N([O-])=O.[Na+].N[C:6]1[C:14]([Br:15])=[CH:13][C:12]([CH3:16])=[CH:11][C:7]=1[C:8]([OH:10])=[O:9].[ClH:17].O>C(O)(=O)C>[Br:15][C:14]1[C:6]([Cl:17])=[C:7]([CH:11]=[C:12]([CH3:16])[CH:13]=1)[C:8]([OH:10])=[O:9]The diazonium chloride of 2-amino-3-bromo-5-methylbenzoic acid is obtained by running an aqueous sodium nitrite solution (0.013 mol) dropwise at -5° C. onto a solution containing 0.0109 mol of 2-amino-3-bromo-5-methylbenzoic acid, 10 ml of hydrochloric acid, 10 ml of water and 30 ml of acetic acid. The reaction mixture is then stirred at 0° C. for 30 minutes and then poured into a large-volume round-bottomed flask containing 0.013 mol of cuprous chloride in 10 ml of acetic acid. The mixture obtained is brought to 60° C., stirred for 2 hours, and then hydrolysed after cooling by addition of ice. The precipitate obtained is filtered and washed with water. 3-Bromo-2-chloro-5-methylbenzoic acid is obtained: (Yield 58%, M.p. 160° C.).
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