3,5-Diphenyl-4-methylpyrazoline → 4-methyl-3,5-diphenyl-1H-pyrazole
Reaction equation
[C:1]1([C:7]2[NH:8][NH:9][CH:10]([C:13]3[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=3)[C:11]=2[CH3:12])[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1>[Pd].C1(C)C(C)=CC=CC=1>[C:1]1([C:7]2[C:11]([CH3:12])=[C:10]([C:13]3[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=3)[NH:9][N:8]=2)[CH:6]=[CH:5][CH:4]=[CH:3][CH:2]=1Participants
4
Reactant 1
Product 1
Reagents, catalysts & solvents 2
Conditions
- Temperature
- 25 °C
Procedure
To the crude wet xylene solution of 3,5-diphenyl-4-methylpyrazoline (from B above), is added 1.0 g of 5% palladium on carbon catalyst. The reaction mixture is slowly heated to reflux, and the water removed by azeotropic distillation using a Dean-Stark apparatus (xylene returned to reactor). Refluxing is continued at 145° C for 4 hours. After the four-hour reflux, the reaction mixture is cooled to 25° C, and the combined 5% palladium on charcoal/3,5-diphenyl-4-methylpyrazole filtered off. The solids are slurried in warm acetone to dissolve the 3,5-diphenyl-4-methylpyrazole. The catalyst is then filtered off. Removal of the acetone in vacuo yields 1.5 g of 3,5-diphenyl-4-methylpyrazole. After recrystallization from hot xylene, pure 3,5-diphenyl-4-methylpyrazole having a melting point of 225°-226° C is obtained.