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Preparation process of a,a,a',a'-tetrachloroortho-xylene

A preparation process and technology of xylene, which is applied in the preparation of halogenated hydrocarbons, organic chemistry, chemical instruments and methods, etc., can solve the problems of difficult control of the chlorination end point and low total yield, etc.

Active Publication Date: 2011-10-12
HUBEI XIANGYUN GROUP CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The current production process of the existing a, a, a', a'-tetrachloro-o-xylene is to use o-xylene as raw material, carry out side-chain chlorination under light in the presence of DMF, chlorinate to a certain extent to cool down and crystallize, and then filter Recrystallization, refining and drying to obtain the finished product, the content of the finished product is >99.0%, and the total yield is about 48% based on o-xylene. The problem of this process is that the end point of chlorination is difficult to control, and the total yield is not high

Method used

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  • Preparation process of a,a,a',a'-tetrachloroortho-xylene

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] Chlorination reaction

[0018] Add 250 g of o-xylene and a benzoyl peroxide catalyst whose mass is 1-1.05% of the o-xylene mass in a 1000 mL four-neck flask. Turn on the ultraviolet lamp, start stirring, and heat with an electric heating mantle. When the temperature reaches 120°C, open the valve on the chlorine cylinder and start to pass chlorine gas. The control reaction temperature is 120~125 ℃, until the amount of feeding chlorine is 220g, sampling is analyzed by gas chromatography, at this moment, the content of trichloro-o-xylene is 60%, the content of dichloro-o-xylene is 30%, and the content of tetrachloro-o-xylene is 30%. content of 10%, and then continue to heat up to 125 ~ 130 ℃, continue to pass chlorine gas. Until the total amount of feeding chlorine is 550g, sampling is analyzed by gas chromatography. At this time, the content of trichloro-o-xylene is 30%, the content of dichloro-o-xylene is 15%, the content of tetrachloro-o-xylene is 50%, and the content ...

Embodiment 2

[0024] Chlorination reaction

[0025] Add 300 g of o-xylene and a benzoyl peroxide catalyst whose weight is 1-1.05% of the weight of the o-xylene in a 1000 mL four-necked flask. Turn on the ultraviolet lamp, start stirring, and heat with an electric heating mantle. When the temperature reaches 120°C, open the valve on the chlorine cylinder and start to pass chlorine gas. The control reaction temperature is 120~125 ℃, until the amount of feeding chlorine is 280g, sampling is analyzed by gas chromatography, at this moment, the trichloro-o-xylene content is 60%, the dichloro-o-xylene content is 30%, and the tetrachloro-o-xylene content is 30%. content of 10%, and then continue to heat up to 125 ~ 130 ℃, continue to pass chlorine gas. Until the total amount of feeding chlorine is 700g, sampling is analyzed by gas chromatography. At this time, the content of trichloro-o-xylene is 30%, the content of dichloro-o-xylene is 15%, the content of tetrachloro-o-xylene is 50%, and the cont...

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Abstract

The invention relates to a preparation process of a,a,a',a'-tetrachloroortho-xylene. The preparation process comprises the following steps of: (1) undergoing a chlorination reaction, naturally cooling reaction liquid and performing suction filtration to obtain filtrate and a filter cake, wherein in the ultraviolet irradiation chlorination reaction process, the total mass of introduced chlorine gas is 2.60-2.80 times the feeding mass of ortho-xylene; at the first stage, the reaction temperature is 120-125 DEG C, and the mass of the introduced chlorine gas is one third of the total mass of chlorine gas; at the second stage, the reaction temperature is 125-130 DEG C, and the mass of the introduced chlorine gas is a half of the total mass of the chlorine gas; and at the third stage, the reaction temperature is 130-135 DEG C, and the mass of the introduced chlorine gas is one sixth of the total mass of the chlorine gas; (2) performing a depth chlorination reaction; and (3) purifying and crystallizing to obtain a target product. The preparation process has the advantages of increasing the total yield of the a,a,a',a'-tetrachloroortho-xylene and reducing the yields of trichloroortho-xylene and pentachloroortho-xylene as much as possible.

Description

technical field [0001] The invention relates to a preparation process of a, a, a', a'-tetrachloro-o-xylene by direct chlorination of o-xylene. Background technique [0002] a, a, a', a'-tetrachloro-o-xylene is an important organic intermediate, which can be used in the synthesis of various pharmaceuticals, pesticides and chemical intermediates o-phthalaldehyde. The current production process of the existing a, a, a', a'-tetrachloro-o-xylene is to use o-xylene as raw material, carry out side-chain chlorination under light in the presence of DMF, chlorinate to a certain extent to cool down and crystallize, and then filter Recrystallization, refining and drying to obtain the finished product, the content of the finished product is >99.0%, and the total yield is about 48% based on o-xylene. The problem of this process is that the chlorination end point is difficult to control, and the total yield is not high. Contents of the invention [0003] The technical problem to be s...

Claims

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Application Information

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IPC IPC(8): C07C22/04C07C17/10
Inventor 桂耀超张险峰陈绪珍李永鹏
Owner HUBEI XIANGYUN GROUP CHEM
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