Reaktion #82589

Reaktionsgleichung

CaCl2

H2O

2-nitro-3,4,5,6-tetrafluoroaniline

benzene

→

3,4,5,6-Tetrafluoro-1,2-diaminobenzene

Lösungsmittel

EtOH

EtOH

EtOAc

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturwas heated m
2. 2
   Temperaturreflux
3. 3
   TemperaturThe reaction mixture was refluxed 5 h
4. 4
   SonstigeThe Zn was removed by vacuum filtration
5. 5
   Waschenthe Zn rinsed with EtOH (30 mL)
6. 6
   SonstigeThe solvent was rotary evaporated
7. 7
   workup.DISSOLUTIONthe residue was dissolved in 20 mL Et2O
8. 8
   Waschenthe solution washed with 2×15 mL H2O and 15 mL
9. 9
   TrocknenThe organic layer was dried (MgSO4) and vacuum
10. 10
    Filtrationfiltered
11. 11
    SonstigeThe solvent was rotary evaporated

Vorschrift

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 m 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 5 mL 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.

Quelle