Synthesis method of 3,5-dichloroaniline

Abstract

The invention discloses a synthesis method of 3,5-dichloroaniline. 1,3,5-trichlorobenzene serves as a raw material, alkali or an ammonia solution or ammonium salt is added into an organic solvent to serve as an ammonia source, a coupling reaction is generated under the effect of a transition metal catalyst and ligand, and the product 3,5-dichloroaniline is obtained. According to the method, the raw materials are simple and easy to obtain, the cost is low, synthesis steps are simple, the product 3,5-dichloroaniline can be obtained through direct coupling of 1,3,5-trichlorobenzene and the ammonia source only through a one-step reaction, fewer byproducts are generated, fewer three wastes are generated, environmental friendliness is achieved, upgrading of the product process is achieved, and great significance is achieved for reducing the synthesis cost of 3,5-dichloroaniline and derivatives thereof.

Description

technical field [0001] The invention relates to 3,5-dichloroaniline and its synthesis method and application, belonging to the technical field of chemical substances and their synthesis. Background technique [0002] 3,5-Dichloroaniline is an intermediate of medicine, pesticide and dyestuff, its English name is 3,5-Dichloroaniline, CAS626-43-7, the pure product is needle crystal, m.p.51~53℃, b.p.259~260 ℃ / 98.7kPa, soluble in ethanol, ether, diethyl carbonate, insoluble in water, highly toxic, corrosive, mainly used in the manufacture of fungicides, procymidone, sclerotin, sclerotin, and sclerotia Li, ethylene clonozolin and iprodione, etc. The compound is also widely used in the synthesis of medicines, dyes, pigments, photochromic materials and plant growth promoters. At present, due to the increase in the output of cyclic imide agricultural fungicides, the intermediate 3,5-dichloroaniline has become a trend that the supply exceeds the demand. Therefore, it is of practica...

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Problems solved by technology

This method has long steps, many wastes, and difficult separation; (2) the second method is to develop mixed dichlorobenzene as raw material, brominated to obtain mixed dichlorobromobenzene, and isomerized to obtain 3,5-dichlorobromobenzene Benzene is finally carried out through ammonification reaction, and the product is obtained by filtration. Although this process selects cheap and easy-to-obtain mixed dichlorobenzene raw materials, the strong acid hydrogen bromide produced in the bromination reaction is very polluting to the environment. In addition, the ammonification reaction needs to be At a higher temperature, potassium chlorate and ammonia water are used for reduction, which is unsafe to operate, and ammonia water also pollutes the environment, which cannot meet the requirements of clean production, and is not a green process

(3) The third method is the 3,5-dichloronitrobenzene reduction method, including hydrogenation reduction, sodium sulfide reduction, hydrochloric acid-iron powder reduction method, which also has the disadvantages of high raw material cost, low reduction efficiency, and many wastes.

Japan generally adopts the bromination and rearrangement of o-dichlorobenzene to obtain 3,5-dichlorobromobenzene, and then ammoniation to obtain 3,5-dichloroaniline. The device capacity is 2000 tons / year, but the same steps long, the three wastes produced are more

The methods for the synthesis of 3,5-dichloroaniline reported in literature and patents mainly include: (1) Chinese Patent Application No. 200410014747.9 discloses a 4-chloro-2-nitrotoluene produced by the production of 6-chloro-2-nitrotoluene 4,6-dichloro-o-nitrotoluene is obtained by chlorination and rectification separation, and then 4,6-dichloroaminobenzoic acid is obtained by oxidation reaction and hydrogenation reduction, and the product 3 is obtained after decarboxylation. 5-dichloroaniline, although the source of raw materials is sufficient and cheap, the total reaction yield is about 60%

(2) Chinese Patent Application No. 201210219294.8 discloses a kind of taking nitrochlorobenzene meta-oil as raw material, adding organic solvent, under the action of catalyst, through one-step chlorination to directly produce pentachloronitrobenzene mixture, then in organic solvent and Under the action of catalyst, dechlorination reduction reaction is carried out to obtain 3,5-dichloroaniline. Although this method utilizes the industrial production residues of p- and o-nitrochlorobenzene as raw materials, the steps are long, and the reaction requires high pressure and reaction time Long, using a large amount of strong acids such as sulfuric acid, hydrochloric acid or chlorosulfonic acid, the cost is high, and it is difficult to reach the degree of industrialization

(3) Chinese Patent Application No. 201310046616.8 uses 2,4-dichloroaniline as a raw material, undergoes acidification, rebromination, and deamination to obtain 3,5-dichlorobromobenzene, and then adds ammonia catalyst to react to obtain 3 , 5-dichloroaniline, this method has longer steps, more equipment required, and high raw material cost, the price of the intermediate product 3,5-dichlorobromobenzene is higher than that of the product 3,5-dichloroaniline, Moreover, bromine is used in the reaction, which causes serious pollution and has no industrial significance

(4) A Japanese patent reports a route for preparing 3,5-dichloroaniline from 1,3,5-trichloroaniline ammonolysis, using copper salt as a catalyst, but the reaction temperature is high and the yield is only 4 %, so it is far from meeting the requirements of the development process

(5) The BuchwaldPhos developed by the famous professor S.L.Buchwald of the Massachusetts Institute of Technology, under the catalysis of palladium, can perform the direct ammonolysis reaction of 3,5-dichlorobromobenzene at 80 degrees. The products are all high, so there is no meaning of industrialization

However, these methods are not suitable for primary ammonolysis of polyhalogenated aromatic hydrocarbons, and polyamine substitution products are inevitably generated, which brings difficulties to the purification of large-scale production products.

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