Hydrochloric Acid → 3-(difluoromethyl)-5-fluoro-1-methyl-1H-pyrazole-4-carboxylic acid
Reaktionsgleichung
[Na].[F:2][CH:3]([F:14])[C:4]1[C:8]([C:9](F)=[O:10])=[C:7]([F:12])[N:6]([CH3:13])[N:5]=1.Cl.S1(=O)(=[O:21])CCCC1>>[F:2][CH:3]([F:14])[C:4]1[C:8]([C:9]([OH:21])=[O:10])=[C:7]([F:12])[N:6]([CH3:13])[N:5]=1Komponenten
5
Versuchsvorschrift
To 400 ml of a 1N sodium hydroxyde aqueous solution, is added dropwise 67.5 g of a solution (10% molar) of 3-(difluoromethyl)-5-fluoro-1-methyl-1H-pyrazole-4-carbonyl fluoride in tetra-hydrothiophene-1,1-dioxide. The temperature is kept below 20° C. during the addition. After 2 hours of stirring at room temperature, the reaction mixture is carefully acidified to pH 2 with concentrated aqueous hydrochloric acid. The resulting white precipitate is filtered, washed with water, and dried to yield 6 g of 3-(difluoromethyl)-5-fluoro-1-methyl-1H-pyrazole-4-carboxylic acid as a white solid. 1H NMR (400 MHz, DMSO-d6) δ ppm: 3.90 (s, 3H); 7.22 (t, 1H, JHF=53.55 Hz); 13.33 (s, 1H).