THE CHLORODIRROMO- AND DICHLOROBROMO-BENZENES. 1283 CXXXV1.-The Chlomdibromo- and Dichlm-obronzo- benzenes. By WILLIAM HOLDSWORTH HURTLEY, D.Sc. (Lond.). ACCORDINU t o theory, there should be twelve trisubstituted benzenes containing either one atom of chlorine and two atoms of bromine, or two of chlorine and one of bromine. Six of these are unsymmetrical in structure, two symmetrical, and four vicinal. Of these twelve, the two symmetrical compounds have been obtained by Hantzsch, Schleis- sing, and Jager ( B e y . , 1897, 30, 2334) ; the s-chlorodibromobenzene by the transformation of the acid s-tribromobenzenediazonium chloride ; and the s-dichlorobromobenzene by the transformation of the same compound on standing and warming. The s-chlorodibromo- vor,. LXXIX. 4 u1204 RURTLEY: THE CHLORODIBROMO- AND benzene was also obtained by them from 3 : 5-dibromoaniline, by re- placing the amino-group by chlorine.I n this paper, the preparation of all the twelve chlorobromobenzenes fromanilines of knownconstitution is described. The unsymmetrical com- pounds were all obtained by replacing the amino-group in di-halogen amines by chlorine or bromine, and, for this purpose, Gattermann’s well-known method (Ber., 1890, 23, 1222) was employed. Several of the unsymmetrical compoiinds were also obtained by replacing the amino-group in tri-halogen anilines by hydrogen. Tbe symmetrical and vicinnl compounds were prepared by replacing the amino-group in the corresponding chlorobromoanilines by hydrogen, by the method first described by Griess (8nnc61?en, 1866, 137, 67).Any unsymmetrical tri-halogen benzene can be prepared from acet- anilide by introducing two halogen atoms, wherr a compound of the Ax results, where X, and also Y, may be either chlorine NHAc li Y or bromine. On hydrolysing the acetyl derivative and replacing the amino-group by chlorine or bromine, the desired compound is obtained. Further treatment with a halogen converts the 2 : 4-halogen anilines into the symmetrical tri-halogen compounds, from which the sym- metrical chlorodibromo- or dichlorobromo-benzenes are obtained by removing the amino-group. Thus : 9 \ Y x()x \/’ Y where X, and also Y, may be either chlorine or bromine. Two, and only two, tri-halogen anilides are obtained when a meta- halogen anilide is treated with chlorine or bromine. One of these has a higher melting point, is less soluble in alcohol, 50 per cent.acetic acid, or benzene, and is formed in much larger amount than the other. The substance of higher melting point has the halogens in the positions 2 : 4 : 5 ; this is proved : (a) By hydrolysing the acetyl derivative and removing the amino- group, when an unsymmetrical tri-halogen benzene results. ( b ) By the fact that the same anilide is obtained as principal pro- duct on introducing one halogen atom into the 3 : 4-halogen anilide. The other anilide may have the halogen atoms in the positions 2 : 3 : 4, 3 : 4 : 5 , or 2 : 3 : 6. It is produced together with a larger amount of the isomeric 2 : 4 : 5-compound when one halogen atom entersDICHLOROBROMO-BENZENES.1295 into the 3 : 4-di-balogen anilide, and, on removing the amino-group, does not yield an unsymmetrical tri-halogen benzene. Hence it is not a 2 : 3 : 6-derivative. It is not a dimeta-derivative, because, apart from the improbability of the formation of such a compound, I have shown that on brominating m-dicbloroacetanilide the product is not identical with that which results on chlorinating m-bromoacetanilide, although both yield the same dichlorobromobenzene. The anilide having the lower melting point must therefore be a 2 : 3 : $-derivative. Thus we have : NHAc NH2 NH2 Y/\ 1 Ix +- '\/ Y Y \/ Y NHAc ,/ \/ Y A i" \ NHAc "w /\Y ' Ix \/ Y /\Y li. Y If this scheme is correct, we should obtain as final products the on brominating m-chloroacet- compounds anilide; the first compound should be identical with that prepared by replacing the amino-group in 2 : 4-dibromoaniline by chlorine, and tho second with that formed on replacing the amino-group in 2 : 6-dibromo- aniline by chlorine.The quantities of the tri-halogen benzenes at disposal for the deter- mination of chemical and physical properties were about 3 grams each in the case of vicinal derivatives, and about 10 grams in each of the others. The vicinal compounds crystallise in well-defined, rhombic plates, the symmetrical in long, slender prisms, and the unsymmetrical in short, thin prisms. The chlorodibromo- and dichlorobromo-benzenes are very soluble i n benzene, ether, chloroform, o r petroleum, but less so in alcohol, from which they can all be readily crystallised.The unsymmetrical com- pounds are very slowly volatile in steam, in which, however, the sym- metrical and vicinal derivatives volatilise readily. The vicinal and unsymmetrical compounds have a characteristic bromobmzpne-like odour, whilst the symmetricJ derivatives have a very faintly mouldy one. The melting and boiling points of these tri-halogen benzenes show interesting regularities ; these constmts, with those of the trichloro- and tribromo-benzeses;, are collected in the following table : p , B r Br/\ Br \/c1 , I IC1 and Br \/ This has been shown to be the case. 4 U 21296 HURTLEY: THE OHLORODIBROMO- AND Trichlorobenxenes. Tv-ibr omo benze ne8. M. p. €3. p. M, p. B. p. 1:2:4 16" 213" 1:2:4 44' 275O 1:2:3 53 218 1:2:3 87 - 1:3:5 63 208 1:3:5 120 271 Dichlorobromobenze~es.Chorodibromobenxenas. C1:Cl:Br M. p. B. p. C1:Br:Br. M. p. B. p. 1 :3:4 36" 256' 1:2:4 27 258 1:2:5 40.5 259 1:2:3 73.5 264 v { ~ ~ ~ ~ ~ 65 242 { 1:2:6 69.5 265 8 1:3:5 77.5 232 1:3:5 99.5 256 A consideration of this table shows that the melting point depends on both the nature and position of the substituents, whilst the boiling point depends more on the former than on the latter. Thus, the melting point of 1 : 3-dichloro-2-bromobenzene is 32' higher than that of 1 : 4-dichloro-2-bromobenzene, whilst the boiling points differ only by 7" ; the melting point of I-chloro-2 : 3-dibromobenzene is 33Ohigher than that of 1-chloro-2 : 5-dibromobenzene, whilst the boiling points differ only by Fie; the melting 'points of the symmetrical compounds are much higher, but their boiling points are slightly lower, than those of the unsymmetrical derivatives.The symmetrical compounds have the highest melting point, the vicinal are intermediate, and the un- symmetrical have the lowest melting poinf ; this is also true for the trictloro- and tribromo-benzenes, I n the case of the boiling points, the vicinal compounds boil at the highest temperature, the unsymmetrical are intermediate, and the symmetrical compounds have the lowest boiling points. This order applies to the trichlorobenzenes and also to the trimethylbenzenes. The boiling point of the vicinal tribromobenzene is not given in Beil- stein's Hundbuch, and those of the unsymmetrical and symmetrical compounds are given as 275" and 278" respectively. As the sym- metrical tribromobenzene would be expected to conform to the same rule as the other compounds, and boil at a lower temperature than the unsymmetrical derivative, I made a specimen of this substance by removing the amino-group from symmetrical tribromoasiline, and purified the product by crystallisation from alcohol and distillation in a vacuum ; it boiled a t 271' under 765 mm.pressure, thus conforming t o the rule. f 1 :2 :4 24.5' 237" as{ 1:3:4 25 235 1:4:2 33 235 60 243DICHLOROBROMO-BENZENES. 1297 Ex P E RI ME NT A L. 1 : 2 .Dic~~loro-4-bronaobenxer~e. This compound was prepared from 2chloro-4- bromoacetanilide, which was obtained from p-bromoacetanilide by the method described by Chattaway and Orton (this vol., p. 820). The base from the 2-chloro-4-bromoacetanilide was dissolved in a large excess of concentrated hydrochloric acid (ten times the calculated quantity), some water added, diazotised at 0' with sodium nitrite, and the solution of the diazochloride added to freshly made, well washed, precipitated copper.This product was extracted with chloroform, filtered, the chloroform removed by distillation, and the residue dis- tilled in a vacuum. From the non-volatile portion, by washing with ether, a substance having all the properties of an azo-derivative was isolated ; it is being examined. The 1 : 2-dichloro-4-bromobenzene was again distilled in a vacuum, when i t boiled constantly at 124" under 33 mm. pressure, with the oil-bath a t 234'. When crystallised from alcohol, i t formed short prisms melting at 24.5'.It boiled a t 237O under 757 mm. pressure. This and all the other boiling points under atmospheric pressure, described in this paper, were determined by Siwoloboff's method (Bey., 18S6, 19, 795). 0.1787 gave 0.3757 AgCl + AgBr and 0.2553Ag. C1= 30.63; Br = 36-74, C,H3Cl,Br requires C1= 31 -38 ; Br = 35-40 per cent.* 1 : 3 - Dich loro-4-bromo benzene. The amino-group in 2 : 4-dichloroaniline was replaced by bromine exactly as above described, except that hydrobromic acid was used in place of hydrochloric acid. Gattermann states that a mixture of sulphuric acid and potassium bromide can be added to the diazo- chloride in place of hydrobromic acid, but in this preparation a better yield resulted when the latter was used. On distilling the copper mix- ture in a current of steam, it was found that the product came over very slowly, and, subsequently, extraction with chloroform was used instead of this process. On distillation in a vacuum, the dichlorobromobenzene boiled at 1 1 1 O under 21 mm.pressure, with the oil-bath at 130'. It crystallised in clusters of small, white prisms which melted at 25" and boiled at 235' under 751 mm. pressure. * The mixed silver salts were weighed in a small Gooch crucible ; this was then placed in a small Rose crucible and heated in a stream of dry hydrogen. In the above analysis, the mixed chloride and bromide was only 0*0002 too high and the silver 0*0008 too low ; as these errois are in opposite directions they make the found percentages of chlorine and bromine show considerable divergence from the calcu- lated values, This occurs in two or three cases in the present paper.1298 HURTLEY: THE CRLORODIBROMO- AND 0.1586 gave 0.3350 AgCl + AgBr and 0.2291 Ag.C1= 32.05; Br = 34.71. C6H,CI2Br requires C1= 31.38 ; Br = 35.40 per cent. This compound was also prepared by removing the amino-group from 2 : 4-dichloro-5-bromoaniline (p. 1302). 1 : 4-DiclJo~*o-2-bromobenxene. 2-Bromo-4chloroaniline was employed for the preparation of this compound. p-Chloroacetanilide was dissolved in glacial acetic acid, and to the solution one molecular proportion of bromine dissolved in acetic acid was added, along with some fused sodium acetate. The product so obtained was precipitated by water, crystallised from alcohol, and hydrolysed, and the amino-group of the resulting aniline replaced by chlorine.After extraction with chloroform and removal of the latter by distillation, the residue was distilled in a vacuum. Prom the non-volatile portion an azo-compound was isolated by wash- ing with ether. The distillate was redistilled, and came over a t 119" under 26 mm. pressure, with the bath at 141". 1 : 4-Dichloro-2-bromo- benzene crystallised from alcohol in short prisms, melted at 33', and boiled a t 236" under 751 mm. pressure. 0.2812 gave 0.5898 AgC1+ AgBr and 0.4014 Ag. C1= 30.87; Br = 36.13. CGH,Cl2Br requires C1= 31 *39 ; Br = 35-40 per cent. This compound was also obtained by removing the amino-group from 3 : 6~dichloro-4-bromoaniline (p. 1301), 1 -Chloroh3 : 4-dibromobenxene. On replacing the amino-group in12- bromo-4-chloroaniline by bromine, only a very poor yield of this compound was obtained.Accordingly, another method of preparation was used : 3 : 4-dibromoacetanilide was prepared by dissolving m-bromoacetanilide in glacial acetic acid, and adding the calculated amount of bromine, also dissolved in glacial acetic acid. After precipitation by water, and crystallisation from alcohol, a pure product was obtained (compare Korner, Gazxetta, 1874, 4, 330). This was hydrolysed, and the aminogroup re2 placed by chlorine, the rest of the process being exactly similar to that already described. Under 19 mm. pressure, the new compound distilled at 121°, with the bath at 141O. As the distillate was slightly green, it was distilled in steam, and three times crystal- lised from alcohol.1-Chloro-3 : 4-dibromobenzene cryatallised in short prisms, which melted at 35.5", and boiled at 256" under 760 mm. pressure.DICHLOROBROMO-BENZENES. 1299 0.2232 gave 0.4285 AgCl + AgBr and 0.2665 Ag. C1= 12-68 ; Br = 59.83. C,H,C1Br2 requires C1= 13.11 ; Br-59.14 per cent. This compound was also obtained by replacing the amino-group in 2-chloro-4 : 5-dibromoaniline by hydrogen (p. 1305). l4Idoro-2 : 4-dibromobenxene. The amino-group in 2 : 4-dibromoaniline is easily replaced by chlorine, and the new compound is obtained in a pure condition in exactly the same way as the preceding-substance. Under 41 mm. pressure, and with the bath at 152", it boils a t 139' ; its melting point is 27", and it boils at 258' unaer 757 mm. pressure. 0'1878 gave 0.3593 AgCl + AgBr and 0-2240 Xg. C1= 13.04 ; Br = 59.04.C,H,C1Br2 requires C1= 13.1 1 ; Br = 59.14 per cent. This compound mas also obtained by eliminating the amino-group from 3-chloro-4 : 6-dibromoaniline (p, 1304). 1-Chloro-2 : 5-di6romobenxene. p-Dibromobenzene was prepared by brominating benzene in presence of iodine (Jannasch, Ber., 1877,10,1355), and nitrated by careful addition of fuming nitric acid, the mixture being kept cool during the process. The p-dibromonitrobenzene was reduced by tin and hydrochloric acid, the amino-group in the resulting aniline replaced by chlorine, and the 1-chloro-2. : 5-dibromobenzene purified as above. It distils a t 121' under 24 mm. pressure, with the bath at 150". Another method employed for its preparation was as follows.3-Bromo- 4-chloroacetanilide mas prepared from m-bromoacetanilide by trans- formation of the nitrogen chloride of the latter, and separated from the 3-bromo-6-chloroacetanilide formed at the same time by hydrolping the mixed anilides with alcohol and sulphuric acid and distilling the product in steam, when 3-bromo-4-chloroaniline remained behind as sulphate. This salt was decomposed, and the aniline purified by distillation in steam and crystnllisation from chloroform. After acetylation, the resulting anilide was brominated, yielding 2 : 5-dibromo- 4-chloroacetanilide which, on hydrolysis and removal of the amino-group, gave 1 -chloro-2 : 5-dibromobenzene. This chlorodibromo-derivative melts at 40.5' and boils at 259' under 764 mm, pressure. 0.1701 gave 0.3299 AgCl+ AgEr and 0.2065 Ag, C1= 13.85; Br = 58.69 C6H,C1Br, requires C1= 13.1 1 ; Br = 59-14 per cent.1300 HURTLEY: THE CHLORODIBROMO- AND 1 : 3-Dichloro-5-bromobemxene.2 * 4-Dichloro-6-bromoaniline was prepared by a d d i q a glacial acetic acid solution of the calculated amount of bromine to a solution of 2 : 4-dichloroaniline in the same solvent, in presence of fused sodium acetate. The product was precipitated by water and crystallised from alcohol. The amino-group, in this and all other cases referred to in this paper, was removed as follows. The aniline was treated with sulphuric acid 01 such a strength that it dissolved fairly readily on warming. The solution, cooled to O", was saturated with nitrous fumes from arsenious oxide and nitric acid (sp. gr.1*35), and the resulting green liquid poured into excess of alcohol. On warming, the 1 : 3'di- chloro-5-bromobenzene crystallised out and was purified by distillation in steam and two crystallisations from alcohol. p-Bromo- aniline, dissolved in glacial acetic acid, was saturated with chlorine, made alkaline, and distilled in steam. The 2 : 6-dichloro 4-bromoaniline so obtained WAS crystallised from alcohol and the amino-group removed as just described. 1 : 3-Dichloro-5-bromobenzene crystallises in long, slender prisms having a very faint, rnouldy odour, melts at 77.5', and boils at 232' under 757 mm. pressure. Hantzsch (Zoc. cit.) gives its melting point as This compound was also obtained by the following method. 82 -84'. 0.1680 gave 0.3538 AgCl -I- AgBr and 0.241 1 Ag.CI = 31.25 ; Br = 35-83. C,H,Cl,Br requires C1= 31.38 ; Br = 35.40 per cent. 1-Chloro-3 : 5-dibrornobenxene. A glacial acetic acid solution of p-chloroaniline was treated with a solution of 2 mols. of bromine in the same solvent, in presence of fused sodium acetate. The resulting 2 : 6-dibromo-4-chloroaniline was pre- cipitated from the solution by water, crystallised from alcohol, and the amino-group removed as already described. To purify the product, it was distilled in steam and crystallised twice from alcohol. This compound was also prepared in a precisely similar manner from o-chloroaniline. 1-Chloro-3 : 5-dibromobenzene closely resembles the symmetrical dichlorobromobenzene. It melts at 99.5' and boils at 256" under 757 mm. pressure. 0.1660 gave 0.3216 AgCl+ AgBr and 0.2011 Ag.CI = 13.63; Br = 58.89. C,H,CLBr, requires C1= 13.11 ; Br = 59.14 per cent. This compound was also prepared from 3 : 5-dibromoaniline (10 grams Hantzsch (Zoc. cit.) gives the melting point as 96'.DI CH LOROBROMO -BENZ EN ES. 1301 of which Dr. Chattaway lzindly gave me for this purpose) by replacing the amino-group by chlorine. 1 : 3-Dicl~o~o-3-bromobenxene. m-Chloroacetanilide was dissolved in glacial acetic acid and the solu- tion treated in presence of fused sodium acetate with the calculated amount of bromine also dissolved in acetic acid. On precipitating the product by water and crystallising from alcohol, pure 3-chloro-4-bromo- acetanilide was obtained. This substance was dissolved in glacial acetic acid and saturated with dry chlorine, when a crystalline solid separated.The solid and the mother liquor were worked up separately as follows. The solid was principally a mixture of nitrogen chlorides; so it was dissolved in alcohol and a little ammonia added to decompose them. Prom this solution crystals melting a t about 170" separated ; they were recrystallised until they melted constantly at 189'. The mother liquor from the crystals, melting a t 170°, was precipitated by water and the precipitate crystallised from alcohol, when a product melting a t about 135" resulted, which was recrystallised until it melted constantly at 138.5'. The mother liquor was precipitated by water and the product dissolved. in alcohol, some ammonia being added for bhe reason just given. The crystals thus obtained melted at about 132" ; and by repeated crystal- lisation from alcohol were separated into a small quantity of the anilide melting a t 189O, and a second anilide melting constantly a t 138.5'.3 : 6-Dicliloro-4-brontoacetaniZ~~e crystallises in thin prisms and is sparingly soluble in alcohol, benzene, or 50 per cent. acetic acid. It melts a t 189'. 0.2143 gave 0.3596 AgCl+ AgBr and 0.2454 Ag. C1= 25.13 ; Br = 28.16. C,H,ONCI,Br requires C1= 25.06 ; Er = 28.26 per cent. 3 : 6-DichZoro- 4-bromoaniZine, obtained from the anilide by hydrolysis It is readily with alcohol and sulphuric acid, crystallises in needles. soluble in alcohol, petroleum, or ether, and melts a t 91". 0.2144 gave 0.4218 AgCl+ AgBr and 0.2875 Ag. C1= 29.23; Br = 33.33. C,H,NC12Br requires C1= 29.43 ; Br = 33.19 per cent.The constitution of this aniline, and therefore t h a t of the anilide also, was proved by removing the amino-group, when 1 : 4-dichloro- 2-bromobenzene was obtained. 2 : 3-l)ichlo~o-4-b~omoacetacnilide is far more soluble in alcohol, benzene?1302 HURTLEY: THE CHLORODIBROMO- AND or 50 per cent. acetic acid than the isomeric unsymmetrical anilide. It crystallises in prisms and melts at 138.5O. 0.2150 gave 0.3602 AgCl + AgBrand 0,2453 Ag. C1= 24.75; Br = 28.68. C8H,0NC12Br requires C1= 25.06 ; Br = 28.26 per cent. 2 : 3-DichZoi~o-4-bronro~niline is readily soluble in alcohol j benzene) petroleum, or ether ; i t crystallises in needles. and melts at 77.5O. 0.2344 gave 0.4688 AgCl+ AgBr and 0.3198 hg. C1= 29.50; Br = 33-27.CGH4NC12Br requires C1= 29.43 ; Br = 83.19 per cent. 1 : 2-Di'chZoro-3-b~*omobenoene.-The amino-group in the preceding compound was removed by the method already described and the product purified by distillation in steam and crystallisation from alcohol. From dilute alcohol, it crystallises in leaflets, but from absolute alcohol in well defined, rhombic plates. It melts at 60' and boils at 243' under 765 mm. pressure, 0.1501 gave 0.3130 AgC1+ AgBr and 0.2131 Ag. C1= 30*75; Br = 35.79, C,H3C12Br requires C1= 31.38 ; Br = 35040 per cent. 1 : 3-DichZoro-2-brornobenxene. m-Bromoacetanilide was chlorinated in glacial acetic acid solution and the two anilides which resulted were separated exactly as in the case of the preceding compound. 2 : 4-Dichloro-5-bromoacettlnilide crystallises in short prisms and melts at 198'.0.2280 gave 0.3774 AgCl + AgBr and 0.2574 Ag. C1= 24.72 ; Br = 27-88. C,H,ONCl,Br requires C1= 25-06 ; Br = 28.26 per cent. 2 : 4-Dichloro-5-6romoaniline crystallises in flattened prisms, melts at 86", and distils at 163' under 16 mm. pressure, 0.2436 gave 0.4811 AgCl + AgBr and 0-3269 Ag. Cl = 28.77; Br = 34.53. C,H4NClaBr requires C1= 29.43 ; Br =.33.19 per cent. The constitution of this aniline was proved by removing the amino- group when 1 : 3-dichloro-4-bromobe~zene mas obtained. 2 : 4-Dichloro-3-b~omoacetccnili&e cryst.allises in prisms from alcohol and in long, fine needles from benzene. 0.2013 gave 0.3405 AgCl + AgBr and 03322EAg. C1= 25.21 ; Br = 28-59. C,H,ONCl,Br requires C1= 25.06 ; Br = 28-26 per cent.It melts at 138'. 2 : 4-D;chZol.o-3-~1.omoa~iline crystallises in plates which melt at 78O. It distils at 172' under 22 mm. pressure.DICHLOROBROMO-BENZENES. 1303 0'2090 gave 0.4083 AgCl + AgBr and 0,2778 -4g. C1= 28.69; Br = 33.74. C,K4NCl2Br requires C1= 29.43 ; Br = 33.19 per cent. 1 : 3-DichZo~.o-2-61.oniober~xene is produced on eliminating the amino- group from the last-mentioned compound, It resembles the preceding vicinal dichlorobromobenzene, melts at 65*, and boils at 242' under 765 mm. pressure. 0.1489 gave 0.31 17 AgCl+ AgEr and 0.2126 Ag. Cl= 31.24; Br = 35.32. C6H,C12Br requires C1= 31.38 ; Br = 35.40 per cent. Dry p-nitroaniline was added to dry benzene and treated with dry chlorine, when much heat was developed and the benzene appeared to boil owing to the escape of hydrogen chloride.The yield of 2 : 6-dichloro- 4-nitroaniline is quantitative, and this method of chlorination is more convenient than that employed by Witt (Ber., 1875, 8, 143), namely, treatment of a hydrochloric acid solution of p-nitroaniline with potass- ium chlorate. In the 2 : 6-dichloro-4-nitroa~iline, the amino-group was eliminated and the resulting 3 : 5-dichloronitrobenzene reduced by tin and hydrochloric acid. By acetylation of the base, 3 : 5-dichloroacet- anilide was prepared and this was treated with one molecular propor- tion of bromine in presence of fused sodium acetate. On addition of a little water to the acetic acid solution, a solid melting a t 215' separ- ated, which, after being twice crystallised from acetic acid, melted constantly at 220'.0.1994 gave 0.3337 AgCl + AgBr and 0.2272 Ag. C1= 24.69; Br = 28.75 C,H,ONCl,Br requires C1= 25.06 ; Br = 28.26 per cent. On hydrolysis, the anilide yielded an aniline which was purified by distillation in steam and crystallisation from alcohol. This base crystallised in rather long needles and melted at 1299 0,2099 gave 0.4130 AgCl+ AgEr and 0.2812 Ag. C1= 29.17; Br = 33.75, C6H,NCl2Br requires C1= 29'43 ; Br = 33.1 9 per cent. From this aniline by elimination of the amino-group 1 : 3-dichloro-2- This compound was also 6btained by the following method. It formed short prisms. bromobenzene was obtained, 1-CI~loro-2 I 6-dibromobenxene. Prom m-chloroacetanilide, by bromination, there was first prepared ~-chloro-4-bromoacetanilide in pure condition, and from this by treat; ment with one molecular proportion of bromine, a mixture of the unsymmetrical and vicinal chlorodibromoacetanilides resulted.These ahilides were separated in a precisely similar manner to those described under 1 : 2-dichloro-3-bromobenzene.1304 THE CHLORODIBROMO- AND DICHLOROBROMO-BENZENES. 3-Chloro-4 : 6-dibrmoacetanilide crystallises in thin prisms and melts at 174". 0.2593 gave 0.4108 AgCl + AgBr and 0.2562 Ag. C1= 10.67 ; Br = 48.81 C8H60NClBr2 requires C1= 10.82 ; Br = 48-84 per cent. 3-Chloro-4 : 6-dibromoaniline has been obtained by Wheeler and Valentine (Amev. Chem. J., 1899, 22, 270). Its constitution is proved by removing the amino-group, when it yields 1-chloro-2 : 4-dibromo- benzene. 3-chloro-2 : 4-dibromoacetanilide crystallises in prisms melting at 152". 0.2192 gave 0.3480 AgCl +AgBr and 0.2169 Ag.C1= 10.75; Br = 49-06. C,H,ONClBr, requires C1= 10.82 ; Br = 48.84 per cent. 3-Chloro-2 : 4-dibromoaniline crystallises in plates which melt at 88". 0.1'772 gave 0.3231 AgCl +AgBr and 0.2016 Ag. C1= 12.52; Br = 56.05. C,H,NClBr, requires C1= 12-42 ; Br = 56.02 per cent. 1-ChZoyo-2 : 6-dibromobenzene, obtained from the last-mentioned com- pound by replacing the amino-group by hydrogen, closely resembles the preceding vicinal chlorodibromobenzenes. This compound was also obtained from 2 : 6-dibromoaniline, for which I am indebted to Dr. Orton, by replacing the amino-group by chlorine-a reaction which goes very smoothly. It melts at 69.5' and boils at 265" under 760 mm.pressure. 0.1780gave 0.3419 AgCl +AgBrand 0.2133 Ag. C1= 13-17; Br= 59.08. C,H,C1Br2 requires C1= 13.1 1 ; Br = 59.14 per cent. 1 -ChZo~o-2 : 3-dibvomobenxene. m-Bromoacetanilide was treated with one molecular proportion of bromine and the 3 : 4-dibromoacetanilide, which is by far the principal product, was purified by two crystallisations from alcohol. The glacial acetic acid solution of this product was saturated with chlorine and the unsymmetrical and vicinal anilides isolated in exactly the same way as the corresponding chloro bromoanilides. 2-Chloro-4 : 5-dib~omoacetanilide crystallises in needles and melts at 198'. 0.2091 gave 0-3343 AgCl + AgBr and 0.2090 Ag. C1= 1195 ; Br = 48-67. C,H60NClBr, requires C1= 10-82 ; Br = 48.84 per cent. 2-Chloro-4 : 5-dibromoamiline melts at 93" and crystallises in flat- tened needles.ACTIVE COMPOUNDS FROM INACTIVE SUBSTANCES. 1 305 0.2060 gave 0.3757 AgCl + AgBr and 0.2344 Ag. C1= 12.51 ; Br = 56-08. C6H,NC1Br, requires C1= 12-42 ; Br = 56-02 per cent. Replacement of the amino-group by hydrogen gave 1-chloro-3 : 4- dibromobenzene. 2-Chloro-3 : 4-dibl.on~occcetanilide crystallises in fine needles from benzene and melts at 1469 0.2287 gave 0.3649 AgCl+ AgBr and 0.2275 Ag. C1= 10.84; Br = 49.23. C,H60NClBr, requires CI = 10-82 ; Br = 48.84 per cent. 2-ch!oro-3 : 4-dibromoaniline crystallises in plates and melts at 9 1'. 0.2165 gave 0.3928 AgCl + AgBr and 0.2450 Ag. C1= 12-13; Br = 55.87. C,H,NClBr, requires C1= 12.42 ; Br = 56.02 per cent. 1 -ChZoro-2 : 3-dibrornobenxsne, obtained from the preceding compound by removal of the amino-group, closely resembles the other vicinal chlorodibromobenzenes. It melts a t 73.5' and boils at 148' under 23 mm. and a t 264O under 754 mm. pressure. 0,2029 gave 0.3881 AgCl+ AgBr and 0.2415 Ag. C1= 12.69; Br = 59.57. C,H,CIBr, requires c1= 13-11 ; Br = 59-14 per cent. I have much pleasure in stating that Dr. Orton drew my attention to the fact that the chlorodi bromo- and dichlorobromo-benzenes had not been prepared, and in acknowledging the help I have received from the advice and criticism of both Dr. Chattaway and Dr. Orton. The examination of these compounds is being continued, and the preparation of some of the chlorobromotoluenes, several of which have been obtained, has also been undertaken. CHEMICAL LABORATORY, ST. BARTHOLOMEW'S HOSPITAL AND COLLEGE.