O-Bromoaniline, diazotization

In a 600-ml. beaker fitted with a thermometer and mechanical stirrer are placed 150 ml. of concentrated hydrochloric acid and 55 g. (0.32 mole) of o-bromoaniline. After brief stirring, 100 g. of ice is added and the beaker is surrounded by an ice-salt bath. The solution is then diazotized by the dropwise addition with stirring of a solution of 24.3 g. (0.35 mole) of sodium nitrite in 100 ml. of water, the temperature being kept at 0-5°. 

Chlorobromobenzene has been prepared by the diazotiza-tion of o-bromoaniline followed by replacement of the diazonium group by chlorine 1 by the elimination of the amino group from 3-chloro-4-bromoaniline 2 by the chlorination of bromobenzene in the presence of thallous chloride,3 aluminum chloride,4 or ferric chloride 4 by the bromination of chlorobenzene without a catalyst6 or in the presence of aluminum,4 iron,4 or ferric bromide 6 by the diazotization of o-chloroaniline followed by replacement of the diazonium group with bromine 4,6 and from o-chlorophenylmercurie chloride by the action of bromine.7... 

A solution of 34.4 g. (0.20 mole) of o-bromoaniline in 120 ml. of concentrated hydrochloric acid is diazotized in the usual manner [Org. Syntheses Coll. Vol. 1, 170 (1941)]. The resulting solution of the diazoniuiia salt is poured in a thin stream into a solution of 80.1 g. (0.50 mole) of potassium ethyl xanthate in 300 ml. of water held at 80°. The precipitated brown oil is separated, washed with water, and heated to reflux for 3 hours with a solution of 57 g. (1.0 mole) of potassium hydroxide in 100 ml. of ethanol and 50 ml. of water. The resulting solution is diluted with 1 1. of water, filtered, and acidified with hydrochloric acid. The precipitated o-bromothiophenol is separated and distilled. There is obtained an 80% yield of colorless oil, boiling in the range 96-98°/ll mm. 

The Schiemann procedure for conversion of an amine to an aryl fluoride is improved considerably by use as intermediate of the aryldiazonium hexafluorophos-phate instead of the aryldiazonium tetrafluoroborate. Since these salts are less soluble than the tetrafluoroborates they are obtained in better yield and can be washed thoroughly for removal of impurities. In the preparation of 2-bromofluoro-benzene from o-bromoaniline the amine hydrochloride is diazotized as usual,... 

Diazotization, m-hromoaniline, 54 o-bromoaniline, 61 p- bromoaniline, 55 3-chloro-4-am inotolu en e, 45 m-chloroaniline, 54 p-chloroaniline, 81 2,4-diaminotoluene, 113 m-iodoaniline, 54... 

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