The general procedure for the synthesis of 4-hydrazinopyridine hydrochloride from 4-chloropyridine was as follows: the target compound was prepared by the method described in J. Chem. Soc., 1972, 1987. The procedure was as follows: 4-chloropyridine (16.5 g, 145 mmol) was dissolved with hydrazine monohydrate (7.76 mL, 160 mmol) in 1-propanol (50 mL) and heated to reflux for 18 hours. After completion of the reaction, the solution was cooled to 0 °C and the precipitated crystals were collected by filtration. The crystals were washed with cold 1-propanol and subsequently air dried to afford 4-hydrazinopyridine hydrochloride (15.2 g, 72% yield). The resulting compound did not require further purification and could be used directly in the subsequent reaction.
[1] Patent: US2003/187014, 2003, A1
[2] Molecules, 2009, vol. 14, # 12, p. 5203 - 5215
[3] Chemical and Pharmaceutical Bulletin, 2016, vol. 64, # 9, p. 1281 - 1287
