Hydrochloric Acid → 1H-Pyrazole, 3-methyl-5-(trifluoromethyl)-

To 1,1,1-trifluoro-2,4-pentadione (15.14 g, 98 mmol) in MeOH (200 ml) was added hydrazine monohydrate (4.92 g, 98 mmol) in MeOH (50 ml) and c.HCl (1.3 ml, 32%). The resulting clear solution was allowed to stir for 12 h. Removal of solvent by distillation up to 200° C. yielded a clear oil which crystallised on cooling. These crystals were dissolved in Et2O, dried over MgSO4, filtered and the solvent removed under reduced pressure. The resulting white solid was sublimed at 80° C. and 10−2 mbar, yielding the pure pyrazole as a white solid (10.91 g, 73 mmol, 74%).

1. customRemoval of solvent
2. distillationby distillation up to 200° C.
3. customyielded a clear oil which
4. customcrystallised
5. temperatureon cooling
6. dissolutionThese crystals were dissolved in Et2O
7. dry with materialdried over MgSO4
8. filtrationfiltered
9. customthe solvent removed under reduced pressure
10. customwas sublimed at 80° C.

ORD record

ord-875d2245001e4439887e16476d0d6f80

Source dataset

uspto-grants-2002_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06492526B1