General procedure for the synthesis of 2-(pyridin-4-yl)acetohydrazide from ethyl 4-pyridyl acetate: a mixture of hydrazine hydrate (0.27 mL, 9.08 mmol), ethyl pyridin-4-yl acetate (0.93 mL, 6.05 mmol), and ethanol (10 mL) was heated and reacted for 10 hours at 80 °C. Subsequently, hydrazine hydrate (0.6 mL) was added to the reaction system and the reaction continued to be heated at 80 °C for 14 hours. After completion of the reaction, the reaction solution was cooled to room temperature and concentrated under vacuum. The final 2-(pyridin-4-yl)acetylhydrazine (0.86 g, 95% yield) was obtained as a white solid. The structure of the product was confirmed by 1H NMR (DMSO-d6) and mass spectra (MS): 1H NMR (DMSO-d6) δ 9.29 (s, 1H), 8.47 (d, J = 5.6 Hz, 2H), 7.27 (d, J = 5.2 Hz, 2H), 4.28 (s, 2H), 3.39 (s, 2H); MS m/z 152 (M + 1).
