Sulfuric Acid → 1-[3-Amino-5-(pentafluorosulfanyl)phenyl]ethanone

N-(3-Acetyl-5-pentafluorosulfanylphenyl)-2,2,2-trifluoroacetamide (4 g, for preparation see example 4d) was suspended in 6 ml of water and 12 ml of acetonitrile, and 6 ml of concentrated sulfuric acid were added dropwise to this suspension. After stirring at 75° C. for 4 h and leaving to stand at RT overnight, the reaction was completed by adding another 2 ml of concentrated sulfuric acid and heating the mixture at 75° C. for 3 h. The reaction mixture was poured onto ice-water and extracted with ethyl acetate. The ethyl acetate phase was washed to neutrality with saturated sodium hydrogencarbonate solution, dried over magnesium sulfate, filtered and concentrated. The crude product was purified by means of chromatography on silica gel. The product-containing fractions were combined and the solvent (heptane/ethyl acetate) was concentrated under reduced pressure. 2.53 g of 1-[3-amino-5-(pentafluorosulfanyl)phenyl]ethanone were obtained.