Hydrazine hydrate (1:1) → 6-phenyl-4,5-dihydro-3(2h)-pyridazinone

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Reaction Steps

A mixture of 3-benzoylpropionic acid (89 g), 80% hydrazine hydrate (25.5 ml) in ethanol (1000 ml) is refluxed for 6 hrs, cooled and filtered to give 75.6 g of 6-phenyl-4,5-dihydro-3(2H)-pyridazinone. Bromine (70 g) is added dropwise to a solution of the above pyridazinone in acetic acid (200 ml) at 80° C. After the addition is over, the mixture is heated to 100° C. for 15 minutes, cooled, filtered and washed with isopropyl ether. The solid is slurried in water, adjusted to pH 10 and filtered to give 60 g of the product 6-phenyl-3(2H)-pyridazinone.

Provenance & Evidence