ATTEMPTED SYNTHESIS OF DINAPHTHACRIDINES 63-Dinaphthacyidines :P-N-P V1.-Attempted Synthesis ofa-hHpCondensation of Meth ylene Dichloride and I-Sub-stituted- %napkt h ylarnines.By ALFRED SENIER and PERCY CORLETT AUSTIN.Two of the six theoretically possible dinaphthacridines (Senier andAustin, Trans., 1906, 89, 1387) are still unknown, and our attemptsto .synthesise derivatives of one of these by using P-naphthylamine64 SENIER AND AUSTIN: CONDENSATION OF METHYLENEin which the neighbouring a-position is substituted have led only tothe formation of dinaphthacridines of the ’-TmP type. But, al-a-CHathough we have not succeeded in obtaining the desired compounds,the results in themselves possess sufficient interest to be recorded.I n view of the experiments described in a former paper on halogenaddition compounds (Senier and Austin, Trans,, 1904, 85, 1196) andof recent work by A.E. Dunstan and Hilditch (Trans., 1907, 91,1659) on the substitution of halogens in acridines by working withhot solutions, the bromo-substitution derivative of ’-?-’ -dinaphth-a-CHaacridine described is worthy of note. It undoubtedly contains thehalogen in the meso-carbon position, for the linking of the naph-thylene groups by means of the meso-carbon must take place at thepcsition previously occupied by the bromine. Further, i t is importantto observe that this synthesis effectually removes any doubt thatremained as to the constitution of Reed’s dinaphthacridine, the proofof which until now was incomplete, since it depended in part on theassumption of Strohbach (Bey., 1901, 34, 4146) that the a-position inP-naphthylamine is more readily substituted than the other@position :N/ \ /, ,\/\Brl I I I j I I/*\/\I/\/\I I CBr I I\/\ -+I I I 1\/ CH,Cl, v \/ \/Taking into consideration the general fact that a linear arrange-ment of the rings in the synthesis of cyclic compounds is only ob-tained with difficulty (Senier and Austin, Zoc.c i t . ) , i t was expected ’-r-’ base, for this con- that it would not be easy to prepare theP-CHPtains a linear arrangement of rings on either side of the acridinenucleus, the only known dinaphthacridine containing a lineararrangement, and that only on one side, being Strohbach’s’-T-’ isomeride. Again, in view of the fact that when P-naphthyl- a-CHBamine condenses with methylene dihnlides or with formaldehyde theneighbouring a-position enters into the reaction, it was hoped that byfixing the a-position before the experiment by substitution the con-densation might then affect the other P-position and give the typeof acridine desired.Methylene dichloride was selected as a con-densing reagent, because, unlike formaldehyde, it reacts with both6- and a-naphthylamines and because the behaviour of formaldehydDICHLORIDE AND 1 -SUBSTITUTED-~-NAPHTHY LAMINES. 65with 1-substituted-2-naphtliylamines has already been the subject ofan investigation by Morgan (Trans., 1900, 77, 814), in which 110indication of the condensation we wished to bring about wasobserved.The results of our experiments shorn that when the a-position nextto that occupied by the amino-group in P-naphthylamine is taken byan easily replaceable element, such as chlorine or bromine, suchsubstituents are eliminated and condensation takes place a t thea-position with the formation either of Reed's base or, in the case ofbromine, of a bromo-derivative of that base; but that when thea-position is taken by such a substituent as the nitro-group, which isnot easily replaced, no condensation takes place.1.Interaction of Methylene DichZoride and l-ChZoro-2-n~p~t~~yl~~rnine.Five grams of 1-chloro-2-naphthylamine were heated in a closedtube with 24 C.C. (excess) of methylene dichloride for a short time toZOOo, when an orange sublimate was noticed at the end of the tube.After the first appearance of this sublimate, the heaticg was onlycontinued for about fifteen minutes.More prolonged heating orhigher temperatures led to unsatisfactory results. When the tubewas opened, the contents were first washed with a little cold acetone,then boiled with methylated spirit to which a little aqueousammonium hydroxide was added, and poured into cold water. Afterdecanting the liquid and recrystallising the dried residue frombenzene, large triboluminescent crystals containing no halogen andmelting at 2 1 6 O mere obtained, They mere identified with '-rep -dinaphthacridine (Reed).U-CHU2. Preparation OJ 1-Bromo-2-naphthylarnine.I n preparing 1-bromo-2-naphthylamine by the methodMorgan (Zoc.cit.), it was found to be of advantage togiven bywarm thesolution of aceto-p-naphthalide in glacial acetic acid to about 60' andtoaddmoreof the solvent whenever the mass became too thick tostir, otherwise an intimate mixture of the reagents was not obtained.Moreover, the brown precipitate thus formed was purified beforehydrolysis. This was done by boiling it with methylated spirit untilno more dissolved, and filtering, when it mas found that the alcoholicfiltrate contained bromoacetonaphthalide in a fairly pure condition.Thie solution was then hydrolysed by boiling with hydrochloric acid,and the hydrochloride thus obtained was treated with alkali to liberatethe base. One crystallisation from light petroleum was generallysufficient to yield crystals of pure 1 -bromo-2-naphthylamine.VOL. XCIII.66 SENIER AND AUSTIN: CONDENSATION OF METHYLENE3. Interaction of Methylene Dichloride azid I-Bromo-2-naphthylarnine.r l - B ~ o r n o - ~ - Y - ~ -dinaphthacridine, C,,H,cz i > C , , H,. U-CHUAfter several partially successful attempts to determine the properconditions, we found that a temperature of 230-240' was mostsuitable for bringing about the acridine condensation. I n our firstexperiment, we heated the closed tube to 200' and obtained as thechief product a black, non-crystdiisable substance, insoluble in benzene,but soluble in alcohol. Distillation of this black substance underreduced pressure gave rise to a yellow substance, which could not becrystallised and was not further examined.The latter compoundis possibly dinaphthacridone.Satisfactory results were, however, obtained by heating 5 grams of1-bromo-2-naphthylamine with 2 C.C. OC methylene dichloride in aclosed tube to 230-240' for three-quarters of an hour. It was notfound advisable to work with larger quantities. The contents of theopened tube were easily removed by boiling with methylated spiritcontaining some potassium hydroxide in solution.A heavy, black, oily substance was obtained, which, when washed bydecantation with cold water, solidified. This mas rubbed with a littlecold acetone, drained on a filter, and dried in a desiccator. It wasthen boiled with benzene, and the highly fluorescent, but dark, solutionfiltered from an insoluble residue, mixed with animal charcoal, boiledfor two hours under a reflux condenser, and again filtered and allowedto stand.The solution was thereby rendered much clearer, and slowlydeposited well-formed, pale brown crystals. One or two furtherrecrystallisations from benzene sufficed to purify them. When purethey are of a very pale yellow colour and melt at 215.5' (corr.) Theycontain bromine, but are not triboluminescent. On analysis :0.1564 gave 0*4011 CO, and 0.0500 H,O.0.1920 ,, 6.7 C.C. nitrogen a t 14' and 756 mm. N=4.08.0.0853 ,, 0.0452 AgBr. Br = 2254.C = 69.94 ; H = 3.54.C21H,,NBr requires C = 70.39; H = 3.35; N -- 3.91 ; Br = 22.34 per cent.The substance is evidently a rnonobromodinaphthacridine. It isessentially different from a dinaphthacridine bromide (compare Senierand Austin, Trans., 1904, 85, 1196), since it may be boiled withalcoholic potassium hydroxide and may even be distilled in a partialvacuum without decomposition.According t o the method of formation, it might be a derivativeeither of Reed's or of Strohbach's base, that is, either 7-bromo-p-N-p dinaphthacridine.'-r-' -dinaphthscridine or 1 -bromo-a- 6 Hp- Q- C HDICHLORIDE AND 1-SUBSTITUTED-2-NAPHTHYLAMINES. 67It is readily soluble in chloroform or carbon disulphide, less so inbenzene or toluene, and very sparingly so in alcohol. It dis-solves easily in hot glacial acetic acid, depositing yellow crystals oncooling. The latter melt at 273" and have not yet been investigated.The hydrochloride of the base is yellow, and is precipitated from analcoholic solution by means of hydrochloric acid.No method wasfound for purifying it. The preparation of double salts with metalswas difficult, owing to the fact that no very suitable solvent could befound.The aurichloride, [CzlH1,NBr],, [ HAuCI,],, was obtained as a yellow,flocculent precipitate when a few drops of auric chloride solutionwere added to a solution of the base in a mixture of alcohol and aceticacid. The yellow precipitate was washed with dry ether and dried a t105'. On analysis :0.0694 gave 0.0156 Au.The plcctinichZorride, [C,,H,,NBr],,H,PtC16, was obtained in a similarIt is a yellow powder, which wasThe specimen mas evi-Au= 29-47.C,3H,,N,C18Br,Au, requires AU = 22.46 per cent.way by using platinic chloride.washed with dry ether and dried at 105'.dently not quite pure :0.0603 gave 0.0108 Pt.Pt = 17-91.C,,€€,,N,C16Br,Pt requirea Pt = 17.31 per cent.4. Replacement of the Bromine in Monobromodinaphthacridine byHydrogen.I n order to prove the constitution of monobromodinaphthacridine, itwas necessary to replace the bromine by hydrogen. The reductiontook place readily by the action of an alcoholic solution of stannouschloride on the base partly dissolved and partly suspended in alcohol.Some tin and free hydrochloric acid were added, and the mixturewas boiled for several hours under a reflux condenser, when a greensubstance gradually formed. When cold, the liquid was removed byfiltration, and the green substance was separated mechanically fromthe residual tin. This green substance was boiled with methylatedspirit, in which it was moderately soluble, then treated with potassiumhydroxide, boiled, mixed with water, and the yellow, flocculent pre-cipitate obtained was dissolved in aqueous pyridine. The filteredsolution deposited orange crystals melting a t 243'. They wereidentified as bis-p-N-P -dinaphthacridine dihydride (Senier and Austin,Trans., 1906, 89, 1398), which is known to give a green hydro-chloride,A H aF 68 SPENCER AND STOKES: THE DIRECT INTERACTION OFThe bromodinaphthacridine is evidently therefore a derivative of '-r-' -dinaphthacridine (Reed).a- C Ha5. Interaction of MethyZe?ze Dichloride and 1 -Nitl.o-a-Ina~htl~yZami?ze.When 1-nitro-2-naphthylamine was heated to 210" in a closed tubewith methylene dichloride for one hour, it was found that no reactionhad taken place, for the original substance was recovered unchanged.Another attempt was made by heating the tube to 250-260' fortwo hours, when the contents of the tube were completely charred,although acridines are stable at this temperature.QUEEN'S COLLEGE,G A LW AY