A method of preparing an o-phenylenediamine intermediate used for carbendazim production

Abstract

A method of preparing an o-phenylenediamine intermediate used for carbendazim production is disclosed. The method includes reacting nitrochlorobenzene and concentrated aqueous ammonia in six tandem autoclaves to obtain 2-nitroaniline; washing ammoniated 2-nitroaniline with water to remove ammonium chloride; performing a hydrogenation reaction by utilizing a 2-nitroaniline dry basis in a molten state, adopting a palladium-on-charcoal catalyst and an organic salt as auxiliary agents, and adopting four tandem hydrogenation kettles; after hydrogenation is finished, conveying a liquid to a next process to obtain the o-phenylenediamine intermediate. After a preliminary reaction step is finished, useful compounds can be recovered effectively, and the o-phenylenediamine content after hydrogenation is 98% or above, thus saving a synthesis cost and increasing economic benefit. The preparing method and process design of the o-phenylenediamine intermediate used for carbendazim production are optimized, and requirements on the preparing method and the process design of the o-phenylenediamine intermediate used for carbendazim production are satisfied.

Description

technical field [0001] The invention relates to the technical field of pesticide synthesis, in particular to a method for preparing an intermediate o-phenylenediamine used in the production of carbendazim. Background technique [0002] O-phenylenediamine is a white crystalline solid, which can be obtained by reduction of o-nitroaniline. It is mainly used in the production of benzimidazole fungicides, such as carbendazim and thiophanate-methyl. Suction-type carbendazim can prevent and control bacterial diseases of various crops, forest trees, fruits and vegetables, and preserve and store fruits and vegetables. In addition, o-phenylenediamine can also be used to prepare developer and surfactant. [0003] At present, there are mainly three methods for the industrial production of o-phenylenediamine in China: iron powder reduction, alkali sulfide reduction, and catalytic hydrogenation reduction. Although the production process of the first two routes is simple, the product yiel...

AI Technical Summary

Problems solved by technology

However, in the existing catalytic hydrogenation process, no matter whether nickel is used as a catalyst or palladium / carbon is used as a catalyst, water or alcohols need to be added as a solvent. However, the use of solvents increases post-processing procedures such as product separation and solvent recovery. As a result, equipment investment and energy consumption increase, especially when alcohols with low boiling point and volatile are used as solvents, the safety and cleanliness of production are greatly reduced

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