4,4’-Difluoro-2,2’-bipyridine

18511-69-8

1189458-67-0

The general procedure for the synthesis of 4,4'-diamino-2,2'-bipyridine from 4,4'-diamino-2,2'-bipyridine was as follows: in a polyethylene reaction vessel, 4,4'-diamino-2,2'-bipyridine (2.00 g, 10.7 mmol), hydrogen fluoride-pyridine complex (65% HF, 31.5 g, 1.02 mol) and toluene ( 30mL). After cooling the mixture to -4°C, sodium nitrite (1.85 g, 26.8 mmol, 2.5 equiv) was added to the reaction vessel. The mouth of the reaction vessel was sealed with polyethylene film and the mixture was stirred at room temperature for 18 hours. Upon completion of the reaction, the pyridine layer was separated by pipette and subsequently alkalized with aqueous sodium hydroxide to pH=10. The alkalized mixture was filtered and the filtrate was extracted with ethyl acetate. The organic layers were combined and dried over anhydrous sodium sulfate. After evaporation of the solvent, the residue was sublimated in vacuo to afford the target product 4,4'-difluoro-2,2'-bipyridine (0.752 g, 36% yield). Product characterization: colorless needle-like crystals. 1H NMR (300MHz, CDCl3) δ 8.64 (dd, J=8.4Hz, 5.4Hz, 2H), 8.18 (dd, J=9.9Hz, 2.4Hz, 2H), 7.08 (dd, J=7.8Hz, 5.4Hz, 2.4Hz, 2H). 19F NMR (283MHz , CDCl3) δ -111.68 to -111.59 (m).