Benzene → 3,4,5,6-Tetrafluorobenzene-1,2-diamine

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Reaction Steps

3,4,5,6-Tetrafluoro-1,2-diaminobenzene was prepared using an adaptation of the method of Tsuji et al., J. Org. Chem. 55: 580 (1990). A suspension of Zn powder (1.95 g, 29.8 mmol), CaCl2 (195 mg) and H2O (2.3 mL) in 7 mL EtOH was heated to reflux with stirring under N2. To this was added slowly dropwise a solution of 2-nitro-3,4,5,6-tetrafluoroaniline (2 g, 12.8 mmol) in 5mL EtOH. The reaction mixture was refluxed 5 h. TLC analysis (silica gel, 2:1 benzene:EtOAc) indicated complete disappearance of the starting material. The Zn was removed by vacuum filtration, and the Zn rinsed with EtOH (30 mL). The solvent was rotary evaporated and the residue was dissolved in 20 mL Et2O and the solution washed with 2×15 mL H2O and 15 mL sat'd NaCl. The organic layer was dried (MgSO4) and vacuum filtered. The solvent was rotary evaporated to yield 396.6 mg (92.5%) of a purple brown solid, mp 120°-125° C., that was used without further purification.

Provenance & Evidence