Hydrochloric Acid → 1-Benzyl-1H-pyrazole-4-carboxylic acid

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Reaction Conditions

Reaction Steps

This known compound [CAS Reg. No. 401647-24-3] was made from 1-benzyl-1H-pyrazole-4-carboxylic acid ethyl ester by saponification: 1-benzyl-1H-pyrazole-4-carboxylic acid ethyl ester (2.35 g) was dissolved in dry THF (25 mL) and then a 1M aqueous solution of LiOH (15.31 mL) was added. The mixture was stirred at 60° C. for 2.5 hours and analyzed by TLC: starting material was still visible. Another batch of LiOH monohydrate (1.29 g) was added and the mixture was allowed to stir at room temperature for 48 hours. The mixture was poured into ice water and acidified with 2M aqueous HCl (20 mL). The aqueous phase was extracted with ethyl acetate and the organic layer was washed with brine, dried over Na2SO4 and evaporated to give the title compound as a colorless solid (1.55 g). MS (m/e, ISP neg. ion)=201.6 [(M−H+)−].

Provenance & Evidence