2,4,6-Tribromopyridine

Synthesis

98027-81-7

506-96-7

2408-70-0

2,6-Dibromo-4-nitropyridine nitride (2.0 g, 0.007 mol) was dissolved in glacial acetic acid (35 mL) in a three-necked round-bottomed flask fitted with a magnetic stirrer, a condenser tube, and nitrogen protection. Acetyl bromide (1.0 mL, 0.013 mol) was added slowly and dropwise at 60 °C and under nitrogen atmosphere. The reaction mixture was stirred under nitrogen protection at room temperature for 0.5 hr and then warmed up to 80 °C for 2 hr. After completion of the reaction, it was cooled to room temperature, the reaction mixture was filtered, the residue was washed with a small amount of glacial acetic acid and dried with KOH under vacuum. The dried product was dissolved in chloroform (25 mL) in a three-necked round-bottomed flask equipped with a magnetic stirrer, condenser tube and nitrogen protection. Phosphorus tribromide (7.9 mL, 0.084 mol) was added dropwise at room temperature and protected by nitrogen, and after continued stirring for 1 hour, the reaction was warmed up to 65 °C for 24 hours. Upon completion of the reaction, the reaction was cooled to room temperature and the reaction mixture was neutralized with saturated aqueous sodium bicarbonate, followed by extraction with dichloromethane three times. The organic layers were combined and concentrated under reduced pressure to give a white powdery product. Purification by ethanol recrystallization gave 2,4,6-tribromopyridine (1.33 g, yield 62.7%) as white crystalline powder. Melting point: 100-102°C. Elemental analysis (calculated value, C5H2Br3N): C, 19.02; H, 0.64; N, 4.44. Measured value: C, 18.88; H, 0.59; N, 4.84.

References