Three common production methods of p-aminoacetophenone

There are various preparation methods for aminoacetophenone, and the following is a brief introduction to three common production methods.
1. Reduction from p-nitroacetophenone: Place stannous chloride and concentrated hydrochloric acid in a reaction tank, cool, stir, and add p-nitroacetophenone. When the temperature rises naturally to 90 ℃, rapidly cool to 85 ℃, continue to cool to room temperature, stir for 1 hour, filter, and add excess sodium hydroxide solution to the filter cake to decompose the complex. Filter to obtain crude para aminoacetophenone, and recrystallize with dilute ethanol to obtain a refined product with a melting point of 105-106 ℃. The yield of 61% can also be reduced by replacing stannous chloride with iron powder and sodium chloride.
2. Acetaminoacetophenone is prepared from acetanilide and acetic anhydride, and then hydrolyzed and neutralized to obtain it. Mix acetic anhydride, acetylbenzene, and anhydrous zinc chloride and keep them slightly boiling for 5 hours. Cool them slightly, pour in concentrated hydrochloric acid, reflux and hydrolyze for 5 hours, and place them at room temperature. Add 25% sodium hydroxide to adjust the pH to 7-8. Add steam to remove the aniline, filter with decolorization carbon, reduce pressure and concentrate, and cool to obtain orange yellow crystals. Filter out the coarse product. Recrystallization and purification with water.
3. Mix acetic anhydride and acetanilide in a 1:1 molar ratio with anhydrous zinc chloride of catalyst amount, heat and reflux for 5 hours, add concentrated hydrochloric acid, and continue reflux hydrolysis for 5 hours. After the reaction is completed, let it cool to room temperature, add 25% sodium hydroxide solution until the oil and water are clearly separated, add water to the separated oil layer, adjust the pH value to 7-8 with 25% sodium hydroxide, and then steam distillation with water to produce aniline. The remaining material is decolorized with activated carbon, the filtered filtrate is subjected to reduced pressure concentration, and the orange yellow crystal obtained by cooling is recrystallized with water to obtain pure p-aminoacetophenone.