Method for preparing 2,4-dichloroacetophenone

A technology of dichloroacetophenone and m-dichlorobenzene, which is applied to the preparation of carbon-based compounds, chemical instruments and methods, and the preparation of organic compounds, which can solve the problems of low preparation yield and poor purity, and achieve simple synthesis process , Promote dissolution and reduce reaction time

Pending Publication Date: 2021-11-09

NINGXIA RUITAI TECH +1

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[0005] The application provides a method for preparing 2,4-dichloroacetophenone, which sol...

Abstract

The invention discloses a method for preparing 2,4-dichloroacetophenone. The method comprises the following steps: S1, weighing dichlorobenzene, aluminum trichloride and an amide auxiliary agent, and carrying out mixing and stirring; S2, when a stirring temperature rises to 40 DEG C, dropwise adding acetyl bromide for a reaction so as to obtain 2, 4-dichloroacetophenone synthetic liquid; S3, adding the 2,4-dichloroacetophenone synthetic liquid obtained in the step 2 into hydrochloric acid for acidolysis layering, and separating and washing an oil layer after layering; S4, dehydrating the washed oil layer in a vacuum environment system, and removing light components when the temperature rises to 98 DEG C; and S5, rectifying the residues after dehydration and light component removal to obtain the 2,4-dichloroacetophenone. According to the invention, acetyl bromide is adopted as a raw material, so the activity of an electrophilic reagent can be effectively reduced, and the yield of the product can be further improved. Meanwhile, the amide auxiliary agent is supplemented in the preparation process of the 2,4-dichloroacetophenone synthetic liquid, so the dissolution of aluminum trichloride is promoted, a contact area of reactants is increased, and reaction efficiency is greatly improved.

Application Domain

Organic compound preparationCarbonyl compound preparation by condensation +1

Technology Topic

Aluminum trichlorideAcetophenone +9

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[0022] In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings.

[0023] see Figure 1-2

[0024] As can be seen from the above technical solutions, 1. a method for preparing 2,4-dichloroacetophenone, comprising the following steps:

[0025] S1: take dichlorobenzene, aluminum trichloride, and amide auxiliary for mixing and stirring;

[0026] S2: when the stirring temperature rises to 40°C, add acetyl bromide dropwise to it to react, the dropwise addition process continues for 2-3 hours and is incubated for 1-2 hours after being heated to 100°C, and is obtained when the temperature is lowered to 50°C 2,4-Dichloroacetophenone synthesis solution;

[0027] S3: adding the 2,4-dichloroacetophenone synthesis solution in step 2 to hydrochloric acid for acidolysis and layering, and separating the oil layer after layering, and washing the separated oil layer for several times until the pH value is 6- 7 obtain the oil layer after washing, the water that the oil layer after washing contains, m-dichlorobenzene;

[0028] S4: dehydrate the oil layer after water washing in a vacuum environment, and dehydrate when the temperature rises to 98°C;

[0029] S5: rectifying the residue after dehydration and delighting to obtain 2,4-dichloroacetophenone.

[0030] Preferably, a method for preparing 2,4-dichloroacetophenone, the dehydration process in the step 4 separates the water in the oil layer after the water washing, and the delighting process in the step 4 separates the water in the oil layer after the water washing. of m-dichlorobenzene.

[0031] Preferably, in a method for preparing 2,4-dichloroacetophenone, the molar ratio of acetyl bromide, m-dichlorobenzene and aluminum trichloride in the step 1 is 1:1.1-1.3:1.05-1.2.

[0032] Preferably, in a method for preparing 2,4-dichloroacetophenone, the concentration of hydrochloric acid in the step 2 is 5%.

[0033] Preferably, in a method for preparing 2,4-dichloroacetophenone, in the step 3, the temperature of acidolysis and stratification is 50-80°C.

[0034] Preferably, in a method for preparing 2,4-dichloroacetophenone, the temperature of the water washing process in the step 3 is 40-60°C.

[0035] Preferably, a method for preparing 2,4-dichloroacetophenone, the amide auxiliary agent in the step 1 is one of N,N-dimethylformamide and N,N-dimethylacetamide or mixed, the molar ratio of the amide auxiliary agent and aluminum trichloride is 10-5:1.

[0036] In the present application, it is preferable to put m-dichlorobenzene (106.4g, 0.72mol), aluminum trichloride (89.5g, 0.66mol) and amide assistant (9.7g, 0.132mol) into a room with a stirrer, a thermometer and a condenser. In the four-necked flask, the temperature was raised to 40° C. with stirring, and acetyl bromide (74.2 g, 0.6 mol) was added dropwise to the four-necked flask, and the dropwise addition was completed in about 2.5 hours. The temperature was raised to 100° C., the temperature was continued for 1.5 hours, and then lowered to 50° C. to obtain 229.5 g of a 2,4-dichloroacetophenone synthesis solution.

[0037] The 2,4-dichloroacetophenone synthesis solution was transferred to the dropping funnel, and added dropwise to another four-necked flask containing 850 g of 5% dilute hydrochloric acid, and the reaction temperature was controlled to be about 60°C. After the dropwise addition was completed, the layers were separated. The oil layer after acid hydrolysis was put into the kettle, and washed with 60 g of water at times, and the washing temperature was controlled to be 45-50 °C during the period. After layering, when the pH of the last water layer is measured to be 6-7, the water washing process is stopped, and the oil layer after water washing is to be treated.

[0038] The oil layer after washing is put into a four-necked bottle, the vacuum of the control system is about 15mmHg, the temperature is increased for dehydration, and the maximum temperature is 95 °C, then the receiving bottle is switched, and the temperature is continued to evaporate m-dichlorobenzene. The maximum temperature of the kettle material is 128°C, the four-necked bottle is switched to the rectification system, the absolute pressure of the control system is 8mmHg, the reflux ratio is adjusted, and the fine 2,4-dichloroacetophenone is extracted. The temperature at the bottom of the kettle should not exceed 150℃. 102.8 g of the product was obtained (content: 99.1%, yield: 89.8%).

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Method for preparing 2,4-dichloroacetophenone

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