Add TFTB-1, sodium hydroxide, ethanol and water to a 20L reaction flask, heat to 85 ° C, and keep the reaction for 3 hours. At the end of the reaction, vacuum distillation at 80-90 ° C until no liquid flows out. Add purified water and continue stirring. The mixture was cooled to room temperature, extracted with dichloromethane, and the aqueous layer was extracted with methylene chloride. The organic layer was combined, and the organic layer was washed with purified water. Filtration, evaporation of the filtrate, addition of acetone, reflux for 30 min, cooling to 20 ° C, filtration, filter cake into a dry box, drying at 60 ° C ± 5 ° C for 4 h, to obtain a white solid, that is, TFTB-2, yield 86%.