Benzene → 3-Bromo-2-chloro-4,5-difluorobenzonitrile

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Reaction Steps

3-Bromo-2-chloro-4,5-difluorobenzenediazonium tetrafluoroborate (35.6 g) was added portionwise during 40 minutes to a solution of cuprous cyanide (18.67 g), potassium cyanide (27.14 g) and sodium carbonate (5.52 g) in water (200 ml) with stirring vigorously at room temperature. After the mixture was stirred for 4.5 hours, benzene (250 ml) was added to the suspension and then the mixture was stirred for 25 minutes. The insoluble materials were collected by filtration, and washed with benzene. The filtrate and washings were combined and washed with water, dried over ahhydrous sodium sulfate and then concentrated. The resulting residue was purified by silica gel chromatography eluting with dichloromethane-n-hexane (1:3) and further recrystallized from n-hexane-dichloromethane to give the title compound (10.9 g) as light yellow needles, mp 71°-72.5° C.

Provenance & Evidence