Ammonia → 4,4,4-Trifluorobutanamide

To a solution of 4,4,4-trifluorobutanoic acid (19.9 g) in THF (200 mL) were added oxalyl chloride (30.5 mL) and DMF (0.54 mL) at 0° C., and the mixture was stirred for 4 hr. The obtained reaction mixture was added to 28% aqueous ammonia (150 mL) at 0° C., and the mixture was stirred for 1 hr. The reaction mixture was filtration, and the filtrate was extracted with ethyl acetate. The extract was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure. The obtained solid was suspended in diisopropyl ether. The precipitate was collected by filtration, washed with diisopropyl ether, and dried to give the title compound (17.9 g) as a solid.