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A kind of synthetic method of 1,2,4-trifluorobenzene

A synthesis method and technology of trifluorobenzene, which are applied in the fields of pesticides, preparation of liquid crystal material intermediates, and medicine, can solve the problems of difficult fluorination and low total yield, and achieve mild operating conditions, low cost of raw materials, and easy availability of raw materials Effect

Active Publication Date: 2021-12-03
ZHEJIANG LINJIANG CHEM
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  • Abstract
  • Description
  • Claims
  • Application Information

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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 total yield is slightly lower

Method used

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  • A kind of synthetic method of 1,2,4-trifluorobenzene
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  • A kind of synthetic method of 1,2,4-trifluorobenzene

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Embodiment 1

[0038] (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%.

[0039] (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 method for synthesizing 1,2,4-trifluorobenzene, which belongs to the field of preparation of pesticides, medicines, and liquid crystal material intermediates. It solves the existing problems such as harsh reaction conditions for synthesizing 1,2,4-trifluorobenzene, a synthetic method for 1,2,4-trifluorobenzene, which is characterized in that it includes the following steps: Chlorofluorobenzene is a raw material, and nitric acid is used as a nitrating reagent, and nitrated to generate 2,4-dichloro-5-fluoronitrobenzene in the presence of sulfuric acid; 2,4-dichloro-5-fluoronitrobenzene is dissolved in In the organic solvent, adding potassium fluoride and the first catalyst, fluorination under the catalysis of the first catalyst to obtain 2,4,5-trifluoronitrobenzene; dissolving 2,4,5-trifluoronitrobenzene in the solvent 2,4,5-trifluoroaniline is obtained by hydrogenation reduction with hydrogen under the catalysis of the second catalyst; 2,4,5-trifluoroaniline reacts with sulfuric acid first, and then reacts with nitrosyl sulfuric acid to generate diazonium after forming a salt oxidization reaction, and then under the catalysis of copper salt, it undergoes deamination reduction reaction with sodium hypophosphite, and finally obtains 1,2,4-trifluorobenzene through steam distillation. 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 has the following routes: [0003] (1) Use 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-trifluorobenzene. The...

Claims

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Application Information

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Patent Type & Authority Patents(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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