Method for purifying 2,5-dichloroaniline by using decompression and continuous distillation

Abstract

The invention discloses a method for purifying 2,5-dichloroaniline by using decompression and continuous distillation. The method is characterized by comprising the following steps: enabling the pressure of a tower top to be 3*10 <-2> to 5*10 <-2> barometric pressure, controlling the temperature inside the tower to be between 50 to 55 DEG C, adding crude product 2,5-dichloroaniline, aniline, m-chloroaniline, 2,5-dichloronitrobenzene and mixed materials with low boiling point and high boiling point into the tower, and carrying out continuous distillation to purify 2,5-dichloroaniline. Accordingto the method, the boiling point of a system feed liquid is lowered, the decomposition of a thermosensitive material is reduced, the loss is reduced, and the byproducts and aftertreatment cost are reduced; by using continuous distillation, the automation level is increased, the manpower is saved, the instability of batch fractionating is reduced, the energy consumption is reduced, the equipment space is saved, the production efficiency is improved, and the method is applicable for green industrial mode. Above all, the method is high in yield, low in energy consumption, high in automation degree, labor-saving, stable in production and few in byproducts, the safety is improved, the production rate is improved, and the social benefit is increased.

Description

1. Technical field: [0001] The invention relates to a distillation process for purifying 2,5-dichloroaniline, in particular to a method for purifying 2,5-dichloroaniline by vacuum continuous rectification 2. Background technology: [0002] 2.5-Dichloroaniline: It is an important dye intermediate. In the pesticide industry, it is used as a pesticide intermediate. It is an intermediate of the herbicides dicamba and quizalofop. The market demand is huge. With the increase of market demand, most of the existing manufacturers use batch distillation to purify and produce 2,5-dichloroaniline products. For batch distillation purification, whether it is the temperature of the tower top, the tower bottom, or the extraction of distillates, all variables are variable, mainly relying on manual operation, which is labor-intensive, unstable product qualification rate, high temperature in the later stage, large amount of tar, and high energy consumption. , the yield is low, and a large amo...

AI Technical Summary

Problems solved by technology

For batch distillation and purification, whether it is the temperature of the tower top, the tower bottom, or the extraction of distillate, they are all variables, mainly relying on manual operation, which is labor-intensive, unstable product qualification rate, high temperature in the later stage, large amount of tar, and high energy consumption. , the yield is low, and a large amount of antioxidant should be added

The addition of antioxidants will cause the product to change color, and the color is not easy to remove; antioxidants themselves have strong toxicity, which is not good for workers' health, and also causes great harm to the environment, which is not conducive to environmental protection