General procedure for the synthesis of 5-chloro-2-methoxybenzoic acid from methyl 5-chloro-2-methoxybenzoate: to a 1 M aqueous sodium hydroxide solution (60 mL, 0.06 mol) was added a solution of methyl 5-chloro-2-methoxybenzoate (2.0 g, 0.01 mol) [Alfa Aesar] in ethanol (60 mL). The reaction mixture was stirred at room temperature for 4 h. The progress of the reaction was monitored by thin layer chromatography (TLC) until completion of the reaction. Subsequently, the reaction mixture was concentrated under reduced pressure to remove ethanol and the residue was separated by extraction with ethyl acetate. The aqueous phase was cooled in an ice bath and the pH was adjusted with concentrated aqueous hydrochloric acid to 2. After continued stirring in an ice bath for 1 h, the precipitated solid was collected by filtration, washed with water and dried in air to afford 1.4 g (74.9% yield) of the target product, 5-chloro-2-methoxybenzoic acid, as a white solid. Mass spectrum (MS): m/z 185.1 (MH+). 1H NMR (500 MHz, DMSO-d6): δ 3.818 (s, 3H), 7.162 (d, 1H), 7.551 (dd, 1H), 7.607 (d, 1H).
