Ethanol → 3-Bromo-4,5-difluorobenzene-1,2-diamine

3-Bromo-4,5-difluoro-1,2-diaminobenzene was prepared using an adaptation of the method of Bellamy et al. (Bellamy, F. D. et al., Tetrahedron Lett. 25:839 (1984)). A mixture of 2-bromo-3,4-difluoro-6-nitroaniline (700 mg, 2.78 mmol) and SnCl2.2H2O (3.14 g, 13.9 mmol) dissolved in 7 mL ethyl acetate and 3 mL absolute ethanol under N2 was heated at 75° C. for 2 h. All the starting material had reacted as evidenced by TLC (silica gel, 2:1 hexanes:ethyl acetate). The reaction was allowed to cool to room temperature and poured into 20 mL crushed ice. Sufficient sat'd NaHCO3 solution was added (foaming!) to bring the pH to 5. The thick yellow white emulsion was then extracted with 3×25 mL ethyl acetate and the combined organic extracts washed with sat'd NaCl solution. The organic phase was dried (MgSO4), vacuum filtered and the solvent rotary evaporated to yield a dark brown oil which crystallized on standing to yield 410 mg (66%). 1H NMR (CDCl3) δ3.59 (br s, 4H, 2(NH2)); 6.52 (m, 1H, H-6).

1. customAll the starting material had reacted
2. additionpoured into 20 mL
3. customcrushed ice
4. additionwas added (foaming!)
5. extractionThe thick yellow white emulsion was then extracted with 3×25 mL ethyl acetate
6. washthe combined organic extracts washed with sat'd NaCl solution
7. dry with materialThe organic phase was dried (MgSO4), vacuum
8. filtrationfiltered
9. customthe solvent rotary evaporated
10. customto yield a dark brown oil which
11. customcrystallized
12. customto yield 410 mg (66%)

ORD record

ord-38b3ca32af194bfbb249e90176b92911

Source dataset

uspto-grants-1997_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05622952