Hydrochloric Acid → 4-Formyl-1H-pyrazole-5-carboxylic acid

Participants

Reaction Steps

To a suspension of ethyl 4-formyl-1H-pyrazole-5-carboxylate (SM2-B, 19 g, 115 mmol) in a solution of MeOH (76 ml) and water (130 mL) was added NaOH (14 g, 345 mmol) in water (130 mL) at 0° C. The reaction mixture was warmed to rt and stirred for 2 h. The solution was adjusted to pH of 1 with concentrated hydrochloride. The solid was collected, washed with water (50 mL), and dried in air to give the product (4-B) (12 g, 75%) as a light yellow solid. 1H NMR (300 MHz, DMSO): δ 8.45 (s, 1H), 10.29 (s, 1H). LC-MS (M+H)+=141.

Provenance & Evidence