Preparation method of 2,4-difluoro-3,5-dichloronitrobenzene

Abstract

The invention provides a preparation method of 2,4-difluoro-3,5-dichloronitrobenzene, which belongs to the field of pesticide intermediate preparation and solves the problem of existing synthesis of 2,4-difluoro-3,5-dichloronitrobenzene such as poor selectivity. The preparation method of 2,4-difluoro-3,5-dichloronitrobenzene comprises the following steps: S01: using 2,3-dichlorofluorobenzene as raw material, using nitric acid as nitration reagent, and obtaining nitration mixture of 2,3-dichloro-4-fluoronitrobenzene and 2-fluorine-3,4-dichloronitrobenzene; S02: under the catalysis of chlorination catalyst, introducing chlorine gas into the nitration mixture in step SO1 to obtain chlorinated mixture of 2,3,5-trichloro-4-fluoronitrobenzene and 2-fluorine-3,4,5-trichloronitrobenzene; S03: under the catalysis of a fluorination catalyst, fluorinating the chlorinated mixture in the step SO2 with potassium fluoride to obtain the 2,4-difluoro-3,5-dichloronitrobenzene. The preparation method hasthe advantages of good reaction selectivity and the like.

Description

technical field [0001] The invention belongs to the field of preparation of pesticide intermediates, in particular to a preparation method of 2,4-difluoro-3,5-dichloronitrobenzene. Background technique [0002] 2,4-difluoro-3,5-dichloronitrobenzene (CAS: 15952-70-2) can be used in the synthesis of the pesticide insecticide chlorfluron. Fufenuron is a new type of benzoylurea insecticide, especially for pests that have developed resistance to organophosphate, pyrethroids, and carbamates, the control effect is better. 2,4-difluoro-3,5-dichloronitrobenzene is a key intermediate that restricts the industrial production of chlorfenuron. [0003] At present, the synthesis of 2,4 difluoro-3,5-dichloronitrobenzene mainly has the following routes: [0004] (1) US4457943 uses 2,3,4,5-tetrachloronitrobenzene as a raw material to obtain 2,4-difluoro-3,5-dichloronitrobenzene through fluorination. However, the raw material of 2,3,4,5-tetrachloronitrobenzene is not easy to obtain. Potass...

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Problems solved by technology

[0006] (2) CN200510049360.1 takes 2,4-difluoronitrobenzene as raw material, chlorination generates 2,4-difluoro-3,5-dichloronitrobenzene under the catalysis of concentrated sulfuric acid and iron powder, the method's The second chlorine is more difficult, the reaction is slower at low temperature, the nitro group is easily replaced by chlorine at high temperature, and the selectivity of the reaction is poor, so it has certain limitations

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