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Preparation method of 2-chloro-4-fluorotoluene

A technology of fluorotoluene and aminotoluene, which is applied in the field of preparation of 2-chloro-4-fluorotoluene, can solve the problems of many impurities and low yield, and achieve the effects of high crude product purity and few impurities

Inactive Publication Date: 2020-02-07
阜新宇泽化工有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a preparation of 2-chloro-4-fluorotoluene in order to overcome the problems of many impurities, low yield and easy occurrence of safety risks in the pyrolysis reaction process existing in the prior art method

Method used

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Examples

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preparation example Construction

[0016] The invention provides a preparation method of 2-chloro-4-fluorotoluene, comprising the following steps: cooling anhydrous hydrogen fluoride to 0-5°C, slowly adding 2-chloro-4-aminotoluene dropwise, and adding Sodium nitrate, keep warm at 0-10°C for 1h; then carry out pyrolysis, keep warm for 19-21h after pyrolysis; cool down to 20°C, separate the organic phase, then neutralize with sodium carbonate to pH=7-8; distill , to get 2-chloro-4-fluorotoluene;

[0017] The pyrolysis process is divided into two stages: the first stage is to raise the temperature to 30°C, and the heating time needs to be controlled between 1.5-2h, and the temperature is raised at a uniform speed; the second stage is to rise from 30°C to 50°C, and the heating time is controlled within 2.5-3h During this period, the temperature was raised at a constant speed.

[0018] The mass ratio of the 2-chloro-4-aminotoluene to anhydrous hydrogen fluoride is (2.4-2.7):1, preferably 2.5:1.

[0019] The mass r...

Embodiment 1

[0022] Cool down the temperature of anhydrous hydrogen fluoride to 0°C, slowly add 2-chloro-4-aminotoluene dropwise, add sodium nitrite after the dissolution is complete, and keep it at 0°C for 1 hour; then carry out pyrolysis, heat it for 19 hours after the pyrolysis is completed; cool down to 20 °C, perform two liquid separations, and neutralize the organic phase with sodium carbonate to pH = 7; distill to obtain 2-chloro-4-fluorotoluene.

[0023] The pyrolysis process is divided into two stages: the first stage is to raise the temperature to 30°C, and the heating time needs to be controlled between 1.5h, and the temperature is raised at a uniform speed; the second stage is to rise from 30°C to 50°C, and the heating time is controlled between 2.5h, Heat up at a constant speed.

[0024] The mass ratio of the 2-chloro-4-aminotoluene to anhydrous hydrogen fluoride is 2.4:1.

[0025] The mass ratio of the sodium nitrite to 2-chloro-4-aminotoluene is 1:1.9.

Embodiment 2

[0027] Cool down the temperature of anhydrous hydrogen fluoride to 0°C, slowly add 2-chloro-4-aminotoluene dropwise, add sodium nitrite after dissolving, and keep warm at 3°C ​​for 1 hour; then carry out pyrolysis, keep warm for 20 hours after pyrolysis; cool down to 20 °C, perform liquid separation twice, and neutralize the organic phase with sodium carbonate to pH = 7.5; distill to obtain 2-chloro-4-fluorotoluene;

[0028] The pyrolysis process is divided into two stages: the first stage is to raise the temperature to 30°C, and the heating time needs to be controlled within 2 hours, and the temperature is raised at a constant speed;

[0029] The mass ratio of the 2-chloro-4-aminotoluene to anhydrous hydrogen fluoride is 2.5:1.

[0030] The mass ratio of the sodium nitrite to 2-chloro-4-aminotoluene is 1:2.

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Abstract

The invention discloses a preparation method of 2-chloro-4-fluorotoluene. The preparation method is characterized by comprising the steps that anhydrous hydrogen fluoride is cooled to 0-5 DEG C, 2-chloro-4-aminotoluene is slowly added dropwise, sodium nitrite is added after dissolution is completed, and the solution is maintained under the temperature of 0-10 DEG C for 1h; then pyrolysis is performed, and the temperature is maintained for 19-21h after the pyrolysis is completed; the temperature is reduced to 20 DEG C through cooling, an organic phase is separated, and then sodium carbonate isused to neutralize the pH to 7-8; and distillation is performed to obtain the 2-chloro-4-fluorotoluene. Through the method, the reaction is more controllable and efficient, the pyrolysis is performedat two stages, the temperature is raised slowly at a uniform velocity, other impurities are reduced, and operation is easy; and a crude product is obtained through the distillation, wherein the crudeproduct has high purity and contains less impurities.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and in particular relates to a preparation method of 2-chloro-4-fluorotoluene. Background technique [0002] Organic fluoride intermediates and fluorobenzene chemicals are widely used in pesticides, medicines, dyes and other fields. As an important intermediate, the development of 2-chloro-4-fluorotoluene is becoming more and more important, which is widely used in pesticide intermediates Synthesis. [0003] The prior art is to salt methylaniline in dilute hydrochloric acid, add sodium nitrite solution dropwise, then add fluoroboric acid aqueous solution, filter out diazonium fluoroborate with little water solubility, wash, dry at low temperature, and then dry the The diazonium fluoroborate is heated by programmed temperature rise to cause a decomposition reaction, nitrogen and boron trifluoride gas escape, and water vapor is introduced for water vapor distillation, layered and rectifi...

Claims

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Application Information

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IPC IPC(8): C07C17/093C07C25/13C07C245/20
CPCC07C17/093C07C245/20C07C25/13
Inventor 姜涛
Owner 阜新宇泽化工有限公司
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