94-05-3

1260243-04-6

The general procedure for synthesizing ethyl 5-amino-1H-pyrazole-4-carboxylate from ethyl ethoxymethylcyanoacetate was as follows: ethyl ethoxymethylcyanoacetate (68 g, 0.4 mol) was added to a reaction vessel containing 200 mL of anhydrous ethanol; 100 mL of hydrazine hydrate was added to the reaction vessel slowly dropwise, and then the reaction system was placed in an electric heater to gradually increase the temperature to 80 °C in 30 min, to Mixture A was obtained; Mixture A was heated to a reflux state, and the reflux reaction was maintained for 4 hours. Upon completion of the reaction, ethanol was removed by distillation under reduced pressure and the remaining solid was evaporated. The resulting solid was cooled to room temperature and left to precipitate a light yellow solid, which was filtered, washed and dried to obtain the intermediate 5-amino-1H-pyrazole-4-carboxylic acid ethyl ester. Cold anhydrous ethanol was used in the washing process. Finally, 41.68 g of ethyl 5-amino-1H-pyrazole-4-carboxylate was obtained with 66.78% yield.