Method for synthesizing 2,5-dichloroaniline by micro-channel reactor

Abstract

The invention provides a method for synthesizing 2,5-dichloroaniline by a micro-channel reactor. A nitratlon reaction and a catalytic hydrogenation reaction are performed by using the micro-channel reactor. The method comprises the following steps of nitratlon reaction: raw materials of nitro-p-dichlorobenzene are dissolved into an organic solvent, and are preheated; concentrated nitric acid and concentrated sulfuric acid are mixed and are preheated; the materials enter a reaction module group to take a reaction after the preheating; and an intermediate product of 2,5-Dichloronitrobenzene is obtained after the refining; and catalytic hydrogenation reaction: the 2,5-Dichloronitrobenzene is dissolved into a solvent; Pd-loaded active carbon catalysts are added; dechlorination inhibitors are added, and then, preheating is performed; after the materials are preheated, hydrogen gas enters the reaction module group to take a reaction; and post-treatment is performed to obtain the 2,5-dichloroaniline. The method provided by the invention has the advantages that the mixing effect is good; the temperature and material proportion control is precise; the reaction yield and the product purity are improved; the reaction is safe and stable; the time is short; no amplification effect exists; and wide application prospects are realized in industrial production.

Description

technical field [0001] The invention relates to the field of organic synthesis, in particular to a method for synthesizing 2,5-dichloroaniline. Background technique [0002] 2,5-Dichloroaniline is an important fine chemical intermediate, widely used in the production of fine chemicals such as dyes, medicines, spices and rubber additives. Its structure is as follows: [0003] [0004] In the agricultural industry, 2,5-dichloroaniline is mainly used for synthesizing the herbicide dicamba, and in the dye industry for synthesizing ice-dyeing dye scarlet base GG, printing and dyeing scarlet cloth color developer; it is also used in the manufacture of nitrogen fertilizer synergists, Such as N-2,5-dichlorophenylsuccinamic acid. Therefore, the market prospect of domestic production of 2,5-dichloroaniline is broad. At present, the domestic production method of 2,5-dichloroaniline mainly uses 1,4-dichlorobenzene as the starting material, and 2,5-dichloroaniline is obtained after...

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Problems solved by technology

[0005] 1. The nitration reaction is a strong exothermic reaction. It needs to be controlled at a relatively low temperature when operating in a conventional reactor. The heat released by the reaction cannot be taken away in time, the reaction temperature cannot be accurately controlled, and the heterogeneous reaction is stirred. Insufficient and other shortcomings, it is easy to cause side reactions such as multiple nitrification and oxidation, the process operation is very complicated, the amplification effect is obvious, the energy consumption is high, and the yield is low

[0006] 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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