1376 MORGAN: INFLUENCE OF SUBSTITUTION ON THE CXXXVIII.-Injuence ofXubstitution on the Formation of Diuxoamines und A minoaxo-compounds. By GILBERT THOMAS MORGAN, D.Sc. THE results recorded in a former communication (this vol., 91) showed that 1 -chloro-j3-naphthylamine, unlike the parent base, P-naphthyl- amine, gives rise to diazoamines when treated with diazonium salts. P-Naphthylamine-8-sulphonic acid behaves similarly (Witt, Ber., 1888, 21, 3483), and it may therefore be generally supposed that the presence of a substituent radicle in either of the positions 1 and 8 of the naphthalene nucleus causes the diazo-complex to remain attached to the aminic nitrogen atom situated in position 2. It has been shown more recently by C. Smith (this vol., 901) that a similar effect is produced by hydrogenising the unsubstituted naphtha- lene nucleus, this investigator having demonstrated that ar-tetrahydro- P-naphthylamine does not, as' was formerly supposed, condense with diazonium salts to form aminoazo-compounds, but under these con- ditions furnishes diazoamines.The products of the action of diazotised m-nitroaniline and m-chloro- aniline on the tetrahydro-base could not, however, be isolated, as they are unstable a t the ordinary temperature and rapidly change into resinous subs tames. m-Nitrobenxene-2-diaxoumino-1-chZoronu~?~t?~aZene, obtained by the action of m-nitrobenzenediazonium chloride on I-chloro-P-naphthyl- amine is, on the contrary, quite stable at the ordinary femperature, Part 11-FORMATION OF DIAZOAMINES AND AMINOAZO-COMPOUNDS. 1377 and is readily obtained in a crystalline form.Nevertheless, it shows itself to be less stable than its 0- and pisomerides by decomposing at a temperature nearly 70° lower than the decomposition point of these substances. o~Niti~obenxene-2-dia~~c~~~no-l-chlo~~onaph~haZene closely resembles the p-isomeride already described (this vol., '99), and is prepared in a similar manner. An attempt made to prepare a similarly constituted mixed diazo- amine from diazotised I-nitro-P-naphthylamine led t o a curious and unexpected result. The solution obtained by treating 1 -nitro-P-naphthylamine suspended in hydrochloric acid with sodium nitrite, when mixed with a glacial acetic acid solution of 1-chloro-P-naphthylamine, gave rise t o a diazo- amine which proved to be 2-diazoamino-l-chloronaphthalene, C1,H6C1*N,*NH*C,,H,C1, the yield of this product being such that it could not possibly be derived entirely from the chloro-base actually intro- duced.All the mother liquors obtained in the experiment were examined, but no trace of the nitro-base or its diazonium salt could be found. The aqueous filtrate from the diazoamine still contained a diazonium salt, and was accordingly added t o an alkaline solution of P-naphthol ; the azo-compound thus produced consisted entirely of 1 -chloronaph thalene-2-axo-P-naphthol. The alcoholic washings from the crude diazoamine were evaporated and the oily residue acetylated, the product being identified as l-chloro- aceto-P-naphthalide, . As a result of this examination, it was found that, although the total yield OF the products accounts for the united weights of the two bases employed, yet the substances formed during the reaction are wholly derived from 1-chloro-P-naphthylamine.This result admits of only one interpretation, namely, that under the above conditions the diazonium salt of the nitro-base becomes transformed into the corresponding derivative of the chloro-base, NO,* Cl,H,*N,Cl -+ C,,H6C1*N,~N0,. This rearrangement corresponds with the observations of Meldola and Eyre (Trans., 1901, 80, 1077, and this vol., 988) as to the behaviour of the diazotised dinitroanisidines ; these substances lose nitro-groups occupying the ortho- or para-position with respect to the diazonium radicle in exchange for hydroxyl or chlorine. Moreover, the replace- ment of substituent radicles by hydroxyl has already been observed in diazo-derivatives of the naphthalene series (Gaess and Ammelburg, Bey., 1894, 2'7, 2211 ; Meldola and Streatfeild, Trans., 1895,67, 909).When the diazo-solution, obtained by adding sodium nitrite to 1-nitro-P-naphthylamine suspended in alcoholic hydrochloric acid, is a t once added to an alkaline solution of @-naphthol, the precipitate pro- duced consist,s of a mixture of l-chloronaphthalene-2-azo-~-naphthol1378 MORGAN: INFLUENCE OF SUBSTITUTION ON THE with the corresponding nitroazo-compound. This result indicates that the transformation requires an appreciable interval of time for its completion, This reaction will be made a subject for further research. Concurrently with the above investigation, the study of the action of diazonium salts on the disubstituted m-diamines has been carried on in conjunction with Mr.G. M, Norman. The action of diazonium salts on diamines of the types I, II, and IV, Y X Y has already been investigated, the results indicating that the bases of the series I and I1 form axo-derivatives in practically theoretical amounts, whereas the symmetrically constituted diamines, IV, give rise t o azo-compounds far less readily, the yields being comparatively small. This difference is attributable to the fact that, in the first two series, the diazo-complex can enter a para-position with respect t o amidogen, whereas in series IV only an ortho-position is available. The diamines corresponding with formula I11 actually contain two reactive para-positions, and i t might be supposed that these bases would yield azo-derivatives with great facility.Experiments were ac- cordingly instituted with the view of placing on record the production of azo-compounds from 2 : 6-diamino-p-xylene and 2 : 5-dichloro-m-phenyl- enediamine. In the case of the former base, our investigations were anticipated by Noelting and Thesmar ( B e y , 1002, 35, 628), who described the azo- compound, benzene-3-azo-2 : 6-diamino-p-xylene, obtained from this di- amine by the action of benzenediazonium chloride. 2 : 5-Dichloro-m-p~enylenediccmine is obtained by the reduction of the corresponding dinitro-p-dichlorobenzene, a substance produced by the direct nitration of p-dichloro ben zene. The nitration product consists chiefly, however, of the isomeric 2 : 5-dinitro-1 : 4-dichlorobenzene, the required 2 : 6-dinitro-1 : 4-dichloro- benzene being only a bye-product.This result is of interest, because it affords another illustration of the fact that as substitution progresses the rules governing the orient- ation of the entrant radicles become considerably modified. ForFORMATION OF DIAZOAMINES AND AMINOAZO-COMPOUNDS. 1379 example, the nitration of nitrobenzene or any benzenoid mononitro- compound containing only one other substituent leads to the formation of a metadinitro-compound as the chief product, this result being in accordance with the ‘( meta ” law of substitution. When, however, the molecule already contains two other substituent radicles in addition to the nitro-group, this law seems to be partially abrogated in favour of a tendency leading to the production of the di-para-compound. Thus, nitro-p-dichlorobenzene undergoes further nitration in accordance with the following scheme : c1 The mixture of diamines, obtained by reducing the crude nitration product, is fractionally crystallised from water, the chief constituent, 2 : 5-dichloro-p-phenylenediamine, being almost insoluble in this medium, whilst the isomeric base, 2 : 5-dichloro-m-phenylenediamine, readily dis- solves in the hot solvent.The latter base is shown to be a meta-diamine by giving, with acetic anhydride, a diacetyl derivative, whereas an ortho-diamine would furnish an anhy dro-base ; moreover, it readily yields azo-compounds and does not condense with phenant hraquinone to form an azine.The action of diazo-compounds on the isomeric 4 : 6-dichloro-rn-phenyl- enediamine has already been investigated (this vol., 97), but an azo-compound, produced by condensation with a simple diazonium salt, has not hitherto been isolated. Combination has now been effected by operating with p-nitrobenzenediazonium chloride in alcoholic solution. Under these conditions, p-nitrobenxene-2-axo-4 : 6-dichlo~o-m-phenylene- diarnine is produced; the yield of azo-compound, however, is not quan- titative, but comparable in amount with that obtained from other disubstituted m-diamines of the series IT. There can be little doubt that the property of forming o-azo-com- pounds is common to all aromatic primary m-diamines having the general formula IV, although experiments made on tetramethyl-4 : 6- diamino-m-xylene tend t o show that this capacity for condensation with diazo-compounds is lost when the bases are completely alkylated (this vol., i, 656). The tendency for the diazo-radicle t o enter the ortho-position with1380 MORGAN: INFLUENCE OF SUBSTITUTION ON THE respect t o the aminic nitrogen atoms may manifest itself even when one of the reactive para-positions is unsubstituted. Noelting and Thesmar (Zoc.cit.) have shown that this occurs when benzenediazonium chloride interacts with 3 : 5-diamino-o-xylene, the product consisting of a mixture of benzene-6-azo-3 : 5-diamino-o-xylene and the o-azo-deriv- ative, benzene-4-azo-3 : 5-diamino-o-xylene. An attempt was made to prepare a disazo-compound of tolylene- 2 : 4-diamine containing one of the azo-complexes in the position con- tiguous to the two aminic nitrogen atoms by treating p-bromobenxene- 5-axotolyleme-2 : 4-diamine with p-nitro benzenediazonium chloride i n alcoholic solution ; the experiment, however, was unsuccessful, the products being ill-defined and tarry.EXPERIMENTAL. I. Diaxoarnines from 1-Ch Zoi.o-P-nccphthyZamine. 0- Nttrobenxene-2-diaxoamino- 1 -chloronaphthalene, NO, C,H,N,*NH*CloH,Cl, prepared by slowly adding a glacial acetic acid solution of l-chloro-/3- naphthylamine to a cold dilute hydrochloric "acid solution of o-nitro- benzenediazonium chloride, separates immediately as a light yellow precipitate, even without the addition of sodium acetate, When crys- tallised from benzene, it forms pale yellow leaflets sparingly soluble i n alcohol but dissolving readily in the solvent in the presence of sodium hydroxide to a deep purple solution of its sodium derivative.The diazoamine, when slowly heated, decomposes a t 194', but when more rapidly heated i t remains unchanged below 202-204' : 0.2140 gave 31.3 C.C. moist nitrogen a t 20° and 765 mm. N = 16.84. 0.1564 ,, 0,0682 AgC1. C1= 10.78. 0.1493 ,, 0.0642 AgCI. 01 = 10.64. CI,HI,0,N4C1 requires N = 17.15 ; C1= 10.87 per cent. m-Nit~~benxene-2-diaxoarnino-l-cklorona~~tkalene, produced in pre- cisely the same manner as i t s isomeride, separates from benzene in transparent, yellowish-brown, prismatic crystals, which, when suddenly heated, decompose at 142O, this decomposition taking place at 137' if the temperature is raised very slowly.It should be pointed out that the decomposition temperatures of the diazoamines derived from 1-chloro-P-naphthylamine vary within very wide limits and appear to be considerably influenced by the size of the crystals, the rate of heating, the quantity of the material employed in the determination, and the amount of agitation to which the substance is subjected.FORMATION OF DIAZOAMINES AND AMINOAZO-COMPOUNDS. 1381 The diazoamine is sparingly soluble in alcohol, but dissolves in alcoholic sodium hydroxide to a dark brownish-red solution : 0.2280 gave 33 C.C. moist nitrogen a t 19' and 765 mm. 0.1207 ,, 0.0546 AgC1. C1= 11.19. 0*1726 ,, 0,0773 Ag3l. GI= 11.08. N = 16.80. C,6H110,N,Cl requires N = 17.15 ; C1= 10.87 per cent. Action of Nitrous Acid on 1 -Nitro-P-nap~thyZamine.The solution obtained by adding the calculated amount of sodium nitrite to 3.2 grams of 1 -nitro-P-naphthylamine suspended in alcoholic hydrochloric acid was treated with 3.5 grams of l-chloro-P-naphthyl- amine dissolved in glacial acetic acid; the mixture assumed a dark orange colour and a yellowish-brown precipitate rapidly separated. Water was added to complete the separation of the insoluble product ; the latter was collected, dried, and extracted with small quantities of warm alcohol in order to remove any uncombined bases, the residue being then crystallised from benzene. The crystalline product con- sisted of 2-diazoamino-1-chloronaphthalene, which separated in orange- yellow needles decomposing at temperatures varying from 145-1 59' according to the rate of heating : 0.1708 gave 17 C.C. moist nitrogen at 19' and 768 mm.0.1154 ,, 0.0862 AgC1. C1= 18.47. The final benzene mother liquors gave a further crop of crystals of 0.0916 gave 9.5 C.C. moist nitrogen at 1 8 O and 758 mm. N = 11.94. Hence the only diazoamine produced in the above condensation is due to the interaction of a 1-chloronaphthalene-2-diazonium salt on 1-chloro-P-naphthylamine. The oily residue, obtained by evaporating the alcoholic extract to dryness, became solid on treatment with acetic anhydride, and the product, when crystallised from hot water containing animal charcoal, separated in felted, white, silky needles melting at 148O, the melting point of 1-chloroaceto-P-naphthalide being 147'.The aqueous filtrate from the crude diazoamine was poured into a cold alkaline solution of P-naphthol, the resulting azo-derivative being crystallised from ethyl acetate. After one crystallisation from this solvent, the azo-compound, l-chloronaphthalene-2-a~o-~-~ap~t~oZ, was obtained in a state of purity : N = 8-43, N= 11.52. C,,Hl,N,C12 requires N = 11.47 ; C1= 19 -39 per cent. this compound, identified by the following analysis : The yield of the product is 5 grams. 0.1472 gave 10.7 C.C. moist nitrogen at 1 8 O and 763 mm. 0.0963 ,, 0.0410 AgC1. C1= 10.67. VOL. LXXXI 4 2 C,,H,,ON,Cl requires N = 8.42 ; C1= 10.67 per cent.1382 MORGAN : INFLUENCE OF SUBSTITUTION ON THE This compound crystallises in dark red prisms having a brilliant bronzy reflex; i t melts a t 2 3 4 O , is sparingly soluble in alcohol, but dissolves more easily in benzene ; with concentrated sulphuric acid, it develops a beautiful bluish-purpl e colorat ion.The quantities of 1-chloroaceto-P-naph t halide and azo- derivative obtained in the preceding operations amounted to 1 gram and 2 grams respectively, and together with the weight of the diazoamine accounted for practically the whole of the two bases employed in the experiment. The diazo-solution, obtained by adding sodium nitrite to 1-nitro-@ naphthylamine suspended in alcoholic hydrochloric acid, when immediately added t o an alkaline solution of P-naphthol furnished a mixture of azo-compounds giving the following numbers on analysis : 0.1 180 gave 10.4 C.C. moist nitrogen at 18' and 758 mm.N = 10.16. 0.1105 ,, 0.0303 AgCl. C1= 6.78. These results correspond with the composition of a mixture of 60 per cent. of the chloroazo-compound, CloH,Cl*N,*CloHG*OH, with 40 per cent. of the nitroazo-derivative, NO,*C,oH,*N,*C,oH,'OH, derived from the untransformed 1-nitronaphthalene-2-diazonium salt, 11. Action of Diuxonium X n l t s on Dichloro-m-phenylens- diaminss. [With GEORGE M. NORMAN, B.Sc.1 Preparation of 2 : 5-DicTiEoro-rn~~~en~/Ienedia~ine. p-Dichlorobenzene is readily converted into nitro-p-dichlorobenzene on nitration with 1.5 parts of a mixture containing two parts of nitric acid of sp. gr. 1-54 and three parts of concentrated sulphuric acid. After mixing the reagents together at the ordinary temperature, the reaction is finished on the water-bath.The introduction of the second nitro-group is far less readily effected, and even after repeatedly treating nitro-p-dichlorobenzene with a mix- ture of fuming nitric and sulphuric acids on the water-bath the pro- duct consisted almost entirely of the unaltered mononitro-compound. The nitration was, however, accomplished a t 110- 115* by the action of excess of fuming nitric acid mixed with sulphuric acid containing 10-15 per cent. of sulphur trioxide. The crude nitration product was reduced in quantities of 50 grams with 65 grams of iron filings, 6 C.C. of hydrochloric acid and 400 C.C. of water, the operation being completed on the water-bath. The product mas rendered alkaline with sodium hydrogen carbonate and filtered while hot, the precipitate of iron oxide being washed with boiling alcohol.The aqueous filtrates on cooling yielded a crystalline base melting at 83-85' ; this substance, after repeated crystallisation from water, finally melted at 99-100'. In each crystallisation, careFORMATION OF DIAZOAMINES AND AMINOAZO-COMPOUNDS, 1383 was taken t o employ an amount of solvent insufficient to dissolve the whole of the material. The insoluble residue accumulated in this manner melted a t 162-163', being thus identified as p-dichloro-p- phenylenediamine, the melting point of which is given as 164'. The residue obtained on evaporating down the alcoholic extracts consisted principally of the p-diamine. The isomeric base, 2 : 5-dichloro-m-phenylenediamine, melting at 99-1 OOO, crystallises from water in long, colourless, silky needles which become faintly pink on prolonged exposure to the atmosphere : N= 15.85.0,1246 gave 17.4 C.C. moist nitrogen a t 19'and 751 mm. 0.1309 ,, 0,2136 AgCI. Cl=40*36. C,H,N2C12 requires N = 15.82 ; C1= 40.11 per cent. Diacetyl-2 : 5 -&A Zoro-m-phen ylenediamine, C,H2CI 2( NH Ac),, obtained by warming the base with excess of acetic anhydride, separates from alcohol in minute, white needles melting above 260' : 0.0738 gave 0.0803 AgC1. C1= 26.91. C,oHlo02N2CI, requires C1= 27.20 per cent. The benxoyl derivative, prepared by the Schotten-Baumann process, crystallises from ethyl acetate in felted acicular prisms melting a t 220' : 0*0488 gave 0.0374 AgC1. C1= 18-96. C,,Hl,02N2C12 requires C1= 18-44 per cent. p-Nitro6e~xe~eLe-4-~xo-2 : 5-~icliZoro-m-phesiy~~ned~a~~ne, N02*C6H,'N2* C6HC12( NH,),, results from the action of p-nitrobenzenediazonium chloride dissolved in dilute hydrochloric acid on an aqueous solution of 2 : 5-dichloro-m- phenylenediamine containing excess of sodium acetate ; the yield of azo compound is satisfactory, the reaction taking place without appreciable evolution of nitrogen.The product did not crystallise readily from the ordinary solvents, and on this account, and also because of the small amount of material available, it was not obtained in a pure con- dition. It separates from benzene in dark brown, nodular aggregates : N = 20.26. 0*2158 gave 37.7 C.C. moist nitrogen a t 18Oand 763 mm. 0.1454 ,, 0.1388 AgC1. 471-23.61 C12Ho02N5C12 requires N = 21 -47 ; C1= 21.80 per cent.The high percentage of chlorine is probably due t o the presence of a certain amount of the hydrochloride of the azo-compound which re- sisted the action of sodium acetate. The substance melts indefinitely a t 210-230O and develops a deep purple coloration with concentrated sulphuric acid,1384 FORMATION OF DIAZOAMINES AND AMINOAZO-COMPOUNDS. p-~~trobenzene-2-~~0-4 : 6-dichloro-m-phenylenediami~e is iaomeric with the preceding compound and results from the action of a dilute hydro- chloric acid solution of p-nitrobenzenediazonium chloride on an alcoholic solution OF 4 : 6-dichloro-m-phsnylenediamine, these reagents being present in molecular proportion ; it separates as a dark red precipitate and crystallises from ethyl acetate in beautiful dark red needles melt- ing at 258'.The yield of this azo-compound is about 45 per cent. of the theoretical : 0.1454 gave 26.2 C.C. moist nitrogen at 20° and 769 mm. N = 20.90. 0,1314 ,, 0.1148 AgCl. Cl=21*61. C12H,02N5C12 requires N = 21.47 ; Cl = 21.80 per cent. U,H,Br*N2*C6H2(NH2)2*CH,, produced by adding excess of ammonia to a dilute hydrochloric acid solution containing equivalent amounts of p-bromodiazonium chloride and tolylene-2 : 4-diamine, separates as a yellow, ochreous precipitate, and is purified by crystallisation from benzene ; it separates from this solvent in golden-yellow leaflets, and from ethyl acetate or alcohol in reddish-yellow flakes with a golden lustre, the melting point being 0.2055 gave 32.9 C.C. moist nitrogen at 20' and 757 mm. N= 18-22. 0,1571 ,) 0.0988 AgBr. Br=26.70. C13H13N4Br requires N = 18.36 ; Br = 26.23 per cent. If sodium acetate is employed instead of ammonia in the preparation of this azodiamine, a stable, red hydrochloride is precipitated which is not decomposed by excess of the acetate. The yield of the azo- derivative is practically quantitative. p-Bromobe~xene-5-aeoto Zy Zene-2 : 4-dimmim) 1'79-18O0 : p-Bromobenxene-5-ccxo-2 : 4-dimetyltolylene-2 : 4-diamine, C,H,Br N,*C6H2Me(NHAc),, produced by gently warming the azodiamine with a mixture of acetic anhydride and glacial acetic acid, crystallises from alcohol in reddish- yellow leaflets and melts at 228O : 0.2066 gave 26.4 C.C. moist nitrogen at 1 8 O and 750 mm. N = 14.56. C17H,702N,Br requires N = 14-40 per cent. The dibenxoyl derivative, prepared by the Schotten-Baumann process, separates from alcohol in small, ill-defined crystals melting above 250'. ROYAL COLLEGE OF SCIENCE, LONDON. SOUTH EENSINBTON, S. W.