2748 BRADBURY AND WEIZMANN :CCLV1.-Some Homologues of Alizarin.By HARRY BRADBURY and CHARLES WEIZMANN.BENTLEY and Weizmann (T., 1908, 93, 435) have shown that whenhemipinic anhydride condenses with veratrole and with pyrogalloltrimethyl ether, in the former case the normal benzoylbenzoic acidis formed, but in the latter one methoxy-group is displaced byhydroxyl, the condensation in both cases being affected by meansof aluminium chloride. The object. of the present work was toinvestigate the condensations of hemipinic anhydride and4-methoxyphthalic anhydride with o-xylene, and the results werequite analogous to those just mentioned, the methoxy-groups beingalso displaced by hydroxyl.The condensation of hemipinic anhydride with o-xylene fur-nished a dihydroxy-2-xyloylbenzoic acid, which, as it gave twodimethylalizarins on heating with sulphuric and boric acids, musthave the constitution I or 11:/\/co\/\%l,OH coOH/\/ \,'\MeI bO,H ,,,!Me OH /CO,H I /Me \/ \/OH\/(1. ) (11.SOME HOMOLOGUES OF ALIZARIN.2749The constitution of one of the two dimetliylalizarins (melting a tthe higher temperature) was determined by oxidation with potass-ium perinanganate in alkaline solution, when pyromellitic acid wasobtained. This could only have been formed according to thescheme :OH coThe constitution of the other dimethylalizarin must be either111 or IV, according as the original acid has the constitution I orI1 respectively :OH CO OH CO Me(11 I . ) ( I V . )owing to lack of material it has not yet been possible t o decide this.The condensation of 4-methoxyphthalic anhydride with o-xyleneproceeds similarly.Two hydroxyxyloylbenzoic acids were obtained,melting respectively a t 228O and 184O. The former, on fusion withpotassium hydroxide, gave m-hydroxybenzoic acid, and when con-densed in the usual way gave only one hydroxydimethylanthra-quinone, the formation of which points t o the acid having theconstitution V or V I :v. )and the quinone VII or VIII:co Mt!(VII.) ( V I I I . )EXPERIMENTAL.Dih ydrozy-2-xyio yl b enzo ic A cid.Ten grams of hemipinic anhydride were dissolved in 50 grams of0-xylene, and 15 grams of aluminium chloride gradually added.The mixture was then heated on the steam-bath for about sixVOL.cv. 8 2'750 BRADBURY AND WEIZMANN :hours, when it was poured into ice and water and steam passedthrough to remove the excess of o-xylem. When cold the solid wascollected and purified by solution in ammonia and precipitationwith hydrochloric acid. The product from which no isomeric acidcould be obtained crystallised from acetic acid in small needlesmelting a t 238O:0.1242 gave 0.3039 CO, and 0.0522 H,O. C=66.78; H=4*65.C,,RI40, requires C = 67.13 ; H =4*90 per cent.Dime t hylalizarins.The above acid was heated with sulphuric acid together with asmall amount of anhydrous boric acid for a short time a t 130°,and the liquid after cooling was poured into ice and water, whenthe dimethylalizarins separated as an orangeyellow powder. Thesewere separated by making use of their solubility in acetic acid.The dimethylalizarin melting a t 198O was readily soluble, whereasthat melting a t 276O was spaiingly soluble; each crystallised inorange-yellow needles, and resembled ordinary alizarin in its pro-perties.The compounds readily dissolved in sodium hydroxide t oa deep purple solution, which dyed mordanted cotton, diff erentshades being cbtained according to the mordant used.The substance melting a t 276O was analysed :0.0682 gave 0.1780 CO, and 0.0266 H,O. C='i'1*26; Ht4.33.Cl&€lz04 requires C = 71.64 ; H = 4-47 per cent.The dimethylalizarin melting a t 276O was oxidised with potass-ium permanganate in alkaline solution, and after removal of %heexcess of permanganate the filtered liquid was evaporated todryness and the residue extracted with alcohol.On evaporationof the filtered extract and acidifying, pyromellitic acid wasobtained. .Wydroxy-2-xy lo ylb enzoic Acids.The condensation of 4-methoxyphthalic anhydride and o-xylenewas carried out in E n exactly similar manner to that employed inthe preparation of the dihydroxy-2-xyloylbenzoic acids. Theproduct, after being purified by dissolving in ammonia and precipi-tation by hydrochloric acid, was boiled with benzene. Very littleappeared €0 pass into solution, and the residue after filtrationapparently consisted of only one acid. This was crystallised fromacetic acid, in which it was fairly readily soluble, and the solutionon concentration deposited small crystals melting a t 228O.Thefusion of this acid with potassium hydroxide was carried out asfollows: Five grams were gradually added t o 15 grams of fusedpotassium hydroxide, and the mixture was heated a t 270-280SOME HOMOLOGUES OF ALIZARIN. 2751for three hours. The cooled mass was dissolved in boiling water,and the' solution acidified with dilute sulphuric acid. On coolingan acid crystallised out, and which, when recrystallised from hotwater, melted a t 200° and was identified as m-hydroxybenzoic acid.The filt'rate from the above acid was extracted several times withether, and after evaporating the ether a residue remained, butthe dimethylbenzoic acid has not yet been isolated in a purecondition.The benzene solution mentioned above was evaporated to asmall bulk, and crystals were obtained which, after further crystal-lisation from benzene, melted a t 184O.The amount, however, ~ 7 a sonly an exceedingly small proportion of the total yield of acid.Hydro x ydim e t h plant hra puino ne.The acid melting a t 228O was-he'ated with sulphuric and boricacids, and on pouring the mixture into water a pale green powderwas obtained. This was collected and crystallised twice fromacetic acid, yielding small, pale green needles, melting a t 210O.No other quinone was detected in the product:0.1462 gave 0.4066 (30, and 0.0630 H,O. C=75.86; H=4.78.Cl,H,,Os requires C = 76-19 ; H = 4.77 per cent.P.relmratio?z of 4 - N e t hoxypJh th n Zic A cid.In the first' experiments 4-methoxyphthalic acid was prepared byBeiitley and Weizmann's method (loc.c i t . ) . This was found,however, to give a comparatively poor yield, and the followingprocess was devised. 4-Hydroxyphthalic acid (1 mol.) was dissolvedin xylene, and methyl sulphate (4 mols.) and anhydrous potassiumcarbonate (4 11101s.) were added in this order. The mixture wasthen heated in an oil-bath f o r three hours a t 135-140°, andagitated. Water was added to the cooled product, and the xylenelayer separated from the aqueous portion. The latter was extractedseveral times with ether, and the ethereal extract added t o thexylene layer. The ether was removed by distillation and the' xyleneby means of a current of steam. The oil remaining was dissolvedin ether, the solution dried and evaporated, and the residuedistilled under diminished pressure. The yield of methyl 4-methoxyphthalate varied from 80 to 90 per cent., depending on theduration of the passage of steam in which it is slightly volatile.The ester was hydrolysed in the usual way by means of a solutionof potassium hydroxide in alcohol, and the acid converted intothe anhydride.TIIE UNIVERSITY,MANCHESTEK