Method for effectively recycling 2,4-dichloro-5-fluoro acetophenone from crystallization mother liquor

Abstract

The invention discloses a method for effectively recycling 2,4-dichloro-5-fluoro acetophenone from crystallization mother liquor, which comprises the following steps of: (a) reacting 2,4-dichloro-5-fluoro acetophenone crystallized mother liquor and neopentyl glycol as raw materials in an inert organic solution A under the action of an acidic catalyst A, then removing water continuously produced in the reaction process, and after sufficient reaction, separating and purifying to respectively obtain 2,6-dichloro-3-fluoro acetophenone and 2,4-dichloro-5-fluoro acetophenone ketal; and (b) carrying out the hydrolysis on the 2,4-dichloro-5-fluoro acetophenone ketal and water in an inert organic solution B under the action of an acidic catalyst B, and after sufficient reaction, carrying out aftertreatment to obtain the 2,4-dichloro-5-fluoro acetophenone. The invention has advanced process route, simple operation, mild reaction condition, high recycle rate of the 2,4-dichloro-5-fluoro acetophenone, environment protection and low production cost; and the neopentyl glycol of the auxiliary reagent can be recycled repeatedly, and the solidoid acidic catalyst can be recycled, thereby the invention is suitable for industrialized large-scale production.

Description

(1) Technical field

[0001] The invention relates to a method for efficiently recovering 2,4-dichloro-5-fluoroacetophenone from 2,4-dichloro-5-fluoroacetophenone crystallization mother liquor. (2) Background technology

[0002] 2,4-Dichloro-5-fluoroacetophenone is a key intermediate for the production of quinolones such as ciprofloxacin, enrofloxacin, and norfloxacin, with an annual market demand of more than 3,000 tons. 2,4-dichloro-5-fluoroacetophenone is prepared by using 2,4-dichlorofluorobenzene, acetyl chloride and aluminum trichloride as raw materials through the Friedel-Crafts acylation reaction. Chloro-5-fluoroacetophenone inevitably produces its isomer by-product 2,6-dichloro-3-fluoroacetophenone, and the main component of the reaction solution is 2,4-dichloro-5-fluoro Acetophenone and 2,6-dichloro-3-fluoroacetophenone, of which 2,4-dichloro-5-fluoroacetophenone content is about 80%, 2,6-dichloro-3-fluoroacetophenone The ketone content is about 20%. The melting po...

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