Sodium Hydroxide → 5-ethyl-1-methyl-1H-pyrazole-3-carboxylic acid

Participants

Reaction Steps

Ethyl 5-ethyl-1-methylpyrazole-3-carboxylate (6.86 g) in ethanol (70 ml) was treated with sodium hydroxide (1.58g) in water (30 ml) and heated under reflux for 6 h. The solution was concentrated and the aqueous phase washed with ethyl acetate before adding dichloromethane (50 ml). The solution was acidified with 5M hydrochloric acid, and the mixture exhaustively extracted with dichloromethane. The remaining undissolved solid was filtered off suspended in water and the pH adjusted to 6 with saturated sodium hydrogen carbonate. The solution was again extracted with dichloromethane. The combined organic layers were dried over anhydrous magnesium sulphate and concentrated to give the title compound as a white solid, (2.72g, 47%); (Found: M+, 154.0742. C7H10N2O2 requires M, 154.0742); nmax (CH2Cl2) 3689 and 1760 cm-1 ; dH (CDCl3) 1.30 (3H, t, J7.4 Hz), 2.64 (2H, q, J7.4 Hz), 3.88 (3H, s) and 6.65 (1H, s).

Provenance & Evidence