Hydrogen Bromide → 4-Bromo-3,5-dichlorobenzotrifluoride

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Reaction Steps

Nitrosyl sulphuric acid, prepared from sodium nitrite (69 g, 1 mol) and concentrated sulphuric acid (600 ml) was added dropwise with stirring to a cooled solution of 2,6-dichloro-4-trifluoromethylaniline (230 g, 1 mol) in glacial acetic acid (1250 ml) at 15°-20° C. The mixture was stirred for 1 hour at ambient temperature. The diazonium mixture was run slowly into a solution prepared from cuprous bromide (143.4 g, 1 mol), hydrobromic acid (48%, 1 l) and ice (approx. 1000 g) at a rate so as not to exceed a temperature of 35° C. After 1 hour the mixture was steam distilled to give 1 l of distillate which was diluted with water (3 l) and extracted with diethyl ether (2×500 ml). The organic fractions were combined and washed with aqueous sodium hydroxide solution (2M, 2×250 ml) and water (250 ml), dried over anhydrous sodium sulphate and evaporated to dryness. The oily residue was distilled to give 1-bromo-2,6-dichloro-4-trifluoromethylbenzene (256.8 g) as a colourless liquid, b.p. 74°-78° C. at 6 mmHg.

Provenance & Evidence