Sodium Hydroxide → 5-Methyl-3-(3-trifluoromethylphenyloxy)pyrazole

Temperature

0 °C

Concentrated hydrochloric acid (3 ml) and water (6 ml) were added to 3-(4-amino-3-trifluoromethylphenyloxy)-5-methylpyrazole, and the mixture was cooled to 0° C. Then, a solution of sodium nitrite (0.54 g, 7.8 mmol) in concentrated hydrochloric acid (2 ml) and water (2 ml) was dropwise added, and the mixture was stirred at an ambient temperature for 1 hour. Then, hypophosphorous acid (2.57 g, 38.9 mmol) was added, and the mixture was stirred at room temperature overnight. After completion of the reaction, the reaction mixture was poured into 1N sodium hydroxide (50 ml) and extracted with ethyl acetate (50 ml×2). An organic layer was washed with water (50 ml×2), dried over anhydrous magnesium sulfate and filtered to remove a desiccant, and the solvent was distilled off from the filtrate under reduced pressure. The resultant crude product was purified with a silica gel column (ethyl acetate/hexane=1/4), to give a yellow viscous substance of 5-methyl-3-(3-trifluoromethylphenyloxy)pyrazole (1.47 g, yield: 78.0%). 1H-NMR (CDCl3, TMS, ppm): δ 2.2.3 (s, 3H), 5.63 (s, 1H), 7.27˜7.46 (m, 4H), 10.91 (br s, 1H).

1. stirringthe mixture was stirred at room temperature overnight
2. customAfter completion of the reaction
3. extractionextracted with ethyl acetate (50 ml×2)
4. washAn organic layer was washed with water (50 ml×2)
5. dry with materialdried over anhydrous magnesium sulfate
6. filtrationfiltered
7. customto remove a desiccant, and the solvent
8. distillationwas distilled off from the filtrate under reduced pressure
9. customThe resultant crude product was purified with a silica gel column (ethyl acetate/hexane=1/4)

ORD record

ord-a6a8017048b04abfb7062c60e36c3a8f

Source dataset

uspto-grants-2010_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07700786B2