Example 13
13.1 Synthesis of methyl 3-bromo-4-chlorobenzoate (13.1). A round bottom flask was charged with 3-bromo-4-chlorobenzoic acid (5.0 g, 21.2 mmol, CAS No. 42860-10-6, available from Aldrich), methanol (60 mL), and a cooled sulfuric acid solution (1.4 mL). The reaction mixture was heated to 80 °C and the progress of the reaction was monitored by thin layer chromatography (TLC). After 17 hours of reaction, it was cooled to room temperature and diluted with water. The aqueous phase was extracted with ether (3 x 50 mL), the organic layers were combined and dried with anhydrous magnesium sulfate. After filtration, the organic solvent was removed by distillation under reduced pressure to give a white solid product 13.1 (5.0 g, 96% yield). The 1H NMR (400 MHz, CDCl3) data of the product were as follows: δ 8.28 (1H, d, J = 2.0 Hz), 7.93 (1H, m), 7.52 (1H, d, J = 8.2 Hz), 3.93 (3H, s).
