A Publication
of Reliable Methods
for the Preparation
of Organic Compounds
Annual Volume
Page
GO
GO
?
^
Top
Org. Synth. 1935, 15, 6
DOI: 10.15227/orgsyn.015.0006
2,6-DIBROMO-4-NITROPHENOL
[Phenol, 2,6-dibromo-4-nitro-]
Submitted by W. W. Hartman and J. B. Dickey.
Checked by Louis F. Fieser and C. H. Fisher.
1. Procedure
In a 5-l. round-bottomed flask, fitted with a liquid-sealed mechanical stirrer, a dropping funnel, and a tube leading to a gas trap to carry off the hydrogen bromide, 278 g. (2 moles) of p-nitrophenol (m.p. 112–113°) is dissolved in 830 cc. of glacial acetic acid. To this solution at room temperature is added, dropwise with stirring during the course of three hours, a solution of 750 g. (240 cc., 4.7 moles) of bromine in 700 cc. of glacial acetic acid. After the addition of the bromine the reaction mixture is stirred for one-half hour and then warmed on the steam bath (internal temperature about 85°) for one hour in order to remove as much of the excess bromine as possible. The last traces of bromine are removed by passing a stream of air into the reaction mixture, which then has a yellow or brown color. The mixture is treated with 1.1 l. of cold water, stirred until cool (Note 1), and allowed to stand in ice, or in an ice chest, overnight. The pale yellow crystalline product is collected on a 19-cm. Büchner funnel and washed first with 500 cc. of 50 per cent aqueous acetic acid and then thoroughly with water. It is dried in an oven at 40–60° or in a vacuum desiccator over sodium hydroxide. The yield is 570–583 g. (96–98 per cent of the theoretical amount) of a nearly colorless product melting with decomposition at 138–140° (Note 2).
2. Notes
1. If the solution is stirred during cooling the product is less likely to cake on the walls of the flask and the resulting crystals are easier to wash.
2. This material is sufficiently pure for most purposes, and the quality is not greatly improved by recrystallization from 50 per cent acetic acid. Samples prepared by bromination, even after purification, invariably decompose at the melting temperature, which is somewhat dependent upon the rate of heating. The material obtained by nitration has been found to melt without decomposition at 144–145°.1
3. Discussion
2,6-Dibromo-4-nitrophenol has been prepared by the nitration of 2,6-dibromophenol1 or of dibromophenolsulfonic acid,2 and by the action of nitric acid on 2,6-dibromo-4-nitrosophenol3 or on 2,4,6-tribromophenol.4 It has been obtained from the corresponding ethyl ether5 and by the action of bromine on p-nitrosophenol,6 4,6-dibromo-2-nitrophenol,7 5-nitro-2-hydroxybenzoic acid,8 and 5-nitro-2-hydroxybenzene-sulfonic acid.9 The dibromination of p-nitrophenol10, 11 has been carried out in sulfuric acid solution12 and in the presence of aluminum chloride.13 The method described here is essentially that of Möhlau and Uhlmann.11
This preparation is referenced from:

References and Notes
  1. Pope and Wood, J. Chem. Soc. 101, 1828 (1912).
  2. Armstrong and Brown, ibid. 25, 859 (1872); Contardi and Ciocca, Gazz. chim. ital. 63, 878 (1933).
  3. Kehrmann, Ber. 21, 3318 (1888); Forster and Robertson, J. Chem. Soc. 79, 688 (1901).
  4. Raiford and Heyl, Am. Chem. J. 43, 395 (1910).
  5. Jackson and Fiske, Ber. 35, 1132 (1902); Am. Chem. J. 30, 60 (1903).
  6. van Erp, Rec. trav. chim. 30, 290 (1911).
  7. Armstrong, J. Chem. Soc. 28, 522 (1875); Ling, ibid. 51, 147 (1887).
  8. Lellmann and Grothmann, Ber. 17, 2731 (1884).
  9. Post, Ann. 205, 94 (1880).
  10. Brunck, Z. Chem. 1867, 204; ibid. 1868, 323; Vaubel, J. prakt. Chem. (2) 49, 544 (1894).
  11. Möhlau and Uhlmann, Ann. 289, 94 (1896).
  12. Datta and Bhoumik, J. Am. Chem. Soc. 43, 310 (1921).
  13. Bodroux, Compt. rend. 126, 1285 (1898); Bull. soc. chim. (3) 19, 759 (1898).

Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)

sulfuric acid (7664-93-9)

acetic acid (64-19-7)

sodium hydroxide (1310-73-2)

nitric acid (7697-37-2)

hydrogen bromide (10035-10-6)

bromine (7726-95-6)

aluminum chloride (3495-54-3)

2,6-Dibromo-4-nitrophenol,
Phenol, 2,6-dibromo-4-nitro- (99-28-5)

2,6-dibromophenol (608-33-3)

dibromophenolsulfonic acid

2,6-dibromo-4-nitrosophenol

2,4,6-tribromophenol (118-79-6)

4,6-dibromo-2-nitrophenol

5-nitro-2-hydroxybenzoic acid (96-97-9)

5-nitro-2-hydroxybenzene-sulfonic acid

p-nitrophenol (100-02-7)

p-nitrosophenol (104-91-6)