Lithium Hydroxide → 1-tert-Butyl-5-(trifluoromethyl)-1H-pyrazole-4-carboxylic acid

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Reaction Steps

To a stirred mixture of 1-tert-butyl-5-trifluoromethyl-1H-pyrazole-4-carboxylic acid ethyl ester (3.000 g; 11.4 mmol) in methanol/water (1:1 ratio, 50 mL) was added lithium hydroxide (0.383 g; 16.0 mmol) at room temperature. The mixture was heated to reflux for 2 hr, then allowed to cool to room temperature and concentrated to approximately half of the original volume. The resulting mixture was acidified with 1N HCl to ˜pH 1 and extracted with methylene chloride. The extracts were dried over sodium sulfate, filtered and concentrated to provide 1-tert-butyl-5-trifluoromethyl-1H-pyrazole-4-carboxylic acid (2.47 g, 92%).

Provenance & Evidence