Step 2: Synthesis of 2-(4-chlorophenoxy)-2-methylpropionic acid
To a solution of ethyl 2-(4-chlorophenoxy)-2-methylpropionate (2.0 g, 8.24 mmol) in tetrahydrofuran (16 mL) was added sequentially water (4 mL) and lithium hydroxide monohydrate (0.69 g, 16.4 mmol) at room temperature. The reaction mixture was stirred at room temperature for 16 hours. After completion of the reaction, the mixture was diluted with water and washed with dichloromethane (DCM). The aqueous phase was separated and acidified with 1 M aqueous hydrochloric acid to pH about 2, followed by extraction with dichloromethane (DCM, 2 times). The organic extracts were combined, washed with brine, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to give 2-(4-chlorophenoxy)-2-methylpropionic acid (p-chlorophenoxyisobutyric acid) as a white solid (1.45 g, 82% yield).
1H NMR (400 MHz, chloroform-d): δ 1.62 (6H, s), 6.89 (2H, d, J = 9.0 Hz), 7.24 (2H, d, J = 9.0 Hz).
