4,5-Dichloro-3-hydroxypyridazine → 5-Chloro-4-methyl-3(2H)-pyridazinone

Participants

Reaction Steps

Into a 500 ml flask, 189 g of methylmagnesium bromide (1 mol/liter of an ether solution) was charged, and 10.0 g of 4,5-dichloro-3(2H)pyridazinone was gradually added thereto at a temperature of about 15° C. The mixture was stirred at a temperature of from 40° to 50° C. for about 3 hours. The disappearance of the starting dichloropyridazinone was confirmed by thin layer chromatography (developer; ethyl acetate:acetone =2:1, v/v), whereupon the reaction was terminated. The reaction solution was transferred to a separating funnel, and about 300 ml of a saturated sodium chloride aqueous solution was added thereto, and then the mixture was vigorously shaken. The aqueous layer was removed. The organic layer was washed with about 200 ml of water, and dried over anhydrous sodium sulfate, and then the solvent was distilled off. The brown crystals thereby obtained were recrystallized from ethyl acetate to obtain 4.54 g of the above identified compound having a melting point of from 132° to 134° C. as colorless crystals.

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