Method for synthesizing 3, 4-dichloro-2-amino-5-fluorobiphenyl

Abstract

The invention discloses a method for synthesizing 3, 4-dichloro-2-amino-5-fluorobiphenyl. The method comprises the following steps: carrying out diazotization reaction on substrate 3, 4-dichloroaniline and nitroso sulfuric acid to prepare diazonium salt; carrying out a coupling reaction on the diazonium salt and 4-fluoroaniline to obtain the product 3, 4-dichloro-2-amino-5-fluorobiphenyl; sodium chloride needing landfill treatment is not generated in the reaction process, and the method has the characteristics of mild conditions, simple operation, high raw material conversion rate and productselectivity, low energy consumption and the like, and is suitable for industrial production; byproduct sodium sulfate generated by the reaction is a brownish yellow solid; a colorless sodium sulfate product is obtained after resin adsorption decoloration and thermal evaporation concentration crystallization combined process treatment, harmless treatment and resource utilization of sodium sulfate-containing waste salt slag are realized in the whole process, the produced sodium sulfate product reaches the industrial-grade anhydrous sodium sulfate product standard, the economic benefit is improved, and the environmental pollution is avoided.

Description

technical field [0001] The invention relates to a new method for synthesizing 3,4-dichloro-2-amino-5-fluorobiphenyl. Background technique [0002] 3,4-dichloro-2-amino-5-fluorobiphenyl is an important intermediate in the synthesis of bixafen, English name: 3,4-dichloro-2-amino-5-fluorobiphenyl, CAS number: 877197- 04-9, molecular formula: C 12 h 8 Cl 2 FN, molecular weight: 256.1. Bixafen (bixafen) is a pyrazole amide fungicide developed by Bayer CropScience and is one of the fastest growing succinate dehydrogenase inhibitor (SDHI) fungicides. A fungicide with a broad spectrum of fungicides. It is specially used for foliar spray, which can effectively control important diseases caused by Ascomycetes, Basidiomycetes and Deuteromycetes on cereal crops. Therefore, optimizing the method of synthesizing 3,4-dichloro-2-amino-5-fluorobiphenyl is of great significance for improving the yield of bixafen, shortening the production time, reducing energy consumption and waste disc...

AI Technical Summary

Problems solved by technology

[0005] (1) Palladium is used as a catalyst, which is expensive and unfavorable for industrialized production

[0006] (2) The synthetic route is longer and the operation is more complicated

[0007] (3) Anhydrous tetrahydrofuran is used in the reaction, the cost of solvent treatment is high, the operation is inconvenient, and it is not convenient for industrial operation

[0008] (4) The preparation process includes Grignard reaction, the danger level is high, and there are certain safety risks in industrial production

[0010] Sodium nitrite is used as a diazotization reagent, and a large amount of industrial waste salt sodium chloride is produced during the reaction process. There is no good treatment method for the by-product sodium chloride at present, and it can only be disposed of by landfill. The landfill cost is 3000~ 5,000 yuan / ton, which not only greatly increases the cost, but also causes environmental pollution, so the use of sodium nitrite for diazotization is obviously a non-optimal choice

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