1-Bromo-4-chloro-2-fluorobenzene synthesis

Yield:-

Reaction Conditions:

Stage #1: 2-fluoro-4-chloroanilinewith hydrogen bromide;sodium nitrite in water at -10; for 0.5 h;
Stage #2: with hydrogen bromide;copper(I) bromide in water at -10 - 55; for 0.333333 h;

Steps:

1.G PROTOCOL G: General procedure for the synthesis of elaborated aryl bromides from anilines; Synthesis of 4-CHLORO-2-FLUORO-1-BROMOBENZENE

[0146] Sodium nitrite (2.35 g, 34.13mmol) solution (40 mL) was added dropwise to 4- Chloro-2-fluoro aniline (4. [5G,] 31mmol) in 170 mL HBr [AT-10°C] bath temperature, then the mixture was stirred for 30 min at-10°C bath temperature. In parallel, copper sulfate (10.22g, 24. [29MMOL)] and sodium bromide (3.79 g, 36. [8MMOL)] were mixed and the reaction mixture was heated at [60°C] for 30 min. Then sodium sulfite (2.66g, 21. [2MMOL)] was added into this copper sulfate reaction mixture and heated for [95°C] for 30 min. The reaction mixture was cooled to room temperature and solid formed was washed with water to afford white solid cuprous bromide. The diazonium salt was portion wise added into the freshly prepared cuprous bromide in 40 mL HBr [AT-10°C] bath temperature and the reaction mixture was then warmed to room temperature. The reaction mixture was heated at [55°C] for 20 min, cooled and then extracted with ethyl acetate three times. The combined organic layer was washed with water and saturated brine solution, dried over sodium sulfate and concentrated. The crude material was purified by column chromatography (5: 95 ethyl acetate: pet ether) to afford solid product.

References:

WO2003/105853,2003,A1 Location in patent:Page 58