General procedure for the synthesis of 3-(2-pyridyl)aminohydrazone from 2-cyanopyridine: In a 1 L four-necked round-bottomed flask equipped with a mechanical stirrer, a reflux condenser, and a nitrogen inlet/outlet, 2-pyridinecarbonitrile (50 g, 480 mmol), hydrazine hydrate (26.4 g, 528 mmol), and ethanol (25 mL) were added. The resulting mixture was stirred at room temperature for 6 h. Subsequent detection by TLC showed that some of the starting material remained unreacted. 7.2 g (144 mmol) of hydrazine hydrate was added and the mixture was heated at 50 °C for 3 hours. After completion of the reaction, the mixture was cooled in an ice bath, filtered and dried to give 40.2 g of solid product. The mother liquor was concentrated, ground with hexane and dried to give another 11.6 g of solid product (total 51.8 g, 381 mmol, 79% yield). The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3): δ 8.50 (m, 1H, Ar-H), 8.01 (d, 1H, Ar-H), 7.68 (t, 1H, Ar-H), 7.28 (m, 1H, Ar-H), 5.38 (br s, 2H, -NH2), 4.62 (br s, 1H, -NH). 2.40 (br s, 1H, -NH).
