General procedure for the synthesis of 2-hydrazinopyridine from 2-chloropyridine: To a solution of hydrazine hydrate (200 mL, 10 vol) of 2-chloropyridine (20 g, 0.176 mol, 1 eq.), the reaction was stirred for 48 hours at 100 °C. The progress of the reaction was monitored by thin layer chromatography (TLC, unfolding reagent ratio of 8:2 ethyl acetate and methanol), and after confirming that the feedstock was completely consumed, the reaction mixture was diluted with water (200 mL) and subsequently extracted with ethyl acetate (5 x 500 mL). The organic phases were combined, dried with anhydrous sodium sulfate (Na2SO4), and concentrated under reduced pressure to remove the solvent to afford the target product 2-hydrazinopyridine (15.0 g, 78% yield) as a red oil. The product was characterized by 1H NMR (300 MHz, CDCl3): δ 8.14 (1H, d, J = 3Hz, Ar-H), 7.51-7.45 (1H, m, Ar-H), 6.71-6.66 (2H, m, Ar-H), 5.78 (1H, brs, -NH), 3.81 (2H, brs, -NH2).LCMS ANALYSIS: The calculated value of C5H7N3[M+H]+ was 109.13 and the measured value was 110.1.
