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

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.

1. customat a temperature of about 15° C
2. customethyl acetate:acetone =2:1, v/v), whereupon the reaction was terminated
3. customThe reaction solution was transferred to a separating funnel
4. additionabout 300 ml of a saturated sodium chloride aqueous solution was added
5. stirringthe mixture was vigorously shaken
6. customThe aqueous layer was removed
7. washThe organic layer was washed with about 200 ml of water
8. dry with materialdried over anhydrous sodium sulfate
9. distillationthe solvent was distilled off
10. customThe brown crystals thereby obtained
11. customwere recrystallized from ethyl acetate
12. customto obtain 4.54 g of the
13. customof from 132° to 134° C.

ORD record

ord-1465523144184db0a5cd112c7574da22

Source dataset

uspto-grants-1992_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05098900