86 MORGAN : INFLUENCE O F SUBSTITUTION ON THE

XI.-Injluence of Substitution on the E’ornza t i on o f il)iazocc.naines a n d Aminoaxo-compounds.

By GILBERT THOMAS MORGAN, D.Sc.

THE action of a diazonium salt on an aromatic amine gives rise to a diazoamine or an aminoazo-compound, according as the diazonium residue RON,* remains attached to the aminic nitrogen or takes up its position in the aromatic nucleus.

The former mode of combination occurs with the primary mono- amines of the benzene series, these bases yielding diazoamines. The mono-alkylated monoamines of the benzene series, on the other hand, exhibit a tendency to form azo-compounds ; methylaniline, for example, when treated with diazobenzenesulphonic acid, yields a mixture of the diazoamino-compound, SO,H*C,H,*N,*NMePh, and the isomeric aminoazo-acid, SO,H*C,H,*N,*C,H,*NHMe (Bernthsen and Goske, Beis,, 1887, 20, 925, Bamberger and Wulz, Ber., 1891, 24, 2082).

A somewhat heterogeneous class of bases including the following substances :-diphenylamine, the naphthylamines and their mono-alkyl derivatives, m-phenylenediamine and certain of its homologues and substitution products, gives rise to aminoazo-compounds without the intermediate formation of stable diazoamines. Dimethylaniline and a few other tertiary amines also yield aminoazo-derivatives, but with these bases the1production of diazoamines is obviously impossible,

There is some reason for believing that the difference between the behaviour of aniline and that of m-phenylenediamine towards diazonium salts is due to the greater reactivity of the disubstituted ring, so that substituent radicles find their way more readily into the aromatic nucleus of the diamine than into that of the monoamine. The introduction of chlorine and bromine by the action of hypo- chlorous and hypobromous acids respectively is a case in point ; the latter halogen enters the nncleus of the diamine so easily that m-phenylenediacetyldibromoamine, C,H,(NBrAc),, could not be isolated (Morgan, Trans., 1900, 77, 1209 ; Chattaway and Orton, Bey., 1901,34, 160), whereas phenylacetylbromoamine, Ph*NErA.c, is a comparatively stable substance (Chsttaway and Orton, Trans., 1899, 75, 1046 ; 1900, 77, 800).

Reasoning by analogy, it seems probable that the initial phase of the interaction between m-phenylenediamine and a diazonium salt involves the formation of an unstable diazoamine, this substance immediately changing into the isomeric aminoazo-derivative. This assumption is, however, not supported at present by any direct experi- mental evidence. With the view of gaining additional information as

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FORMATION OF DIAZOAMINES A R D AMINOAZO-COMYOU NDS. 8’7

to the course of this reaction, the formation of azo-derivatives of the homologues and substitution products of m-phenylenediamine has been studied. 2 : 4-Tolylenediamine has long been known to be as reactive towards diazocompounds as m-phenylenediamine itself, and more re- cently this was also shown to be true of 1-chloro-2 : 4-phenylenediamine and its bromine analogue. These bases readily yield azo-compounds, which, except for some slight differences in shade of colour, closely resemble those derived from the parent base, The hydrochlorides of chloro- and bromo-chrysoidines, for example, are obtained in crystals very similar in shape and colour to those of the ordinary chrysoidine of commerce.

The disubstituted m-diamines may be divided into two series with reference to their behaviour towards diazonium salts. The first series consists of the bases having the general formula

Y

whilst the second comprises all those disubstituted m-diamines which contain one free para-ortho-position with respect to the amino-groups. The bases of the second series can be grouped together, because, pro- viding this condition is fulfilled, the nature and position of the two substituent radicles exercise very little influence either on the course of the reaction or on the colour of the resulting azo-compound. An amine of this series may possess any one of the following formulae :

X Y Y Y

11. 111. I v. Diamines corresponding with formulz I1 and I11 have been investi- gated and the results compared with those obtained in the case of their isomerides belonging to series I.

The first diamines to be examined from this standpoint were the two diamino-m-xylenes described by Greviogk (Bey., 1884, 17, 2426), these bases having tho following constitutions :

Me NK,

The former is produced by the reduction of 3 : 6-dinitro-nz-xylene, the chief product of the nitration of m-xylone; whilst the latter is

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88 MORGAN: INFLUENCE OF SUBSTITUTION ON THE

obtained from 2 : 4-dinitro-m-xylene, this nitro-compound being a bye- product in the same operation.

Grevingk (Zoc. c i t . ) states that both these bases, when treated with benzenediazonium chloride, give colouring matters of the chrysoidine type, but he does not seem to have isolated any definite products. Witt, however, after an unsuccessful attempt to prepare an azo-compound by the action of diazobenzenesulphonic acid on the symmetrical base, main- tains that this diamine does not yield chrysoidine derivatives (Ber., 1888, 21, 2419).

As a matter of fact, the two isomerides behave very differently towards diazonium compounds. The consecutive base reacts just like 2 : 4-tolylenediamine, readily yielding a red azo-compound when treated with benzenediazonium chloride in the presence of sodium acetate ; the symmetrical diamine, on the other hand, gives rise to a volumin- ous, brownish-yellow precipitate, which froths considerably, evolving nitrogen, and finally becomes resinous, even while in contact with the ice-cold mother liquor. This unpromising result was experienced with other symmetrically disubstituted m-diamines and seemed to confirm Witt’s conclusion.

These failures could not, however, be accepted as conclusive evidence that the diamines of the type indicated by formula I cannot yield azo-compounds, inasmuch as the firm of Oehler & Go. has patented the production of colourirg matters derived from 2 : 4-tolylenediamine- 5-sulphonic acid (D.R.-P. 40905),

Me

a substance having a constitution similar to tha t of the bases in question. Accordingly, further experiments were made with different diazo-compoundP, until, finally, it was found tha t these bases would combine with primulin dyed and diazotised on the cotton fibre. Under these conditions, the symmetrically disubstituted diamines yielded azo-colouring matters possessing a yellowish-brown colour, and differing altogether from the reddish-brown compounds produced by similar means from the diamines belonging to the second series. These results show unmistakably tha t the relative position of the azo- and amino-groups is the most important factor in determining the shade of colour produced.

With the experience gained in these experiments on diazotised primulin, another attempt was made to prepare azo-compounds from 4 : 6-diamino-m-xylene and the simpler diazonium salts. The product of reaction mas allowed to remain in the ice-cold solution for

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FORMATION OF DIAZOAMINES AND AMINOAZO-COMPOUNDS. 89

one or two hours and the tarry precipitate then washed, dried, and carefully extracted with alcohol or benzene, In this way, a small yield of aminoazo-compound was produced and the reaction was shown to occur both with benzene- and p-toluene-diazonium salts.

The investigation was now extended to the symmetrical base, 5-chloro-2 : 4-tolylenediamine, simultaneously described by Reverdin and Crdpieux (Bey., 1900, 33, 2507) and by Morgan (Trans., 1900,77, 1209), and also to its isorneride, 2-chloro-3 : 5-tolylenediamine, prepared by Nietzki and Rebe (BRT., 1892, 25, 3005). The latter compound contains one free para-ortho-position with respezt to the amino-groups and might be expected to resemble 2 : 4-tolylenediamine and 2 : 4- diamino-m-xylene in its behaviour towards diazonium salts. This anticipation was completely confirmed ; the interaction resulted in the immediate Formation of an azo-compound, the yield being practically quantitative.

The symmetyical isomeride behaved like the similarly constituted 4 : 6-diamino Ira-xylene ; a brownish-yellow, voluminous precipitate was again produced, which evolved nitrogen and speedily became resinous. I n this case, also, an xzo-compound was extracted from the tarry product, but the yield was even poorer than tha t obtained in the experiment with the xylene base.

Since 4 : 6-dichloro-m-phenylenediamine (Trans., 1900, 77, 1206) combines with diazotised primulin, an attempt was made to condense it with benzenediazonium chloride and its p-toluene homologue. i n these experiments, there was a considerable amount of frothing and formation OF resinous product, but the precipitate, on extraction, yielded a large amount of unaltered base and did not furnish any azo- compound. Although this result does not establish beyond doubt the fact that an azo-derivative is not produced, yet, in conjunction with the evidence obtained from the preceding experiments, i t seems to indicate that, with these symmetrically disubstituted m-diamines, the tendency to form an azo-compound diminishes as the acidity of the molecule increases. This increase in acidic character results from the gradual replacement of methyl by chlorine, the pairs of substituent radicles in the three diamines being respectively 2Me, ClMe, and 2C1.

The brownish-yellow precipitates, which evolve nitrogen and become tarry, are probably unstable diazoamines. This conjecture receives additional support from the fact that under comparable conditions diaminomesitylene yields a similar, readily decomposable product, and in this instance the unstable substance cannot possibly be an azo- derivative. Meldola has also noticed the formation of a labile inter- mediate diazoamino-compound in the preparation of p-nitrobenzene- 5-azo-4-m-xylidine (Trans., 1883, 43, 428).

The aminoazo- bases derived from 4 : 6-diamino-nt-xylene and 5-chloro-

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90 MORGAN: INFLUENCE OF SUBSTITUTION ON THE

2 : 4-tolylenediamine contain the azo-groups in the position contiguous to the two amino-radicles, their constitution being indicated by the general formula

Y NH,

The azo-compound derived froin 2 : 4-diamino-m-xylene has the constitution

Me NH, /--\

since the position ocoupied by the azo-group is the only reactive position available in the original diamine.

In the case of 2-chloro-3 : 5-tolylenedinmine, the azo-group may enter the ring in either the di-ortho-position or in one of the two para-ortho- positions with respect to the amino-radicles. The ease with which the azo-compound is produced in almost theoretical yield renders it in the highest degree probable that the entrant radicle takes up the para-ortho- psit ion forming a colour base having the following configuration,

C1 Me

Noreover, the azo-compound produced on the cotton fibre from this diamine and diazotised primulin has the reddish-brown colour charac- teristic of the colouring matters having this constitution.

The naphthglamines and their derivatives containing hetero- nmleal substituents belong to the class of amines yielding azo- compounds without the intermediate formation of stable diazoamines, and are thus distinguished from aniline and its homologues, the o d y exception on record being P-naphthylamine-8-sulphonic acid, which, unlike its isomerides, gives a stable diazoamino-compound with benzenediazonium chloride (Witt, Ber., 1888, 21, 3483).

A similar difference has been noticed in the behaviour of' the two series of amines towards formaldehyde, P-napb thylamine yielding derivatives containing the methglene carbon atom attached to the aro- matic nuclei (Trans., 1898, 73, 536), whereas aniline and its homo- logues give rise to intermediate compounds of the methylenenniline and methylenedianiline types, containing methylene united with the nitrogen of one or two amino-groups, The investigation of these methylene cornpounds (Morgan, Trans., 12100, 77, S14) also showed

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FORMATION OF DIAZOAMINES AND AMINOAZO-COMPOUNDS. 91

that the presence of a substituent radicle in the a-position contiguous to the amino-radicle of P-naphthylamine prevented the transference of methylene into the ring.

Inasmuch as in their reactions with aromatic amines, formaldehyde and diazonium salts attack similar positions in the basic molecule i t might be expected tha t a /3-naphthylamine derivative substituted in the manner indicated mould yield a diazoamine but not an azo- compound.

One compound of this type, namely, 2-diazoamino-1-chloro-4-bromo- naphthalene, has already been obtained by Meldola and Streatfeild (Trans., 1895, 6’7, 911) by the action of nitrous acid on 1-chloro-4- bromo-P-naphthylamine. If the production of this diazoamine is deter- mined by the presence of the chlorine atom in the a-position conti- guous to the amino-radicle, then it should be possible to obtain similar compounds from 1-chloro-P-naphthylamine. The experimental results amply confirmed this assumption. The action of nitrous acid (I mol.) on this amine (2 mols.) gave rise to 2-diazoamino-l-chIoronaphthalene,

C1

a, well defined diazoamine resembling the compound described by Meldola and Streatfeild.

Mixed diazomines also were produced by the interaction of various diazonium salts and 1-chloro-/I-naphthylamine. p-Nitrobenzene-2- diazoamino-1-chloronaphthalene, prepared by the action of p-nitro- benzenediazonium chloride on this base, was also produced by the con- densation of 1 -chloro-2-naphthalenediazon~um chloride on p-nitroaniline ; this result indicates tha t Kekulh’s rule relating to the €ormation of mixed diazoamines is applicable to those containing both naphthalene and benzene nuclei.

These diazoamines do not show any tendency to change into amino- azo-compounds containing the azo-group attached to the naphthalene nucleus. Here also, as in the case of the methylene derivatives, the directing influence of the amino-radicle in P-naphthylamine seems to be exerted only in one direction, and accordingly the substituent radicles readily shift into the contiguous a-position, but do not replace the hydrogen attached to the adjacent &carbon atom.

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92 MORGAN: INFLUENCE OF SUBSTITUTION ON THE

X X P E R I M E N T AL.

A c ~ i o n oj' Dinxo~iiuri~ Xcdts on the m-Diamino-m-qlenes.

Prcpccration of the Diaenines.-m-Xylene is nitrated in quantities of 250 grams by slowly adding a well-cooled mixture of concentrated nitric and sulphuric acids (2-3 parts HNO, of sp. gr. 1-52 to 2 parts H,SO,) to the hydrocarbon surrounded by ice and salt. When the hydrocarbon is added to the acid, a considerable amount of trinitro- xylene is formed a t the commencement of the operation. The mixture, after remaining for several hours a t the ordinary temperature, is warmed for two hours at 40-50' and then poured on to ice. The crude, viscid nitro-compounds are drained .from oily products and the solid residue is crystallised from alcohol, the last operation being repeated two or three times. The crystals obtained in this manner consist of 4 : 6-dinitro-m-xylene melting a t 91-92' (Grevingk, Zoc. cit., gives m. p. 93'). The alcoholic mother liquors, when united and allowed to evaporate spontaneously, deposit an oily substance which is withdrawn as soon as the separation of crystalline product commences. This second crop of solid nitro-compound is crystallised repeatedly from alcohol, and the final product consists, very largely, OF 2 : 4-dinitro- m-xylene, crystallising in rosettes of hard, well-defined, flattened needles which melt somewhat indefinitely at 58-61'. Grevingk gives 80' as the melting point of the pure compound. As repeated crystallisation does not raise the melting point, the substance is reduced without further purification, The alcoholic mother liquors obtained by working up 1250 grams of m-xylene yield about 120 grams of the partially purified nitro-compound. The final mother liquors furnish a further quantity of oily nitro-compound. These oily products, obtained at various stages of the operation, when united and reduced give rise to impure 4 : 6 -diamino-wz-xylene.

The diamines are obtained by reducing the respective dinitro- xylenes with iron, 100 grams of the nitro-compound being treated with 130 grams of iron filings, 800 C.C. of water, and 12 C.C. of con- centrated hydrochloric acid. The whole of the water is not added at the commencement of the operation, but about 300 C.C. are introduced gradually during the reduction in order to moderate the reaction, which sometimes becomes very violent, The product, rendered alkaline with 8 grams of sodium hydrogen carbonate, is filtered from iron oxide; the filtrate acidified with acetic acid is treated with excess of acetic anhydride (about 60 grams). The precipitated diacetyl derivative is collected after 12 hours ; the filtrate, when concentrated and treated with a further quantity of the anhydride, yields a second crop of diacetyldiaminoxylene. After crystallisation from glacial acetic acid,

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FORMATION O F DTAZOAMINES A N D AMINOAZO-COMPOUNDS, 93

the diacetyl compound is hydrolysed with concentrated hydrochloric acid and the resulting diuminoxylene hydrochloride crystallised from water and then decomposed with the calculated amount of concentrated po tassi um hydroxide solution,

The 4 : 6-diamino-m-xylene separates in the solid form and is finally purified by crystallisation from water; it then melts at 104O, the melting point being identical with that given by Grevingk. The isomeric 2 : 4-diamino-m-xylene separates as an oil ; this, after separa- tion from the potassium chloride solution by means of ether, is dis- tilled under diminished pressure. After three distillations, a viscid oil is obtained boiling a t 170-174" under 13 mm. pressure ; this sub- stance, when cooled to - lo", gradually solidifies to a mass of crystals melting indefinitely at about 17". The yield from 1250 grams of xylene is about 25 grams.

These bases have been characterised by means of their acyl deriva- tives, as these latter are well defined substances easily prepared by the ordinary processes.

Diformyl-4 : 6-diarnino-m-xylene crystallises from water in colour- less, slender, flattened, silky needles and melts at 182-183".

0.2122 gave 27.1 C.C. moist nitrogen at 18"and 758mm. N=14.71. C,,H120,N2 requires N = 14.58 per cent.

The diacetyl derivative is very sparingly soluble in alcohol, but dissolves more readily in glacial acetic acid ; it crystallises in lustrous, silky needles and melts above 260'.

The dibenzoyl derivative, C,H,Me,(NH*CO*C6H,),, crystallises from alcohol or ethyl acetate in small, lustrous plates and melts at 25 2-25 3".

0.1570 gave 11.5 C.C. moist nitrogen a t 18" and 758 mm. N = 8-43. C22H,,02N, requires N = 8-13 per cent.

Diformyl-2 : 4-diamino-m-xylene crystallises from water, alcohol, or ethyl acetate in rosettes of colourless needles and melts a t 219-220°.

0.1148 gave 14.4 C.C. moist nitrogen a t 19" and 759 mm. N = 14.29. Cl,,H1202N2 requires N = 14.58 per cent.

The diacetyl derivative is sparingly soluble in alcohol and crys- tallises from glacial acetic acid in colourless, felted needles; i t melts above 260'.

The dibenxoyl derivative crystallises from alcohol in felted needles and melts a t 232".

0.1458 gave 10.8 C.C. moist nitrogen a t 18" and 759 mm. N = 8-56, C2,H2002N, requires N = 8.13 per cent.

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94 MORGAN: INFLUENCE OF SUBSTITUTION ON THE

Action of Benzenediaxoizium Chloride o n 2 : 4-Diumino-m-xylene. -A solution of benzenediazonium chloride, prepared from 5.4 grams of aniline hydrochloride, is added to a dilute ice-cold solution of 5 grams of the diamine acidified with 3 C.C. of concentrated hydrochloric acid. The solution remains clear until excess of crystallised sodium acetate (10 grams) is added and then a gelatinous red precipitate is produced which after remaining for a few hours is collected. The substance is purified by crystallisation from methyl alcohol.

Benzene-5-azo 2 : 4-diamino-m-xylene crystallises in yellowish-brown needles and melts a t 208-209O.

0.0308 gave 6-2 C.C. moist nitrogen a t 1 8 O and 769 mm. N = 23-54, C14H16N4 requires N = 23.33 per cent.

The azo-compound is distinctly basic and dissolves in dilute hydro- chloric acid ; the hydrochloride, however, is amorphous and separates in masses of red filaments. The platinichloride is a brick-red, amor- phous, insoluble salt.

Benxene-5-azo-2 : 4-d~acet&?iccmino-m-xylene, C6H,*N2*C,HMe,(NH*CO*CH3)2,

prepared by warming the crude azo-base for a few minutes with a mixture of glacial acetic acid and acetic anhydride, crystallises from alcohol in orange plates melting above 260O.

N = 17.16. 0.1952 gave 28.8 C.C. moist nitrogen a t 19' and 769 mm. C,,H2,0,N4 requires N = 17.28 per cent.

A comparative experiment made with 2 : 4-tolylenediamine shows that the two bases behave in a precisely similar manner towards diazonium salts.

Benzene-5-azo-2 : 4-tolylenediamine (compare Stebbins, Bey., 1880, 13, 717) crystallises in orange-brown needles or leaflets and melts at 161'.

Benzene-5-axo-2 : 4-diacetyltolylenediami./~e, C,H,*N,*C,H,Me(NH* CO-CH,),,

crystallises in flattened, orange prisms and melts at 216-2179

0.1756 gave 27.4 C.C. moist nitrogen a t 20Oand 769 mm. N = 18-06. C17H,,0,N, requires N = 18.06 per cent.

Action of Dicc;zonium Xalts on 4 ; 6-Diarnino-m-xyZene.--The same proportions of diamine and benzenediazonium chloride are employed as in the preceding experiment, On adding the sodium acetate to the clear solution containing the other reagents, a bulky, brotvnish- yellow precipitate is formed which rapidly darkens and becomes resinous. After 2 hours, the product is collected, washed, dried, and extracted with alcohol. From this extract, benxens-5.ccxo-4 : 6-diamino-m-

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FORMATION OF DIAZOAMIXES AND AMINOAZO-COMPOIJNDS. 95

xylene, C,H,*N,*C,RMe,( NH,),, separates in deep red, rhombic plates which after two crystallisations melt a t 182-183'. The compound is not decomposed on long boiling with alcoholic hydrochloric acid. It develops a deep orange coloration with concentrated sulphuric acid, and readily yields acyl derivatives by the ordinary processes.

0.0832 gave 0.2140 GO, and 0.0503 H,O. 0.1030

C = 70.14; H = 6.70. ,, 20-3 C.C. moist nitrogen a t 1 8 O and 767 mm. N=22*98.

C14H,,N, requires C = 70-0 ; H = 6.66 ; N = 23.30 per cent.

The diacetyl derivative, C,H,*N,*C,HMe,( NH*CO*CH,),, obtained from the preceding base by the action of acetic anhydride, crystallises from alcohol in brownish-red needles and melts above 260".

0,1390 gave 20.8 C.C. moist nitrogen a t 18' and 759 mm. N = 17.10. C,,H,,O,N, requires N = 17.28 per cent.

p-Toluene-5-axo-4 : 6-diamino-m-xylene, C,H,Me*N,*C,H~e,(N H,),, obtained by substituting an equivalent amount of p-toluidine for the aniline employed in the preparation of the preceding azo-diamine, crystallises from alcohol or benzene in deep red, rhombic plates and melts at 165-166'. I t closely resembles its homologue in chemical and physical properties.

0.1517 gave 34-5 C.C. moist nitrogen a t 2 1 O and 754 mm. N = 21.43. C15HlsN4 requires N = 22.04 per cent.

Action of Diaxonizcm # a h on 5-Chloro-2 : 4tolyylenediccmine and 2-Chloro-3 : 5-tolylenediarnine.

5-Chloro-2 : 4-tolylenediamine can be readily obtained in large quan- tities by the author's method (Trans., 1900, 77, l209), and i t has been further characterised by the prepzration of a series of its diacyl derivatives.

pre- pared by heating the base for 3 hours with 2-3 parts of concentrated formic acid, is obtained as a dark brown precipitate on treating the product with dilute ammonia ; it is purified by three crystallisations from water in the presence of animal charcoal, and finally separates from this solvent in colourless, silky needles melting at 166".

Diformyl-5-chloro-2 : 4-tolylenediamine, C,H,UeCl(NH* CHO),,

0.1218 gave 0.2370 CO, and 0,0520 H,O. 0.2076 ,, 24 C.C. moist nitrogen a t 18" and 768 mm. N = 13.49. 0,1318 ,, 0.0869 AgC1. C1= 16.31.

C9H,0N,Cl requiresC = 50.82; H = 4.23; N = 13.18; C1= 16.70 per cent.

The diacetyl derivative melts above 260", and not at 240' as pre- viously indicated j it is obtained free from the moooacetyl compound

C=51*72 ; H=4*74.

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96 MORGAN : INFLUENCE OF SUBSTITUTION ON THE

by heating the base with excess of acetic anhydride, and crystallising the product from glacial acetic acid; it is sparingly soluble in methyl, ethyl, or amyl alcohol, separating i r o m any of these solvents as a microcrystalline powder ; it crystallises from pyridine o r acetic acid in small prisms.

C1= 14.83. Cl,H1,ON,C1 requires C1= 14.76 per cent.

0.1405 gave 0.0842 AgC1.

The dibenxoyl derivative, prepared by the Schot ten-Baumnnn method, crystallises from alcohol in colourless, acicular lamell 8 and melts a t 205'.

0.2209 gave 0.0890 AgC1. C1= 9.96. 0.1576 ,, 10.5 C.C. moist nitrogen a t 19" and 761 mm. N=7*70.

C,,,H170N2CI requires C1= 9.74 ; N = 7.68 per cent.

Benzene-3-axo-5-ch2os.o-2 : 4-tolylenediamine, C,H5*N2* C,HClMe(NH,),. -The brownish-yellow precipitate produced by adding an excess of sodium acetate to a dilute hydrochloric acid solution containing equi- valent quantities of benzenediazonium chloride and 5 -chloro-2 : 4-tolyl- enediamine, is allowed to remain in contact with the mother liquor for 2 hours and then collected, dried, and extracted with alcohol. The filtered extract slowly deposits a crop of dark brown crystals con- taminated with tar ; the crude benzene-3-axo-5-chloro-2 : 4-tolylenedi- artzine is repeatedly crystallised from alcohol and finally obtained in dark brownish-red plates melting a t 147O. The compound is not de- composed by prolonged boiling with alcoholic hydrochloric acid and develops a deep yellowish-brown coloration with concentrated snlphuric acid; it readily yields acyl derivatives when treated with the appro- priate reagents.

The dibenxoyl derivative, C,H;N,* C,KMeCI(NH* CO*CGH5)2, pro- duced by the Schotten-Baumann method, crystallises from alcohol in transparent, brownish-yellow plates and me1 ts at 236-237'.

0.1692 gave 17.3 C.C. moist nitrogen a t 19" and 765 mm. N = 11.83. C2,H,,0,N,C1 requires N = 11 *95 per cent.

The acetyl derivative crystallises from alcohol in brownish-red,

p-Toluene-3 -axo-5-ch~oro-2 : 4-tolylenediamine, flattened prisms, and melts at 225'.

C,H,Me* N, C,HClMe( NH,),. -This azo-compound closely resembles its lower homologue and is pre- pared in a precisely similar manner. In this case also there a considerable evolution of nitrogen accompanied by the formation of much tarry product, and the yield of crystalline base is small. The substance crystallises from alcohol in dark brown plates and melts at 152".

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FORMATION OF DIAZOAMINES AND AMINOAZO-COMPOUNDS. 97

0.1196 gave 0.0600 AgCl. C1= 12.41. 0.1971 ,, 35.2 C.C. moist nitrogen a t 21' and 754 mm. N = 20.16.

C,,H,,N,CI requires C1= 12.93 ; N = 20.00 per cent.

A dilute hydrochloric acid solution of 4 : 6-dichloro-m-phenylene- diamine and benzenediazonium chloride, when treated with sodium acetate, yields a yellow precipitate, which, when crystallised from alcohol, separates in brown leaflets melting a t 137'. The product contains from 37 to 39.6 per cent. of chlorine and seems to consist chiefly of unchanged diamine; this base melts at 137' and contains 40.11 per cent. of chlorine, whereas the percentage of this element in the required azo-compound would be 25.26. A negative result was also obtained with ptoluenediazonium chloride ; in this experiment, 14-7 grams of the diamine were employed, and 8.7 grams of the unchanged base were recovered after recrystallisation, the other products of reaction being tarry and indefinite.

On the other hand, the dichlorodiamine combines with diazotised primulin, for a piece of cotton cloth impregnated with this diazo- compound and placed in an aqueous solution of the base gradually acquires a brownish-orange colour, similar in shade to the azo-colouring matters produced under these conditions from 5-chloro-2 : 4-tolylene- diamine and 4 : 6-diamino-m-xylene.

Benzene-6-axo-2-chZoro-3 : 5-toZyZenediamine.-2-Chloro-3 : 5-tolylenedi- amine (Bw., 1892,25,3005), is readily obtained from 3 : 5-dinitro-2-chloro- toluene, the nitration product of o-chlorotoluene, by the iron-filings method of reduction. The iron oxide is freed from the diamine by washing with alcohol; the alcoholic and aqueous extracts are mixeci together, acidified with acetic acid, and treated with excess of acetic anhydride. The acetyl derivative, crystallised from glacial acetic acid, is hydrolysed with hydrochloric acid, and the free base purified by crystallisation from water, in which solvent it is more soluble than its symmetrical isomeride ; it separates in long needles melting a t 74'.

The azo-compound, prepared in the ordinary way, separates im- mediately as a flocculent, yellow precipitate on the addition of sodium acetate to the hydrochloric acid solution of its generators ; it crystallises from a mixture of benzene and petroleum in tufts of long, orange-red, acicular prisms, these crystals being sometimes more than an inch in length. The substance melts at 134O, yields a deep brownish-red coloration with concentrated sulphuric acid, and is not decomposed by prolonged boiling with alcoholic hydrochloric acid.

N = 21-00. 0.1448 gave 26.2 C.C. moist nitrogen a t 1 8 O and 766 mm. 0,1643 ,, 0.0928 AgC1. C1= 13.97.

VOL. LXXXI. H C,,H,,N,CI requires 01 = 13.62 ; N = 21-49 per cent.

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98 MORGAN : INFLUENCE OF SUBSTITUTION ON THE

Benzene-6-axo- 2- chloro-3 : 5-diacet y Ztol ytenediamine, C,H,*N2*C,HMeCl( NH*CO *CH,),,

produced by gently heating the azo-base with acetic anhydride, is readily soluble in acetic acid or benzene, but dissolves only sparingly in alcohol or ethyl acetate; it crystallises in silky, orange needles and melts a t 251O.

001074 gave 14.6 C.C. moist nitrogen a t 17Oand 762 mm. N = 15.68. 0.1631 ,, 0.0663 AgC1. C1= 10.06.

C17H170,N,CI requires C1= 10.30 ; N = 16.25 per cent.

The dibenxoyl derivative obtained by the Schotten-Baumann method crystallises from benzene in orange needles and melts at 233O.

0,1162 gave 11.7 C.C. moist nitrogen at 1 8 O and 758 mm. N = 11.69, 0.0717 ,, 0.0213 AgCl. C1=7*35.

C,7H,,0,N,C1 requires C1= 7.58 ; N = 11 *95 per cent.

Action, of Bircxonium XaZts on 1-Chloro-P-naphthyzamine.

2-Diazoamino- 1 -chZoronaphthaleme, CloH,CI- N, NH* CloH,Cl, separates as a light yellow precipitate on adding excess of sodium acetate to the mixture formed by slowly dropping a glacial acetic acid solution of I-chloro-/I-naphthylamine (1 mol.) into a hydrochloric acid solution of 1 -chloro-2-naphthalenediazonium chloride (1 mol.) ; it crystallises from benzene or chloroform in golden-yellow needles and melts at 1 5 2 O . The diazoamine may also be produced by adding sodium nitrite (1 mol). to an ice-cold alcoholic solution of 1 -chloro-P-napht hylamine (2 mols.) acidified with hydrochloric acid, the precipitation of the compound being completed by the addition of a saturated aqueous solution of sodium acetate. The product obtained in this way is, however, often contaminated with an amorphous,-red substance, which is not readily removed in the subsequent crystallisations.

0.1711 gave 17.1 C.C. moist nitrogenat 215Oand 769 mm. N=11.49. 0.2358 ,, 0.1817 AgCl. C1=19.19.

C20€113N3C12 requires C1= 19.39 ; N = 11.47 per cent.

Although insoluble in alcohol, i t readily dissolves in alcoholic potassium hydroxide, yielding a deep orange-coloured solution, this result pointing to the existence of a potassium derivative. The com- pound is remarkably sensitive to light, and after a few weeks' exposure its crystals, although retaining their shape, acquire a dark chocolate colour ; it is decomposed on warming with hydrochloric acid, evolving nitrogen and yielding 1 -chlor o-P-napht hylamine and resinous pro- ducts.

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FORMATION OF DIAZOAMINES AND AMINOAZO-COMPOUNDS. 9 9

p-Nitrobenzene-2-diazoarnino- 1 -chZoi.onaiu~~tl~alene, NO,* C,H,*N, *NH C,,H,Cl,

is obtained by adding a hydrochloric acid solution of p-nitrodiazonium chloride (prepared from 3 grams of p-nitroaniline) to a cooled alcoholic solution of 1-chloro-/3-naphthylamine (4 grams), the precipitation of the diazoamine being completed by the addition of sodium acetate. It may also be prepared by mixing together solutions containing equivalent quantities of 1-chloro-2-naphthalenediazonium chloride and p-nitro- aniline. The diazoamine produced by either of these processes is obtained as a voluminous, yellow precipitate ; it is almost insoluble in alcohol and only sparingly soluble in benzene, separating from the latter solvent in brownish-yellow leaflets melting and decomposing at 197-198'.

0,1342 gave 19.8 C.C. moist nitrogenat 21' and 759 mm. N = 17.08. 0.1614 ,, 0.0692 AgC1. C1= 10.65.

C,,H,,O,N,Cl requires C1= 10.87 ; N = 17.15 per cent.

The diazoamine is fairly soluble in hot chloroform, but when boiled for some time with this solvent it partly decomposes. It is acidic in character and its potassium derivative, produced by dissolving the compound in an alcoholic solution of potassium hydroxide, yields a a deep purple solution.

Ethyl Derivative of p-Nitrobenxene-3-diaxoami.fLo-l-chlorornap~t~aZene, ~0,*C6H,*N,*NEt*CloH6~~.-An alcoholic solution of the potassium derivative of the preceding diazoamine is boiled with a slight excess of ethyl iodide until the deep purple coloration of the mixture changes to orange. The crystalline product obtained on cooling the alcoholic solution is purified by crystallisation from benzene, and separates from this solvent in hard, orange-yellow, prismatic crystals melting at 193-194'. This compound does not develop a purple coloration with alcoholic potassium hydroxide and on analysis gives numbers corre- sponding with those required for an ethyl derivative of the mixed diazoamine.

0,2382 gave 32.1 C.C. moist nitrogen at 19' and 769 mm. N = 15.68. 0.1452 ,, 0.0584 AgCl. C1= 9.96.

C,,H,,O,N,Cl requires C1= 10.01 ; N = 15.80 per cent.

A diazoamine resembling the preceding ethyl compound, but melting at 182-1 83", is produced by adcling a solution of I-chloro-2-naphthalene- diazonium chloride to an alcoholic solution of ethyl-p-nitroaniline. The study of these alkyl derivatives of naphthalenoid diazoamines is, however, still incomplete owing to the difficulty experienced in a1 ky lating 1 -chloro-P-naph t hy lamine and its analogues.

H 2

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100 MOIR : CYANOHYDROXYPYRIDTNE DERIVATIVES

My best thanks are due to Miss F. M. G. Micklethwait for assisting in the preparation and analysis of several of the compounds described in this communication, and to Mr. E. Lodge for examining the tinctorial properties of the two series of nminolzzo-derivatives,

ROYAL COLLEGE OF SCIENCE, LONDON. SOUTH KENSINGTON, S. W.

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