Preparation method of azoxystrobin

Abstract

The invention discloses a preparation method of azoxystrobin disclosed as Formula (1), which comprises the following steps: a) under the catalytic action of aza-bicyclo-tertiary amines and / or salts thereof, carrying out etherification reaction on a compound disclosed as Formula (2) and 2-cyanophenol and / or salts thereof in a medium butyl acetate to obtain an azoxystrobin-containing butyl acetate solution; and b) cooling the azoxystrobin-containing butyl acetate solution to precipitate the azoxystrobin disclosed as Formula (1) from the butyl acetate. The method disclosed by the invention can obviously enhance the yield of azoxystrobin and obtain the higher-purity azoxystrobin product.

Description

technical field [0001] The invention relates to a preparation method of azoxystrobin. Background technique [0002] As an efficient and broad-spectrum fungicide, azoxystrobin is widely used in the prevention and treatment of various plant diseases. [0003] A synthetic method of azoxystrobin is disclosed in WO92 / 08703. In this method, a compound of the structure shown in formula (2) is mixed with 2-hydroxyphenol and potassium carbonate, and a copper halide is used as a catalyst in a polar solvent, especially N, An etherification reaction occurs in N-dimethylformamide. After the reaction, the reaction mixture is filtered and washed with N,N-dimethylformamide, and the crude product is obtained by vacuum distillation in a water bath at 70°C. Then the crude product was dissolved in methanol by reflux and cooled to 0-5°C to crystallize, and finally the crystallized product was washed with petroleum ether, and vacuum-dried at 50°C to obtain the product. [0004] [0005] WO20...

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Problems solved by technology

[0007] The process of the etherification reaction in the above prior art is mostly carried out in an aprotic polar solvent. After the reaction is completed and the solvent is removed, the product is crystallized by an organic solvent.

However, its defect is that the good water solubility of the aprotic polar solvent leads to difficulties in the subsequent separation and recovery of the product, especially when distillation is used to remove the solvent for the etherification reaction. Stirring in the distillation process is hindered, the heat transfer of the reaction system is poor, and a considerable part of the solvent cannot be recovered, and finally enters the environment, which not only increases the production cost, but also causes environmental pollution

At the same time, because the reactant 2-cyanophenol and / or its salt in the above etherification reaction process is easy to oxidize to produce tar, and the structural compound shown in formula (2) is easy to polymerize and hydrolyze, resulting in azoxystrobin in the crude product obtained from the reaction. The content of the azoxystrobin product is low, and it is usually necessary to recrystallize the product with a suitable solvent to obtain a product with high purity, and the purity of the obtained azoxystrobin product is low, usually lower than 98%

Since azoxystrobin products are widely used globally, a large number of impurities are applied to the environment along with azoxystrobin, which will pose a potential threat to environmental safety

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