Trifluoroacetic acid → 1,1-Di(p-fluorophenyl)urea

Participants

Reaction Steps

Di(p-fluorophenyl)amine (102.5 g., 0.5 mole) and NaOCN (65 g, 1.0 mole) were stirred in 700 ml CH2Cl2 at 16° C. F3CCOOH (84.5 ml, 117 g, 1.025 mole) was added as a thin stream over 5 minutes, during which the reaction mixture exothermed to 28° C. The exotherm peaked at 32° C. shortly after addition was complete. The reaction mixture was stirred at 23°-25° for 21 hours, diluted with 350 ml H2O and stirred 0.5 hour. The organic layer was separated and stirred 0.25 hour with 40 g NaOH in 500 ml H2O. The layers were separated, and the aqueous layer back washed with 100 ml CH2Cl2. The combined organic layer and back wash was dried (MgSO4), concentrated to 600 ml, diluted with 600 ml isopropanol, reconcentrated to 600 ml, rediluted with 600 ml of fresh isopropanol, reconcentrated to 800 ml, rediluted with 400 ml fresh isopropanol and again reconcentrated to 800 ml. The mixture was cooled to room temperature (product began to crystallize) and then to 0°-5° C. Title product was recovered by filtration, 104.9 g, m.p. 150°-153° C.

Provenance & Evidence