4,5-DICHLORO-2-METHYLPYRIDAZIN-3-ONE

932-22-9

74-88-4

933-76-6

Step 1: A round bottom flask was charged with 4,5-dichloropyridazin-3(2H)-one (10.0 g, 60.6 mmol), potassium carbonate (16.8 g, 121.2 mmol), iodomethane (4.0 mL, 64.3 mmol) and acetonitrile (80 mL). The reaction mixture was heated to reflux for 12 hours and then cooled to room temperature. After completion of the reaction, the mixture was filtered and the filtrate was concentrated. The residue was purified by column chromatography (dichloromethane as eluent) to afford 4,5-dichloro-2-methylpyridazin-3-one 8.21 g (76% yield). The product was confirmed by 1H NMR (400 MHz, DMSO-d6): δ 8.18 (s, 1H), 3.70 (s, 3H); mass spectrum (m/z) = 179 ([M+H]+).