Phosphorus oxychloride → 2-Chloro-4,4'-bipyridine

Temperature

110 °C

The suspension of 4,4′-bipyridine-1-oxide (8.50 g, 49.36 mmol) in phosphorus oxychloride (80 mL) was heated to 110° C. overnight. The mixture was concentrated and the residue was treated with saturated aqueous NaHCO3 solution (150 mL) slowly and then Na2CO3 solution (2M) until it was basic. The alkaline solution was extracted with chloroform (4×300 mL). The combined organic layer was dried, treated with activated carbon and filtered through celite. The filtrate was concentrated and the resulting solid was purified by flash column chromatography (4% MeOH in CH2Cl2) to give 2-Chloro-4,4′-bipyridine (3-2) as a off-yellow solid. 1H NMR (CDCl3) δ 8.77 (dd, 2H, J=4.5, 1.6), 8.53 (d, 1H, J=5.1), 7.58 (s, 1H), 7.52 (dd, 2H, J=4.7, 1.7), 7.46 (dd, 1H, J=5.2, 1.5).

1. concentrationThe mixture was concentrated
2. additionthe residue was treated with saturated aqueous NaHCO3 solution (150 mL) slowly
3. extractionThe alkaline solution was extracted with chloroform (4×300 mL)
4. customThe combined organic layer was dried
5. additiontreated with activated carbon
6. filtrationfiltered through celite
7. concentrationThe filtrate was concentrated
8. customthe resulting solid was purified by flash column chromatography (4% MeOH in CH2Cl2)

ORD record

ord-b2c282375c9e4c858b9f05362345d92d

Source dataset

uspto-grants-2006_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07125888B2