Catechol → 2-Bromo-1,3,2-benzodioxaborole

Solid catechol (800 gms) was added (via a Gooch tube connected to an Erlenmeyer flask) to a 12 liter round bottom flask containing BBr3 (2 kg) in methylene chloride (3.5 liters) at -78° C. over a 6 hour period. The reaction mixture was slowly warmed to ambient temperature and stirred overnight. The solvent and excess hydrogen bromide were removed by distillation at 20 mm Hg. The residue was transferred in a minimal amount of methylene chloride to a 5 liter three neck round bottom flask and evacuated overnight at 30 mm. At this point the reaction product was very crystalline. The solid was warmed cautiously to a melt while slowly reducing the pressure. Ultimately, at a pressure of 10-15 mm an a mantle temperature of about 130° C., there was formed a colorless distillate at a head temperature of about 95° C. The liquid crystallized rapidly on cooling. The solid was transferred to Teflon bottles to yield 1.32 kg (92% yield) of 2 -bromo-1,3,2 benzodioxaborole, a colorless, fuming, pourable solid.

1. customconnected to an Erlenmeyer flask
2. customThe solvent and excess hydrogen bromide were removed by distillation at 20 mm Hg
3. customevacuated overnight at 30 mm
4. temperatureThe solid was warmed cautiously to
5. customUltimately, at a pressure of 10-15 mm an a mantle temperature of about 130° C., there was formed a colorless distillate at a head temperature of about 95° C
6. customThe liquid crystallized rapidly
7. temperatureon cooling

ORD record

ord-c68dc0ed2aba4b3ea426b2fa4957de7e

Source dataset

uspto-grants-1987_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04652635