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Method for synthesizing 2,3,4-trifluoro phenyl formic acid

A technique for the synthesis of trifluorobenzoic acid, which is applied in the field of preparation 2, can solve the problems of difficult preparation of butyllithium, high requirements for reaction equipment, and difficulty in general adoption, and achieve the effect of mature industrial operation, low price, and simple operation

Inactive Publication Date: 2002-07-17
SHANGHAI INST OF ORGANIC CHEM CHINESE ACAD OF SCI +2
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  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The reaction uses butyllithium, but the preparation of butyllithium is difficult and dangerous, and the reaction needs to be carried out under anhydrous, anaerobic and low temperature conditions, and the requirements for reaction equipment are also high, so it is difficult to be widely used and expanded. to industrial production

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 11、2

[0034] Embodiment 11,2,3, the synthesis of 4-trifluorobenzonitrile

[0035] Put 14.7 grams of 2,3,4-trifluoroaniline, 38 ml of water and 47 ml of glacial acetic acid into a 250 ml reaction flask, add 15 ml of concentrated sulfuric acid under cooling, and add 7.6 grams of NaNO 2 Dissolve in 26ml of water solution, keep warm for 15min.

[0036] Take another 1L three-neck bottle, add 80ml of water, and then add 108g of NaHCO 3 , 11.6 grams of CuCN and 17.6 grams of NaCN, then add 80ml of toluene, gradually drop the prepared diazonium salt solution, heat to 45-55 ° C for 2-3 hours, cool, separate the organic layer, water, 10% Each was washed once with NaOH, then dried and concentrated to obtain 18.7 g, the crude product had a purity of 93% (GC), and was distilled under reduced pressure to obtain 10.3 g of a colorless liquid with a purity of 98%.

[0037] Theoretical yield: 15.7 grams,

[0038] Actual yield: 10.1 grams,

[0039] Actual yield: 64.3%.

[...

Embodiment 21、2

[0057] Embodiment 21. Synthesis of 2,3,4-trifluorobenzonitrile

[0058] Add 14.7 grams of 2,3,4-trifluoroaniline, 38ml of water and 47ml of glacial acetic acid into a 250ml Erlenmeyer flask, slowly add 15ml of concentrated sulfuric acid dropwise under cooling, cool to 0-5°C after adding, add 7.6g of NaNO 2 Dissolve the solution in 26ml of water and keep warm for 15-30min.

[0059] Add 80ml of water and 108g of NaHCO to a 250ml Erlenmeyer flask 3 , 11.6 g of CuCN and 80 ml of toluene, heated to 50-60 ° C for 3-5 hours, cooled, separated the organic layer, washed with water, NaOH aqueous solution, and water once, dried, concentrated, and distilled under reduced pressure to obtain 9.0 g of colorless liquid , content > 98%.

[0060] Theoretical yield: 15.7 grams,

[0061] Actual yield: 9.0 grams,

[0062] Actual yield: 57.3%.

[0063] IRν(cm -1 )3322, 2976, 1750, 1502, 1169, 1126

[0064] 1 H NMR (CDCl 3 )δ7.13 (m, 1H), 7.37 (m, 1H) ppm

[0065] 19 ...

Embodiment 31、2

[0081] Synthesis of Example 31, 2,3,4-trifluorobromobenzene

[0082] Add 220 grams of glacial acetic acid and 160 grams of water into a 1L three-necked bottle, and slowly add 128 grams of concentrated sulfuric acid under cooling to control the internal temperature below 50°C. Add 67 grams of 2,3,4-trifluoroaniline into the dropping funnel, start to add dropwise, keep the internal temperature below 50°C, and after the addition is complete, cool the system to -1-4°C.

[0083] Dissolve 32 grams of sodium nitrite in 51 grams of water, drop it into the reaction flask, and control the internal temperature at -5 to 10°C. After the dropwise addition is completed, keep the temperature for 30 minutes for later use.

[0084] Take another 1L three-necked bottle, add 124 grams of 50% hydrobromic acid, add 102 grams of cuprous bromide, raise the temperature to 55-65°C, add the diazonium salt solution prepared above dropwise, and control the reaction temperature b...

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Abstract

The present invention relates to two synthesis methods for preparing 2,3,4-trifluorobenzoic acid, in which 2,3,4-trifluoroaniline is used as raw material, the diazotization of amino group and nitrile grouping actino are used to obtain 2,3,4-trifluorobenzonitrile, processed with acid hydrolysis to obtain the invented product, in another mether, 2,3,4-trifluoroaniline processed by diazotization of amino group and bromization to obtain 1-bromo-2,3,4-trifluorobenzene, then reacted with metal magnesium to obtain Grignard reagent, and reacted with carbon dioxide and processed by acid hydrolysis so as to synthesize the invented product.

Description

technical field [0001] The invention relates to two synthetic methods for preparing 2,3,4-trifluorobenzoic acid. Background technique [0002] 2,3,4-Trifluorobenzoic acid is an important pharmaceutical intermediate. Due to the special activity of fluorine in medicine, pesticide and bioactive molecules, it has been widely used in medicine and pesticide. In addition, after introducing fluorine atoms into organic molecules, the original physical properties of the molecules can be changed, their chemical and thermal stability can be increased, and the viscosity and the birefringence of light can be reduced. In the liquid crystal system, fluorine atoms are used to replace hydrogen, which makes the liquid crystal habit and other physical properties of liquid crystal molecules produce exciting changes. Therefore, 2,3,4-trifluorobenzoic acid ester compounds are a kind of good liquid crystal materials ( Chinese J. Chem. Vol. 17, No. 1, 1999, 69.). Thus, the application prospect of ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/00C07C51/15C07C63/70
Inventor 姜标周健李欢
Owner SHANGHAI INST OF ORGANIC CHEM CHINESE ACAD OF SCI
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