A method for preparing 99% content 2,6-dichloro-4-trifluoromethylaniline

Abstract

The invention relates to a method for preparing 99 percent of 2,6-dichloro-4-trifluoromethyl phenylamine, which includes the following two steps of reaction: (1) amination reaction: 3,4-dichloro-5-nitrobenzotrifluoride reacts with ammonia to generate 3--chloro-4-amino-5-nitrobenzotrifluoride; (2) chlorination reaction: 3--chloro-4-amino-5-nitrobenzotrifluoride reacts with chlorine to generate 2,6-dichloro-4-trifluoromethyl phenylamine. The advantages of the invention are as follows: the target product 2,6-dichloro-4-trifluoromethyl phenylamine is prepared with 3,4-dichloro-5-nitrobenzotrifluoride as a material; the specific implementation route includes amination and chlorination, only simple distillation or steam distillation is needed, 99 percent of target product can be obtained without rectification, and the method has the advantages of mild reaction conditions, high safety and high product content; the process is suitable for mass industrial production, pollution is little, energy is saved, and the environment is protected.

Description

technical field [0001] The invention relates to the technical field of chemical industry, in particular to a method for preparing 2,6-dichloro-4-trifluoromethylaniline with a content of 99%. Background technique [0002] 2,6-Dichloro-4-trifluoromethylaniline (target product) is a key intermediate of the pesticide fipronil. The chemical name of fipronil is 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoromethylsulfinylpyrazole, trade name Fipronil is a high-efficiency insecticide developed by the French Rhone-Planck Company from 1987 to 1989 and registered in China in 1992; the methods for synthesizing the compound mainly include the following categories; Trifluoromethylaniline is a raw material, and the target product is obtained after chlorination; the second type is to use p-chlorobenzotrifluoride as a starting material, which is first aminated to obtain p-trifluoromethylaniline and then chlorinated to obtain the target product; The third type is based...

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Problems solved by technology

The chemical name of fipronil is 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-trifluoromethylsulfinylpyrazole, trade name Fipronil is a high-efficiency insecticide developed by the French Rhone-Planck Company from 1987 to 1989 and registered in China in 1992; the methods for synthesizing the compound mainly include the following categories; Trifluoromethylaniline is a raw material, and the target product is obtained after chlorination; the second type is to use p-chlorobenzotrifluoride as a starting material, which is first aminated to obtain p-trifluoromethylaniline and then chlorinated to obtain the target product; The third type is based on 3,4,5-trichlorobenzotrifluoride as the starting material, and the target product is obtained by amination; the fourth type is based on 3,4-dichlorobenzotrifluoride as the starting material, and after amination and chlorination The target product is obtained; the fifth type is to use p-methylaniline as the starting raw material, first make p-methyl isocyanate and then chlorinate and fluorinate to obtain the target product; the first type of synthetic method sees CN103408437A, and its shortcoming is that the raw material trifluoromethyl Aniline is difficult to obtain; the conversion rate of the second type of method can only reach less than 50% when preparing p-trifluoromethylaniline from raw material p-chlorobenzotrifluoride, and high temperature and pressure are also required, and an economically reasonable method has not been found yet; the third type of synthesis The method is described in CN101289400. Amination is an unavoidable problem of selectivity. There are about 25% of the by-product 3-amino-4,5-dichlorobenzotrifluoride, which requires rectification to obtain 95% of the target product The fourth type of synthetic method is described in detail in CN1468838. Like the third type, there are 5-10% by-product 3-amino-4-chlorobenzotrifluoride, which requires rectification to obtain 95% of the target product; the fifth Phosgene is used in the preparation of p-methyl isocyanate by a similar synthetic method, which is highly toxic and uneconomical; in summary, several existing methods have unavoidable defects, either economically unreasonable, or by-products are unavoidable , content less than 99%

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