General procedure for the synthesis of 3-hydrazino-6-methylpyridazine from 3-chloro-6-methylpyridazine:[Ref. Example 35] Hydrazine monohydrate (45 mL) was added to a suspension of 3-chloro-6-methylpyridazine (3.00 g) in ethanol (45 mL), and the resulting mixture was heated and refluxed for 2.5 hours. Upon completion of the reaction, the mixture was cooled in air and the solvent was subsequently removed by evaporation under reduced pressure to give a residue. The residue was purified by silica gel column chromatography using chloroform-methanol-water (7:3:1, v/v) as the lower solvent as eluent, resulting in the title compound 3-hydrazino-6-methylpyridazine (2.35 g, 81% yield) as a solid. The structure of the product was confirmed by 1H-NMR (400 MHz, DMSO-d6): δ 2.39 (3H, s), 4.20 (2H, br), 6.94 (1H, d, J = 9.3 Hz), 7.18 (1H, d, J = 9.3 Hz), 7.64 (1H, br).ESI-MS m/z: 125 ([M + H]+).
