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Synthetic method for 1,2,4-trifluorobenzene

A synthesis method and technology of trifluorobenzene, applied in chemical instruments and methods, preparation of nitro compounds, preparation of amino compounds, etc., can solve the problems of difficult fluorination and low total yield, and achieve mild operating conditions and low cost of raw materials , The effect of low safety risk factor

Active Publication Date: 2019-11-26
ZHEJIANG LINJIANG CHEM
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The raw material 2,6-dichloro-3-fluoroacetophenone used in the process is 2,4-dichlorofluorobenzene and acetyl chloride to produce 2,4-dichloro-5-fluoroacetophenone through Friedel-Crafts acylation Isomers, resource utilization, and cost advantages, but fluorination is difficult, requires a stronger fluorination catalyst, and the overall yield is slightly lower

Method used

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  • Synthetic method for 1,2,4-trifluorobenzene
  • Synthetic method for 1,2,4-trifluorobenzene
  • Synthetic method for 1,2,4-trifluorobenzene

Examples

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Embodiment 1

[0037] (1) Add 165g of 2,4-dichlorofluorobenzene to a 500mL four-neck flask, use 70.7g of fuming nitric acid (98% in mass fraction) and 70.7g of concentrated sulfuric acid (98% in mass fraction) to form a mixed acid, Add mixed acid dropwise at 60°C, keep warm at the same temperature for 3 hours after dropping, let stand for half an hour, separate the layers, wash the organic layer with water and alkali respectively, and obtain 205.8g of 2,4-dichloro-5-fluoronitrobenzene by layering, GC The purity is 99.5%, and the molar yield is 98.0%.

[0038] (2) Add 200g of 2,4-dichloro-5-fluoronitrobenzene and 200g of sulfolane to a 500mL four-neck flask, heat up to 100°C, remove water under reduced pressure, and add 121.5g of spray-dried potassium fluoride, 2g after dehydration for 1 hour Tetrabutylammonium bromide, heated up to 170-180°C, followed by GC, when the raw material was less than 3%, the reaction was terminated, rectified, and 146.5g of 2,4,5-trifluoronitrobenzene was obtained,...

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Abstract

The invention provides a synthetic method for 1,2,4-trifluorobenzene, belongs to the field of pesticide, medicine, and liquid crystal material intermediate preparation, and solves the problem of harshreaction conditions of a current method for synthesizing 1,2,4-trifluorobenzene. The synthetic method for the 1,2,4-trifluorobenzene is characterized by comprising the following steps: performing nitration by using 2,4-dichlorofluorobenzene as a raw material and nitric acid as a nitrating agent to form 2,4-dichloro-5-fluoronitrobenzene in the presence of sulfuric acid; dissolving the 2,4-dichloro-5-fluoronitrobenzene into an organic solvent, adding potassium fluoride and a first catalyst, and performing fluorination under the catalysis of the first catalyst to obtain 2,4,5-trifluoronitrobenzene; dissolving the 2,4,5-trifluoronitrobenzene into a solvent, and performing hydrogenation reduction with hydrogen under the catalysis of a second catalyst to obtain 2,4,5-trifluoroaniline; and performing a reaction on the 2,4,5-trifluoroaniline and sulfuric acid, after a salt is formed, performing a diazotization reaction on the salt and nitroso-sulfuric acid, performing a deamination reductionreaction with sodium hypophosphite under the catalysis of a copper salt, and finally performing steam distillation to obtain the 1,2,4-trifluorobenzene. The method provided by the invention has the advantages of mild reaction conditions and the like

Description

technical field [0001] The invention belongs to the field of preparation of pesticides, medicines and liquid crystal material intermediates, and in particular relates to a synthesis method of 1,2,4-trifluorobenzene. Background technique [0002] 1,2,4-Trifluorobenzene (CAS: 367-23-7) is an important intermediate in the preparation of pesticides and medicines. It can be used to produce the hypoglycemic drug sitagliptin phosphate, and can also be used to synthesize clinfloxacin and sitagliptin The key intermediates of fluoroquinolones such as floxacin can also be used as raw materials for liquid crystal materials. At present, the synthesis of 1,2,4-trifluorobenzene mainly contains the following routes: [0003] (1) Using 2,4-difluoroaniline as the starting material [Journal of the American Chemical Society (Journal of the American Chemical Society), 78, 2593-6; 1956], first make fluoroborate with fluoroboric acid, and then After diazo cracking, generate 1,2,4-trifluorobenzen...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C17/35C07C25/13C07C201/08C07C201/12C07C205/12C07C209/36C07C211/52C07C303/34C07C307/02
CPCC07C17/35C07C201/08C07C201/12C07C209/36C07C303/34C07C25/13C07C205/12C07C211/52C07C307/02
Inventor 易克炎易苗吴文良尹新尹凯
Owner ZHEJIANG LINJIANG CHEM
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