Synthetic method for 1,2,4-trifluorobenzene

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...

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

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