1202 MORGAN : CONTRIBUTION TO THE CXII1.-Contribution to the Chemistry of the Aromatic Metadiamines, By GILBERT THOMAS MORGAN, D.Sc. THE halogen derivatives of m-phenylenediamine and its homologues have hitherto been prepared either by the direct action of the halogen on the base or its acyl derivative (Jackson and Calvert, Amer. Chem. J., 1896, 18, 465)) or by the reduction of aromatic dinitro-compounds containing chlorine or bromine (Nietzki and Rebe, Ber., 1892, 25, 3005). The latter method, however, does not always lead to the formation of a substituted diamine, owing to the fact that the halogen radicles situated in the ortho- or para-positions relatively to the nitro- groups of the dinitro-compounds are readily removed by the action of the reducing agent. 1 -Chloro-2 : 4-dinitrobenzene, when reduced with tin and hydrochloric acid, yields 1-chloro-2 : 4-phenylenediamine (Beilstein and Kurbatoff, Annalen, 1879, 197, 76), whereas the corre- sponding bromo-compound, under these conditions, loses its halogen radicle, and becomes converted into m-phenylenediamine (Zincke and Sintenis, Ber., 1872, 5, 791).Similarly, Jackson and Calvert (Zoc. cit.) showed that 1 : 3 :5-tribromo-2 : 4-dinitrobenzene lost all its bromine when treated with tin and hydrochloric acid, giving rise to m-phenylene- diamine, and also that the halogen is not removed by reduction with zinc and acetic acid.CHEMISTRY OF THE AROMATIC METADIAMINES. 1203 Further investigation shows, however, that l-bromo-2 : 4-dinitrobenz- ene may be reduced, without the elimination of bromine, by the action of iron filings in the presence of a small quantity of hydrochloric acid, the method employed in the commercial preparation of the aromatic diamines.The constitution of the new base, l-bromo-2 : 4-phent~lenediamine, is known from its mode of formation, and also from the fact that, on treatment with nitrous acid in the presence of cuprous bromide, it yields 1 : 2 : 4-tribromobenzene; it is isomeric with the bromo-m- phenylenediamine (m. p. 93-94') obtained by Jackson and Calvert on reducing 1 : 3 : 5 : 6-tetrabromo-2 : 4-dinitrobenzene with tin and hydro- chloric acid, the latter diamine having, in all probability, the symmetrical formula indicated by these investigators. l-Uhloro-2 : 4-phenylenediamine is readily prepared by the iron and hydrochloric acid method of reduction; the corresponding iodo-base could not, however, be obtained from 1-iodo-2 : 4-dinitrobenzene, for, under these conditions, the iodine atom is simultaneously eliminated, and m-phenylenediamine results. Diacetyl-l-chloro-2 : 4-phenylenediamine, when treated with chlorine in glacial acetic acid solution, yields a dichloro-derivative, which, 011 hydrolysis, is converted into 1 : 5-dichloro-2 : 4-phenylenediccrnine ; this base may also be prepared by the direct chlorination of diacetyl-m- phenylenediamine, its constitution being determined by converting i t into 1 : 2 : 4 : 54etrachlorobenzene by means of the Sandmeyer reaction.The researches of Bender (Ber., 1886, 19,2272), Slosson (Ber., 1895, 25, 3265), Chattaway and Orton (Trans, 1899, 75, 1046; this vol., 134, SOO), and others have shown that the acyl derivatives of the primary aromatic monamines, on treatment with hypochlorous or hypo- bromous acid, yield substituted nitrogen chlorides or bromides contain- ing the halogen atom attached to nitrogen, &c., and also that these sub- stances, by intramolecular rearrangement, give rise to the acyl deriva- tives of the corresponding halogen-substituted bases.A similar reaction occurs with the diacyl derivatives of m-phenylene- diamine, each molecule of diacetyl-rn-phen ylenediamine, for example, taking up two atoms of chlorine, and forming m-phenylenediacetzd~ chloranzine ; this dichloride, on digestion with warm glacial acetic acid, is readily transformed into diacetyl-1 : 5-dichloro-2 : 4-phenyZeizediamine, the changes involved in these operations being indicated by the follow- ing diagram : NHAc NClAc NHAc1204 MORGAN : CONTRIBUTION TO THE The reaction with hypobromous acid takes a similar course, and the dibromo-m-phenylenediamine, produced by hydrolysing the diacyldi- bromo-m-phenylenediamine, is found to be identical with the base obtained by Jackson and Calvert by direct bromination.The constitution of the dibromo-base is determined by means of the Sandmeyer reaction ; under this treatment, it yields 1 : 2 : 4 : 5-tetra- bromobenzene, and is therefore 1 : 5-dibromo-3 : 4-phenylenediamine ; this substance may also be prepared from diacetyl-1-bromo-2 : 4- phenylenediamine by direct bromination and subsequent hydrolysis.When diacetyl-2 : 4-tolylenediamine is treated with chlorine in glacial acetic acid, i t yields a monochloro-derivative, which, on hydro- lysis, gives rise to a new chloro-3: 4-tolylenediamine. This base is isomeric with 2-chloro-3 : 5-tolylenediamine obtained by Nietzki and Rebe (Zoc. cit.), and is shown t o be 5-chloro-2 : 4-tolylenediamine, by conversion into the coresponding trichlorotoluene, through the agency of the Sandmeyer reaction. The trichlorotoluene produced melts at 82O, and is identical with 2 : 4 : 5-trichlorotoluene, obtained by the direct chlorination of toluene (Limpricht, Annalen, 1866, 139, 326) ; the constitution of this substance was demonstrated by Seelig, who con- verted it successively into 2 : 4 : 5-trichloro-3 : 6-dinitrotoluene, 2 : 4 : 5- trichloro-3 : 6-tolylenediamine, and trichlorotoluquiuone (Annulen, 1887, 237, 116).EXPERIMENTAL. 1 -B~omo-2 : 4phenylenediamine. An excess of iron filings (70 grams) is slowly added to 40 grams of 1-bromo-2 : 4-dinitrobenzene suspended in 400 C.C. of hot water acidi- fied with 5 c . ~ . of concentrated hydrochloric acid, the mixture being continually shaken during the operation, The dinitro-compound gradually disappears, the solution darkens, and considerable heat is developed, 400 C.C. of cold water being added during the reduction in order to moderate the action. When the odour of the nitro-compound has almost disappeared, the mixture is heated to boiling on the sand- bath, and 10 grams of sodium hydrogen carbonate are introduced ; the solution is then rapidly filtered from the black precipitate of hydrated magnetic oxide and unaltered iron, the latter washed with 100 C.C. of boiling water, and the total filtrate cooled by a mixture of ice and salt. After several hours, the solution deposits brownish-grey, acicular crystals of 1-bromo-2 : 4-phenylenediamine, the yield being about 14-15 grams.The filtrate still contains a considerable amount of the diamine, as may be shown by the formation of a chrysoidine by the action of diazotised aniline. The dissolved base may either be extracted with chloroform or obtained as hydrochloride by evaporating down the acidified solution; the latter method, however, is not to beCHEMISTRY OF THE AROMATIC METADIAMINES. 1205 recommended, as a portion of the substance is destroyed by atmospheric oxidation.A larger yield of the crystalline precipitate cannot be obtained by employing less water in the reduction, for, under these conditions, the reaction becomes so violent that the bromo-base is totally destroyed, and nz-phenylenediamine and ammonia only are produced. 1 -Bromo-Z : 4-phenylenediamine readily dissolves in hot water, but is less soluble in the cold; the base rapidly oxidises when moist, and it is therefore preferable to crystsllise the compound from an anhydrous solvent. It separates from benzene in irregular clusters of colourless, acicular prisms which soon turn pink ; its melting point is 111-112". The base is readily soluble in the ordinary organic solvents, excepting light petroleum, in which it dissolves but sparingly.0.1491 gave 0.1498 AgBr. Br = 42.75. C,H7N2Br requires Br = 42.78 per cent. Dibenxogl-1 -b~omo-2 : 4-phenylenediamine, readily obtained by the Schotten-Baumann reaction, crgstallises from benzene or chloroform in felted, white needles, and melts at 178.5'. 0.2100 gave 0.0964 AgBr. Br = 19.53. 0.3705 ,, 24-1 C.C. moist nitrogen at 22' and 761 mm. N=7*38. C,,H,,N,Br requires Br = 20.25 ; N = 7.27 per cent. Dincetyl-1-6romo-2 : 4-phenylenediumine, prepared by adding 1-bromo- 2 : 4-phenylenediamine to a mixture of equal parts by weight of glacial acetic acid and acetic anhydride, crystallises from chloroform or benzene in white, felted needles and melts a t 197-198'. Thediamine is readilyIacetylated by acetic anhydride without the application of ex- ternal heat; prolonged boiling of the base with the above mixture results in the formation of tarry products.Br = 30-25. 0,1145 gave OoOS19 AgBr. 1-Bromo-2 : 4-phenylenediamine readily reacts with diazonium salts ; with benzenediazonium chloride, it yields bromochrysoidine hydro- chloride, a substance crystallising from dilute hydrochloric acid in greenish-black, anthracitic needles, Potassium bromochrysoidine- sulphonate, obtained by the action of diazobenzenesulphonic acid, crystallises from water in yellowish-brown leaflets with a bronzy reflex. A solution of 6 grams of 1-bromo-2 : 4-phenylenediamine and 5 grams of cuprous bromide in 40 C.C. of concentrated hydrobromic acid and 20 C.C. of water, when treat.ed a t 90' with a 20 per cent. solution of sodium nitrite (2 mols.) and subsequently distilled in steam, yields a distillate containing 1 : 2 : 4-tribromobenzene ; this substance, after CloHllN2Br requires Br = 29.52 per cent.1206 MORGAN : CONTRIBUTION TO THE two crystallisations from alcohol, melts at 42-43', the melting point of the pure tribromo-compound being 44'.1-Chloro-2 : 4-phenylenediamine is readily prepared from the corre- sponding dinitro-compound by the method of reduction described above. The solution produced by reducing the 1-chloro-2 : 4-dinitrobenzene, derived from 100 grams of chlorobenzene, with 260 grams of iron filings, 30 C.C. of hydrochloric acid, and 1500 C.C. of water, yielded, after neutralisation with 35 grams of sodium hydrogen carbonate, 80 grams of crystallised base, whilst a further yield of 20 grams was obtained from the filtrates by extraction with chloroform, Dibenxoyl-1-chloro-2 : 4-phenylenediamine, produced from the chloro- base by the Schotten-Baumann reaction, crystallises from chloroform or benzene in white, felted needles melting at 178'.C1= 10.31. 0*1800 gave 0.0750 AgC1. C,,,H,,N,Cl requires C1= 10.13 per cent. Chlorochrysoidine hydrochloride, prepared by adding a solution of benzenediazonium chloride to a dilute hydrochloric acid solution of 1-chloro-2 : 4-phenylenediamine, crystallises from water in long, fusi- form clusters of greenish-black, a.nthracitic needles. The base C,H,N,*C,H,Cl(NH,), crystallises from benzene in orange leaflets melting at 149'. 0-1489 gave 0.0860 AgCl. 01 = 14.12. 0.2253 ,, 46-1 C.C. moist nitrogen at 20' and 766 mm.N = 22.57. When dyed on cotton mordanted with tannin, it gives a somewhat redder shade of orange than ordinary chrysoidine. Potassium chloro- chrysoidinesulphonate, obtained by the action of diazobenzene- sulphonic acid on I-chloro-2 : 4-phenylenediamine, crystallises from water in orange-brown leaflets having a bronzy reflex. C,,Hl1N,CZ requires C1= 14-40 ; N = 22.81 per cent. 1 : 5-Bichloro-2 : 4-phenylenediarnine. Diacetyl-1-chloro-2 : 4-phenylenediamine, prepared by adding 28 grams of powdered l-chloro-1 : 2-phenylenediamine to a mixture of 15 grams of glacial acetic acid and 50 grams of acetic anhydride, separates from the solution on cooling and, after recrystallisation from water, melts at 242-2439 A current of chlorine passed into a solution of this diacetyl derivative in 2-3 parts of glacial acetic acid produces a precipitate of diacetyl-1 : 5-dichloro-2 : 4-phenylenediamine, this substance being almost insoluble in the solvent.When recrystal- lised from benzene, diacetyl-1 : 5-dichloro-2 : 4-phenylenediamine melts above 260'. 1 : 5-Dichloro-2 : 4-phenylenediamine, C6H,Cl,(NH,)2, is precipitated from a solution of its diacetyl derivative in excess ofCHEMISTRY OF THE AROMATIC METADIAMINES. 1207 sodium hydroxide on prolonged boiling; the hydrolysis may also be effected by the action of hot alcoholic hydrochloric acid. The base crystallises from dilute alcohol in colourless needles, and from benzene in feathery aggregates of acicular prisms ; it darkens slightly on exposure and melts at 136-1379 0.1167 gave 0.1882 AgC1. C1= 40.75.0.1092 ,, 15-6 C.C. moist nitrogen at 22O-and 759 mm. N= 16.16. a6H6N2Cl2 requires C1= 41-13 ; N= 15.82 per cent, Diacetyl-1 : 5-dichloro-2 : 4-phenylenediamine may also be prepared by the direct chlorination of diacetyl-m-phenylenediamine, the latter substance, when dissolved in 3-4 parts by weight OF glacial acetic acid and treated with excess of chlorine (over 2 mols.), yields the dichloro- derivative exclusively ; there is apparently no tendency for the forma- tion of a trichloro-compound. Three grams of the dichloro-base and 3.2 grams of cuprous chloride are dissolved in 35 C.C. of concentrated hydrochloric acid and 10 C.C. of water and treated at 80-90' with 1.6 grams of sodium nitrite dissolved in 16 C.C. of water ; the solution is then heated to boiling for a short time, and subsequently distilled in steam.The solid, yellow product obtained in the 'distillate has an odour of chloranil, and on crystallisation from alcohol yields 1 : 2 : 4 : 5-tetrachlorobenzene; this compound, when purified by sublimation, is obtained in long, colourless needles melting at 137-1 38'. Action of Hypochlwous Acid on Diacetyl-m-phenylenediccmi.lze. Ten grams of diacetyl-rn-phenylenediamine are dissolved in 400 C.C. of boiling water, and the solution rapidly cooled to obtain small crystals ; 30-40 grams of potassium hydrogen carbonate are then added, and the mixture treated with 150 C.C. of a sodium hypochlorite solution containing 30 grams of chlorine per litre. After a short time the precipitate is collected, washed until free from hypochlorite, and dried on porous plates.The product, m-phenylenediucetyZdichloi*amine, C6H4(NC1*CO-CH,),, is readily soluble in benzene or chloroform, and crystallises from its solution, on the addition of light petroleum, in hard, colourless prisms or octahedra. The compound liberates iodine from a solution of potassium iodide, and a quantitative examination showed that it contains 2 atoms of labile chlorine. Weighed portions were dissolved in chloroform, treated with excess of potassium iodide solu- tion, and titrated with standard thiosulphate. 0.1'718 liberated 0.3358 I. C1= 27.42. 0*2110 ,, 0.4129 I. C1=27*45. C,oH,o0,N2C12 requires e l = 27.20 per cent.1208 MORGAN : CONTRIBUTION TO THE m-Phenylenediacetyldichloramine melts at 150-15 1' t o a colourless liquid, which almost immediately decomposes with explosive violence ; when boiled with glacial acetic acid, it is converted into diacetyl-1 : 5- dichloro-2 : 4-phenylenediamine, the latter compound crystallising from the solvent in white, felted needles.The diamine produced through the agency of hypochlorous acid was shown t o be identical with that obtained by chlorination by the direct comparison of the two specimens and their benzoyl derivatives ; moreover, i t yields 1 : 2 : 4 : 5-tetra- chlorobenzene when submitted to the Sandmeyer reaction. Dibenxoyl- 1 : 5-dichloro-2 : 4-phenylenediamine, prepared as a means of identifying the dichloro-base, crystallises from benzene or chloroform in white, felted needles which darken on exposure t o light, and melt at 187'.0.1128 gave 0.083 AgC1. C1= 18.20. C,,H,,N,Cl, requires C1= 18.44 per cent. When finely divided dibenzoyl-m-phenylenediamine is suspended in a saturated solution of potassium hydrogen carbonate and treated with excess of sodium hypochlorite, it yields a dichloramine correspond- ing with m-phenylenediacetyldichloramine ; it is, however, less stable than this compound, and readily passes into dibenzoyl-1 : 5-dichloro- 2 : 4-phenylenediamine (m. p. 187') on boiling with chloroform or benzene. Bromination, of Diacetyl-1-brorno-2 : 4-phenylenediamine. Ten grams of diacetyl-1-bromo-2 : 4-phenylenediamine, dissolved in two parts by weight of glacial acetic acid, are treated with 1 inol. of bromine diluted with two parts by weight of the same solvent; the product, added to water containing a little sulphurous acid, yields a brown precipitate which is hydrolysed with 30 C.C.of concentrated hydrochloric acid. The base, obtained on neutralising the acid solu- tion, crystallises from alcohol in needles and melts a t 135'; it appears t o be identical with the dibromo-2 : 4-phenylenediamine prepared by Jackson and Calvert by the direct bromination of diacetyl-m-phenylene- diamine (Amer. Chem. J., 1896, 18, 483). This diamine, when submitted t o the Sandmeyer reaction in the presence of cuprous bromide, yields a tetrabromobenzene, which, after sublimation and recrystallisation from alcohol, melts at 174' and does not depress the melting point of the 1 : 2 : 4 : 5-tetrabromobenzene prepared by the direct bromination of p-dibromobenzene ; accordingly, the base is 1 : 5-dibromo-2 : 4-phenylenediamine.CHEMISTRY OF THE AROMATIC METADlAMINES. 1209 Action of Hypohromous Acid on Diacetyl-rn-phenylene~i~m~n~. The finely divided diacetyl-m-phenylenediamine is suspended in a cold, saturated solution of potassium hydrogen carbonate and treated with excess of potassium h ypobromite solution ; the insoluble product has a yellow colour when fiist collected, but becomes almost colourless on drying.This substance still gives the substituted bromamine reaction with potassium iodide, but seems to consist principally of the transformed diacetyldibromo-m-phenylenediamine. A portion crystal- lised from chloroform melts at 259-260°, this being the melting point of diacetyl-1 : 5-dibromo-2 : 4-phenylenediamine ; the melting point of the diamine, obtained on hydrolysis, is 1 3 3 O , whilst that of pure 1 : 5-dibromo-2 : 4-phenylenediamine is 135'.5-Chloro-2 : 4-tolylenediamine. A solution of diacetyl-2 : 4-tolylenediamine (m. p. 221') in 3% parts by weight of glacial acetic acid, when treated with 1 mol. of chlorine and subsequently diluted with water, yields a brownish-white, crystalline precipitate of diacetyl-5-chloro-2 : 4-tolylenediamine. The corresponding diamine, obtained by hydrolysing the preceding com- pound with alcoholic hydrochloric acid and neutralising the hydro- chloride solution with ammonia, crystallises from water in colourless, nacreous leaflets which turn pink on exposure t o the air. When crystallised from benzene, the base separates either in long, colourless, elastic lamells or in thin, rectangular plates ; it melts a t 12O-12lc.0.1328 gave 0.1226 AgC1. C1= 22.82. 0.2185 ,, 34.2 C.C. moist nitrogen a t 18' and 758 mm. N = 18.03. The diacetyl derivative crystallises in small, acicular prisms melting at 239-240'. Three grams of sodium nitrite, dissolved in 30 C.C. of water, are slowly added to a hot solution of 4 grams of 5-chloro-2 : 4-tolylene- diamine and 4 grams of cuprous chloride in 30 C.C. of concentrated hydrochloric acid and 10 C.C. of water ; the mixture is maintained a t 80-90' until the evolution of nitrogen has ceased, and subsequently distilled in steam. The volatile product, consisting of 1.5 grams of crude trichlorotoluene, is purified by sublimation and recrystallisation from alcohol ; it crystallises in colourless, flattened needles and melts at 81-5', the melting point of Limpricht's 2 : 4 : 5-trichlorotoluene being 82'. 1 : 5-Dichloro-2 : 4-phenylenediamine, its bromine analogue, and C7H,N,C1 requires C1= 22.68 ; N = 17.89 per cent.1210 MORGAN: ACTION OF AROMATIC ALDEHYDES ON 6-chloro-2 : 4-tolylenediamine all contain substituent radicles in both the para-ortho-positions relatively to the amino-groups, and they react less readily with diazonium salts than the mono-substituted m-phenylenedismines ; they do, however, combine with certain diazo- compounds such as diazobenzenesulphonic acid, and hence the azo- residue must enter the ortho-position contiguous t o the two amino- radicles. A study of these azo-compounds will form the subject of a subsequent communication. ROYAL COLLEGE OF SCIENCE, LONDON, SOUTH KENSINGTON, S. W.