Thionyl Chloride → HCID 15023841, compound

Participants

Reaction Steps

300 ml of thionyl chloride were added to a solution of 100.0 g (0.52 moles) of 2,4,5-trifluoro-3-hydroxybenzoic acid [(XXIII), X=X'=F] (prepared as described in Preparation 13) in 400 ml of benzene, and the mixture was heated under reflux for 3 hours. At the end of this time, the solvent and excess thionyl chloride were removed by distillation under reduced pressure, to give 2,4,5-trifluoro-3-hydroxybenzoyl chloride. The whole of this chloride was added dropwise to 1500 ml of 28% w/v aqueous ammonia, whilst stirring and ice-cooling, and the mixture was then stirred for a further 2 hours. At the end of this time, the mixture was allowed to stand at room temperature overnight, after which it was acidified by the addition of dilute aqueous hydrochloric acid. The reaction mixture was then extracted with ethyl acetate, and the extract was washed with water and dried over anhydrous sodium sulfate. The solvent was then removed by distillation under reduced pressure, to give 88.2 g of 2,4,5-trifluoro-3-hydroxybenzoyl amide as a colorless powder, melting at 153°-155° C.

Provenance & Evidence