The general procedure for the synthesis of 3,5-dicyanofluorobenzene from 3,5-dibromofluorobenzene and cuprous cyanide was as follows: a mixture of 3,5-dibromofluorobenzene (30 g, 120 mmol) and cuprous cyanide (I) (42.1 g, 470 mmol) in N,N-dimethylformamide (DMF, 200 mL) was heated and refluxed for 16 hours. After completion of the reaction, the reaction mixture was concentrated under reduced pressure and the residue was suspended with dichloromethane (DCM, 350 mL). The brown precipitate was removed by Arbocel filtration. The filtrate was concentrated by evaporation under reduced pressure and the residue was partitioned between water (50 mL) and dichloromethane (150 mL), the organic layer was separated, dried over anhydrous sodium sulfate and subsequently concentrated under reduced pressure to give a yellow solid product. The solid was dissolved in ether (400 mL), washed sequentially with water (2 x 50 mL) and saturated saline, dried over anhydrous sodium sulfate and concentrated under reduced pressure to give 3,5-dicyanofluorobenzene in 52% (9.2 g) yield. The melting point of the product was 98-100 °C. 1H NMR (400 MHz, CD3OD) δ: 8.29 (m, 2H), 8.36 (m, 1H).
