Ethanol → 1,2-Diamino-4,5-difluorobenzene

4,5-Difluoro-1,2-diaminobenzene was prepared using an adaptation of the method of Tsuji et al., Crsuji, Y. et al., J. Org. Chem. 55:580 (1990)). Zn powder (942 mg, 14.4 mmol), CaCl2 (94.4 mg), H2O (1.0 mL) and 4.0 mL EtOH were combined and brought to reflux as described for 4-fluoro-1,2-diaminobenzene (see Example 11) and to this mixture was added slowly dropwise a solution of 4,5-difluoro-2-nitroaniline (200 mg, 1.15 mmol) in 2 mL ETOH. Analysis and workup were as described for 4-fluoro-1,2-diaminobenzene (Example 11) except that the reaction was dissolved in 5 mL H2O and the solution extracted with 3×10 mL Et2O. The organic layers were combined and treated with activated charcoal, dried (MgSO4), and filtered through a pad of Celite. The solvent was evaporated at reduced pressure to yield 111.5 mg (67.3%) of a brown crystalline solid. 1H NMR (CDCl3) δ 3.34 (br s, 4H, NH2, 6.53 (t, 2H, ArH).

1. temperatureto reflux
2. extractionthe solution extracted with 3×10 mL Et2O
3. additiontreated with activated charcoal
4. dry with materialdried (MgSO4)
5. filtrationfiltered through a pad of Celite
6. customThe solvent was evaporated at reduced pressure

ORD record

ord-b616646760d046928159df051b201e1d

Source dataset

uspto-grants-2001_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06251903B1