Dimethylformamide → 5-chloro-1,3-diphenyl-1H-pyrazole-4-carbaldehyde

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Reaction Steps

At 5° to 10° 97.3 g of phosphorus oxytrichloride are added dropwise to 92.7 g of dimethylformamide and the mixture is stirred for completion of the complex formation for 30 minutes at room temperature. Following this 30 g of 1,3-diphenyl-2-pyrazoline-5-one are added and while stirring heating is carried out for 1 hour at 55° C. and for 20 hours at 70°. The product is poured on to approximately 600 g of ice neutralised with concentrated sodium hydroxide solution to pH 3-4, vacuum filtered and washed with water. 5-Chloro-1,3-diphenyl-pyrazole-4-carboxaldehyde is obtained with a yield of 93 %; F 109°-110° (from petroleum ether).

Provenance & Evidence