4-Antipyrinecarboxaldehyde

4-Antipyrinecarboxaldehyde is prepared as follows:
(1)Add antipyrine to the preparation tank, then add the dosed amount of sulfuric acid and water, formulate the acidic solution with the content of 34-36%, then nitrosation reaction with sodium nitrite solution in the nitrosation vat, the reaction solution is put into the reduction tank, add the reducing agent for the reduction reaction, and then transfer the reduction solution to the hydrolysis tank, add the hydrolysis of sulfuric acid, and then pass the ammonia to neutralize it, to make 4-amino antipyrine oil;
(2) Add 4-aminoantipyrine oil to the acylation tank with methyl formate or formic acid for acylation reaction, and then cooling down crystallization centrifugation to get 4-antipyrine formaldehyde crystals.