Synthetic method of fenbendazole

Abstract

A synthetic method of fenbendazole belongs to the technical field of insect repellents, and specifically comprises the following steps: carrying out condensation reaction on 5-chloro-2-nitroaniline and a sodium thiophenol aqueous solution in a mixed solution of n-propyl alcohol and water to obtain 5-thiophenyl-2-nitroaniline; carrying out reduction reaction on the 5-thiophenyl-2-nitroaniline in a high-pressure kettle under the catalysis of raney nickel to generate 4-thiophenyl o-phenylenediamine; and mixing the 4-thiophenyl o-phenylenediamine and N-(trichloromethyl) methyl carbamate for a cyclization reaction to obtain fenbendazole; the method has the advantages that conditions are mild, operation is easy and convenient, ammonium chloride can be prevented from being generated in the cyclization process, and the three-waste cost is low; the generation of amine salt is avoided, and the treatment cost of three wastes is greatly reduced; and the yield of the fenbendazole can reach 84.27% to 89.99%, and the purity of the fenbendazole can reach 96.39% to 99.71%.

Description

technical field [0001] The invention relates to the technical field of insect repellants, in particular to a synthesis method of fenbendazole. Background technique [0002] Fenbendazole belongs to the class of benzimidazoles. It is a low-toxicity, high-efficiency, and broad-spectrum anthelmintic. It can drive away parasites such as hookworms, roundworms, whipworms, some tapeworms, and strongyloids in the gastrointestinal tract of animals. , and has a strong insecticidal egg effect, with long-lasting efficacy, safety and low toxicity, and good palatability. [0003] Patent US3954791 discloses a synthetic method for preparing benzimidazole compounds. The method first prepares 5-phenylthio-2-nitroaniline by refluxing 5-chloro-2-nitroaniline and thiophenol in DMF, and then It is reduced to 4-phenylthio-o-phenylenediamine with tin chloride, and finally cyclized with S-methylisothiouronate methyl ester to obtain benzimidazole. This method requires the use of DMF as a solvent, whi...

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Problems solved by technology

This method needs to use tetrabutylammonium bromide to increase the cost, the three wastes produced by ferric chloride reduction pollute the environment, and the synthesis cost of hydrazine hydrate process is relatively high, although using methyl cyanocarbamate as cyclizing agent can reduce the cost, it will Ammonium chloride is produced, which is difficult to separate after mixing with the sodium salt in the three wastes

[0005] At present, the mainstream cyclizing agents are still S / O-methylisothioureaformate and methyl cyanocarbamate, but the production cost of the former is relatively high, and the latter will produce amine salts during the cyclization process. As a result, it is difficult to separate the sodium salt and amine salt in the three wastes, which increases the cost of the three wastes

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