412 SMITH AND DAVIS ON THE LXIV.-An Additional Evidence by Analysis of the Qwholirze Hole-c d e that this Base belongs to the Aromatic Series of Organic Subs f ances. By WATSON SMITH and G. W. DAVIS. MERZ in conjunction with Ruoff Moe Zetter (Innug. Disserts.) and other pupils of his showed that on exhaustive perchlorination all iiiembers of the aromatic series break up so as to yield perchloroben-zene unaccompanied or accompanied with perchlorinated paraffin groups according to circumstances. An exception occurs in the case of diphenyl which forms perchlorodiphenyl and this body refused to disintegrate on further chlorination. The formation of perchloro-diphenyl was found to be of very rare occurrence. Of course in many cases the formation and separation of perchlorobenzene made it pos-sible to predict what the perchlorinated members of the paraffin group formed at the same time in the general disintegration of the aromatic molecule must be.Thus light was obtained and thrown upon the constitution of several aromatic compounds besides which a remarkable confirmation of the truth lying at the root benzene-ring hypothesis was obtained. I f quinoline has the constitution now generally assigned CH CH of Kekul6's to it-(and this has been made clear to a considerable extent by the several rasearches of Dewar Baeyer Konigs and Skraup) then by an exhaustive perchlorination according to the method of V. Merz it might be expected that in the disintegration following that portion o ,4ROMATIC SERIES OF ORGANIC SUBSTANCES. 413 the compound nucleus containing nitrogen would prove least stable as being most complex and would consequently give way yielding per-chlorethane perchloromethane and nitrogen whilst the other portion would yield perchlorohenzene.It will now be interesting to examine what the actual experience of Xerz and Ruoff was in their perchlorination of naphthalene. They found that on repeated treatment in sealed tubes with antimony penta-chloride at gradually increased temperatures finally at 350" to about 400" C. naphthalene first changes to perchlornaphthalene becomes disintegrated gradually and yields perchlorobenzene perchlorethane, and perchlormethane, This reaction as regards the appearance both of perchlor-methane and -ethane is better interpreted by assuming as Graebe proposes the presence in the naphthalene molecule of the group (CJ&)" which becomes spIit off from the chlorinatsd benzene-ring as the first step of disintegration and by the action of the chlorine is converted into per-chlorbutane which then immgdiately after its formation (as Krafft and Merz (Ber.1875 1300) have actually shown in the case of per-chlorbutane) at the high temperature is first broken up into perchlor-propane and perchlormethane and the former later on into perchlor-ethane and perchlormethane thus :-cl()c1 + 4C12 = CljCI + c&cl,,. c,c1, + c12 = C3C1 -I- CCI, C3CIs + c12 = C,c& + ccl& In our experiments then we might expect to realise the following, possibly :-C,CI,?? t 7c1 = cljc16 c3CIs N. C3C18 + c1 = c,c1 + CClJ.Perchlornaphthalene has of course been. prepared and studied by Berthelot and Jungfleisch (Ann. Chim. Phys. [4] 15 331) ; perchlor-quinoline has so far as we are aware not been prepared as yet. We took 1.7' grams of chemically pure quinoline and placed it in a strong tube of hard glass together with ten times its weight of anti-mony pentachloride slowly and cautiously added. The tube was well sealed up and heated to 170" then to 280" to 320° and finally to 400" about each for a space of five hours leaving the contents to cool and 2 K 414 SMITE AND DAVIS ON THE AROMATIC SERIES ETC. opening the tube after each heating to allow hydrochloric acid gas and nitrogen t o escape. Dry chlorine gas was then passed into the brown mass for about 20 minutes and the tube after re-sealing was again heated at the above intervals as before.The chlorinating and heating were repeated till on opening the tube no more hydrogen chloride was evolved. The contents of the tube were now quite black from separation of carbon but the m8ss was also crysta,lline. This black mass was now washed out with strong hydrochloric acid into a beaker and washed by decantation several times with strong hydro-chloric acid and afterwards with a strong tartaric acid solution till a portion of the filtrate from the mass gave no longer a precipitate of antimony snlphide with H,S. The residue dried and a portion sub-mitted to sublimation yielded vapours haring the characteristic camphor-like odour of perchlorethane which condensed to small white needles having a melting point of 210".Now the melting point of perchlorethane is 193" hence probably this first crop was contaminated with some perchlorbenzene which melts at 2.20-223". This crop first obtained was submitted to a careful re-sublimation when a melting point in the crop now obtained was exactly 182" the correct melting point of perchlorethane. After the perchlorethane was all sublimed and expelled from the black mass the iemperature was further raised, when after some time long white needle-shaped crystals formed them-selves on the surface of the dark mass in the sublimation apparatus. A quantity of these needles was carefully collected and it was ob-served on heating a portion of them that the vapour possessed only an extremely faint odour unlike that of the perchlorethane ; in fact the vapour might be described as odourless.The melting point of these crystals ww 223" which is the cc3rrect melting point of per-chlorobenzene. Quinoline is a substance which is exhaustively perchlorinated with the greatest difficulty and in future experiments we should recom-mend a 10-hours' heating at each successive temperature already mentioned. The opening of the sealed tubes is by no means unat-tended with danger and for the sake of safety we should recommend that after heaking and leaving it to cool the tube should be opened by just allowing the drawn-out point to project from the oven and then t o let the flame of a lamp play upon it. No perclilormethane could be detected and this was probably owing to the volatilityof the substance by virtue of which it would be carried off in the violent rushes of gas ensuing on opening the tube from time to time.The danger of the operation of opening the tube illdeed prevented any observations of the nature of gaseous bodies galerated during the proceps from being made. It may now just be pointed out how our experience just describe NEVILE AND WlNTHER ON ORCaTOL ETC. 415 coincides with that of Dewar who in 1877 obtained quinoIinic acid (this Journal 1881 p. 1044) (C6H4(NH2) .CH,.CO.COOH) by the oxidation of quinoline this acid on distilling with soda-lime yielding aniline (C6&,.NH2). Dewar thus by an oxidation process obtains analytically proof of the aromatic nature of quinoline actually getting the benzene-nucleus with the still adherent nitrogen now in the form of an amido-group. We have succeeded in obtaining analytically by a chlorination process the perchlorinated benzene-nucleus (c,c16), together with half the remainder of the residue containing the nitro-gen-atom also as a perchlorinated group vie as perchlorethane (c2c16) I I Writing quinoline as CGH1.N C2H2 CIE we have obtained by ch1or.i-- + + nation the following groups . . . . . . . -. . C$16 as perchlorinated products - whereas-Dewar obtained . . C6H5.NH2 (aniline) as the result of an oxidation process followed by a distillation of the product with soda-lime. CzC1