Phosphorus oxybromide → 2,9-Dibromo-1,10-phenanthroline

Participants

Reaction Conditions

Reaction Steps

Under a stream of argon, to compound (9) (8.4 g; 29.1 mmol), phosphorus oxybromide (3.25 g; 174 mmol) and phosphorus pentachloride (15.4 g; 35.8 mmol) were added in an ice bath. The reaction temperature was raised to 65 to 75° C., and the resulting reaction mixture was stirred for 5.5 hours. The reaction mixture was cooled in an ice bath and evaporated under reduced pressure. Excess phosphorus oxybromide was removed and the resulting reaction concentrate was poured into ice water, and was made alkaline with concentrated aqueous ammonia. While solids which precipitated out were separated by filtration, they were washed with water to give crude title compound (10). The crude compound (10) was dried, and separated and purified by silica gel column chromatography (SiO2 300 g) (CHCl3/methanol=50/1 to 40/1 to 30/1) to give 8 g (yield: 81%) of the title compound (10).

Provenance & Evidence