Hydrochloric Acid → 1-tert-butyl-5-methyl-1H-pyrazole-4-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

In a mixture of ethanol:water:dioxane (1:1:1, 21 mL) was placed ethyl 1-tert-butyl-5-methyl-1H-pyrazole-4-carboxylate (1.48 g, 7.04 mmol) and lithium hydroxide hydrate (886 mg, 21.12 mmol). The reaction was stirred at 40° C. for 3 hrs and then at RT overnight. The reaction was diluted with water (25 μL) and ether (25 mL). The ether layer was discarded and the aqueous phase made acidic (pH˜=4) with 1N HCl. The acidic phase was then extracted with ethyl acetate (2×25 mL) and the combined ethyl acetate layers were washed with brine, dried (Na2SO4), evaporated at reduced pressure to give 1-tert-butyl-5-methyl-1H-pyrazole-4-carboxylic acid as a white solid (1.12 g, 87% yield). 1H NMR (300 MHz, DMSO-d6): δ 1.56 (s, 9 H), 2.67 (s, 3 H), 7.65 (s, 1 H), 12.13 (s, 1 H); MS (ESI) m/z: 183.0 (M+H+).

Provenance & Evidence