1,3-Dibromobenzene → (3-Bromophenyl)boronic acid

N-Butyllithium (2.5M; 44 mL; 0.11M) was added dropwise over 15 mins. to a vigorously stirred solution of m-dibromobenzene (25 g; 0.106M) in 500 mL of anhydrous ether at -78° under nitrogen. After stirring 10 mins. more, a solution of triisopropylborate (25.3 mL; 0.11M) in anhydrous ether (200 mL) was added over 20 mins. The cooling bath was then removed, and the stirring solution was allowed to warm to R.T. over ~2 hrs. A small amount of solid separated. After stirring 15 mins. more at R.T., 150 mL of ice cold 8% aqueous hydrochloric acid was cautiously added, and the stirring was continued for 15 mins. The organic phase was separated, washed with 2×100 mL of saturated sodium chloride solution, and dried over anhydrous magnesium sulfate. Solvent removal gave -30G of crude product as a semi-solid, which was shaken well with 150 mL of hexane. The solid was filtered and washed with 2×25 mL of hexane. The resulting silky solid (mp 178°-9° C. after softening at ~160° C.) (6.5 g) was used as 3-bromophenylboronic acid with a small amount of contamination. The hexane filtrate was concentrated and the residue was stirred well with 150 mL of petroleum ether (30°-60°). The resulting solid was filtered and washed with 2×25 mL of petroleum ether. This resulting solid (4.4 g) melting at 178.3°-179° C. was the desired 3-bromophenylboronic acid.

1. customat -78°
2. customThe cooling bath was then removed
3. customA small amount of solid separated
4. stirringAfter stirring 15 mins
5. additionmore at R.T., 150 mL of ice cold 8% aqueous hydrochloric acid was cautiously added
6. waitthe stirring was continued for 15 mins
7. customThe organic phase was separated
8. washwashed with 2×100 mL of saturated sodium chloride solution
9. dry with materialdried over anhydrous magnesium sulfate
10. customSolvent removal
11. customgave -30G of crude product as a semi-solid, which
12. filtrationThe solid was filtered
13. washwashed with 2×25 mL of hexane
14. customThe resulting silky solid (mp 178°-9° C. after softening at ~160° C.) (6.5 g)
15. concentrationThe hexane filtrate was concentrated
16. stirringthe residue was stirred well with 150 mL of petroleum ether (30°-60°)
17. filtrationThe resulting solid was filtered
18. washwashed with 2×25 mL of petroleum ether

ORD record

ord-0533ff14ca5b46eb8dda6070b31cc8d7

Source dataset

uspto-grants-1994_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05342933