Cinnamoylbenzene → 3,5-diphenyl-4,5-dihydro-1H-pyrazole

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Reaction Steps

Benzalacetophenone (12.5 parts) is reacted with hydrazine hydrate (3.1 parts by volume) in methanol to form 3,5-diphenyl-2-pyrazoline. Panasol AN-2 (30 ml), nitrobenzene (7.4 parts) and 5% palladium on carbon catalyst (2 parts) are then added and the mixture heated. Following the distillation of methanol and water from the reaction mixture, the temperature is raised to 200°C. and held at that temperature for 24 hours. The mixture is then cooled to 50°C., filtered, and the catalyst bearing cake of 3,5-diphenylpyrazole is 79.5%, m.p. 194°C. to 199°C.

Provenance & Evidence