 parts of boiling water. Soluble in 3.5 parts of boiling absolute alcohol. SoIuble in 125 parts of ordinary ether. Easily decomposed when its watery solution to which sul-phuric acid has been added is boiled. When a dilute alcoholic solu-tion containing silver nitrate is shaken up with three times its volume of ether the latter acquires R crimson colour; the colour soon fades metallic silver being a t the same time deposited. An aqueous solution gives with stannous chloride a light red pre-cipitate. By the action of bromine crys-tallised tetrabromoquercitrin is formed. By the action of chlorine on the substance suspended in water a yellow body is formed which contains chlorine and is insoluble in water but soluble in alcohol, the alcoholic solution leaving, Rutin.Soluble in 170 parts of boiling water. Soluble in 5 parts of boiling absolute alcohol. Soluble in 335 parts of ordinary ether. Very slowly decomposed by the action of boiling dilute sul-phuric acid. A dilute alcoholic solution con-taining silver nitrate shaken up with ether imparts to the latter a light yellow colour. An aqueous solution gives with stailnous chloride a bright yellow precipitate. By the action of bromine only amorphous products are obtained. On passing chlorine through water with rutin in suspension, the latter dissolves entirely. The solution on evaporation over sulphuric acid leaves a brown amorphous residue which has a OF RUTIN AND QUERCITRIN.265 Rutin. Quercitrin. I on evaporation an amorphous residue. ~ astringent taste and shows some ' of the reactions of tannin the watery solution giving a dark-green coloration with ferric chlo-ride and a flocculent precipitate with gelatin. Rutin dyes the same colours on mordanted calico as quercitrin the alumina mordant acquiring a yellow and the iron mordant a more or less intense olive colour but using equal weights of both substances the shades produced by quercitrin are perceptibly darker. Rutin yielded on analysis the following results :-0*4686 gram of substance dried in the desiccator lost on heating at 130" 0.0186 gram water equal to 3.97 per cent.1.7352 grams substance dried in the desiccator lost on heating at 130° 0.0696 gram water equal to 4.01 per cent, I. 0.5510 gram substance dried at 130" gave 1.0588 gram CO and 11. 0.4748 gram substance dried at 130' gave 0,9152 gram CO and These numbers correspond in 100 parts to-0,2623 gram H,O. 0.2348 gram H,O. I. 11. C 52.40 52-55 H . . 5-28 5-49 On adding sulphuric acid to a watery solution of rutin and boiling, yellow crystalhe needles are deposited consisting of a product of decomposition. The boiling must be continued for some time the decomposition being much more slowly effected than with quercitrin. After cooling the yellow needles are collected and washed. They have the properties of quercetin and also the same composition as the following results of their analysis show :-I.0.5002 gramsubstance heated for 24 hours at 130" gave 1.0896 11. 0.2667 gram substance dried at 130" gave 0.5928 gram CO and 0.3050 gram quercetin from quercitrin gave 0.6700 gram CO and These numbers correspond in 100 parts to-gram CO and 0.1784 gram H,O. 0.0851 gram H,O. 0.1022 gram H,O. VOL. LIXI. 266 SCHUNCK ON THE SDPPOSED IDENTITY Quercetin I. 11. Mean. from quercitrin. C 59.49 60.62 60.05 59.90 H . . . . . . . . 3.96 3.54 3.75 3.74 The formula C2,H,,0, for quercetin requires-C 60.00 H 3-33 By acting on the product from rutin with acetic anhydride and sodium acetate an acetyl compound was obtained crystallising i n white needles and having the same appearance and showing the same melting point as the componnd formed in the same way by acting on the quercetin from quercitrin.The product soluble in water formed along with quercetin by the action of sulphuric acid on rutin is isodulcite. It is obtained from the filtrate after remo.ral of the acid by evaporating to a syrup, dissolving the latter in absolute alcohol adding several times its volume of ether to the alcoholic solution and allowing the liquid after the milkiness caused by the addition of ether has subsided as a syrupy deposit to evaporate slowly. The substance thus obtained has the same crystalline form and general proFerties as the isodulcite from quercitrin. Its melting point is 90-91". The products of decomposition of quercitrin and rutiu with acids being the same there remains only one way of explaining the difference between the two substances and that is to suppose that the relative quantities of the products of decomposition formed differ in the two cases.Now the formula C42H50025 which I would propose for rutin requires in 100 parts-C . . . . 52.83 H 5.24 with which as will be seen the numbers found by experiment agree. According to Zwenger and Dronke rutin dried at 150-160" contains-C . . 52.66 H 5.00 numbers which also correspond with those required by the above formula. The substance dried a t 100" still retains it would appear 2 mols. H,O which are expelled a t 130". According to the formula C,,H,,O, + 2H,O the loss on heating would be 3.63 per cent. Ex-periment as stated above gave 3.97-4.01 per cent. The formula C42H50015 + 2H20 requires-C .. 50.90 H 5.4 OF RUTIN AbD QUERCITRIS. 26'7 The following numbers show the results obtained by various experimenters in the analysis of rutin dried at the ordinary tempera-ture or at 100':-Rochleder Z m e n g e r Boriitrager and Hlaswietz and Dronhe Schunck, from rue. from capers. from capers. from buckwheat. C 50*30 50.15 49.44 49-85 H . . . . 5.60 5-70 5-52 5-88" If the formula given above be adopted then the decomposition of rutin by acids must be represented by the following equation :-C~zH50025 + 4H20 = C24Hie,Oi1 + 3C6H1406. Quercetin. Isodulcite. In accordance with this equation 100 parts of rutin should yield-50.31 quercetin and 57.22 isodulcite. Experiment gave-48.50 quercetin and 55.20 isodulcite ; numbers which approximate to those required by theory and differ widely from the respective amount's 60.76 and 46.08 corresponding with the formula C36H38020 which according to Iiebermann and Hamburger is that of quercitrin.It would appear therefore that whereas quercitrin contains 2 mols. of isodulcite to 1 of quercetin r u t h has 3 mols. of isodulcite to 1 of quercetin. This being admitted the great resemblance subsisting between the t w o substances as well as the differences observed, such as in the degree of solubility and tinctorial power would be easily explained. I have been assisted in these experiments by Mr. Percy Carter Bell, whose services as a skilful manipulator and a careful worker I have much pleasure in acknowledging. f These numbers agree still better with the formula C42Hc50025 + 3H20 which requires in 100 parts-C 50.00 H . 5.55 Tn accordance with this formula the 1055 on heating should be 5-38 per cent. Zwenger ard Dronke found that rutin dried a t 100" lost on being heitted for some tiiiie at lX-ICiO" 5.92 per cent. of water