反应详情

Add dropwise 292 ml of a 25% ammonia solution to a suspension of 513 g of 1-methoxycarbonyl-3-(5-nitro-2-furyl)pyrazole-4-carboxaldehyde-ethyleneacetal in 2000 ml of dimethylformamide and 250 ml water at 20° to 25° C within a period of approximately 20 minutes, whereupon the precipitate is dissolved. Then stir for a further 30 minutes. While cooling to a moderate extent, add approximately 1000 ml of 2N hydrochloric acid; a strongly acidic reaction is obtained. Stir for 2 hours at 30° C and add 1.7 kg of ice. Draw off the thrown-down precipitate under cold conditions and wash with water until neutral to obtain 3-(5-nitro-2-furyl)-1H-pyrazole-4-carboxaldehyde [m.p. 187° to 187.5° C]with a yield of 96%.

1. dissolutionwhereupon the precipitate is dissolved
2. temperatureWhile cooling to a moderate extent
3. customa strongly acidic reaction
4. customis obtained
5. stirringStir for 2 hours at 30° C
6. washwash with water until neutral