Boron tribromide → 4-(2,6-Dibromo-4-nitrophenoxy)-2-isopropylphenol

Participants

Reaction Conditions

Reaction Steps

A 12 L three-necked round bottom flask equipped with a mechanical stirrer, an addition funnel, and a temperature probe was charged with 4-(2,6-dibromo-4-nitrophenoxy)-2-isopropylanisole (752.1 g, 1.69 moles), which was dissolved by stirring in dichloromethane (2 L) at room temperature. The mixture was cooled to 8.7° C. in an ice-water bath. A solution of boron tribromide (2.050 L, 1M in CH2Cl2, 2.05 moles) was added over 30 min. An increase of approximately 10° C. in the temperature of the reaction mixture was observed. The ice-water bath was removed and the reaction mixture was allowed to stir at room temperature until the reaction was complete, as assayed by HPLC. The reaction mixture was cooled once more in an ice-water bath, then quenched by slow addition of methanol (850 mL), during which the temperature of the reaction mixture was maintained below 18° C. Saturated aqueous sodium bicarbonate solution was added until the pH of the reaction mixture was 6 or 7. The aqueous phase was separated and washed with aliquots of ethyl acetate (2×1 L). The organic layers were combined and the solvent removed under a vacuum at room temperature to yield crude 4-(2,6-dibromo-4-nitrophenoxy)-2-isopropylphenol (796 g, 110%).

Provenance & Evidence