P-chlorobenzene acetic acid, phthalic anhydride and freshly melted sodium acetate were added to the reaction kettle in a certain ratio. The reaction was rapidly heated to about 250 °C and continuously stirred at 240-250 °C for 3 h. The water generated during the reaction was discharged through the tail of the reactor. Subsequently, the reaction mixture was transferred to an open heat-resistant vessel and continued to be heated. After the reaction mixture cooled, cold anhydrous ethanol was added. The mixture was heated until the solid was as dissolved as possible, then cooled and filtered. The filter cake was washed with anhydrous ethanol, filtered again and dried. The dried solid was dissolved in aqueous sodium hydroxide solution and stirred under reflux conditions for 4 hours. After completion of the reaction, the mixture was cooled, diluted with water and acidified with 20% hydrochloric acid to pH 2-3. After stirring and cooling, a solid oily precipitate was formed. The precipitate was filtered and dried to give the crude product. The crude product was evaporated from acetone by dissolving in acetone and filtering out the insoluble material. The residue was recrystallized with ethyl acetate to give the final target product 2-(4-chlorophenylacetyl)benzoic acid. The product had a melting point of 142-144 °C and a yield of 80%.
