Sodium Hydroxide → 1-(4-Methylbenzyl)-5-methyl-1H-pyrazole-3-carboxylic acid

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Reaction Conditions

Reaction Steps

To a solution of methyl 5-methyl-1-(4-methylbenzyl)-1H-pyrazole-3-carboxylate (Intermediate A, 16.3 g, 66.7 mmol) in ethanol (500 mL) was added NaOH (1N aq., 133 mL, 133 mmol), and the mixture was heated at 70° C. for 16 h. The organic solvent was evaporated under vacuum and the residue was acidified with HCl (1N aq., 150 mL) until a white solid completely precipitated from solution. The solid was filtered, washed with water (1.5 L), and was dried in a vacuum oven to afford the title compound as a white solid (14.6 g, 95%): 1H NMR (300 MHz, DMSO-d6) 7.0 (d, 2H), 7.08 (d, 2H), 6.56 (s, 1H), 5.35 (s, 2H), 2.30 (s, 3H), 2.27 (s, 3H); ES-MS m/z 231.0 (MH)+, HPLC RT (Method B) 3.12 min.

Provenance & Evidence