Aniline → 4'-Amino-2,5-difluorobenzophenone

Participants

Reaction Steps

To stirred 90° C. polyphosphoric acid (125 g) was added 2,5-difluoro-benzoic acid (10.0 g, 6.32 mmol) and aniline (5.87 g 6.3 mmol) and the bath temperature raised to 180°-190° C. and held there for 1 hour. The heating bath was removed and the stirred mixture (sublimate above the solution) was treated cautiously with 50 mL of water. The mixture was stirred at 140°-155° C. for 1 hour, the heating bath removed, 45 mL of 3N HCl added, the mixture poured into 650 mL of water and filtered through a pad of Celite. The filtrate was basified with 15% sodium hydroxide and the mixture filtered through a pad of Celite. The Celite pad was washed well with methylene chloride, the methylene chloride dried (MgSO4), filtered and the solvent removed in vacuo. Purification by flash column chromatography (methylene chloride) followed by recrystallization twice from 50% ethanol (80 mL) yielded the aniline as a yellow solid (3.08 g, 21%); mp 101°-103° C. 1H-NMR (300 MHz, CDCl3): 4.27 (s, 2H, NH2) 6.63-6.67 (m, 2H, aromatic) 7.09-7.19 (m, 3H, aromatic) 7.68-7.71 (m, 2H, aromatic). MS (CI, CH4): 234 (M+1).

Provenance & Evidence