(1) Thermal reaction: 47.2 g (content of 95.0%, 0.8 mol) of KOH was added to the reaction system, and the reaction was carried out at 120° C. for 3 hours, and the rest of the operations were the same as that of Example 1; (2) Condensation reaction: according to the method of Example 1, the 4-(phenylbutoxy)benzoate shown in Formula (IV) was used as a raw material, and 101.9 g of 4-(phenylbutoxy)benzonitrile oil was obtained. The purity was 96.2% (GC) and the molar yield was 97.5% (calculated based on 4-chlorobenzonitrile); (3) Alcoholysis reaction: 4-(phenylbutoxy)benzonitrile oil (101.9 g, purity 96.2%, 0.33 mol) obtained above was mixed with 713.3 g of anhydrous methanol, and an alcoholysis reaction was carried out for 6 hr at 60 °C. The rest of the operation was the same as that in Example 5, to obtain 110.5 g of 4-(phenylbutoxy)benzoic acid methyl ester oil, with a purity of 98.8% (GC) and a molar yield of 98.4% (calculated based on 4-(phenylbutoxy)benzonitrile); (4) Hydrolysis reaction: 4-(phenylbutoxy)benzoic acid methyl ester oil (116.3 g, purity of 98.8%, 0.384 mol) obtained as described above was added to 200 ml of water, and solid KOH was used to adjust the aqueous solution to pH 14, and the temperature was raised to 80 °C for hydrolysis reaction for 3 h. After the reaction was completed, it was cooled to room temperature. After the reaction was completed, it was cooled to room temperature and adjusted to pH 2 with concentrated hydrochloric acid, and a large amount of white solid was precipitated. After filtration, the cake was washed with water to neutral pH and dried with hot air to give 79.1 g of 4-(phenylbutoxy)benzoic acid white crystals with a melting point of 130-131 °C, a molar yield of 98.7% (based on the calculation of 4-(phenylbutoxy)benzoic acid nitrile), and a purity of 99.3% (HPLC).
