General procedure for the synthesis of 3-chloro-4-fluorobenzoic acid from 3-chloro-4-fluorobenzoyl chloride: 2 g of 3-chloro-4-fluorobenzoyl chloride (99.6% purity, GC [a/a]) was mixed with 4 g of 50% sodium hydroxide solution and 20 g of water, and the reaction was carried out at 60 °C with cautious hydrolysis. After completion of the reaction, the reaction solution was continued to be stirred at room temperature for 2 hours. Subsequently, the reaction mixture was acidified with concentrated hydrochloric acid to pH 1. The precipitated 3-chloro-4-fluorobenzoic acid was washed sequentially with dilute hydrochloric acid and water and then dried. 1.68 g of white powdery 3-chloro-4-fluorobenzoic acid was finally obtained in 92.8% yield of the theoretical value. Melting point of the product: 136 °C (literature value: 136 °C).
