To a three-neck flask equipped with a stirrer, a nitrogen introduction tube and a Dean-Stark splitter, 228 g of potassium carbonate (Aldrich, reagent grade), 200 g of 4,4'-difluorodiphenylsulfone and 155 g of phenol were sequentially added. The system was subjected to nitrogen displacement and the dehydration reaction was carried out at 150 °C in a solvent mixture of 500 mL of N,N-dimethylacetamide (DMAc) and 200 mL of toluene. The toluene was then evaporated at elevated temperature and the reaction was continued at 165°C for 2 hours. Upon completion of the reaction, the mixture was separated and extracted using a chloroform/water system, and the resulting organic phase was washed with methanol and dried to give 221 g of 4,4'-diphenoxy diphenyl sulfone. Next, 221 g of 4,4'-diphenoxy diphenyl sulfone was dissolved with 227 g of aluminum chloride in 570 mL of dichloromethane, and a dichloromethane solution (100 mL) containing 224 g of 4-fluorobenzenesulfonyl chloride was slowly added dropwise at 0 °C. After the dropwise addition was completed, the reaction was gradually warmed to room temperature and continued for 4 hours.
