Synthesis of (3,5-Dichlorophenyl)-(4-fluorophenyl)methanone.
3,5-Dichlorobenzoic acid (12.5 g, 65 mmol) was heated at reflux with thionyl chloride for 4 h. After removal of the thionyl chloride, fluorobenzene (5.6 mL, 5.76 g, 60 mmol) and anhydrous aluminum chloride (8.53 g, 64 mmol) were added to the oily residue and the reaction mixture was stirred at 140 °C for 3 h. After cooling to 70 °C, it was poured under vigorous stirring onto ice-water (500 g). The crude product was filtered off, washed with water, and recrystallized from ethanol to give (3,5-Dichlorophenyl)-(4-fluorophenyl)methanone (11.9 g, 73.6 %) as colorless crystals.Mp. 65-67 °C (ethanol);
1 H NMR (CDCl3, 200 MHz, 25 °C): δ 7.85 (2H, dd, J = 8.8 Hz, 4 JHF = 5.5 Hz); 7.61 (2H, d, J = 1.8 Hz); 7.58 (1H, d, J = 1.8 Hz); 7.20 (2H, t, J = 8.8 Hz). IR (KBr): 1663, 1598 cm-1. Anal. Calcd for C13H7Cl2FO (269.10): C, 58.02; H, 2.62; Cl, 26.35. Found: C, 57.80; H, 2.60; Cl, 26.07 %.
