Toluene → p-Chlorophenylboric acid

Participants

Reaction Conditions

Reaction Steps

4-Bromochlorobenzene (70.6 g) is added into a four mouth flask connecting with a mechanical stirring apparatus, two constant pressure funnels and a temperature probe. Toluene (588.3 ml) and tetrahydrofuran (THF) (147 ml) are added under stiffing at room temperature under argon, and dissolved to obtain a colorless transparent liquid. Then triisopropyl borate (109.2 ml) and n-butyllithium (176.4 ml, 2.5M in hexane) are respectively added into two constant pressure funnels, and cooled the inner temperature to below −78° C., then n-butyllithium solution is dropped to the flask under controlling a dropping speed to keep the inner temperature below −78° C. After addition, the mixture is kept at the temperature for 1 hour, then triisopropyl borate is dropped into the mixture under the temperature below −78° C., and kept at the temperature for 1 hour after addition, and then the cooling system is removed to naturally warm up to −20° C. HCl solution (360.4 ml, 2.2M) is added to the mixture to warm up to about 10° C., and then placed for layer separation. The aqueous phase is reextracted with toluene (58.8 ml, 2 times). The organic phase is combined together and washed with saturated brine to pH=7 to obtain a colorless transparent liquid, dried with anhydrous sodium sulfate, filtered, and evaporated under reduced pressure to remove most of solvents and the white solid is finally precipitated, filtered to obtain a crystal of 4-chlorophenylboric acid (48 g).

Provenance & Evidence