4,4'-Diamino-2,2'-bipyridine

51595-55-2

18511-69-8

General procedure for the synthesis of 4,4'-diamino-2,2'-bipyridine N,N'-dioxide from 4,4'-dinitro-2,2'-bipyridine N,N'-dioxide: first, a 38 mL ethanol mixture containing 350 mg of 4,4'-dinitro-2,2'-bipyridine N,N'-dioxide and 630 mg Pd/C (5%) was purged with nitrogen. Subsequently, the suspension was heated to reflux under nitrogen protection. After the reactants were completely dissolved, 2.7 mL of a 10 mL ethanol solution of hydrazine hydrate was added slowly and dropwise over a period of 20 min. The reaction mixture was kept at reflux for 15 hours. Immediately after completion of the reaction, the mixture was filtered under reduced pressure and washed with boiling ethanol. After solvent removal, the resulting yellow precipitate was ground in 20 mL of water and allowed to stand overnight at 2°C. The white solid was isolated by vacuum filtration, washed with cold water and dried at 50 °C. A final 195 mg of white powdery product was obtained in 83% yield.