Methylhydrazine → 3H-Pyrazol-3-one, 2,4-dihydro-2-methyl-5-phenyl-

Participants

Reaction Conditions

Reaction Steps

Ethyl benzoylacetate (1,538 g, 8 moles) dissolved in isopropanol (6 l) is placed in a 12 l flask under an atmosphere of nitrogen. Methylhydrazine (410 g, 8.7 moles) in isopropanol (800 ml) is added with stirring in a dropwise manner to the ethyl benzoylacetate solution prewarmed to about 80° C. During the addition external heating is removed. Seeding of the reaction mixture with the product at the point of one-third addition of methylhydrazine causes a copious precipitate of product. This procedure eliminates a large exotherm from occurring at a later stage. After the addition is completed, the reaction mixture is held at about 80° C. for 2 hours. Cooling the slurry to 20° C. and filtering off the solid, a yield of 1,131 g (81%) of product after drying and having a melting point of 211° C. is obtained.

Provenance & Evidence