Sodium Hydroxide → 3-Chloro-4-(propan-2-yloxy)benzoic acid

Temperatur

80 °C

To methyl 3-chloro-4-hydroxy-benzoate (3.0 g, 16.1 mmol) in DMF (19 mL) was added potassium carbonate (8.9 g, 64.3 mmol) followed by 2-iodopropane (5.5 g, 3.2 mL, 32.2 mmol). The reaction mixture was heated at 60° C. for 1.5 hours. The reaction mixture was cooled, filtered and diluted with EtOAc and the solvent was concentrated in vacuo. The material was dissolved in EtOAc and washed with water (3×10 mL) and brine (1×10 mL). The organic layer was dried over Na2SO4, filtered and the solvent was removed in vacuo to give methyl 3-chloro-4-isopropoxybenzoate. To the ester was added dioxane (47 mL) and sodium hydroxide (42.7 mL of 1 M, 42.7 mmol) and the reaction was heated at 80° C. for 15 minutes. The reaction was cooled and solvent was removed in vacuo. The resulting residue was dissolved in water and washed with EtOAc (3×10 mL) and the layers were separated. The aqueous layer was acidified to pH 1 and was extracted with EtOAc (3×10 mL). The organic layer was separated and dried over Na2SO4, filtered and the solvent was removed in vacuo to yield 3-chloro-4-isopropoxy-benzoic acid (2.86 g, 83%) as a white solid. ESI-MS m/z calc. 213.6. Found 215.3 (M+1)+; Retention time: 1.51 minutes (3 min run). 1H NMR (400.0 MHz, CDCl3) δ 8.05 (d, J=2.2 Hz, 1H), 7.90-7.87 (dd, J=8.8, 2.2H, 1H), 7.06 (d, J=8.8 Hz, 1H) and 3.90 (s, 3H) ppm.