93224-85-2

off-white powder

2-Bromo-6-chlorobenzoic acid is used in the syntheis of Diclofenac Monobromo Sodium Salt Impurity (D436490).

Step 1. Synthesis of 2-bromo-6-chlorobenzoic acid: Diisopropylamine (3.5 mL, 25 mmol) was slowly added to a tetrahydrofuran (THF, 70 mL) solution of n-butyllithium (n-BuLi, 10 mL, 25 mmol, 2.5 M hexane solution) cooled at -78 °C under anhydrous conditions. After stirring the reaction mixture for 15 minutes, 1-chloro-3-bromobenzene (4.32 g, 25 mmol) was added dropwise and stirring was continued at -78 °C for 2 hours. Subsequently, dry ice (solid CO2) was added to the reaction system and after 15 min of reaction, aqueous 2N hydrochloric acid (100 mL) was slowly added to quench the reaction. The reaction mixture was extracted with ethyl acetate (EtOAc) and the organic phases were combined. The product was purified by recrystallization from hexane and finally isolated to give 5 g of 2-bromo-6-chlorobenzoic acid in 85% yield.

[1] Organic Letters, 2009, vol. 11, # 5, p. 1051 - 1054
[2] Tetrahedron Letters, 1997, vol. 38, # 9, p. 1559 - 1562
[3] Patent: WO2008/124582, 2008, A1. Location in patent: Page/Page column 117
[4] Patent: WO2008/124575, 2008, A1. Location in patent: Page/Page column 108
[5] Organic Process Research and Development, 2005, vol. 9, # 6, p. 764 - 767