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Preparation method of m-fluoroaniline

A technology for fluoroaniline and m-aminoacetanilide hydrochloride, applied in the field of preparation of m-fluoroaniline, can solve the problems of expensive CsF, difficult to prepare, low reaction yield and the like, and achieves the effects of easy industrialization, easy acquisition and simple process

Inactive Publication Date: 2009-02-18
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0017] Halogen exchange method is relatively easy to generate ortho- and para-fluorides, meta-fluorides are difficult to prepare, the reaction yield is relatively low, and CsF is more expensive
[0018] From the preparation methods of the above-mentioned several m-fluoroanilines, some catalysts are more difficult to prepare, some raw materials are more expensive, and the yield is lower, resulting in higher cost

Method used

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  • Preparation method of m-fluoroaniline
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  • Preparation method of m-fluoroaniline

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] 1. Preparation of diazonium salt:

[0031] In a 500 mL four-necked bottle, add 60 mL of water and 54.7 g of m-aminoacetanilide hydrochloride. Stir, add ice-water bath to cool to -5~0°C, add 30mL of 25% NaOH aqueous solution, neutralize to pH 6, stir until all raw materials are dissolved. Add 125 grams of 40% fluoboric acid aqueous solution and keep it at -5-0°C. Then slowly add 18.7 g NaNO 2 Solution dissolved in 30mL of water, the temperature in the bottle is controlled at -5~0°C, the dropwise addition time is about 25 minutes, after the dropwise addition is completed, react at -5~0°C for another 3 hours, and the diazotization reaction is completed.

[0032] Lower the temperature in the four-necked bottle to -5°C, quickly suction filter, discard the filtrate, and suck and filter the filter cake as dry as possible. The filter cake was beaten and washed with 60 mL of cold ethanol and 60 mL of cold ether, respectively, sucked and filtered as dry as possible, and dried ...

Embodiment 2

[0038] Preparation of diazonium salt:

[0039] In a 500 mL four-necked bottle, add 87 mL of water and 54.7 g of m-aminoacetanilide hydrochloride. Stir, add ice-water bath to cool to -10~-5°C, add 32mL of 25% NaOH aqueous solution, neutralize to pH 7, stir until all raw materials are dissolved. Add 115 grams of 40% fluoboric acid aqueous solution and keep it at -10~-5°C. Then slowly add 25 grams of NaNO 2 Solution dissolved in 30mL of water, control the temperature in the bottle at -10~-5°C, add dropwise for about 25 minutes, after the dropwise addition is completed, react at -10~-5°C for another 5 hours, and the diazotization reaction is completed.

[0040] Then in the same manner as in Example 1, 58 grams of m-acetamidoaniline diazonium fluoroborate were obtained.

[0041] 2. Thermal decomposition and hydrolysis of diazonium salt

[0042] Put 20 grams of the above-mentioned diazonium salt into a 500mL four-necked bottle, heat and decompose carefully, raise the temperature...

Embodiment 3

[0046] Preparation of diazonium salt:

[0047] In a 500 mL four-necked bottle, add 70 mL of water and 54.7 g of m-aminoacetanilide hydrochloride. Stir, add an ice-water bath to cool to 0-5°C, add 31 mL of 25% NaOH aqueous solution, neutralize to pH 6.5, and stir until all raw materials are dissolved. Add 153 grams of 40% fluoboric acid aqueous solution and keep it at 0-5°C. Then slowly add 21 grams of NaNO 2 Solution dissolved in 30mL of water, the temperature in the bottle is controlled at 0-5°C, the dropwise addition time is about 25 minutes, after the dropwise addition is completed, react at 0-5°C for another 3 hours, and the diazotization reaction is completed.

[0048] Then in the same manner as in Example 1, 56.6 grams of m-acetamidoaniline diazonium fluoroborate were obtained.

[0049] 2. Thermal decomposition and hydrolysis of diazonium salt

[0050] Put 20 grams of the above-mentioned diazonium salt into a 500mL four-neck bottle, heat and decompose carefully, rais...

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Abstract

The present invention relates to a preparation method of m-fluoroaniline. Water and m-amino acetanilide hydrochloride are mixed, cooled to be at the temperature of minus 5 DEG C and 0 DEG C, and added into NaOH aqueous solution to be neutralized; borofluoric acid aqueous solution is added; and the temperature of the mixed solution is maintained between minus 5 DEG C and 0 DEG C. Then NaNO2 aqueous solution is dropped for diazo reaction, and the borofluoric diazonium salt is prepared. The diazonium salt is added into a reaction bottle to be heated and decomposed until nearly no gas is emitted; and the decomposition and fluorination are stopped. NaOH aqueous solution are added into the reaction bottle, acetyl is eliminated through mixing and hydrolysis, steam distillation and static demixing are completed, and the product m-fluoroaniline is in the oil layer. The main raw materials for synthesis, m-amino acetanilide hydrochloride, NaNO2, borofluoric acid and NaOH are all cheaper and easily accessible, the technologies of diazo reaction, decomposition and fluorination are simpler, the cost is low, and the present invention is easy for industrialization.

Description

technical field [0001] The invention belongs to a preparation method of fluorine-containing aromatic amines, in particular to a preparation method of m-fluoroaniline. Background technique [0002] M-Fluoroaniline is an important intermediate of fine chemicals such as medicines and dyes, and has a wide range of uses. About its synthetic method mainly has: [0003] 1. Hydrazine hydrate catalytic reduction method of m-fluoronitrobenzene [0004] [0005] The hydrazine hydrate reduction method has the advantages of cleanness, safety, simple post-treatment, high conversion rate, etc., and has certain application prospects. However, a higher concentration of hydrazine hydrate is required, the price is higher, excessive hydrazine hydrate is more polluting, and the cost of raw materials is higher. [0006] 2. High-temperature reduction method of m-fluoronitrobenzene in sodium trimethylsilyl sulfide [0007] [0008] Although the yield of this reaction is as high as 94%, th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C211/52C07C209/62
Inventor 张天永李晓旭
Owner TIANJIN UNIV
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