4612-26-4

121-43-7

106-37-6

4612-26-4

Under the protection of nitrogen atmosphere, 200 mL of tetrahydrofuran (THF) was added to the reaction flask and cooled to 15°C. 0 g (0.62 mmol) of magnesium and 1.0 g (0.004 mol) of iodine were slowly added followed by the dropwise addition of 300 mL of THF solution containing 68.4 g (0.29 mol) of 1,4-dibromobenzene at a controlled titration rate maintaining the reaction temperature at 30°C. The reaction was continued for 3 hours. After completion, the reaction was continued for 3 hours. After completion of the reaction, the reaction mixture was cooled to -70°C and a mixed solution consisting of trimethyl borate (78.5 mL, 0.72 mol) and 300 mL of THF was slowly added dropwise. After the dropwise addition was completed, the reaction was continued at -70°C for 1 hour, then slowly warmed to room temperature and stirred for 12 hours. To the reaction mixture was added 950 mL of 2.5 M hydrochloric acid, stirred rapidly for 15 minutes and the solid product was collected by filtration. The solid was washed 3 times with 300 mL of hexane and finally dried under vacuum to give 40.7 g of white solid 1,4-phenylenediboronic acid in 84.6% yield.