C([Li])CCC.[Cl:6][C:7]1[CH:12]=[C:11]([O:13][C:14]([F:17])([F:16])[F:15])[CH:10]=[CH:9][C:8]=1Br.[C:19](=[O:21])=[O:20]>CCOCC>[Cl:6][C:7]1[CH:12]=[C:11]([O:13][C:14]([F:17])([F:16])[F:15])[CH:10]=[CH:9][C:8]=1[C:19]([OH:21])=[O:20]n-Butyllithium (2.5M in hexane, 38 ml) was added to a stirred, cooled solution of 2-chloro-4-trifluoromethoxybromobenzene (25 g) in ether while maintaining the temperature below 70° C. The mixture was stirred at -78° C. for 4 hours then poured onto solid carbon dioxide with stirring. The mixture was allowed to warm to room temperature and acidified to pH 1. The layers were separated and the organic layer was washed with water, dried (MgSO4) and filtered. The filtrate was evaporated to dryness and the residue was triturated with cyclohexane and filtered to give 2-chloro-4-trifluoromethoxybenzoic acid as a white solid mp 90.6°-91.2° C.
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