Benzoylhydrazine → N'-(1-Methylpiperidin-4-yl)benzohydrazide

Participants

Reaction Steps

272 g (2 mol) of benzoic acid hydrazide are added to 1500 ml of methanol with stirring. Over 1 hour, 226 g (2 mol) of 1-methyl-4-piperidinone are then added dropwise at a temperature of 30° C. Slight cooling is necessary. The reaction mixture is stirred for half an hour at 30° C. and then for a further 1 hour at 60° C. The solution is then cooled to 0° C. and over a period of 2 hours 68 g (1.8 mol) NaBH4 is added using a spatula (strong foaming). Towards the end of the addition the mixture is warmed to room temperature. The solvent is evaporated off using a rotary evaporator and to the residue 900 g ice and 1000 ml dichloromethane are added with stirring. The organic phase is separated using a separating funnel and the aqueous phase is shaken twice with 300 ml dichloromethane in each case. The combined organic fractions are dried over MgSO4, the dichloromethane evaporated off and the residue recrystallized in 1 liter of isopropanol with the addition of 10 g active charcoal. The reaction product is dried in a drying cupboard at 50° C. in vacuo. (M.p. 149°-150° C.).

Provenance & Evidence