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Preparation method of 2-bromo-4-fluoroacetanilide

A technology of fluoroacetanilide and p-fluoroaniline, which is applied in the field of preparation of 2-bromo-4-fluoroacetanilide, can solve the problems of affecting the yield of monobrominated products and the low yield of monobrominated products, and achieves favorable treatment, The effect of reducing the concentration and increasing the yield

Inactive Publication Date: 2015-03-25
常州化工研究所有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The deficiency of this method is: although the main product of p-fluoroacetanilide bromination is monobromine product (that is 2-bromo-4-fluoroacetanilide), bromination still can produce certain dibromine product ( That is, 2,6-dibromo-4-fluoroacetanilide), thus affecting the yield of monobrominated product
But, it still adopts bromine to carry out bromination, therefore, still can produce certain dibromine product, and monobromine product yield is still not high

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1）

[0024] In a 2000L reactor, put 355kg (3.2kmol) of p-fluoroaniline, stir and add 333kg (3.3kmol) of acetic anhydride dropwise, when the exothermic temperature of the reaction rises to 105-110°C, control the rate of addition, within this temperature range for 1.5 hours After dripping, keep warm for 1 hour. Sampling control, the raw material p-fluoroaniline < 0.5%, the acylation reaction is completed, slowly distill acetic acid under reduced pressure (no distilling to -0.09Mpa). A by-product acetic acid with a content greater than 97wt% is obtained.

[0025] Put 800kg of chlorobenzene into the above reaction kettle while it is hot, then cool to 40-45°C and put in 648kg (3.8kmol) of hydrobromic acid (concentration: 48wt%), stir for half an hour, then cool down to 35-40°C and start adding hydrogen peroxide ( Concentration is 30wt%) 544kg (4.8kmol), the reaction is exothermic, the rate of addition is controlled to keep the reaction temperature at 40-45°C, and the temperature is kep...

Embodiment 2～ Embodiment 5）

[0029] Each embodiment is basically the same as Embodiment 1, and the differences are shown in Table 1.

[0030] Table 1

[0031] Example 1 Example 2 Example 3 Example 4 Example 5 p-Fluoroaniline 355kg 355kg 355kg 355kg 355kg Acetic anhydride 333kg 352kg 330kg 359kg 347kg Acetylation reaction temperature 105～110℃ 110～115℃ 105～110℃ 100～105℃ 105～110℃ hydrobromic acid 648kg 731kg 594kg 810kg 678kg hydrogen peroxide 544kg 626kg 435kg 725kg 586kg bromination reaction temperature 40～45℃ 40～45℃ 45～50℃ 40～45℃ 35～40℃ 2,6-Dibromo-4-fluoroacetanilide ＜0.1% ＜0.1% ＜0.1% ＜0.1% ＜0.1% 2-Bromo-4-fluoroacetanilide 632kg 646kg 640kg 636kg 642kg yield 85.2% 87.0% 86.2% 85.7% 86.5% purity 99.8% 99.7% 99.8% 99.8% 99.7%

Embodiment 6）

[0033] In a 2000L reactor, put 335kg (3.2kmol) of p-fluoroaniline and 1200kg of chlorobenzene, and add 256kg (3.3kmol) of acetyl chloride dropwise with stirring. Within 1.5 hours, the dripping is completed, and the temperature is kept for 1 hour. In the control of sampling, the raw material p-fluoroaniline is less than 0.5%, the acylation reaction is completed, and the generated hydrogen chloride is driven out slowly by nitrogen gas. Absorption produces dilute hydrochloric acid with a concentration greater than 30wt%.

[0034] Cool the acylate in the above reaction kettle to 40-45°C, put in 648kg (3.8kmol) of hydrobromic acid (concentration: 48wt%), stir for half an hour, cool down to 35-40°C and start adding hydrogen peroxide (concentration: 30wt%) ) 544kg (4.8kmol), the reaction is exothermic, the rate of addition is controlled to keep the reaction temperature at 40-45°C, and the temperature is kept at this temperature for 3 hours after the addition is completed. Sampling ...

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PUM

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Abstract

The invention discloses a preparation method of 2-bromo-4-fluoroacetanilide. The preparation method comprises steps as follows: 4-fluoroaniline is taken as a raw material and subjected to acetylation and bromination to obtain 2-bromo-4-fluoroacetanilide; the bromination reaction is that acetylate is bromized by hydrobromic acid to produce 2-bromo-4-fluoroacetanilide under the presence of an oxidizing agent; a mole ratio of 4-fluoroaniline, hydrobromic acid and the oxidizing agent is 1: (1.0-2.0): (1.0-3.5); the oxidizing agent is one of hydrogen peroxide, sodium hypochlorite, sodium hypobromite and peracetic acid; and the bromination reaction temperature is in a range from 30 DEG C to 60 DEG C. The bromination reaction adopts hydrobromic acid to replace bromine to serve as a bromination reagent, so that very little 2, 6-dibromo-4-fluoroacetanilide is generated in the bromination reaction, and the yield of 2-bromo-4-fluoroacetanilide is increased.

Description

technical field [0001] The invention belongs to the technical field of fine chemicals, and in particular relates to a preparation method of 2-bromo-4-fluoroacetanilide. Background technique [0002] Bixafen (Bixafen) is a broad-spectrum fungicide with pyrazole or amide structure, which can be used for the control of various diseases such as powdery mildew, rust, and downy mildew. 2-Bromo-4-fluoroacetanilide ( BFA) is the key intermediate for the preparation of bixafen. [0003] At present, the preparation method of 2-bromo-4-fluoroacetanilide is mainly based on p-fluoroaniline, which is sequentially brominated and acetylated (such as international patent document WO031053945) or sequentially acetylated and brominated (such as Chinese patent document CN102120723A, CN102320987A, CN102295572A). [0004] Since the main product of the direct bromination of p-fluoroaniline is 2,6-dibromo-p-fluoroaniline, the yield of the final 2-bromo-4-fluoroacetanilide is very low. Therefore,...

Claims

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Application Information

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IPC IPC(8): C07C233/15C07C231/12
Inventor 徐新
Owner 常州化工研究所有限公司
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