Synthesis
233g (1.0mol) of 2-bromobiphenyl and 1400ml of THF were added to a 5000ml four-necked flask. Butyllithium solution (1.2mol) was added dropwise between -50℃ and -65℃. After the addition was complete, the temperature was maintained for 1 hour, and the reaction was monitored by gas chromatography until the reactants were fully reacted. 244.5g (1.3mol) of triisopropyl borate was added dropwise at -50℃, maintaining the temperature below -5℃. After the addition was complete, the temperature was maintained at this level for 1 hour, then allowed to rise naturally to room temperature. Hydrochloric acid was added to adjust the pH to 1, causing the mixture to separate into layers. The THF was removed under reduced pressure, and water was added to form a slurry. The mixture was then filtered, and the filter cake was further slurried with toluene and dried to obtain 169g of 2-biphenylboronic acid. The HPLC purity was 99.3%, and the yield was 85.5%.
