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1) Obtained by acetylation of p-aminophenyl ether. A mixture of benzene, acetic anhydride and p-aminophenyl ether is heated in an oil bath for azeotropic reaction for 4 hours. After the reaction is completed, the reactants are cooled to precipitate phenazone, which is filtered, washed with cold benzene and dried to obtain the product. The yield is 86% of the theoretical amount.

(2) Obtained by the reaction of acetaminophenol with sodium ethoxide: first add p-acetaminophenol to sodium ethoxide, then slowly add iodoethane, heat and reflux for 1 hour, cool, filter, dissolve the obtained crude product in ethanol, filter, dilute the filtrate with hot water, cool, filter and dry to obtain the finished product. The yield is 80% of the theoretical amount. The first method can also use acetic acid instead of benzene as the solvent. The process is as follows. Heat 40% dilute acetic acid to boiling, add p-aminophenyl ether, evaporate water, add glacial acetic acid when the temperature rises to 150℃, reflux for 1h, continue to evaporate, and when the temperature rises to above 150℃, take samples to determine free aminophenyl ether, add acetic anhydride according to the residual amount of aminophenyl ether, reflux for 0.5h, check the end point, reduce pressure after passing, recover acetic acid until the amino content is below 0.046 and the acid content is below 0.2%, press the reaction liquid into the hot refined mother liquor, stir and cool to 40℃, filter, and obtain phenacetin crude product. Refining, add boiling water or refined mother liquor to phenacetin crude product, heat and stir to dissolve, filter, adjust the filtrate to pH=4.5-4.7 with acid, add activated carbon and sodium thiosulfate to stir and decolorize, filter, cool the filtrate to crystallize, discard and filter, air flow dry, and obtain phenacetin.

Uses Antipyretic and analgesic, used to treat fever, headache, neuralgia, etc. The antipyretic effect is stronger than the analgesic effect. The drug efficacy is comparable to that of aspirin, with a slow and lasting effect and low toxicity. Studies have shown that this product and its metabolite paracetamol both have antipyretic effects. Because when phenacetin is unable to be converted into paracetamol by using enzyme inhibitors, it can still show a significant antipyretic effect. Therefore, the antipyretic effect after administration of the product is not only caused by its active product paracetamol. The mild analgesic effect of phenacetin can generally last for 3-4 hours; the synergistic effect of using it in combination with salicylates enhances the analgesic effect. It is mainly used clinically for antipyretic and analgesic effects in small animals. This product is also one of the components of APC tablets.