Sulfuric Acid → 1,2-Difluoro-3-nitrobenzene

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Reaction Steps

To a solution of 2,3-difluoroaniline (5.0 g, 38 mmol) in aqueous tetrafluoroboric acid (48%, 18 ml) was added sodium nitrite (3.9 g, 57 mmol) over 20 min while cooling in an ice/salt bath. After 1 h the mixture was filtered and washed successively with aqueous tetrafluoroboric acid and a mixture of acetone/diethyl ether (40:60). The precipitate was added to a mixture of copper (8.0 g, 121 mmol) and sodium nitrite (39 g, 570 mmol) in water (90 ml) over 20 min. After 1 h the mixture was acidified with concentrated sulphuric acid, extracted with ethyl acetate and evaporated in vacuo. The residue was purified by flash chromatography on silica (eluant EtOAc:pet. ether 20:80); yield 1.4 g (25%).

Provenance & Evidence