Method for preparing 2,6-dichloro-4-nitroaniline through direct chlorination of chlorine gas and oxidative chlorination of hydrogen peroxide

Abstract

The invention relates to a method for preparing 2,6-dichloro-4-nitroaniline through direct chlorination of chlorine gas and oxidative chlorination of hydrogen peroxide. The method comprises the following steps: (1) adding paranitroaniline into hydrochloric acid at the concentration of 5-35wt%, heating to 40-80 DEG C, stirring for uniformly mixing, slowly inflating the chlorine gas within 0.5-5h, slowly adding hydrogen peroxide dropwise, and after adding the chlorine gas and the hydrogen peroxide, continuing to preserve heat and react for 0.3-1.5h; (2) filtering a product obtained in the step (1), washing a filter cake to be neutral, and drying to obtain the 2,6-dichloro-4-nitroaniline. By regulating a dosage ratio of the chlorine gas to the hydrogen peroxide, the concentration of the hydrochloric acid in a reaction system can be kept unchanged, the reaction process is steady and easily controlled, and the product is high in yield and purity.

Description

technical field [0001] The present invention relates to a preparation method of 2,6-dichloronitro-4-aniline, in particular to a method for simultaneously preparing 2,6-dichloro-4-nitroaniline by direct chlorine chlorination and hydrogen peroxide oxidative chlorination, The invention belongs to the technical field of organic intermediate chemical industry. Background technique [0002] 2,6-Dichloronitro-4-aniline (alias: 2,6-dichloro-p-nitroaniline; Chloronitroamine), English name: 2,6-Dichloro-4-nitroaniline, molecular formula: C 6 h 4 Cl 2 N 2 o 2 , Molecular weight: 207, Appearance: Yellow needle-like crystal, hardly soluble in water, easily soluble in ethanol and ether, slightly soluble in acetone, chloroform, ethyl acetate, melting point: 186-190°C. 2,6-Dichloronitro-4-aniline is an important dye intermediate, mainly used in the production of disperse dyes such as disperse yellow brown 3GL, disperse yellow brown 2RFL, disperse brown 3R, disperse orange S-4RL, disper...

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Problems solved by technology

However, due to the formation of hydrochloric acid as a by-product, the concentration of hydrochloric acid gradually increases as the reaction progresses, resulting in dark color and low purity of the product

Sodium chlorate chlorination method and sodium hypochlorite chlorination method generate a large amount of inorganic salt waste liquid due to the by-product sodium chloride, forming waste hydrochloric acid containing a large amount of inorganic salt that cannot be recycled, and the post-treatment amount is large, resulting in high production costs

The dichlorosulfuryl method produces a large amount of sulfur dioxide and hydrogen chloride gas, and it is difficult to treat the three wastes

Hydrogen peroxide oxidative chlorination method, due to the water brought in and the water generated during the oxidation process, the concentration of hydrochloric acid gradually decreases, making the later stage chlorination more difficult, resulting in low product yield and low purity