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Method for preparing 3,4-dichloro bromobenzene

A technology of dichlorobromobenzene and bromine water, which is applied in 3 fields, can solve the problems of difficult separation and purification of 3,4-dichlorobromobenzene, reduce the utilization rate of raw materials, etc., achieve good separation and purification effect, increase yield, and rationally utilize Effect

Active Publication Date: 2014-07-16
福建桦智工程技术有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

3,4-dichlorobromobenzene and 2,3-dichlorobromobenzene are isomers, and the by-product 2,3-dichlorobenzene is inevitably generated when the bromination reaction generates 3,4-dichlorobromobenzene Chlorobromobenzene not only reduces the utilization rate of raw materials, but also brings difficulties to the separation and purification of product 3,4-dichlorobromobenzene
The solution crystallization method is widely used in the separation and purification process of various organic chemical products, but there is no relevant report on the purification process of 3,4-dichlorobromobenzene

Method used

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  • Method for preparing 3,4-dichloro bromobenzene
  • Method for preparing 3,4-dichloro bromobenzene

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Put o-dichlorobenzene and reducing iron powder into the bromination reaction kettle at a molar ratio of 1:0.02, and slowly add Br 2 , o-dichlorobenzene and Br 2 The molar ratio is 1:1.1, and the temperature is kept at 20~25°C. Waiting for Br 2 After the dropwise addition was completed, the stirring reaction was continued for 2 hours to reach the end of the reaction. After the reaction solution was washed and dried, a colorless transparent oily liquid was obtained, which was the crude 3,4-dichloro product obtained from the bromination reaction. The contents of 3,4-dichlorobromobenzene and impurity components were determined by gas chromatography. The purity of 3,4-dichlorobromobenzene in the crude product reaches 91.8%, the content of the by-product 2,3-dichlorobromobenzene is 6.7%, and the content of the reaction raw material o-dichlorobenzene is 0.7%.

[0029] The solution crystallization of the present invention adopts the operation mode of intermittent stirring c...

Embodiment 2

[0034] By implementing the case 1 method, get the 90.1% 3,4-dichlorobromobenzene crude product of bromination gained and press the same three-stage crystallization discharge flow process, the crude product is refined, and the process conditions are as follows:

[0035]

[0036] The purity of the product obtained by the third stage crystallization reaches 99.4%, and the total crystallization yield is 80.7%.

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Abstract

The invention belongs to the chemical engineering field, and particularly discloses a method for preparing 3,4-dichloro bromobenzene. The method comprises steps of adding reduced iron powder into the raw material o-dichlorobenzene, inletting bromine water under certain pressure and temperature, and carrying out bromination reaction in a bromination kettle; carrying out multistage crystallization on the crude bromized 3,4-dichloro bromobenzene through solution, so as to purify the 3,4-dichloro bromobenzene, wherein the crude bromized 3,4-dichloro bromobenzene is crystallized by at least one stage, generally by multiple stages, namely, from one stage to three stages, so that a complete cycle of crystallization and purification of the 3,4-dichloro bromobenzene product is formed. The method has the main beneficial effects that the product is not polluted by foreign solvents or other materials, for the byproduct 2,3- dichloro bromobenzene generated in preparation of 3,4-dichloro bromobenzene through o-dichlorobenzene is used as the solvent; particularly, reduction of the yield of 3,4-dichloro bromobenzene caused by intensified side reaction of the 2,3- dichloro bromobenzene due to rectification high temperature is avoided; the method has the characteristics of high yield of the product, high purity and high production efficiency.

Description

technical field [0001] The invention belongs to the field of chemical industry and specifically discloses a preparation method of 3,4-dichlorobromobenzene. Background technique [0002] 3,4-Dichlorobromobenzene, also known as 4-bromo-1,2-dichlorobenzene, is an important intermediate compound for the production of 3,4-dichloroaniline from o-dichlorobenzene. 3,4-Dichloroaniline is widely used in the pesticide and dye industries, and can be used in the synthesis of propanil, rituron, mezapyr and azo dyes, and is also a biologically active intermediate. Using o-dichlorobenzene as raw material, 3,4-dichloroaniline can be obtained through two-step reaction of bromination and ammonolysis. This process has the characteristics of simple operation, low cost and less pollution. It is an ideal method for industrial production of 3,4- A preferred process route for dichloroaniline. [0003] High-quality 3,4-dichloroaniline is crucial to the production of synthetic dyes and pesticides, s...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C25/02C07C17/12C07C17/392
Inventor 郑辉东赵素英吴丹王碧玉
Owner 福建桦智工程技术有限公司
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