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Method for preparing 2,4-dichlorotoluene by using parachlorotoluene

A technology of p-chlorotoluene and dichlorotoluene is applied in the preparation of halogenated hydrocarbons, chemical instruments and methods, metal/metal oxide/metal hydroxide catalysts, etc., and can solve the problem of low product yield, many by-products, acidity There are many problems such as waste water, etc., to achieve the effect of high product yield, simple method and easy operation.

Inactive Publication Date: 2016-03-02
NANJING ZHONGTENG CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method has low selectivity of 2,4-dichlorotoluene in industrial production, many by-products, many acid waste water, and large catalyst consumption
[0004] (2) Obtained by isomerization of dichlorotoluene, and the isomerized products are separated by mesoporous molecular sieves. The production cost of this method is relatively high, and it is difficult to realize industrial production
[0005] (3) Using 3-chloro-p-toluidine as raw material, carry out diazotization reaction with sodium nitrite to obtain 2-chloro-4-diazonium methyl salt, and use cuprous chloride to convert the diazo group into chlorine , after separation and purification, 2,4-dichlorotoluene is obtained, the method is complex and the product yield is low
[0006] (4) Using p-chlorotoluene and chlorine gas as raw materials and using NaKL zeolite as a catalyst, one-step direct chlorination synthesis of 2,4-dichlorotoluene in a fixed-bed continuous reactor. The conversion rate of toluene and the yield of 2,4-dichlorotoluene are low, only about 55%

Method used

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Examples

Experimental program
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Effect test

Embodiment 1

[0020] (a) Preparation of chlorination catalyst: After mixing 15 parts of alumina, 30 parts of ferric chloride, 20 parts of aluminum trichloride and 10 parts of silicon dioxide, they are mixed with silica sol, and then treated at 80°C for 6 hours Prepare a chlorination catalyst;

[0021] (b) chlorination of p-chlorotoluene: add p-chlorotoluene in reactor, add chlorination catalyst, open and stir and make catalyzer be evenly distributed in material, open the chlorine flowmeter valve of chlorine buffer tank, to be equipped with ortho-chlorotoluene Chlorine gas is introduced into the reaction kettle, the tail gas absorption circulating water pump is turned on to absorb the tail gas produced after the reaction, the flow rate of chlorine gas is controlled, and the molar ratio of p-chlorotoluene and chlorine gas in the reaction kettle is controlled at 1:0.5, and the temperature in the reaction is controlled at 40± 5°C; the reaction time of chlorine flow is controlled at 15 hours, th...

Embodiment 2

[0025] (a) Preparation of chlorination catalyst: After mixing 30 parts of alumina, 50 parts of ferric chloride, 40 parts of aluminum trichloride and 20 parts of silicon dioxide, they are mixed with silica sol, and then treated at 120 °C for 4 hours Prepare a chlorination catalyst;

[0026] (b) chlorination of p-chlorotoluene: add p-chlorotoluene in reactor, add chlorination catalyst, open and stir and make catalyzer be evenly distributed in material, open the chlorine flowmeter valve of chlorine buffer tank, to be equipped with ortho-chlorotoluene Chlorine gas is introduced into the reaction kettle, the tail gas absorption circulating water pump is turned on to absorb the tail gas produced after the reaction, the flow rate of chlorine gas is controlled, and the molar ratio of p-chlorotoluene and chlorine gas in the reaction kettle is controlled at 1:0.8, and the temperature in the reaction is controlled at 40± 5°C; the reaction time of chlorine flow is controlled at 18 hours, ...

Embodiment 3

[0030] (a) Preparation of chlorination catalyst: After mixing 20 parts of alumina, 40 parts of ferric chloride, 30 parts of aluminum trichloride and 15 parts of silicon dioxide, they are mixed with silica sol, and then treated at 100 ° C for 5 hours Prepare a chlorination catalyst;

[0031] (b) chlorination of p-chlorotoluene: add p-chlorotoluene in reactor, add chlorination catalyst, open and stir and make catalyst evenly distributed in material, open the chlorine gas flowmeter valve of chlorine surge tank, to house o-chlorotoluene Chlorine gas is introduced into the reaction kettle, the tail gas absorption circulating water pump is turned on to absorb the tail gas produced after the reaction, the flow rate of chlorine gas is controlled, and the molar ratio of p-chlorotoluene and chlorine gas in the reaction kettle is controlled at 1:0.7, and the temperature in the reaction is controlled at 40± 5°C; the reaction time of chlorine flow is controlled at 16 hours, the chlorine fl...

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Abstract

The invention discloses a method for preparing 2,4-dichlorotoluene by using parachlorotoluene. The method comprises the steps of (a) adding a chlorination catalyst; (b) chlorinating the parachlorotoluene; and (c) separating components. According to the method, a mixture of aluminum oxide, ferric chloride, aluminum trichloride and silicon dioxide is taken as the catalyst for a chlorination reaction, so that the selectivity for 2,4-dichlorotoluene is effectively promoted. The production of poly-chlorotoluene such as benzotrichloride and tetrachlorotoluene is effectively inhibited due to a low reaction temperature, and the yield of 2,4-dichlorotoluene is improved. Moreover, the method is simple and convenient; the operation is easy; the effects are good; and the product yield is high.

Description

technical field [0001] The invention belongs to the technical field of organic chemistry and relates to a method for preparing 2,4-dichlorotoluene from p-chlorotoluene. Background technique [0002] 2,4-Dichlorotoluene is a colorless and transparent liquid. It is an important chemical raw material, mainly used in organic synthesis, pharmaceutical and dye industries, and is also a good high-boiling organic solvent. At present, the synthesis routes at home and abroad mainly include the following: kind: [0003] (1) Using p-chlorotoluene and chlorine gas as raw materials, it is prepared by chlorination reaction under the catalysis of Lewis acid. The method has low selectivity of 2,4-dichlorotoluene in industrial production, many by-products, many acid waste water, and large catalyst consumption. [0004] (2) Obtained by isomerization of dichlorotoluene, and the isomerized products are separated by mesoporous molecular sieves. The production cost of this method is relatively h...

Claims

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Application Information

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IPC IPC(8): C07C25/02C07C17/12B01J23/745
CPCC07C17/12B01J23/002B01J23/745B01J2523/00
Inventor 钟华陆敏山陈秀珍蔡伟忠
Owner NANJING ZHONGTENG CHEM
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