Preparation method of flubendazole

Through the steps of palladium carbon hydrogenation catalytic reduction of nitro and hydrogen peroxide oxidation, the preparation process of flubendazole is optimized, which solves the problems of pollution in the alkali sulfide reduction process and long cyclization reaction time, and achieves the effects of shortened reaction time and cost reduction.

CN107698516AInactive Publication Date: 2018-02-16JIANGSU BAOZONG & BAODA PHARMACHEM
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Patent Information

Application Number
CN201711123626.1
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2017-11-14
Publication Date
2018-02-16
Estimated Expiration
Not applicable · inactive patent

AI Technical Summary

Technical Problem

Among the existing flubendazole preparation methods, the alkali sulfide reduction process is highly polluting and costly, the cyclization reaction time is long and the utilization rate of raw materials is low, resulting in high production costs and limited production capacity.

Method used

Palladium carbon hydrogenation is used to catalytically reduce the nitro group, simplifying the nitro reduction reaction, and combining the hydrogen peroxide oxidation step to shorten the overall reaction time. By optimizing the cyclization reaction system, low-cost cyanocarbamate methyl ester is used as the cyclizing agent to reduce production costs.

Benefits of technology

The overall reaction time is shortened, production costs are reduced, raw material utilization and reaction efficiency are improved, the cyclization reaction is smoother, and the process is cleaner and more environmentally friendly.

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Abstract

The invention relates to a preparation method of flubendazole. The preparation method comprises the following steps: dropwise adding thionyl chloride into a reaction system taking 4-chloro-3-nitrobenzoic acid and o-dichlorobenzene as solvents, wherein DMF (Dimethyl Formamide) is used as a reaction catalyst; then dropwise adding an acylated reaction solution into a fluorobenzene and aluminum trichloride system and carrying out Friedel-Crafts reaction; adding ammonia water, methane and a Friedel-Crafts product into a closed reactor for carrying out amination reaction; adding aminate, the methaneand a palladium carbon catalyst into a high-pressure hydrogenation reactor for reducing; adding a cyclization agent into a reduced reaction solution from which a catalyst is removed for cyclizing; finally, dropwise adding hydrogen peroxide into the cyclized reaction solution for oxidizing. The preparation method disclosed by the invention has the advantages that firstly, during cyclization reaction, an intermediate has an passivation action of carbonyl, so that the cyclization reaction is smoother and reaction time is greatly shortened; secondly, nitro is reduced by adopting a hydroreductionmethod which has better economic and environment-friendly properties compared with a traditional sulfuration alkaline method; thirdly, the cyclization agent adopts lower-price methyl cyanocarbamate,so that production cost is reduced.
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