反应详情

Add 37 g of phosphorus oxychloride dropwise to 153 ml of dimethylformamide at from 10° to 20° C. Stir the thus-obtained admixture for 30 minutes at room temperature before adding 18.3 g of 5-nitro-2-acetylfuran-p-chlorophenylhydrazone in portions, thus causing the temperature to rise to 40° C. Stir for 4 additional hours at 40° C and then pour the solution containing the 4-pyrazolylmethylenedimethylammonium salt onto 1 kg of ice and water. Heat the so-cooled solution for 1 hour at 40° C, and then (vacuum) filter it at room temperature. Wash filter residue with water to obtain a 92% yield of 1-(p-chlorophenyl)-3-(5-nitro-2-furyl)pyrazole-4-carboxaldehyde [m.p. 192° to 193° C (from toluene)].

1. customto rise to 40° C
2. stirringStir for 4 additional hours at 40° C
3. additionpour the solution
4. temperatureHeat the so-cooled solution for 1 hour at 40° C
5. filtration(vacuum) filter it at room temperature
6. washWash
7. filtrationfilter residue with water