Method for preparing difenoconazole

Abstract

The invention relates to a method for preparing difenoconazole, which comprises the steps of cyclization reaction, bromination reaction, condensation reaction and etherification reaction in sequence, wherein the cyclization reaction refers to reacting 2,4-dichloroacetophenone with 1,2-propylene glycol in the presence of an acid catalyst in a solvent to form a ketal; the bromination reaction is to drip liquid bromine into a system obtained after cyclization reaction to form brominated ketal; the condensation reaction is to react the brominated ketal with triazole potassium in an N,N-dimethylformamide solvent to form metaconazole; and the etherification reaction is to react the metaconazole with p-chlorophenol potassium in a solvent at 100 to 180 DEG C to form difenoconazole. By the method, the synthesis route is reformed to reduce isomer content, increase product yield, reduce waste gas, water and residue and ensure safe operation and pollution-free production.

Description

technical field [0001] The invention relates to a preparation method of difenoconazole. Background technique [0002] Difenoconazole, chemical name: cis, trans-3-chloro-4-[4-methyl-2-1H-1,2,4-triazol-1-ylmethyl]-1, 3-Dipentan-2-yl)phenyl 4-chlorophenyl ether (cis, trans ratio is about 45:55); melting point: 78.6°C; vapor pressure: (20°C): 120nPa; solubility (25°C) : Water 15mg / L, easily soluble in organic solvents, ethanol 330g / L, acetone 610g / L, toluene 490g / L. [0003] Difenoconazole is a broad-spectrum triazole fungicide with the characteristics of high efficiency, safety, and low toxicity. It is widely used in the world for seed treatment and foliar spraying of food crops and economic crops to control fungal diseases. Because of its high efficiency, low toxicity, high chemical stability, and broad-spectrum sterilization, it has become a star product that domestic and foreign pesticide manufacturers are vying to develop. [0004] There are many manufacturers of difenoc...

AI Technical Summary

Problems solved by technology

There are different disadvantages in the traditional process: the content of 1,3,4-difenoconazole isomers produced in the condensation reaction is ≥15%, it is difficult to achieve the ideal quality and yield, and it brings difficulties to the purification of the final product. a lot of difficulty

In terms of refining methods, the salt-forming-powdering method requires a large amount of organic solvent, which is also lost in the process of recovering the organic solvent, which is easy to cause air pollution. In addition, during the washing process, a large amount of waste water is produced and pollutes the environment; the distillation-powdering method will The difenoconazole crude product obtained from the condensation reaction is distilled under reduced pressure, the distillate temperature is ≥250°C, and the heating temperature is ≥300°C. High temperature poses a great safety hazard. At the same time, high temperature causes the product to decompose, producing a large amount of tar, which affects Powder yield

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