Preparation of Fenebute
1. Prepare the first intermediate
Benzaldehyde and ethyl acetoacetate into ethanol, stir at room temperature under the catalysis of organic alkali reaction with filter cake filtration after 45 ~ 50 h, after the completion of the filter with ethanol elution filter cake, dry cake solids, then ethanol filtrate concentrated to a quarter of the original volume, to cold, concentrate filtering alcohol washing, solid, merging two solid is the first intermediate; The mole ratio of benzaldehyde, ethyl acetoacetate and ethanol is 1:2.5 -3:12-15.
2. Prepare the second intermediate
The first intermediate is added to the mass concentration of 20% sodium hydroxide solution, and the reaction is stirred at 85-90°C for 2-5 hours. After filtration, the filter cake is used for filtration. After filtration, the filter cake is washed, the filtrate is combined and cooled, and the filtrate is cooled by stirring for 3h. Solid second intermediate; The mass ratio of the first intermediate to the sodium hydroxide solution is I: 1.8-2.0;
3. Prepare the third intermediate
The second intermediate was dissolved in pure acetic anhydride solution for reflux 3 ~ 5h. After the reflux, the acetic anhydride was concentrated and dissolved with toluene. After the dissolution, ammonia water was added, and the reaction took place at 60_65°C for 1 ~ 1.5 h. Filtrate, wash and dry the precipitated solid to get the solid third intermediate; The mass ratio of the second intermediate, pure acetic anhydride solution, toluene and ammonia water is 5:1-1.2:0.5-0.8:0.5-0.8;
4. Prepare Finebute
The third intermediate was dissolved in 25% sodium hydroxide solution and cooled to _5°C ~ 10°C. After cooling, sodium hypochlorite was added slowly within 15-20min for 1h reaction, followed by ice bath reaction of 0.5 ~ 1.5 h and water bath reaction of 0.5 ~ 1.5 h. Finally, the temperature was gradually increased to 60 ~ 80°C for 1-5 h, and the reaction was cooled again after completion. After cooling, hydrochloric acid was added in the ice water bath to adjust the PH to 2, and the decolorization was stirred at room temperature. After filtration, sodium hydroxide was added in the ice water bath to adjust the PH to 6-7, and the cooling was stirred for 2 hours. The mass ratio of the third intermediate, sodium hydroxide solution and sodium hypochlorite is 1.0:0.8-1.0:1.0-1.1.
