453565-90-7

453565-89-4

453565-90-7

4-Amino-3-bromo-5-(trifluoromethoxy)benzoic acid (1.5 g, 5 mmol) was used as starting material, which was mixed with ethanol (15 mL) at 0 °C. Subsequently, concentrated sulfuric acid (2.26 g, 10.2 mmol) was slowly added. An aqueous solution (1.2 mL) of sodium nitrite (0.38 g, 5.5 mmol) was added dropwise at 0 °C and the dropwise process lasted for 1 hour. After the reaction mixture was gradually warmed to room temperature, it was heated to reflux for 45 min. Upon completion of the reaction, the reaction was terminated by the addition of water. The reaction mixture was extracted with dichloromethane and the organic phase was separated. The dichloromethane layer was dried and concentrated to give the crude product. The crude product was dissolved in 1M sodium hydroxide solution and extracted with ether to remove impurities. The aqueous phase was acidified with 2M HCl to pH=2 and precipitated as a solid, which was filtered and dried to give the target product 3-bromo-5-(trifluoromethoxy)benzoic acid (1.08 g, 75.5% yield).