Aniline → 4'-Amino-2,3-difluorobenzophenone

Participants

Reaction Conditions

Reaction Steps

To stirred polyphosphoric acid (125 g) heated to 90° C. was added 2,3-difluorobenzoic acid (10.00 g, 63.3 mmol) followed by aniline (5.72 g, 61.7 mmol). The reaction mixture was heated at 180°-185° C. for 1 hour (solid dissolved at 135° C.), then the oil bath was removed and distilled water (35 mL) was cautiously added in small portions through the condenser. The oil bath was returned, and the reaction mixture heated at 135°-145° C. for 1 hour. The oil bath was again removed, 3N HCl (55 mL) was added to the solution, the reaction mixture was then poured into water (750 mL) and stirred for one hour. The aqueous solution was filtered through Celite and the filtrate basified with 15% NaOH to a pH of 8. A green solid was collected by filtration and purified by flash column chromatography (methylene chloride). Trituration with hexane yielded the title benzophenone (1.43 g, 10%) as a yellow solid; mp 104°-106° C. 1H-NMR (250 MHz, d6-DMSO): 6.41 (s, 2H, NH2) 6.60 (d, 2H, J=8.7 Hz, aromatic) 7.22-7.37 (m, 2H, aromatic) 7.50 (d, 2H, J=8.6 Hz, aromatic) 7.53-7.64 (m, 1H, aromatic). MS (CI, CH4): 234 (M+1). Analysis for C13H9F2NO: Calculated: C, 66.94; H, 3.90; N, 6.00. Found: C, 66.87; H, 3.80; N, 5.91.

Provenance & Evidence