Method for synthesizing 3,4-dichloroaniline by using micro-channel reactor

Abstract

The invention provides a method for synthesizing 3,4-dichloroaniline by using a micro-channel reactor. The micro-channel reactor is used for nitration and catalytic hydrogenation. The method comprisesthe following steps: nitration: preheating o-dichlorobenzene, mixing and preheating concentrated nitric acid and concentrated sulfuric acid, allowing the preheated materials to enter a reaction module group for a reaction and carrying out refining so as to obtain an intermediate 3,4-dichloronitrobenzene; and catalytic hydrogenation: dissolving 3,4-dichloronitrobenzene in a solvent, adding a Pd-loaded active carbon catalyst, adding a dechlorination inhibitor, then carrying out preheating, allowing a preheated product and hydrogen to enter a reaction module group for a reaction and carrying outpost-treatment so as to obtain 3,4-dichloroaniline. The method provided by the invention is good in material mixing effect, accurate in material proportion control, capable of improving reaction yield and product purity, safe and stable in reactions, short in synthesis time and free of amplification effect, and has good application prospects in industrial production.

Description

technical field [0001] The invention relates to the field of organic synthesis, in particular to a method for synthesizing 3,4-dichloroaniline. Background technique [0002] 3,4-Dichloroaniline is a commonly used chemical intermediate in the field of organic synthesis, mainly used as pesticides and industrial dyes, the structure is as follows: [0003] [0004] In the pesticide industry, it is mainly used for the synthesis of herbicides such as Diuron and Bizazone; in the dye industry, it is mainly used as an azo dye; in medicine, it is used to synthesize fungicide TCC, etc., and can be mixed with ammonium thiocyanate to obtain 3,4 - Dichlorophenylthiourea, which can be used as an intermediate for biologically active components. In addition, it can also be used to prepare 3,4-dichlorophenol and woolen fabrics. Generally speaking, the demand for herbicide raw materials in my country is large, which has laid a foundation for the wide application of 3,4-dichloroaniline, so...

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Problems solved by technology

[0006] 1. The nitration reaction is a strong exothermic reaction, and it needs to be controlled at a relatively low temperature when operating in a conventional reactor. If the heat released by the reaction cannot be taken away in time and the reaction temperature cannot be accurately controlled, a large amount of Isomer 1,2-dichloronitrobenzene, the process operation is very complicated, the amplification effect is obvious, the energy consumption is high, and the yield is low

[0007] 2. Catalytic hydrogenation reaction is a typical gas-liquid-solid three-phase reaction. When operating in a reactor, in order to ensure full contact between the three phases, it usually requires high temperature and high pressure and long-term reaction, high energy consumption, and due to If the reaction time is too long, a large amount of dechlorination impurities will appear in the reaction system, and the final product has many impurities, which is not suitable for purification and low yield; and due to H 2 Inflammable and explosive properties, if leakage occurs during production, there will be a great safety hazard; at the same time, the reaction time is too long under high temperature conditions, and the surface structure of the catalyst has undergone relatively large changes, so it is difficult to directly apply the catalyst after recovery

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