General procedure for the synthesis of 2-chloro-6-hydrazinopyridine from 2,6-dichloropyridine: 2,6-dichloropyridine (50.0 g, 0.34 mol) was dissolved in a solvent mixture of 80% hydrazine monohydrate solution (120 mL, 1.92 mol) and ethanol (200 mL), and heated and refluxed for 4 hours at 100 °C. The progress of the reaction was monitored by thin layer chromatography (TLC) to confirm complete consumption of 2,6-dichloropyridine. Upon completion of the reaction, the reaction solution was cooled to room temperature and subsequently concentrated to dryness in a rotary evaporator. The resulting crude product was purified by recrystallization from petroleum ether to afford 2-chloro-6-hydrazinopyridine (31.0 g, 64%) as a white solid. The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3): δ 7.42 (dd, J = 7.2 Hz, 0.4 Hz, 1H), 6.65 (t, J = 7.2 Hz, 2H), 6.14 (s, 1H), 3.63 (s, 2H).
