Benzene → 2,4-Difluoro-1,1'-biphenyl

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of 25.0 g. of trichloroacetic acid in 250 ml. of benzene was added 2.0 g. of copper powder and 20 g. of anhydrous magnesiumsulfate, and the mixture cooled to +5° C. At this temperature, 14 g.of isopropyl nitrite was quickly added, immediately followed by the dropwise addition of a solution of 12.9 g. of 2,4-difluoroaniline in 100 ml. of benzene over about 20 min. The temperature was kept at 10°-15° C. throughout the addition, then gradually let warm to 25° C. After 1 to 11/2 hours the nitrogen gas evolution subsided, the solids were filtered off, and the filtrate washed with water5 × 500 ml. to neutrality. The organic layer was dried over 20 g. of magnesium sulfate, treated with 3 g. of charcoal, filtered and concentraedunder vacuum to an oil. This oil was dissolved in 150 ml. of hexane and stirred with 5 g. of silica gel, which removed most of the color. Upon filtration, the pale yellow filtrate was concentrated under reduced pressure to give 17.5 g (91%) of off-white crystalline 2,4-difluorobiphenyl (II), m.p. 59.5°-63°., quant. vpc showing 95% purity. All physical data obtained confirmed the structure.

Provenance & Evidence