2684 - AND P~CRKIN REDUCTION PRODUCTS OF CCCLXVII.-Beduction Products of the Hydroxyunthru-quinones. Part VII. By W m BERTRAM MILLER and A R T H ~ ~ GEORGE PERKIN. A COBWAXISON of the formula of the hydroxyanthrones obtained during the reduction of 1-hydroxyanthraquinone and of 1 2-dihydroxganthraquinone (alizarin) is of interest because whereas the former (I) contains the hydroxyl adjacent to the carbonyl group, in the latter (11) the hydroxyls are in the 3 4-positions thereto TEE EYDBOXYAXl!ERAQUINONES. PART VII. 2685 As is well known the hydroyxl group adjacent to the carbonyl group in hydroxy-ketones difEers in properties from those present in other positions and to explain this it is assumed to be involved with the carbony1 to form an ortho-quinonoid or a six-membered, chelate grouping (Sidgwick and Callow J.1924,125 627) or that in any case some form of attraction exists between the two. If the reduction of the hydroxyanthraquinones follows the scheme applicable to anthraquinone ifself, it is reasonable to assume that owing to the attraction of the a-hydroxyl for carbonyl in the change from b to c these will take up adjacent positions as indeed occurs with the 1-bydrownthrone (I) derived from 1-hydroxyanthraquinone. For a similaz reason, it is to be expected that zw the a-hydroxyl is present in alizarrin a h , this on reduction will yield the 1 2-dihydroxyanthrone whereas as a matter of fact the 3 4dihydroxy-compound is produced @I). To account for this it seems likely that in this caae the attraction of the a-hydroxyl for the carbonyl is either non-existent or is auppmmed by the greater atfraction of the p-hydroxyl for the para-position thereto and thus in the change from (b) to (E) the 3 4-dihydroxy-compound mults.In mpprt of thie is the fact that 2-hydroxyanthraquinone when reduced givw 3-hydroxyanthrone (V) and therefore there is reason to presume that in these cases the p-hydroxyl is the determining factor or that in other &ds a para-quinonoid structure is preferred even when a- and @-hydroxyh are gimnlfaneously present. It waa inte&ing therefore to study the behaviour of alizarin 2-methyl ether * in these c k d n c e s , for owing to the etherification of the 2-hydroxyl group this compound more closely resembles in general propertiea 1-hydroqmnthquinone than alizarin itself and it was to be anticipated that I-hydroq-2-methoxyanthrone (IV) would result.With stannous chloride and hydrochloric acid as reducing agent this is the case although in According to Graebe and Th& (An& 1906 349 207) alizarin h - 1 ether d u d With dnat and giVea 3 I - d h & h O q -anthrone together with 8 second compound probably 1 2-dimsthoxy-8 n t b 2686 XILLER AND PERXIJY REDUCTION PRODUCTS OF addition to this compound which is the main product a small amount of 4-hydroxy-3-methoxyanthrone (deoxyalizarin mono-methyl ether ; III) is produced accompanied by much viscid matter. In order to determine the constitution of these compounds recourse was had to the bemanthrone reaction followed by a study of the behaviour of each product when methylated by means of methyl iodide and alkali.From the pale yellow anthrone (III) in this manner benzalizarin methyl ether (VI) was obtained and in proof of this an identical compound was prepared from benzalizarin itself (J. 1920 117 702). On the other hand the orabge-coloured anthrone (IV) gave, although in small amount a compound to which formula (VII) has been assigned demethylation having occurred during the reaction; it has not been ascertained however whether the hydroxyls occupy the 3 :4- or 5 6-positions. Whereas it waa previously shown (h. cit.) that both hydroxyls of benzalizarin are readily methylated with methyl iodide and alkali with the compound (VII) for which the name isobenzalizarin is suggested this is not the case as under drastic tratment with these reagents only a monomethyl ether is produced.Evidently therefore a hydroxyl is here present adjacent to the cwbonyl group and this view is supported by the fact that, whereas numoacetylisobendizurin is readily obtained the diacetyl compound can be prepared therefrom only by prolonged digestion with boiling acetic anhydride and pyridine. Be '. and isobenzalizarin differ widely in their dyeing properties with mordants for whereas the former gives shades analogous to those of alizarin itself (loc. cit.) the latter dyes yellow and is scarcely a strong colouring matter. This is of intemt, because it is generally assumed that the tinctorial properties of the hydroxyanthmquinone dyestuffs as e.g. alizarin are due at least in part to an ortho-quinonoid or some similar arrangement in which the l-hydroxy- and the adjacent carbonyl group are involved.In such a sense however benzalizarin must be regarded as a para-quinonoid and isobenzalizarin as an ortho-quinonoid dyestuff and this suggests that the dyeing properties of alizarin,* which resemble those of benzaliza;rin but differ markedly from those of isobenzalizarin , * -4 para-quinonoid structure was suggested by one of us for the mono-alkali salta of the hydroxyanthraquinones (J. 1899 75 433) THE HYDBOXYANTHRAQUIXONES. PART YII. 2687 may be due to the presence of a para-quinonoid rather than to an ortho-quinonoid grouping. If a survey be made of the phenolic mordant dyestuffi and more especially of those in which adjacent hydroxyl groups are present, it wiIl be observed that for most of them a para-quinonoid arrange-ment only is possible; of the very numerous instances which can be given hetin (VIII) and the dihydroxybenzylideneoumaranone (IX; Fridiinder and Rudt Ber.1896 29 878) both powerfnl dyestuffs may be cited. 0 OH 0 (VIII.) co (IX4 On the other hand whereas other colouring adjective class as for instance gallacetophenone (X) and the hydroxyanthraquinones may be considered to dye by virtne of either an ortho- or para-quinonoid grouping there is with the exception of such feeble dyes as euxanthone which do not contain adjaeent hydroxyls an almost complete lack of colouring matters to which an ortho-quinonoid grouping only can be applied. Experiments are in progress with t6e hope of obtaining in addition to isobendizarin dyes which come under the latter category.A preliminaq study of the behaviour of anthrapurpurin 2 7-di-methyl ether on reduction has at present resulted in the isolation in small yield of but one anthrone which is probably the 4-hydroxy-3 6-dimethoxy-compound. Much viscid matter is simultaneously produced. E x P E R I M E N T A L. Alizurk 2-Met4yZ Ether.-To a boiling solution of commercial alizarin paste (150 g.) in 10% sodium hydroxide solution (525 c.c.), methyl sulphate (110 c.c.) was gradually added and the mixture was repeatedly treated with sodium hydroxide solution (50 c.c.) and the equivalent quantity of methyl sulphate.* The product was collected stirred with sodium carbonate solution to remove alizarin the crude methyl ether (30 g.) dissolved in benzene and precipitated therefrom as potassium salt by alcoholic potassium hydroxide ; some alizarin dimethyl ether remained in solution.The potassium salt was decomposed with acid and the alizarin 2-methyl ether thus obtained was recrystallised from benzene until the melting point 229-230" was constant (Found C 70.8; H 4.05%). In addition to the alizarin dimethyl ether m. p. 214-215" a second In all, 875 C.C. of caustic sods solution and 195 C.C. of methyl dphate were employed. A modilkation of the method of Gmbe and mode (h. cif.) 2688 MILLER AND PERKIN REDUCTION PRODUCTS OF dimethyl ether of identical appearance but melting at 169-171" could be isolated from the final mother-liquor if the crude alizarin 2-methyl ether was crystalli~ed from benzene.Thig w&s evidently a methylalizarin dimethyl ether derived from 2-methylalizarin present in the dyestuff employed in that it could not be produced by the further methylation either of alizarin 2-methyl ether or of alizarin dimethyl ether with methyl sulphate and alkali. Reduction. A mixture of alizarin 2-methyl ether (10 g.) stannous chloride (100 g.) and 33% hydrochloric acid (500 c.c.) wa8 boiled for l$ hours. The crystah without apparent solution were con-verted into a brown tar which on cooling solidified to a hard, brittle mass some yellow crystals simultaneously separating from the acid liquid. The ground product was dissolved in about 100 C.C. of alcohol and the crystals which separated on cooling were collected (yield 6 g.).The dark-coloured mother-liquor on evaporation yielded an orange-brown resin from which nothing defbite could be isolated. The crystals when extracted with a little boiling benzene gave a pale yellow residue (A) in small amount whereas from the extract orange-red needles (B) separated on cooling. (A) crystallised from much benzene with the aid of animal charcoal gave pale yellow needles which were recrystallised from alcohol (Found C 75.1; H 5.1; CH, 6-1. Cl,H1,O requires C 75.0 ; H 5.0 ; CH, 6.25%). 4-Hydmxy-3-~h~xyanthrm, m. p. 202" yields an acetyl compound which crystallises in lemon-yellow needles m. p. 185-186" and is oxidised by chromic acid in acetic acid solution to acetylalizarin 2-methyl ether. (B) crystallised from alcohol in which it w a ~ less soluble than A, in orange-red needles m.p. 135-137" (Found C 74-9; H 5.0; CH, 6-2. c1&&03 requires C 75.0; H 5.0; CH, 6.25%). l-Hydr~~-2-methnthrmte is thus obtained in much larger amount than its isomeride. Like this on oxidation it yields alizarin 2-methyl ether. The diacetyE derivative crystallises from alcohol-acetic acid in yellow plates m. p. 202" (Found C 70.3; H 4-9; C2H402 36.7. C,,Hl,O5 requires C 70-4 ; H 4-9 ; C,H,02 37.0%). Benzalizarin Monomethyl Ether.-A mixture of 4-hydroxy-3-methoxyanthrone (4 g.) sdphuric acid (47 c.c.) water (23 c.c.), and glycerol (8 g.) was gradually heated a t 125-130" being well stirred and kept for 1 hour. The solution when cold was poured into water the green precipitate collected washed dried, and in the ground condition repeatedly treated with boiling alcohol.The extra,ct was concenfrated poured into much ether the solution filtered washed with water evaporated to dryness and the pale brown friable residue (1-4 g.) titurated with ether to remove resinous matter. By acet'ylation crystals were obtained which after re THP H Y D B O X Y A N ~ Q ~ O N ~ . PART VII. 2689 CFygtalliSation from alcohol-acetic acid gave 0.4 g. of pale yellow needles m. p. 205-207" (Found C 75-3; H 4-15; CH, 4.85. C&EZI4O4 requires C 75-4 ; H 4-4 ; CH& 4.7 yo). This compound which is uc&yZbt?nzuZizarin met789 ether when hydmlysed with hydrochloric acid in presence of acetic acid gave 86-13y0 of bendizamn lnonometiryl ether whereas theory requires 86.8%.The latter is thus obtained as long orange needles m. p. 247-249" sparingly soluble in caustic soda solution and in alcohol, soluble in sulphuric acid with a violet-red coloration (Found: C 78-0 ; H 4.55. Sulphuric acid in presence of acetic acid gives the oxonium sulphate as long hair-like maroon-coloured needles. The product from the Zeisel determination of the acetyl compound was poured into bisulphite solution. The crystals produced had all the properties of benzalizarin and yielded an acetyl compound, the melting point of which 202-204" was slightly bigher than that previously given (h. cit.). Benzalizarin monomethyl ether waa also obtained by the -1 methylation of benzalizrtrin itself. Acetylbemalizasin (0-95 g.) in boiling methyl alcohol (20 c.c.) and methyl iodide (8 c.c.) was gmduaIly treated with caustic potash (0.35 g.) in methyl alcohol.The crystalline substance produced (0.64 g.) m. p. 247-249O after recrystallisation wit8 identical with the benzalizarin methyl ether described above. A small amount of benzaljzarin dimethyl ether wm present in the original mother-liquor. isoBenzaEizarin.-A mixture of l-hydroxy-2-methoxyanfhrone (substance B) (4 g.) sulphuric acid (47 c.c.) water (2-5 c.c.) and gIycerol wm heated at 12O-130" for 1 hour. The solution was poured into water the precipitate collected dried and the colouring matter present isolated by means of the alcohol and ether treatment described under benzalizarin methyl ether. The orange-red powder thus obtained (1.4 g.) was washed with acetone to remove resin, and after recrystallisation from the same solvent gave 0.6 g.of orange-yellow needles. These by treatment with boiling acetic anhydride and pyridine for a few seconds gave a crystalline deposit of the acetyl compound which crystallised from much acetone in bright orange-yellow flat needles (0.3 g.) ; * m. p. 243-246" (Found : C 74.85; H 4.35. CI9Hl2O4 requires C 75.0; H 309%). This compound nwnamtylisobend izarin is very sparingly soluble in acetone or alcohol. It contains no methoxy-group and C,,H,O requires C 78-3 ; H 4.3%). Thie mudl yield of kobenzalizarin was evidently due to the I-hydroxy-8-methoxyanthne d e r i n g alteration on heating with dphuric acid. An amorphous product waa thus produced which was soluble in caustic soda with a reddish-brown tint and in cold acetone with a red colour 2690 REDUGTIOX PRODUCTS OF THE HYDROXYANTHBAQUINONES.when hydrolysed givea 86.6% of isobenzalizarin theory requiring 8602%. This crystallised from nitrobenzene in orange needles, m. p. 260-262" (Found C 77.8; H 3.9. Cl,Hlo03 requires C 77.9; H 308%). iSoBenzalizarin givea with sulphuric acid a green fluorescent, orange-red liquid and with boiling dilute alkalis orange-yellow solutions with which baqta water yields orange-red precipitates. By dige-sting the monoacetyl derivative with boiling alcoholic potassium acetate orange needles of a potassium salt are deposited. It is undtered by long boiling with hydriodic acid. isoBenzalizarin is somewhat resistant to fbll acetylation but by a long digestion with acetic anhydride and pyridine a diacetyl derivative is obtained which crystallises from acetic anhydride in yellow needles m.p. 214" (Found C 73.3 ; R 4.0. C21H1405 requires C 72-8 ; H 4.0%). isoBenzalizarin Monomethyl Ether.-A mixture of isobenzalizarin (0-3 g.) methyl alcohol (20 e.c.) and methyl iodide (8 c.c.) was boiled during 8 hours caustic potash (0.2 g.) * in methyl alcohol being gradually added. The crystals produced were washed with hot dilute hydrochloric acid to decompose a potassium salt present and crystallised from much alcohol giving deep yellow needles (0.186 g.), m. p. 196-198" (Found C 78.2 ; H 4-15 ; CH, 5.17. C1,Hl,O, Tbe mother-liquor contained a small amount of the same com-pound but the presence of a more highly methylated product could not be detected.By prolonged digestion with acetic anhydride and pyridine the trace of isobenzalizarin methyl ether available gave an acetyl compound which crystallised in yellow needles m. p. about 178-180". isoBenzalizarin dyes mordanted woollen cloth shades which are very distinct from those given by benzalizarin. boBe '* * . Brownish- Greenish- Pale Brown. Be- . Bmwnish- Dullreddish- Bright Brownish-reqnire~ C 78.3; H 4.3; CH, 5.4%). chromium. A l u m i n i n . Tin. Iron. yellow. yellow. yellow. m o o n . orange. orange. black. Anthraprpurin Dimethyl Ether.-Triacetylanthrapurpurin (5 g. ) was methylated as in the preparation of alizarin 2-methyl ether (wide mpa) 37 C.C. of methyl sulphate and 185 C.C. of caustic soda solution being used in all.After removal of the anthrapurpurin trimethyl ether present and crystallisation from benzene the dimethgl ether wat3 obtained in orange-red needles m. p. 234-235" * Approximately 2f timea the quantity required for the production of a dimethyl ether KARTUNG STUDIIS WITH THE MICBOBAL4XCE. PART II. 2691 (Found C 67.9 ; 33 4.2 ; CH, 10.4. H 4.2 ; CH 10.6%). C,,H,,O requires C 67.6 ; The &yZ compound forms yellow needles m. p. 2-205". A&hrvprimnthranul DiMhyl Ethr.-A miXtnre of a n t b -purpurin dimethyl ether (5 g.) sfannous chloride (50 g.) and 30% hydrochloric acid (250 c.c.) boiled for 14 hours yielded a black, granular mass which was collected washed with dilute hydrochloric acid and dried. The product dissolved in alcohol was poured into ether the precipitated amorphous impurity removed the cleas liquid evaporated and the sandy residue washed with acetone until colonrless. This on digestion with acetic anhydride and pyridine yielded diacetyhndhraprprinunthrad dimethyl ether which c v - from alcohol-acetic acid in colourlem needles m. p. 178' (Found C 69.6; H 5.0. C&E€lsOs requires C 67-8; H, 5-1 %). The authors are much indebted to the British AGzarine Go. Ltd. TEE UNIVXBSITP LEEDS. for the alizarin and anthrapurpurin u d in this investigation. [Receiue& Augclet 16th 1925.