[NH2:1][C:2]1[CH:10]=[CH:9][C:8]([Br:11])=[CH:7][C:3]=1[C:4](O)=[O:5].Cl.[N:13]([O-])=O.[Na+].[O-]S([O-])=O.[Na+].[Na+]>O>[Br:11][C:8]1[CH:7]=[C:3]2[C:2](=[CH:10][CH:9]=1)[NH:1][N:13]=[C:4]2[OH:5]To a solution of 2-amino-5-bromobenzoic acid (50 g) in water (200 mL) was added HCl (46 mL). To the mixture was added aqueous NaNO2 solution (17.7 g/37 mL) at 0° C., and the mixture was stirred at 0° C. for 30 minutes. To the reaction solution was added dropwise aqueous Na2SO3 solution (79.3 g/200 mL) at 0° C., and the mixture was stirred at room temperature for 2 hours. To the mixture was added HCl (70 mL), and the mixture was stirred at room temperature for 18 hours and then at 80° C. for 4 hours. The precipitated solid was dissolved by basifying the reaction solution, and then the solution was acidified to precipitate a solid. The solid was collected by filtration and dried under reduced pressure to give Compound Q2 (36 g).
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