Dimethylformamide → 4-Amino-2,3-difluorobenzonitrile

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A stirred mixture of the crude 4-bromo-2,3-difluoroaniline, 36 g of cuprous cyanide and 908 mL of DMF is heated 7 hours at reflux under an N2 atmosphere. After cooling, 900 mL of 10% aqueous NaCN is added and 45 minutes later 2 L of H2O. The black solution is extracted three times with CH2Cl2 (total volume 4 L). The CH2CL2 extract is washed with H2O, saturated NaHCO3 and H2O (500 mL of each) and then stripped in vacuo. The resulting black oil is purified by dry-column chromatography on silica gel using CH2CL2 as eluent. There is obtained 31.17 g (55% overall yield) of 4-amino-2,3-difluorobenzonitrile, m.p. 108°-110° C., with the expected ion at 156 in the mass spectrum and consistent NMR and IR spectral data.

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