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

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Reaction Steps

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%).

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