A kind of preparation method of fenbendazole

Abstract

The invention discloses a preparation method of fenbendazole. It is characterized in that: (1) using m-dibromobenzene as a starting material, through nitric acid / sulfuric acid system nitration reaction, to prepare intermediate 1 (2,4-dibromonitrobenzene); (2) using intermediate 1 as a raw material , through the ammoniation reaction that ammonia methanol solution participates in, prepares intermediate 2 (5-bromo-2-nitroaniline); (3) takes intermediate 2 and sodium thiophenolate solution as raw materials, through condensation reaction, prepares Intermediate 3 (4-phenylthio-2-nitroaniline); (4) Intermediate 3 is subjected to palladium-carbon catalytic hydrogenation reduction to generate intermediate 4 (4-phenylthio-1,2-phenylenediamine) (5) Intermediate 4 and methyl cyanamide formate aqueous solution, through cyclization reaction, generate product fenbendazole. The method is clean and environmentally friendly, with low production cost, product purity of more than 99.5%, and yield of not less than 84.0%.

Description

technical field

[0001] The invention relates to the preparation of fenbendazole and an intermediate thereof, in particular to a preparation method of fenbendazole. Background technique

[0002] Fenbendazole, also known as benzimidazole, chemical name is 5-phenylthiobenzimidazole-2-carbamic acid methyl ester, is a benzimidazole anthelmintic. It not only has high anthelmintic activity on gastrointestinal nematodes adults and larvae, but also has good effects on reticulate nematodes, fasciola and tapeworms, and has a strong insecticidal egg effect. It has the advantages of maggot spectrum light, low toxicity, good tolerance, wide safety range and good palatability.

[0003] At present, m-dichlorobenzene is often used as the starting material in the selection of synthetic routes at home and abroad, and liquid ammonia needs to be selected as the ammoniation reagent during the ammoniation reaction. The reaction pressure needs to be above 8.0 MPa, and the temperature needs to be a...

Images