c) Preparation of 3-(2-fluorophenyl)propionic acid
A mixture of ethyl 3-(2-fluorophenyl)propionate (25.54 g, 0.130 mol) with 50% aqueous sodium hydroxide solution (30 mL) in water (130 mL) was refluxed for 2 hours. Upon completion of the reaction, the mixture was cooled to room temperature and subsequently washed with ether (2 x 100 mL) to remove organic impurities. The aqueous phase was cooled in an ice bath and the pH was adjusted to 3 by slow dropwise addition of hydrochloric acid to promote precipitation of 3-(2-fluorophenyl)propionic acid. The white precipitate formed was collected by filtration and washed several times with water to remove residual inorganic salts. Finally, the product was dried under vacuum at 60 °C for 18 h to afford 18.66 g (85% yield) of 3-(2-fluorophenyl)propionic acid as a white solid with a melting point of 72°-74 °C. The purity of the product met the requirements for subsequent use without further purification.
