Preparation method of triclabendazole

Abstract

The invention discloses a method for synthesizing triclabendazole by taking 1,2,3-trichlorobenzene as a raw material. The triclabendazole is generated through three steps by taking the 1,2,3-trichlorobenzene as a starting raw material. The method has the advantages that the inexpensive 1,2,3-trichlorobenzene is used as the starting raw material, and expensive 2,3-dichlorophenol with strong sensitization is not used. The 1,2,3-trichlorobenzene is hydrolyzed in high-concentration alkali liquor to prepare 2,3-dichlorophenol sodium which reacts with 4,5-dichloro-2-nitroaniline in a methylbenzene aqueous solution, and free 2,3-dichlorophenol is not generated again, so that the reaction yield is improved, and pollutions generated during production are avoided. The 4-chloro-5-(2,3-dichlorophenoxy)-2-nitroaniline is reduced by adopting a hydrogen catalytic transfer method, so that a large amount of iron mud which is difficult to treat and pollutes the environment is not generated; and an adopted hydrogen donator is low in price and does not cause any pollution to the environment, so that the triclabendazole is suitable for large-scale industrial production.

Description

technical field [0001] The invention relates to veterinary medicine triclabendazole, in particular to a preparation method of triclabendazole. Background technique [0002] At present, the effective insecticide used for ruminants such as cattle, sheep and goats is triclabendazole. According to the retrieval of patent literature and scientific literature, the existing synthesis techniques of triclabendazole mainly include the following two types: [0003] The first method: using 2,3-dichlorophenol and 4,5-dichloro-2-nitroaniline as raw materials, condensation reaction to obtain 2-amino-4-chloro-5-(2,3-dichloro phenoxy)-nitrobenzene, through a two-step reductive ring-closure reaction to obtain 5-chloro-6-(2,3-dichlorophenoxy)-2-mercapto-benzimidazole, and then with dimethyl sulfate Methylation reaction produces triclabendazole. This is reported in detail in Chinese patent ZL200910027417.6. This route uses 2,3-dichlorophenol, which is easy to sublimate and has strong allergen...

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Problems solved by technology

This is reported in detail in Chinese patent ZL200910027417.6. This route uses 2,3-dichlorophenol, which is easy to sublimate and has strong allergenicity, as a starting material. Special protection is required in the production process. At the same time, this scheme uses iron Powder is used as a reducing agent, and a large amount of iron sludge that is difficult to filter will be produced during the reaction process, which requires high production equipment and will cause great pollution to the environment.

[0004] The second method: react 2,3-dichlorophenol with 1,2,4-trichlorobenzene, and obtain triclabendazole through high-pressure ammoniation. The reaction risk of this process is relatively high, and it is not suitable for industrial production

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