Ammonia → 2,3,4,5-Tetrafluoro-6-nitroaniline

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Reaction Steps

2-Nitro-3,4,5,6-tetrafluoroaniline was prepared using an adaptation of the method of Brooke et al., J. Chem. Soc. 802 (1961). Ammonia gas was bubbled through a solution of pentafluoronitrobenzene (3.00 g, 114.1 mmol) in 200 mL anhydrous diethyl ether for 4 h. During this time the color changed from clear white to a deep yellow and a white precipitate formed. The precipitate (ammonium fluoride) was separated by vacuum filtration and washed with ether (30 mL). The filtrate was rotary evaporated and the resulting orange crystals gave 3 spots on TLC (alumina, benzene). Purification of this sample was achieved by column chromatography (basic alumina, benzene). Purification of this sample was achieved by column chromatography (basic alumina, activity II) on a 1.5"×20" column. The first band was collected and concentrated to yield a yellow solid 1.88 g (63.0%), mp 44.5-45 (lit. 42.5°-43.5° C.). 19F NMR (C6F6 external standard, δ -162.9) δ -149.9(m), -1.56.6(m), -162.0 (m), -178.3(m).

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