Preparation method of 2, 4-dichloro-5-fluoroacetophenone

Abstract

The invention provides a preparation method of 2, 4-dichloro-5-fluoroacetophenone. The method comprises the following steps: by taking 2, 4-dichlorofluorobenzene as a raw material, carrying out Friedel-Crafts reaction on 2, 4-dichlorofluorobenzene and vinylidene chloride in the presence of anhydrous aluminum chloride and protonic acid at the same time to generate 1-(1, 1-dichloroethyl)-2, 4-dichloro-5-fluoroacetophenone benzene, carrying out hydrolysis reaction on the intermediate product under the catalysis of Lewis acid to generate 2, 4-dichloro-5-fluoroacetophenone and hydrogen chloride, adding a proper amount of water for layering after the reaction is finished, and rectifying an organic layer to obtain the product. According to the method, the cost of raw materials and auxiliary materials is greatly reduced, the post-treatment pressure is relieved, the yield can reach 85% or above, and the method belongs to the technical field of organic chemical industry.

Description

technical field [0001] The invention belongs to the technical field of organic chemical industry and relates to a preparation method of 2,4-dichloro-5-fluoroacetophenone. Background technique [0002] 2,4-dichloro-5-fluoroacetophenone is an important chemical raw material, used as a pharmaceutical intermediate, and the main intermediate of the third-generation broad-spectrum high-efficiency quinolone antibacterial agents ciprofloxacin and anthranofloxacin body. [0003] At present, fluorochloroacetophenones are generally produced in the industry by acetylation of 2,4-dichlorofluorobenzene. According to the different acylating agents, it can be roughly divided into three routes: 1. use acetic acid as an acylating agent, react with aluminum chloride in DMF and thionyl chloride, and the resulting yield is about 84%. Eliminated; ②Using acetic anhydride as an acylating agent and aluminum chloride as a catalyst for Friedel-Crafts reaction, the yield is only 29%, which is not sui...

AI Technical Summary

Problems solved by technology

[0004] Because the carbonyl group present in acetyl chloride will complex with aluminum chloride, it is theoretically determined that in the Friedel-Crafts acetylation reaction, the amount of aluminum chloride used is far greater than the catalytic amount, and in actual industrialization, the amount of aluminum chloride The use of equivalents has reached the level of more than 2 equivalents, that is, about 1.5 tons of anhydrous aluminum chloride will be consumed for every 1 ton of 2,4-dichloro-5-fluoroacetophenone produced, and this part of aluminum chloride will eventually be consumed. In the presence of a large amount of water, hydrolysis decomplexation enters the hydrolysis mother liquor and cannot be reused, resulting in a high cost of anhydrous aluminum chloride in the Friedel-Crafts reaction

The characteristics of the Friedel-Crafts reaction determine that the acylating reagent acetyl chloride is difficult to react completely, and the residual acetyl chloride aluminum chloride complex will also be hydrolyzed to generate acetic acid during the hydrolysis and decomplexation process, and the Friedel-Crafts reaction itself will produce a large amount of organic impurities. This part of impurities will also enter the hydrolysis mother liquor, resulting in complex components of the hydrolysis mother liquor and difficult treatment of wastewater. The Friedel-Crafts reaction mother liquor has always been one of the core problems restricting the Friedel-Crafts reaction.

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