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Preparation method of pentafluoroaniline

A technology of pentafluoroaniline and pentafluorobenzamide, which is applied in the chemical industry, can solve the problems of unsuitability for industrial production, harsh reaction conditions, and difficulty in obtaining hexachlorobenzene, and achieve the effects of low cost, convenient operation, and less three wastes

Active Publication Date: 2013-04-03
FUXIN RUIGUANG FLUORINE CHEM
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] At present, it has been reported in the literature that the process for preparing pentafluoroaniline is: (1) through fluorination of hexachlorobenzene, and then high-pressure ammoniation of the obtained perfluorobenzene, but because the raw material hexachlorobenzene is very difficult to obtain, and the reaction conditions are very harsh , so it is not suitable for industrial production; (2) Using pentafluorobenzoic acid as raw material, pentafluorobenzoyl chloride is generated by acid chlorination, and then reacted with hydroxylamine hydrochloride to obtain N-hydroxypentafluorobenzamide, which is then hydrolyzed to pentafluorobenzoyl chloride Aniline, the method has a long route, cumbersome handling, harsh reaction conditions, and high cost

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  • Preparation method of pentafluoroaniline

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Effect test

Embodiment 1

[0019] Step (1): In a 1000ml four-neck flask, start stirring, add 120ml of water and 800g (8.00mol) of 98% sulfuric acid in sequence, then add 240g (1.24mol) of pentafluorobenzonitrile, heat up to 110°C for 4 hours, Then the reaction solution was added to water for crystallization, stirred at room temperature for 30 minutes, filtered, the filter cake was washed with water until neutral, and dried to obtain 249 g of pentafluorobenzamide, the gas phase content was ≥99%, and the yield was 94.9%.

[0020] Step (2a): Under stirring, add 500ml of water into a 2000ml four-necked flask, and add 90g (0.43mol) of pentafluorobenzamide obtained in step (1), and then cool the suspension to 0-10°C. Then, add 60ml (0.45mol) of 30% sodium hydroxide solution under stirring, and keep the temperature within the range of 0-10°C while adding. Next, 300 g (0.48 mol) of 12% sodium hypochlorite solution was added under stirring. During the entire dropping period, the temperature was kept within the r...

Embodiment 2

[0023] Step (1): In a 1000ml four-neck flask, start stirring, add 80ml of water and 800g (8.00mol) of 98% sulfuric acid in sequence, then add 240g (1.24mol) of pentafluorobenzonitrile, heat up to 100°C for 4 hours, Then the reaction solution was added to water for crystallization, stirred at room temperature for 30 minutes, filtered, and the filter cake was washed with water until neutral, and dried to obtain 252 g of pentafluorobenzamide, the gas phase content was ≥99%, and the yield was 96.0%.

[0024] Step (2a): Under stirring, add 500ml of water into a 2000ml four-necked flask, and add 90g (0.43mol) of pentafluorobenzamide obtained in step (1), and then cool the suspension to 10-20°C. Then, add 60ml (0.45mol) of 30% sodium hydroxide solution under stirring, and keep the temperature within the range of 10-20°C while adding. Next, 350 g (0.57 mol) of 12% sodium hypochlorite solution was added under stirring. During the entire dropping period, the temperature was kept within ...

Embodiment 3

[0027] Step (1): In a 1000ml four-neck flask, start stirring, add 80ml of water and 800g (8.00mol) of 98% sulfuric acid in sequence, then add 240g (1.24mol) of pentafluorobenzonitrile, heat up to 90°C for 4 hours, Then the reaction solution was added to water for crystallization, stirred at room temperature for 30 minutes, filtered, the filter cake was washed with water until neutral, and dried to obtain 242 g of pentafluorobenzamide, the gas phase content was ≥99%, and the yield was 92.2%.

[0028] Step (2a): Under stirring, add 500ml of water into a 2000ml four-necked flask, and add 90g (0.43mol) of pentafluorobenzamide obtained in step (1), and then cool the suspension to 0-10°C. Then, add 60ml (0.45mol) of 30% sodium hydroxide solution under stirring, and keep the temperature within the range of -10~0°C while adding. Next, 350 g (0.57 mol) of 12% sodium hypochlorite solution was added under stirring. During the entire dropping period, the temperature was kept in the range ...

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Abstract

The invention provides a preparation method of pentafluoroaniline. The preparation method is characterized by comprising the following steps of: (1) adding pentafluorobenzonitrile into sulfuric acid with the concentration of 70-98% for hydrolysis, controlling the hydrolysis temperature to be 70-120 DEG C and the reaction time to be 3-5 hours, and then adding the product into water to separate out, and filtering to obtain pentafluorobenzamide; and (2) mixing the pentafluorobenzamide prepared by step (1) with alkali solution and halogen or hypohalite, preserving the heat for 4-6 hours at -10 to 20 DEG C and then heating up to 70-110 DEG C to carry out Hoffman degradation, controlling the reaction time to be 0.5-3 hours, and then performing steam distillation to obtain the pentafluoroaniline. The method provided by the invention has the advantages that the raw materials are easily available, the process is simple, the operation is convenient, the product purity is high (99% or higher), the yield is high (as high as over 80%), the cost is low, and the method is safe and efficient with energy conservation, consumption reduction and little discharge of three wastes, so the method provided by the invention is suitable for industrial production on a large scale.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and in particular relates to a preparation method of pentafluoroaniline. Background technique [0002] Pentafluoroaniline (2,3,4,5,6-Pentafluoroaniline) is a very important medicine, pesticide, and liquid crystal intermediate, with the molecular formula C 6 h 2 f 5 N, CAS No. 771-60-8. [0003] At present, it has been reported in the literature that the process for preparing pentafluoroaniline is: (1) through fluorination of hexachlorobenzene, and then high-pressure ammoniation of the obtained perfluorobenzene, but because the raw material hexachlorobenzene is very difficult to obtain, and the reaction conditions are very harsh , so it is not suitable for industrial production; (2) Using pentafluorobenzoic acid as raw material, pentafluorobenzoyl chloride is generated by acid chlorination, and then reacted with hydroxylamine hydrochloride to obtain N-hydroxypentafluorobenzamide, whic...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C211/52C07C209/58
Inventor 姜殿平陈昌盛李成斌周业慎
Owner FUXIN RUIGUANG FLUORINE CHEM
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