The reaction of an aromatic heterocycle with a proton is called a protonation. One of articles about this theory is 《o-Halogenated p-nitroaniline and its derivatives》. Authors are Korner, G.; Contardi.The article about the compound:3-Bromo-4-chloronitrobenzenecas:16588-26-4,SMILESS:BrC1=C(C=CC(=C1)[N+](=O)[O-])Cl).Safety of 3-Bromo-4-chloronitrobenzene. Through the article, more information about this compound (cas:16588-26-4) is conveyed.
When p-NO2C6H4NH2 is dissolved or suspended in HCl and Cl or Br added a mixture, difficult to sep., of mono- and dihalogenated anilines with the halogen in the o-position is formed. If, however, gaseous Cl (mol. ratio 1 : 1) is passed into the b. HCl solution 2,4-Cl(O2N)C6H3NH2 is almost the sole product. This derivative mixed with some di-Cl derivative is obtained on chlorinating at -o°(Casella & Co., Ger. Pat., 109,189). At room temperature, on adding Cl slowly to the HCl solution, the di-Cl deriv, + quinone are formed. Chlorinating by Noelting’s method, using Ca(ClO)2, gave mixtures Similar results were obtained with Br. These derivatives are obtained by warming 1-nitro-3,4-dibromo (or dichloro) benzene with alc. NH3 in the scaled tube at 190°. The NH2 group substitutes p to NO2. By halogenating these monohalogen derivatives it is possible to get derivatives with 2 different halogens in the same ring. The action of ClI on a glac. AcOH solution of p-NO2C6H4NH2 gives mixtures from which the mono- and di-I derivatives can be separated by EtOH. 1-Nitro-3-chloro-4-aniline, bright yellow needles from hot H2O, m. 104.5°; acetyl derivative, straw-yellow flat prisms from EtOH, m. 139°. Diazotizing in H2SO4 or HNO3 suspension with gaseous HNO2 gives the diazo compound which, by way of the perbromide, goes into 1-nitro-3-chloro-4-bromobenzene, prisms from CHCl2, m. 62°. 1-Nitro-3-chloro-4-iodobenzene, almost colorless needles from EtOH, m. 103°, is obtained similarly, by way of the periodide. 1-Nitro-3-bromo-4-aniline, bright yellow needles, m. 104.5°, which with Ac2O gives the monoacetyl derivative, flat prisms, m. 114°, and the diacetyl derivative, short fat prisms, m. 132°. also from the mono derivative, by the action of Ac2O + traces of POCl3. Diazotizing and halogenating as above gives 1-nitro-3-bromo-4-chlorobenzene, white or colorless prisms, volatil with steam, m. 61°, is identical with the compound similarly obtained from 2,5-Cl(O2N)C6H3NH2. 1-Nitro-3-bromo-4-iodobenzene, prisms from AcOEt, m. 106°, was obtained similarly. 1-Nitro-3-iodo-4-aniline presents 2 forms: (1) stable yellow-red prisms, and (2) the labile forms golden yellow plates in C6H6, below 17°, m. 109°; monoacetyl derivative, bright yellow prisms; diacetyl derivative, more soluble than the mono compound, white needles. The diazo compound, on adding Cl, gives 1-nitro-3-iodo-4-chlorobenzene, needles, m. 78°, identical with the compound obtained similarly with I from 2,5-Cl(O2N)C6H2NH2. 1-Nitro-3,5-dichloro-4-aniline, yellow shining needles, m. 195°, slightly soluble in dilute and concentrate inorganic acids, unchanged by fuming HNO3 in the cold. To diazotize suspend in HNO3 (d. 1.38) and add gaseous HNO2 at o°; on diluting the explosive diazonium nitrate seps., fairly soluble in H2O. Ac2O + traces of POCl3 give the monoacetyl derivative, almost colorless needles, m. 215°, and the diacetyl derivative, monoclinic (Artini, Rend. ist. lombardo sci. lett., [2] 45, 1912), prisms, m. 142.5°, d. 1.565, more soluble than the mono compound In absolute EtOH + some concentrate H2SO4 + EtONO it gives 1-nitro-3,5-dichlorobenzene, plates, m. 65.4°, which on reducing with Sn + HCl gives 3,5-dichloroaniline, needles, m. 51.5°. The latter, by replacing NH3 with Cl, gives 1,3,4-trichlorobenzene, white needles, to. 63.5°, which is also obtained from 2,4,6-Cl3C8H2NH2, m. 77.5°, by replacing NH3, with H. 3,5-Cl2C4H3NH2 by replacing NH2 with Br gave 1-bromo-3,5-dichlorobenzene, needles, m. 75.8°. 1-Iodo-3,5-dichlorobenzene, m. 54°, was obtained similarly and is identical with that prepared similarly from 2,4,6-ICl2C6H2NH2, m. 84°. Anilines containing 3 identical halogen ats. in the 2,4,6-positions may be obtained by direct halogenation of PhNH2 of which they are the end products. The mixed halogenated anilines are made from anilines halogenated in p-position by adding two halogens (Br or ClI) in the o-position in glac. AcOH. o,p- or o,o-dihalogenanilines may even be used, but displacing of weak halogens may take place. All of the theoretically possible trihalogenbenzenes can be obtained by thus substituting halogen for NH2 in anilines. 2,6,4-Cl2(O2N)C6H2NH2 gives 1-nitro-3,4,5-trichlorobenzene, bright yellow prisms, m. 72.5°, volatil with steam; reduction and elimination of NH2 gives 1,2,3-C6H2Cl3, identical with that from 2,6-Cl2C6H3NH2 by the same method. 1-Nitro-3,5-dichloro-4-bromobenzene, from the above aniline, yellow. prisms, m. 88°, volatile with steam; similarly 1-nitro-3,5-dichloro-4-iodobenzene, yellow prisms, m. 154.8°, less volatile; reduction, etc., gives 1,3-dichloro-2-iodobenzene, thin plates, m. 68°, volatile with steam, also from 3,6-C;2C4H3NH2 with I. p-NO3 C4H4NH2 + Br gives 1-nitro-3,5-dibromo-4-aniline, yellow plates, m. 202.5°; Ac2O as above gives the monoacetyl derivative, colorless needles or triclinic prisms, isomorphous with the di-Cl compound, and the diacetyl derivative, prisms, m. 136°, triclinic pinacoidal, a : b : c = 1.0901 : 1 : 0.8325, a = 88° 43′ 4”. β = 70° 49′ 34”. γ = 93° 25′ 39”, d. 1.939.3 Diazotizing the above or 2,4.6-Br2(O2N)C5H2NH3 with EtONO, etc., gives 1-nitro-3,5-dibromobenzene, almost colorless needles, m. 104.5°; on reduction with Sn + HCl, etc., it gives sym.-dibromochlorobenzene, m. 119°, with Cl, or dibromoiodobenzene, m. 124.8°, with 1. Both are easily volatil with steam and may be prepared from the corresponding anilines and the latter also from 2,4,6-IBr2C6H2NH2. 1-Nitro-3,4,5-tribromobenzene, from the o,o-dibromoaniline by replacing NH3 with Br, yellowish prisms, m. 111.9° on reduction, etc., gives 1,2,3-C6H3Br3, m. 87.8°. 1-Nitro-3,5-dibromo-4-chlorobenzene from the same aniline, yellowish prisms, m. 92-7°, on reduction, etc., gives 2,6-Br2C6H3Cl, m. 71°, identical with the compound similarly obtained from 2,6-Br2C6H3NH2 by replacing NH2 with Cl. 1-Nitro-3,5-dibromo-4-iodobenzene, from 2,6,4-Br2(O2N)C6H2NH2, prisms, 135.5°, cannot be reduced to the aniline. The 2,6-Br2C6H2I was obtained from 2,6-Br2C6H3NH2, prisms, m. 72°. 1-Nitro-3,5-diiodo-4-aniline, from p-NO2C6H4NH2 + ClI in AcOH, yellow needles; m. 245°; monoacetyl derivative, yellow needles, m. 249°; diacetyl derivative, paler yellow prisms, m. 171°, triclinic pinacoidal, a : b : c = 0.9682 : 1 : O.7260, α = 83° 6’43”, β = 76°8’29”, γ = 99° 42′ 44”, d. 2.290. 1-Nitro-3,5-diiodobenzene, from the preceding, difficultly volatile with steam, yellowish prisms, m. 104.5°, on reducing with FeSO4 + NH3 gives 3,5-I2C6H2NH3, needles, m. 110°. 2,6,4-I2ClC6H2NH2 gave 1,3-diiodo-5-chlorobenzene, needles, m. 101°, discolors brown in the light. Similarly the 5-bromoaniline gave 1,3-diiodo-5-bromobenzene, m. 140°, slightly volatile with steam. 1,3,5-Triiodobenzene, from 2,4,6-I2C6H2NH2 or 3.5-I2C6H3NH2, opaque needle, m. 184.2°. Decompose of 2,6,4-I2(O2N)C6H2N2NO3 with b. aqueous Cu2Cl2 gave 1-nitro-3,5-diiodo-4-chlorobenzene, needles, m. 110°; reduction with FeSO4 + NH3 gives a poor yield, (NH4)2S gives a better yield of the aniline together with some S-containing compound The aniline gives 2,6-I2C6H3Cl, rhombic plates, m. 82°. 2,6,4-I2(O2N)(C6H2NH2 gives 1-nitro-3,5-diiodo-4-bromobenzene, white needles from EtOH, yellow prisms from CHCl3 m. 125.4°, and 1-nitro-3,4,5-triiodobenzene, yellow prisms from EtOH, contain C6H6 of crystallization when crystallized from C6H6; reduction with FeSO4 + NH3 gives 3,4,5-triiodoaniline with difficulty; (NH4)2S gives sym.-I2C6H2NH2. The I2C6H2NH2 gives 1,2,3-C6H2I2 on changing NH2 for H, m. 116°, which is identical with that from 2,3-I2C6H3NH2. 2,4-Cl(O2N)C6H3NH2 + Br gives 1-nitro-3-chloro-5-bromo-4-aniline, bright Yellow needles, m. 177.4°; monoacetyl derivative, straw-yellow needles, m. 224°; diacetyl derivative, prisms or plates, m. 139°, monoclinic, prismatic, a : b : c = 1.1127 : 1 : 0.8509, β = 70-36°, d. 1-749. 1-Nitro-3-chloro-5-bromobenzene, from the above aniline, plates, m. 81.2°. and this on reducing with Sn + HCl, etc., gives 3-chloro-5-bromoaniline, needles, or prisms. The latter, as well as 2,4,6-BrClIC6H2NH2, m. 110.5°, gives 1-chloro-3-bromo-5-iodobenzene, needles, m. 85.8°. 1-Nitro-3,4-dichloro-5-bromobenzene, yellowish prisms, m. 82.5°, 1-Nitro-3,4-dibromo-5-chlorobenzene, yellowish prisms, m. 99.5°, and 1-nitro-3-chloro-4-iodo-5 bromobenzene, needles, 159°, by replacing NH2 with a halogen in the preceding nitroaniline. 1,2-Dibromo-3-chlorobenzene, by reducing 3,4,5-Br2ClC6H2NO2, rhombic plates. m. 72.6°. 2,4-Cl(O2N)C6H2NH22, in HOAc + ClI gives 1-nitro-3-chloro-5-iodo-4-aniline, bright yellow needles, 195°; monoacetyl derivative, white prisms, m. 207°; diacetyl derivative, prisms, m. 113°, monoclinic, a : b : c = 1.038 :-1 : 0.799, β = 71.44°, d. 1.913. This aniline gives 1-nitro-3-chloro-5-iodobenzene, yellow prisms, m. 70.4° by replacing NH2 with Cl. 1-Nitro-3,4-dichloro-5-iodobenzene, from the aniline with Cl, bright yellow prisms, m. 59°, is not easily reduced by FeSO4 + NH3, but Sn + HCl gives 3,5-CHC6H3NH2, plates, m. 69.8°; with Br the aniline gives 1-nitro-3-chloro-4-bromo-5-iodobenzene, almost colorless needles, m. 95°; and with I it gives 1-nitro-3-chloro-4,5-diiodobenzene, almost colorless needles, m. 146.5°. 3,4,5-Cl2IC6H2NO2 + (NH4)2S in EtOH gives 3,4-Cl2C6H3NH2. 2,4-Br(O2N)C6H3NH2 + CH in HOAc gives 1-nitro-3-bromo-5-iodo-4-aniline, needles, m. 221°; monoacetyl derivative, yellowish prisms, m. 226°; diacetyl derivative, prisms, m. 134°, triclinic pinacoidal, a : b : C = 0.9470 : 1 : 0.7288, α = 83° 59′ 54”, β = 77° 30′ 18”, γ = 99° 6′ 14”, d.2.112. 1-Nitro-3-bromo-5-iodobenzene, by replacing NH2 with H in the preceding aniline, needles, m. 97.5°; 1-nitro-3-bromo-4-chloro-5-iodobenzene, by replacing NH2 with Cl, yellowish prisms or colorless needles, m. 84°.
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