Elarzone, Dausse, France ,1973
77 g (0.25 mol) of phenylbutazone, 30 ml of a 30% strength solution of formaldehyde and 50 ml of ethyl alcohol are introduced into a 500 ml flask, 25 g (0.25 mol) of N-methylpiperazine are slowly added to this mixture which is stirred mechanically. The mixture is then heated for one hour on a water bath, left to cool, and crystallization started by scratching.
After being left in the refrigerator overnight the mixture, which has set solid, is triturated with 50 ml of isopropyl alcohol and the solid product filtered off and dried in vacuo over phosphorus pentoxide. 63 g (60% yield) of 1,2diphenyl-3,5-dioxo-4-n-butyl-4-(N'-methylpiperazinomethyl)pyrazolidine are obtained, melting at 129°C after recrystallization from 150 ml of isopropyl alcohol.
