I. 0.2352 gave 0·4422 CO2 and 0·0842 H2O. C=51·23; H=3·99. II. 0.1355 0.2542 CO2 0-0485 H2O. C-51.16; H-3-97. III. 0.3070 12.7 c.c. nitrogen at 21° and 758 mm. N = 4.81. C12HON requires C=51·24; H=3·91; N=4.98 per cent.

11

Specimen I was obtained by reduction with tin and hydrochloric acid; II and III by reduction with sodium hydroxide and aluminium. The ethyl ester melted with decomposition at 235-236° (uncorr.), and was analysed with the following results:

C=53·84; H=4·77.
C=53·29; H=4·65.

I. 0.2330 gave 0·4600 CO, and 0·1002 H2O. II. 0.1589 0.3105 CO2 0.0665 H2O. III. 0.2583 10.3 c.c. nitrogen at 16° and 748 mm. N=4·57. C14H15ON requires C=54.36; H=4·85; N=4·53 per cent.

Specimen I was obtained by reduction with tin and hydrochloric acid; II and III by reduction with sodium hydroxide and aluminium. UNIVERSITY CHEMICAL LABORATORY,

CAMBRIDGE.

CXIII. 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 nitrogroups 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 (loc. 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-phenylenediamine, and also that the halogen is not removed by reduction with zinc and acetic acid.

Further investigation shows, however, that 1-bromo-2 : 4-dinitrobenzene 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, 1-bromo-2: 4-phenylenediamine, 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-mphenylenediamine (m. p. 93-94°) obtained by Jackson and Calvert on reducing 1:3:5: 6-tetrabromo-2: 4-dinitrobenzene with tin and hydrochloric acid, the latter diamine having, in all probability, the symmetrical formula indicated by these investigators.

1-Chloro-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-1-chloro-2 : 4-phenylenediamine, when treated with chlorine in glacial acetic acid solution, yields a dichloro-derivative, which, on hydrolysis, is converted into 1:5-dichloro-2: 4-phenylenediamine; this base may also be prepared by the direct chlorination of diacetyl-mphenylenediamine, its constitution being determined by converting it into 1:24:5-tetrachlorobenzene 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, 800), and others have shown that the acyl derivatives of the primary aromatic monamines, on treatment with hypochlorous or hypobromous acid, yield substituted nitrogen chlorides or bromides containing the halogen atom attached to nitrogen, &c., and also that these substances, by intramolecular rearrangement, give rise to the acyl derivatives of the corresponding halogen-substituted bases.

A similar reaction occurs with the diacyl derivatives of m-phenylenediamine, each molecule of diacetyl-m-phenylenediamine, for example, taking up two atoms of chlorine, and forming m-phenylenediacetyldichloramine; this dichloride, on digestion with warm glacial acetic acid, is readily transformed into diacetyl-1 : 5-dichloro-2 : 4-phenylenediamine, the changes involved in these operations being indicated by the following diagram :

The reaction with hypobromous acid takes a similar course, and the dibromo-m-phenylenediamine, produced by hydrolysing the diacyldibromo-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-tetrabromobenzene, and is therefore 1: 5-dibromo-2: 4-phenylenediamine; this substance may also be prepared from diacetyl-1-bromo-2:4phenylenediamine by direct bromination and subsequent hydrolysis. When diacetyl-2 : 4-tolylenediamine is treated with chlorine in glacial acetic acid, it yields a monochloro-derivative, which, on hydrolysis, gives rise to a new chloro-2 : 4-tolylenediamine. This base is isomeric with 2-chloro-3: 5-tolylenediamine obtained by Nietzki and Rebe (loc. cit.), and is shown to be 5-chloro-2: 4-tolylenediamine, by conversion into the coresponding trichlorotoluene, through the agency of the Sandmeyer reaction. The trichlorotoluene produced melts at 82°, 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 converted it successively into 2:4: 5-trichloro-3: 6-dinitrotoluene, 2:4:5trichloro-3:6-tolylenediamine, and trichlorotoluquinone (Annalen, 1887,

237, 146).

EXPERIMENTAL.

1-Bromo-2 : 4-phenylenediamine.

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 acidified with 5 c.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 sandbath, 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 be

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 m-phenylenediamine and ammonia only are produced.

1-Bromo-2 : 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 crystallise 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.

CH,N,Br requires Br=42.78 per cent.

Dibenzoyl-1-bromo-2 : 4-phenylenediamine, readily obtained by the Schotten-Baumann reaction, crystallises 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=738. C20H15N2Br requires Br= 20.25; N=7·27 per cent.

Diacetyl-1-bromo-2: 4-phenylenediamine, prepared by adding 1-bromo2: 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 at 197-198°. The diamine is readily acetylated by acetic anhydride without the application of external heat; prolonged boiling of the base with the above mixture results in the formation of tarry products.

01145 gave 0-0819 AgBr. Br=30.25.

C10H1N,Br requires Br= 29.52 per cent.

1-Bromo-2: 4-phenylenediamine readily reacts with diazonium salts; with benzenediazonium chloride, it yields bromochrysoidine hydrochloride, a substance crystallising from dilute hydrochloric acid in greenish-black, anthracitic needles. Potassium bromochrysoidinesulphonate, 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 treated at 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

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 corresponding 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.

Dibenzoyl-1-chloro-2: 4-phenylenediamine, produced from the chlorobase by the Schotten-Baumann reaction, crystallises from chloroform or benzene in white, felted needles melting at 178°.

0.1800 gave 0.0750 AgCl. Cl = 10·31.

C20H15N2Cl requires Cl=10·12 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, fusiform clusters of greenish-black, anthracitic needles.

The base CH,N,∙CH¿Cl(NH2), crystallises from benzene in orange leaflets melting at 149°.

0.1489 gave 0·0860 AgCl. Cl = 14.12.

0.2253 46.1 c.c. moist nitrogen at 20° and 766 mm. N = 22.57. C12H11NCI requires Cl=14·40; N=22.81 per cent. When dyed on cotton mordanted with tannin, it gives a somewhat redder shade of orange than ordinary chrysoidine. Potassium chlorochrysoidinesulphonate, obtained by the action of diazobenzenesulphonic acid on 1-chloro-2: 4-phenylenediamine, crystallises from water in orange-brown leaflets having a bronzy reflex.

1:5-Dichloro-2: 4-phenylenediamine.

Diacetyl-1-chloro-2 : 4-phenylenediamine, prepared by adding 28 grams of powdered 1-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 242-243°. 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 recrystallised from benzene, diacetyl-1 : 5-dichloro-2 : 4-phenylenediamine melts above 260°. 1:5-Dichloro-2: 4-phenylenediamine, CH2Cl2(NH2), is precipitated from a solution of its diacetyl derivative in excess of