Method for synthesizing cyhalofop-butyl

Abstract

The invention discloses a method for synthesizing cyhalofop-butyl. The method comprises the following steps: taking R-2-(4-hydroxyphenoxy) propionic acid and 3,4-dichlorobenzonitrile as raw materials;and carrying out salifying, etherification, neutralization, esterification, fluorination reaction and post treatment to obtain the cyhalofop-butyl. According to the synthetic method disclosed by theinvention, by taking 3,4-dichlorobenzonitrile as the raw material, the cost of the raw material is greatly reduced; a reaction rout is simple and acidchloride reaction is avoided, so that the requirement on equipment is reduced and simplicity and convenience in operation are realized; in addition, both a solvent and a catalyst can be recycled and reused; the discharge amount of three wastes is small, and reaction conditions are mild; and the method is favorably popularized to industrial production.

Description

technical field [0001] The invention relates to the technical field of herbicide preparation, in particular to a method for synthesizing cyhalofop-methyl. Background technique [0002] Cyhalofop-ethyl is a rice field herbicide with high efficiency, low toxicity and high selectivity. It has excellent effect on barnyardgrass, stephenia chinensis, and Aurantia chinensis, etc., and is very safe to rice crops. Therefore, a simple and efficient synthetic The route to prepare cyhalofop-ethyl has great guiding significance for process scale-up and industrial production. Its chemical structural formula is as follows: [0003] [0004] Among the multiple synthetic techniques that have been announced so far, cyhalofop-methyl is obtained through reactions such as etherification and substitution using 3,4-difluorobenzonitrile and hydroquinone as raw materials, but this synthetic route is subject to raw materials and reaction conditions. The impact of the reaction, there is racemizat...

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Problems solved by technology

[0004] Among the multiple synthetic techniques that have been announced so far, cyhalofop-methyl is obtained through reactions such as etherification and substitution using 3,4-difluorobenzonitrile and hydroquinone as raw materials, but this synthetic route is subject to raw materials and reaction conditions. The impact of the reaction, there is racemization in the reaction, there are many isomers, and the side reaction will increase the unit consumption of 3,4-difluorobenzonitrile, and 3,4-difluorobenzonitrile is expensive, so the overall route is complicated and the cost is high ; There are also R-2-(4-hydroxyphenoxy)propionic acid and 3,4-difluorobenzonitrile as raw materials, through condensation and photochemical reaction to generate intermediate R-2-(4-(2-fluoro- 4-cyano)-phenoxy)-propionyl chloride, and finally carry out esterification reaction with n-butanol to obtain cyhalofop-methyl, but this route requires acid chloride reaction, and poisonous and corrosive phosgene is used during the reaction Or raw materials such as thionyl chloride have high requirements on equipment and operation, and are highly dangerous

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