ON SOME DERIVATIVES OF ANTHRAQVINONE. 831 LXIX.- On some Derivatives of Antbrapinone. By A. G. PERKIN and W. H. PERRIN Jun. Ph.D. IN a previous papel. on this subject which we had the honour of com-municating to the Society some time since (Trans. 1885 47 679), we described a series of experiments on the products of the destructive distijlation of sodium anthraquinonemonosulphonate. This salt when heated in an iron tube yielded a brownish-red dis-tillate which on examination 'was found to contain metahydroxy-anthraquinone anthraquinone and a peculiar red substance which after purification by recrystallisation gave numbers agreeing with the formula CzsH,,O6 ; it is nearly insoluble in all the usual solvents, and curiausly enough in alkalis also. On oxidahion with chromic acid it yields a white crystalline substance of the formula C,,H,O, and when distilled with zinc-dust anthracene is produced proving the substance t o be an anthracene-derivative.The remarkable character of this decomposition of sodium anthraquinonemonosulphonate has led us t o continue our experiments with a view to obtain some clue as to the constitution of the compound C2,H,,06. The extreme difficulty however of obtaining it in any quantity owing to the tediousness of it's prepara-tion and purification has prevented us from making as thorough an examination of the subject as we could have wished. We hope at some future date to be able to complete these experiments and to establish without doubt the constitution of these derivatives. Before proceeding with the examination of the red substance C,sH,406 we thought it advisable to again analyse it in order that there might be no doubt as to its formula.A quantity was therefore prepared and very carefully purified by repeated recrystallisations from glacial acetic acid. The pure substance was thus obtained as an orange satiny crystalline mass which after careful drying at 110-120" gave the following results on analysis :-3 L 892 A. G. AND W. H. PERKIN JUN. OX 0.1609 gram substance gave 0.0495 gram H,O and 0.4450 gram CO,. Theory. C 2 J ~ 1 . 1 0 6 ' Found. C . . 75-34! per cent. 75.37 per cent. H . 3.14 , 3.42 ,, 0 21-52 , 21.21 'I, I f a hot dilute solution of this substance in glacial acetic acid is slowly cooled groups of small orange-coloured cryatah separate, just visible to the naked eye ; these when collected washed and dried, present the appearance of beautiful satiny orange-coloured flakes.If hot saturated solutions are rapidly cooled the substance is deposited as an orange-coloured gelatinous mass. I n the previous paper it was stated that t.his compound C2SH1106, was converted into alizarin on fusion with potash. As it was important t o be quite sure of this the experiment mas repeated with somewhat larger quantities the decomposition being conducted in the following manner :-About 2 grams of C,,H,,O were heated with rz very con-centrated solution of caustic potash at 180" f o r about 12 hours in a closed iron tube. The contents of the tube which in appearance very much resembled an ordinary alizaih melt were extracted with boiling water the violet-coloured solution filtered from a small quantity of insoluble matter and a little slaked lime added.The alizarate of lime thus precipitated was collected well washed suspended in water, decomposed with a little dilute hydrochloric acid and the orange pre-cipitat e obtained was purified by recrystallisation from benzene. The product consisted of red needles melting at about 285" and showing all the properties of alizarin. On analysis it gave the following numbers :-0.1107 gram substance gave 0.0396 gram H,O and 0.2821 gram c 0,. Theory. C14H804. Found. C . . 70.00 per cent. 69.50 per cent. 0 26-66 , 26.53 ,, H . 3.33 , 3-97 ,, The filtrate from the alizarate of lime was of n reddish colour with a green fluorescence ; on treatment with hydrochloric acid it depo-sited a very small quantity of a nearly white precipitate which when washed on a filter changed to a dirty green.On fusion with potash and t,reatment of the fused mass with water a solution was obtained having all the properties of potassic alizarate. This substance is therefore intermediate between the red substance and alizarin ; it is probably identical with a substance C28H1107 whic SOME DERIVATIVES O F AXTHRAQUIKONE. 833 will be described later on under the heading " Action of Nitric Acid on C28H1106." When fused with potash Ci8H,iOG is probably first oxidised to C,,H,,O, which then takes up the elements of water and is converted into alizarin thus :-C:sHI,O + HZO = 2C,4H804. That such a change really takes place is all the more probable, from the fact that the substance C28H2407 when fused with potash, also gives alizarin.The residne from the fusion insoluble in water was crystallised from acetic acid and thus obtained in orange needles which were found to consist of unchanged C2sH,,0,. 0.1491 gram substance gave 0.0470 gram II,O and 0.4097 gram co,. Theory . C?,H,,% Bound. C 75.34 per cent. 75.01 per cent. H . 3.14 , 3.50 ,, 0 21.52 , 21-49 ,, Action of Sui$hwic Acid on Cz8H,,OG. Cold Nordhausen sulphuric acid dissolves the red substance forming a dirty green solntion which in contact with the air absorbs moisture, and deposits the unchanged substance as a transparent jelly. When the solution in Nordhausen acid is heated to 190" the colour gradually changes to a brownish-red and if at the end of about half an hour the mixture is poured into water it dissolves to a clear solution which on cooling sets to an opaque jelly.All attempts to free this mixture from sulphuric acid by treatment with the carbonates of lead OT barium failed owing to the salts of the sulphonic acid being in-soluble. If the mixture of the sulphonic acid and sulphuric acid is neutrslised with potash and slowly evaporated the dark solution deposits a small quantity of a crystalline salt which under the microscope is seen to consist of long needles ; these when heated to 100" fuse to a gummy mass. Fused with strong potash in an iron tube for some hours and then decomposed with hydrochloric acid a substance is obtained which dyes mordanted clot,h shades intermediate between those produced by anthrapurpurin and flavopurpurin.Action of Nitric Acid on C28H1P06. On gradually adding the red substance C,,H,,O, to cold fuming nitric acid of sp. gr. 1.5 i t dissolves without evolution of red fumes 534 A. G. RPU'D W. 13. PERKIN JUN. ON forming a bromine-coloured solution. In examining the product of this reaction the mass was allowed to stand for a short time and then diluted with water. This caused the precipitation of a yellowish-white amorphous substance which was filtered off well mashed and dried. It was then dissolved in a little hot aniline or nitrobenzene, filtered and boiling alcohol added drop by drop to the hot solution until the mixture showed a tendency to become milky.On aJlr>wing this to cool slowly minute cr-j-stals were deposited which after col-lecting mashing with alcohol and drying at l l O o gave the following iiumbers on analysis :-I. 0.1366 gram substance gave 0.0418 gram H,O and 0.3658 11. 0.1650 gram substance gave 0.0505 gram H,O and U-4420 gram CO,. gram COL. Found. Theory. f--n-- -7 C,,H,,~;. I. 11. C 72-72 p. c. 73-01 '73.05 p. c. H 3-03 , 3.40 3.40 ,, 0 24.24 , 23.59 23.55 ,, This substamnee has therefore the formula C26H1407 being produced from the red substance C,,H,,O by the simple addition of oxygen, thus :-C,H,,O + 0 = C2,H,,O,. Ci.ystallised from a mixture of aniline or nitrobenzene and alcohol, this substance C26H,407 appears iindcr the microscope as groups of short colourless needles.Prom hot acetone however in which it is only very slightly soluble it can be obtained in l a q e r crystals. It is slightly soluble in coal-tar naphtha more soluble in acetic acid. When heated it melts a t a high temperature to a yellow liquid which on cooling solidifies to a hard crystalline niass. At higher temperatures it chars only a very small quantity subliming in microscopic needles. C28Hl,01 dissolves readily in hot aniline or nitrobenzene a n d the solu-tions on cooling deposit small plates of a brownish colour. These substances which are evidently additive compounds of C,,H,,0 with aniline and nitrobenzene have not as yet been analjsecl. They are readily obtained pure by adding cautiously t o the hot solution i n aniline or nitrobenzene about twice the volume of benzene.On cool-ing the compound separates out in glistening plates. On boiling with alcohol they are quickly split u p into their constituents. Boiled with zinc-dust and potash solution C,,H,,O slowly dissolves, forming a reddish-brown solution which on shaking w i t h air instan-taneously decolorises with precipitat'ion of a white gelatinons snb-stance S031E DERIVATIVES O F BNTHRAQUIXO1U’E. 833 The following reaction is characteristic of this substance :-If a trace be boiled with a strong solution of pobash in methyl alcohol in a test-tube it will gradually dissolve with an olive-green coloratioc. On continued boiling the solution becomes darker and darker coloured as the methyl a1 coho1 evaporates the green gradually changing to a beautiful brownish-pink.On adding water a violet solution is obtained which does not decolorise on shaking with air, aud therefore possibly consists of potassic alizarate. Action of Nitric and Sublauric Acids on C,,H,,OG. If C2,HI1O6 is treated with a mixture of nitric and sulphuric acidF, ,z reaction quite different from the above takes place. In studying this, a small quantity of substance was boiled with a mixture of equal parts of nitric and sulphuric acids for a short time the product poured into water and the precipitate well washed and dried. I n order to purify it it was dissolved in hot acetic anhydride the solution poured into an equal bulk of hot alcohol and allowed to cool slowly. A beautiful yellow crystalline powder was thus obtained which on heating with potassium and then testing with ferrous and ferric chlorides was found to contain a considerable amount of nitrogen.We have not as yet analysed this nitro-derivative but its properties resemble very much those of the nitroanthraquinones except that it does not sublime when heated but is almost entirely decomposed leaving a black residue. If heated with sulphuric acid a violent reaction sets in, and on diluting the product with water a red-violet precipitate is obtained which dissolves in potash with a blue colour. When boiled with sodium sulphide a brick-red amido-compound is obtained re-sembling amidoanthraquinone with which however it does not appear to be identical. Fusion of Cz8Hla07 with Potash. In carrying out this experiment the substance was heated in a closed iron tube with concentrated potash solution for 12 hours a t 180”.The product was then boiled with water filtered a small quantity of lime added to the violet-blue filtrate again filt’ered and t h e residual violet powder washed with water and decomposed with hydrochlcric acid. The orange-coloured precipitate formed was washed with water, dried and once or twice recrystallised from benzene. Red needles were thus obtained which melted a t about 285” and showed all the properties of alizarin. The analysis gave the following numbers : 836 A. G. ASD W. H. PERKIK JUN. OS 0.1471 gram substance gave 0.0488 gram H,O and 0.3749 gram GO,. Theory. C14H8O.i. Found. C 70.00 per cent. 69.57 per cent. H . 3.33 , 3.62 ,) 0 26.66 , 26.81 ,, The filtrate from the alizarate of lime was a red solution with cz green fluorescence which on acidifying gave a white precipitate, changing to green on washing.This substance of which oiily a minute quantity was obtained appeared to be unat tacked C1YH1107. That portion of the product which was insoluble in water after re-peated recrystallisation from glacial acetic acid appeared under tho microscope as orange-red needles giving with sulphuric acid a red-dish-violet solution and in all other respects showing the properties of the red substance C,H1406. Dried a t 120" it gave the following results on analysis :-0.0859 gram substance gave 0.0269 gram H,O and 0.2365 gram c02. Theory. C28H140,. Found. C 75.34 per cent. 75.09 per cent.H . 3.14 , 3.48 ,, 0 21.52 , 21-43 ,, Two distinct reactions therefore take place when C2sHl,0 is fused In the first place the elements of water are taken up 1 mol. of with potash. C28H1407 splitting up into 2 mols. of alizarin thus :-whereas at the same time a certain amount of reduction takes place, some of the C28H1407 being reduced to the original red substance, thus :-C28H1407 + H = C,~Hiio + J%O. Action of Chromic Acid on C28H1407. In the first paper ori these anthraqninone-derivatives (Zoc. cit., p. 683) we showed that when the red substance C,6Hl,06 is oxidised with chromic acid in acetic solution it is converted into a white sub stance of the formula CI4H6O4 thus :-C28HuO6 + 0 = 2 0 4 + J&O SOME DERITBTIVES OF ANTHRAQIJIKONE. 837 On considering the results just described it appeared likely that thc substance CZ8H,,O7 was really the first product of the action of oxidising agents on C2PH1406 and that this therefore on further oxidation should yield the same substance C1,H604 as is obtained direct by the action of chromic acid on C28H1406.In order to decide this point a small quantity of the substance C,,H1407 was dissolved i n hot glacial acetic acid and treated with chromic acid until the violent reaction which set in a t first had subsided. On allowing the green solution to cool a white crystalline powder wzs deposited. This was collected washed dried and several times recrystallised from glacial acetic acid. In this way the product was easily separated into two portions, one of which was considerably more soluble i n acetic acid than the other.The less soluble portion on analysis gave the following numbers :-0.1583 gram substance gave 0.0385 gram H,O and 0.4100 gram c 0 2 . Theory. o 4 . Found. C 70.59 per cent. 70.63 per cent. H . 2.52 , 2.70 ,, 0 26.89 , 26-67 ,, The substance therefore has the formula Cl4H6O4 arid a careful comparison showed that it is without doubt identical with that pro-duced by the direct oxidation of the red substance C,8H1r06 with chromic acid. Attempts to produce the subst,ance C,8H,,07 by cautious oxidation of C28H1406 with chromic acid were unsuccessful the reaction in all cases going as far as the formation of the compound C,,H,O,. The more soluble substance cbt'ained in the above oxidation was found on examination to consist of unchanged substance as the following analysis shows :-0.1699 gram substance gave 0.0490 gram HzO and 0.4520 gram co,.Theor?. C?sH1407. Found. C 72.72 per cent. 72.51 per cent. H . 3-03 , 3.20 ,, 0 24-25 , 24-29 ,, Action of Hydriodic Acid on C28H1406. Experiments were next made with the object of removing some of the oxygen-atoms from the molecule Cz,H140e in the hope of thn 838 A. G. AND W. H. PERKIN JUN. ON obtaining some well-known compound the formation of which might tlirow additional light on the iiature of the red substance. I f Cz8Hl4O6 is suspended in hot glacial acetic acid and fuming aqueous hydriodic acid added drop by drop the crystals rapidly dissolve forming a deep red solution which contains free iodine ; this is filtered and poured into water when a lemon-yellow precipitate is deposited which is collected well washed dried and purified by recrystallisation from a mixtiire of hot aniline and alcohol ; on cooling it is deposited as a yellow crystalline powder.Two different samples dried a t 110" were analysed with the following resnlts :-I. 0.1457 gram substance gave 0.0470 gram H,O and 0.4160 gram 11. 0.0659 gram substance gave 0.0212 gram H,O and 0.1880 gram CO,. co,. Found. Theory. /-+ (-A-I. 11. C?SHIQOS. C?,H16$. C . . . . 77.86 77.80 p. c. 78-14 77-77' p. c. H . . . . . 3.58 3.57 , 3-26 3 i O ,, 0 . . . . 18.56 18-53 , 1S.60 18.52 ,, The nunibers obtained agree therefore better with the formula C,,H,,O than with C2,Hl6O5 and i t is probable that this new com-pound is formed from the red substance simply by eliniination of oxygen thus :-C,,H1406 + H = Cz,H,,O5 t H,O.This substance C2sH1105 which is insoluble in aqueous potash dis-solves in a strong hot solution of potash in methyl alcohol with an intense orange-brown coloiir which on long boiling does not change. If the alcohol is evaporated the colour becomes intenser as the solution becomes stronger until a t last a dark-brown residue is left ; this dissolves in water with an orange-red colour which how-ever alniost disappears on shaking with air. Wheii boiled with zinc-dust and potash C,,HI4O5 gives scarcely any coloration but it dissolves in concentrated sulphuric acid forming an intense reddish-brown solution. The ease with which the red substance C,,H,,O loses 1 atom of oxygen and is reduced to C28H1105 led us to think that it would be interesting t o study the further action of hydriodic acid on this substance.For this purpose a mixture of 0.5 gram of the pure red substance 5 grams of fuming hydriodic acid and 5 grams of glacial acetic acid were heated in a sealed tube for about half an hour t o 160". The dark-red liquid thiis obtained was gently evaporated to get rid of most of the acetic acid the residue freed from iodine b SOME UERIVATIVES O F AXTHRAQUXXONE. 839 boiling with dilute aqueous sulphurous acid. The precipitate which separated on cooling was collected filtered washed with water and dried on a porous plate. On extracting the product with alcohol, nearly the whole dissolved leaving a small quantity of a yellow substance behind.This residue after careful drying and sublimation in a test-tube formed microscopic yellow needles melting at about 260-265" and which on boiling with potash solntion and zinc-dust gave a red solution becoming colourlcss again on shaking with air. This substance was therefore probably anthraquinone. The alcoholic solution on evaporation deposited a considerable quantity of a somewhat sticky yellow substance which especially when boiled with water possessed in a marked degree the peculiar odour of dihydroanthracene. In order to determine whether the reduction really had gone as far as this the crude substance was distilled in a test-tube the solid distillate washed with a little alcohol, and then recrjstallised from this solvent.I n this way small crystals were obtained which melted at 104-106" and otherwise showed all the properties of dihydroanthracene. Action of S d p h u ~ i ~ Acid o n C,sH,407. I n studying this action a small quantity of the substance was heated with fuming sulphuric acid at 180". The reddish-brown solution first formed became gradually darker and eventually after 20 minutes' heating of a hluish-red colour. At this stage the decom-position was evidently complete the product dissolving completely in water sliowing that a sulphonic acid had been formed. On adding acetic acid t o the strong hot solution and allowing it to cool a small quantity of a crystalline precipitate separated. I t was however, found inipracticable t o purify the sulphoriic acid by this method as it was too soluble in acetic acid to admit of sufficient washing.The mixture of the sulphonic acid and sulphuric acid dissolved in water forming a greenish solution with which lead or barium carbonate yielded insoluble compounds only. 111 order if possible t o determine the nature of the sulphonic acid ihus formed resort was had t o fusion with potash. The solution was mixed with a considerable excess of concentrated aqueous potash and heated in closed iron tubes at 180" for about 12 hours. The product dissolved in water formiiig a red-violet solution and on the addition of acids a brownish-yellow precipitate was thrown down which was collected and well mashed with water. This substance dyed mordanted cloth shades intermediate be tween those given by anthrapurpurin and flavopurpurin and therefore, probably consists of a mixture of these two substances 840 A.G . AND TT. H. PERKIN JUN. OX Fusion of C,,H,O with PotasJh. This substance the preparation of which was given in the previous paper (Zoc. cit. p. 683) is formed by the oxidation of the red substance, C28H1406 with chromic acid in act tic acid solution. Considering the interesting constitution previously assigned to this substance and its mode of formation from the red substance it was thought that valuable results might be obtained from the further study of its properties. The first decomposition which was studied was the action of caustic potash a t high temperatures on this substance. Two grams of pure CldH607 were heated with concentrated potash solution for about 12 hours a t l80" the dark-coloured product extracted with boiling water and filtered.A small quantity of lime was then added to the bluish-violet filtrate the lime compound thus precipitated collected, washed with water and decomposed with dilute hydrochloric acid. This caused the precipitation of an orange-red compound which after collecting washing with water drying and recry stallising once 01' twice from benzene was obtained in long red needles ; i t melts a t about 285" and possesses all the properties of alizarin. The analysis gavs the following numbers:-0.1175 gram substance gave 0.0391 gram H20 and 0.1175 gram GO,. Theory. ~14Ht304. Found. C 70.00 per cent. 69.98 per cent. H . 3-33 , 3.69 >, 0 20.67 , 20.43 ,, The portion of the product insoluble in water obtained during the fufiion of C,H,O with potash was extracted several times with glacial acetic acid and boiling water added to the filtrate.On cooling long orange-coloured needles were deposited which on analysis gave numbers corresponding with the formula CI4H,O2. I. 0.1235 gram substance gave 0.0465 gram H,O and 11. 0.1285 gram substance gave 0.0466 gram H,O and Theory. F - - 7 Cl4H802. I. 11. 0.3648 gram CO,. 0.3800 gram CO,. Found. C 80.i7 p. c . 80.60 80.65 p. c. 0 15.39 , 15.23 15-32 ,, H 3.84 , 4.17 4.03 ,, This compound obtained by the fusion of C,4H60 with potash did not a t all resemble anthraquinone outwardly as however often it wa SOME DERIVATIVES OF ANTHRAQUINONE.841 recrg-stallisecl it was always deposited in flat silky needles of an orange colour. It melted however at 275" the melting point of anthraquinone and when heated strongly it sublimed much in the same way as ordinary anthraquinone so that there can be no doubt as to its identity with that substance. The action of caustic potash on CI4HGO4 appears therefore to be entirely a reducing action alizarin and anthraquinone being formed according t o the equations-1. cI~Htjo* + RZ = C14H801, 11. ClaHGOi + 3H ClaHSOZ + 2Hz0. Action of Sulpliuric Acid on ClaH6Oi. I n studying this reaction the substance CI4H6O4 was heated with three or four parts of Nordhansen sulphuric acid at 200" until a sample taken out dissolved entirely in water. As soon as this was found t o be the case the product was poured into glacial acetic acid drop by drop the whole being constantly stirred during the operation.This caused the separation of a white substance which when examined under the microscope was seen to consist of R mass of small crystals. When the precipitation was complete, about twice the bulk of glacial acetic acid was added the mixture thrown on a filter washed with glacial acetic acid till free from sulphuric acid and then well drained. The product was dissolved in a little water and alcoholic soda added to the solution until the white crystalline salt thus formed had been completely precipitated. After collecting well washing with alcohol and drying at loo" tliis salt gave the following numbers on analysis :-0.1963 gram substance gave 0,0333 gram HzO.0.3540 gram CO,. 0.0415 gram N&301. Theory. C14H50,.S0,Na. Found. C 49.41 per cent. 49.18 per cent. H . 1.47 , 1.88 ,, Na 6.76 , 6-84 ,, 0 32-95 ,, S - 9-41 ,, Solutions of this salt give precipitates with salts of copper lead, barium and other metals. On fusion with potash this sulphonic acid yields a reddish-violet solution which on addition of acids, deposits a yellow precipitate. This after being collected and washe 842 A. G. AND IT. H. PERICIY JUN. ON with water was found to dye niordanted cloths shades vcry closely resembling those produced by flavopurpurin. As the substance also gave the same absorption-bands as flavopurpurin there can be no doubt of its identity with this substance. In order to examine more completely the action of snlphuric acid on CIIHBOI the acetic acid filtrate from the precipitated sulphonic acid was next experimented on thus :-After distilling off the acetic acid the residue was dissolved in potash fused with an excess of strong potash solution in an iron tube and the product isolated in the usual way.The yellowish-brown flocculent precipitate thus obtained dyed mordanted cloth with shades slightly yellower than but otherwise exactly similar to those produced by anthrapurpurin and a careful examination of the substance showed that it agreed with this compound in all its reactions. By the action of Nordhausen sulphuric acid on CI4H6O4 it would appear therefore that two suiphonic acids are formed, of which one is insoluble and the other soluble in glacial acetic acid.On fusion with potash the former yields flavopurpurin and the latter anthrapnrpurin. Theoretical Remarks. On considering the results described in the body of this paper it appears very doubtful whether the red substance C,,H,,O can have the formula first assigned to it (loc. cit. p. 684) namely-co co /\ /\ ,CO-C CH-CH C-CO CcH4\ 11 I I 11 )C6H*? GO-C CH CH C-CO x v/ CH as this formula does not in any way explain the formation of the oxidation compound C'28H140i or the decomposition into alizarin by fusion with potash. A reaction of this kind would involve the severing of the two anthraquinone molecules which would hardly take place so easily if they were joined simply carbon to carbon as shown above. I n order t o be a3le to explain the formation of its various deriva-tives it is necessary to suppose that the two anthraquinone molecules are linked together in a much more feeble way as for instance with the intervention of an oxygen-atom.The most probable formula f o r the red substance CzsHI4O6 and one which would explain all its decompositions would be SOME DERIVATIVES O F ANTHRAQUIKONE. 843 co C H /\ CO-C”CH-0-4 C-CO C6H4’ )I I 1 I/ )C,H4. >g 2.6 ‘CO-C C H CH C-CO By the action of nitric acid this substance is converted into C,,H,,O,, which would be represented by the formula-co co /\ /\ CO-C CH-0-CH C-CO C H C-CO \/ \/ CH HC I 11 >c6=4* C6H4’ 11 I \CO-C CH On further oxidation this substance is converted into 2 mols. of CI4H6O4 a change which is easily understood if we assume that the latter substance has the constitution which was previously assigned to i t ; that is-co /\ co-c co ‘CO-C C H CsH4’ )I I There is every reason to believe that this substance has the simde formula C&,O; and not the double formula C2sH1208.The cornpaia-tively low melting point of this substance (about 300°) and the fact that it sublimes easily and completely when heated almost exclude the possibility of its having the double molecular weight C,,H,,O,. The constitutional formula given above for this substance easily explains the reduction to alizarin and anthraquinone by the action of potash at a high temperature. Lastly the substance CzsH1405 produced by the action of hydriodic acid on C,H,,06 would be represented by t,he formula-CH CH /\ co-c c-0-CPC-co C6H4< 11 I I II ‘CGHL, CO-C CH C H C-CO 844 TURNER THE IKFLUESCE OF SILICON which in its turn would easily explain the formation of anthraquinone and dihydroanthracene by the further reducing action of hydriodic acid