Preparation method of 3, 4, 5-trichlorobenzonitrile

Abstract

The invention discloses a preparation method of 3, 4, 5-trichlorobenzonitrile, which comprises the following steps: mixing p-hydroxybenzonitrile, a Lewis acid catalyst, a phenyl phosphonic acid dialkyl ester cocatalyst and a chlorobenzene organic solvent, heating to 40-80 DEG C, introducing chlorine for chlorination reaction, heating to 120-180 DEG C, and continuing chlorination reaction to obtain the 3, 4, 5-trichlorobenzonitrile. According to the preparation method of the 3, 4, 5-trichlorobenzonitrile, the p-hydroxybenzonitrile is taken as a raw material, and the 3, 4, 5-trichlorobenzonitrile can be generated through high-selectivity and high-yield reaction by optimizing the reaction temperature under the combined action of the lewis acid catalyst and the dialkyl phenylphosphonate cocatalyst; the method has the advantages of simple process, convenience in operation, easily available raw materials, low cost, high safety, high yield, less pollution and the like, is convenient for large-scale preparation, is favorable for realizing industrial application, and can meet the requirements of different fields on 3, 4, 5-trichlorobenzonitrile.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic compound synthesis and relates to a preparation method of 3,4,5-trichlorobenzonitrile. BACKGROUND

[0002] 3,4,5-trichlorobenzonitrile is an important organic chemical intermediate. For example, a downstream product of 3,4,5-trichlorobenzonitrile is 3,4,5-trichlorobenzaldehyde, which is a pharmaceutical intermediate. Meanwhile, a downstream product of 3,4,5-trichlorobenzonitrile is 3,4,5-trifluorobenzaldehyde, which is an intermediate for synthesizing bactericides.

[0003] At present, there are few synthesis methods of 3,4,5-trichlorobenzonitrile. Meanwhile, the existing synthesis method of 3,4,5-trichlorobenzonitrile is to use copper chloride as a catalyst, use 1,2,3-trichloro-5-(trichloromethyl)benzene and ammonium chloride as raw materials, and react at 220-225 DEG C to prepare 3,4,5-trichlorobenzonitrile. However, in the method, the raw material used is 1,2,3-trichloro-5-(trichloromethyl)benzene, which is not easy to obtain, and needs to be reacted at high temperature. In the reaction process, hydrogen chloride gas is continuously released, and there is a risk of uncontrollable decomposition of ammonium chloride at high temperature. It can be seen that the method is not suitable for industrial production.

[0004] Therefore, obtaining a preparation method of 3,4,5-trichlorobenzonitrile with simple process, convenient operation, easy-to-obtain raw materials, low cost, high safety, high yield and less pollution has important promoting effect on promoting the industrial production of 3,4,5-trichlorobenzonitrile and meeting different market demands. SUMMARY

[0005] The technical problem to be solved by the application is to overcome the shortcomings of the prior art and provide a preparation method of 3,4,5-trichlorobenzonitrile with simple process, convenient operation, easy-to-obtain raw materials, low cost, high safety, high yield and less pollution.

[0006] To solve the above technical problems, the application adopts the following technical solutions: A preparation method of 3,4,5-trichlorobenzonitrile comprises the following steps: S1, mixing p-hydroxybenzonitrile, a Lewis acid catalyst, a phenyl phosphonic acid dialkyl ester catalyst, and chlorobenzene organic solvent to obtain a mixed solution A; S2, heating the mixed solution A obtained in step S1 to 40-80 DEG C, and introducing chlorine to perform chlorination reaction to obtain a mixed solution B; S3, heating the mixed solution B obtained in step S2 to 120-180 DEG C, and introducing chlorine to perform chlorination reaction to obtain 3,4,5-trichlorobenzonitrile.

[0007] The preparation method is further improved, and in step S1, the Lewis acid catalyst is at least one of anhydrous ferric chloride, anhydrous aluminum chloride and anhydrous zinc chloride; and the molar ratio of the Lewis acid catalyst to the p-hydroxybenzonitrile is 1-1.2:1.

[0008] The preparation method is further improved, and in step S1, the phenyl phosphonic acid dialkyl ester-based cocatalyst is at least one of dimethyl phenyl phosphonate, diethyl phenyl phosphonate, diisopropyl phenyl phosphonate and dibutyl phenyl phosphonate; and the mass ratio of the phenyl phosphonic acid dialkyl ester-based cocatalyst to the p-hydroxybenzonitrile is 0.01-0.1:1.

[0009] The preparation method is further improved, and in step S1, the chlorobenzene-based organic solvent is at least one of chlorobenzene, o-dichlorobenzene and m-dichlorobenzene; and the mass ratio of the chlorobenzene-based organic solvent to the p-hydroxybenzonitrile is 3-6:1.

[0010] The preparation method is further improved, and in step S2, the molar ratio of the chlorine gas to the p-hydroxybenzonitrile is 2-3:1.

[0011] The preparation method is further improved, and in step S2, the chlorine gas is introduced within 2-4 hours.

[0012] The preparation method is further improved, and in step S3, the molar ratio of the chlorine gas to the p-hydroxybenzonitrile is 1-2:1.

[0013] The preparation method is further improved, and in step S3, the chlorine gas is introduced within 1-3 hours.

[0014] The preparation method is further improved, and in step S3, after the chlorination reaction is completed, the following treatment is further included: cooling the reaction solution to room temperature, filtering, collecting the filtrate, washing the filtrate with water, desolventizing under reduced pressure, collecting the residue, recrystallizing by adding a methanol-water solution, filtering, drying and obtaining 3,4,5-trichlorobenzonitrile.

[0015] The preparation method is further improved, and the volume ratio of methanol to water in the methanol-water solution is 9:1.

[0016] In the present application, the chemical reaction formula for preparing 3,4,5-trichlorobenzonitrile from p-hydroxybenzonitrile and chlorine gas under the joint action of a Lewis acid catalyst and a phenyl phosphonic acid dialkyl ester-based cocatalyst is as follows: .

[0017] Compared with the prior art, the present application has the following advantages: In view of the problems of the existing 3,4,5-trichlorobenzonitrile synthesis method, such as difficult to obtain raw materials, harsh reaction conditions, easy to produce toxic and harmful gas, high cost, low product yield, low safety and the like, the application creatively provides a preparation method of 3,4,5-trichlorobenzonitrile, which takes p-hydroxybenzonitrile as a raw material, and according to the positioning rules of the electrophilic substitution reaction on the benzene ring, the cyano group of p-hydroxybenzonitrile is a meta-positioning group, and the hydroxyl group is an ortho- and para-positioning group, the influence of the cyano group and the hydroxyl group on the benzene ring is comprehensively considered, and the chlorination reaction is preferentially performed at the ortho position of the hydroxyl group, so that 3,5-dichloro-4-hydroxybenzonitrile can be selectively generated by taking p-hydroxybenzonitrile as a raw material and reacting with chlorine, specifically, under the joint action of a Lewis acid catalyst and a phenyl phosphonic acid dialkyl ester catalyst, the p-hydroxybenzonitrile is first reacted with chlorine by being heated to 40-80 DEG C, so that 3,5-dichloro-4-hydroxybenzonitrile and 3,4,5-trichlorobenzonitrile can be generated, further, the 3,5-dichloro-4-hydroxybenzonitrile is reacted with chlorine by being heated to 120-180 DEG C to generate 3,4,5-trichlorobenzonitrile, so that 3,4,5-trichlorobenzonitrile can be generated with high selectivity and high yield. Compared with the conventional preparation method, the preparation method of 3,4,5-trichlorobenzonitrile provided by the application fundamentally improves the raw materials and synthesis route from the design of the reaction path, and has the following obvious advantages: (1) the synthesis steps are few, and 3,4,5-trichlorobenzonitrile can be synthesized from the bulk raw material p-hydroxybenzonitrile through one-pot reaction; (2) the yield and purity are high, the product yield is 90.5-94.8%, and the content is 97.5-98.6%; (3) the raw materials, catalysts, catalyst promoters and solvents are all cheap and easily available bulk chemical raw materials, and the production is not limited by the raw materials; (4) the process is simple, and is conducive to industrialized production; (5) the safety is high, and the raw materials do not have the risk of decomposition out of control in the reaction process. Therefore, the preparation method of 3,4,5-trichlorobenzonitrile provided by the application takes p-hydroxybenzonitrile as a raw material, and 3,4,5-trichlorobenzonitrile can be generated with high selectivity and high yield under the joint action of a Lewis acid catalyst and a phenyl phosphonic acid dialkyl ester catalyst by optimizing the reaction temperature, and the method has the advantages of simple process, convenient operation, easily available raw materials, low cost, high safety, high yield, less pollution and the like, is convenient for large-scale preparation, is conducive to industrialized application, and can meet the demand of 3,4,5-trichlorobenzonitrile in different fields. DETAILED DESCRIPTION

[0018] The application will be further described below in combination with specific preferred embodiments, but the protection scope of the application is not limited by this.

[0019] Example 1: A preparation method of 3,4,5-trichlorobenzonitrile, which comprises the following steps of: taking p-hydroxybenzonitrile and chlorine as raw materials, and preparing 3,4,5-trichlorobenzonitrile under the joint action of a Lewis acid catalyst and a phenyl phosphonic acid dialkyl ester co-catalyst. In a 2000 mL four-necked flask with mechanical stirring, a thermometer, a gas inlet tube and a reflux condenser, 121.55 g (98%, 1 mol) of p-hydroxybenzonitrile, 167.22 g (97%, 1 mol) of anhydrous ferric chloride, 729.3 g of chlorobenzene and 1.22 g of dimethyl phenyl phosphonate were added and uniformly mixed, and then heated to 40 DEG C, 142 g (2 mol) of chlorine was introduced within 4 h, and then heated to 120 DEG C, 142 g (2 mol) of chlorine was introduced within 3 h, and the complete reaction of the raw material p-hydroxybenzonitrile and the intermediate state 3,5-dichloro-4-hydroxybenzonitrile was monitored.After the reaction was completed, the reaction liquid was cooled to room temperature, filtered, the filtrate was washed with water, and then desolved under reduced pressure, the obtained residue was recrystallized in a methanol-water solution (the volume fraction of methanol in the solution was 90%, and the volume fraction of water was 10%), filtered, and dried to obtain 197 g of white solid, which was 3,4,5-trichlorobenzonitrile of the present application.

[0020] The content of 3,4,5-trichlorobenzonitrile determined by liquid chromatography external standard method was 98.3%, and the yield was 93.8%.

[0021] Example 2 A preparation method of 3,4,5-trichlorobenzonitrile, which comprises the following steps of: taking p-hydroxybenzonitrile and chlorine as raw materials, and preparing 3,4,5-trichlorobenzonitrile under the joint action of a Lewis acid catalyst and a phenyl phosphonic acid dialkyl ester co-catalyst. In a 2000 mL four-necked flask with mechanical stirring, a thermometer, a gas inlet tube and a reflux condenser, 121.55 g (98%, 1 mol) of p-hydroxybenzonitrile, 167.22 g (97%, 1 mol) of anhydrous ferric chloride, 729.3 g of chlorobenzene and 1.22 g of dimethyl phenyl phosphonate were added and uniformly mixed, and then heated to 40 DEG C, 142 g (2 mol) of chlorine was introduced within 4 h, and then heated to 120 DEG C, 142 g (2 mol) of chlorine was introduced within 3 h, and the complete reaction of the raw material p-hydroxybenzonitrile and the intermediate state 3,5-dichloro-4-hydroxybenzonitrile was monitored.After the reaction was completed, the reaction liquid was cooled to room temperature, filtered, the filtrate was washed with water, and then desolved under reduced pressure, the obtained residue was recrystallized in a methanol-water solution (the volume fraction of methanol in the solution was 90%, and the volume fraction of water was 10%), filtered, and dried to obtain 197 g of white solid, which was 3,4,5-trichlorobenzonitrile of the present application.

[0022] The content of 3,4,5-trichlorobenzonitrile determined by liquid chromatography external standard method was 98.3%, and the yield was 93.8%.

[0023] Example 3 A method for preparing 3,4,5-trichlorobenzonitrile, using p-hydroxybenzonitrile and chlorine as raw materials, under the joint action of Lewis acid catalyst and phenyl phosphonic acid dialkyl ester co-catalyst, includes the following steps: In a 1000 mL four-necked flask with mechanical stirring, thermometer, gas inlet tube and reflux condenser, 121.55 g (98%, 1 mol) of p-hydroxybenzonitrile, 200.66 g (97%, 1.2 mol) of anhydrous ferric chloride, 364.65 g of o-dichlorobenzene and 6.08 g of phenyl phosphonic acid diethyl ester were added and mixed uniformly. First, the temperature was raised to 60°C, and then 177.5 g (2.5 mol) of chlorine was introduced within 3 h. Then the temperature was raised to 140°C, and 106.5 g (1.5 mol) of chlorine was introduced within 2 h. The reaction was monitored until the raw material p-hydroxybenzonitrile and the intermediate state 3,5-dichloro-4-hydroxybenzonitrile were completely reacted. After the reaction was completed, the reaction liquid was cooled to room temperature, filtered, and the filtrate was washed with water. The residue obtained by vacuum desorption was recrystallized in a methanol-water solution (the volume fraction of methanol in the solution was 90%, and the volume fraction of water was 10%). After filtration and drying, 193.87 g of white solid was obtained, which was 3,4,5-trichlorobenzonitrile of the present application.

[0024] The content of 3,4,5-trichlorobenzonitrile was 98.5% and the yield was 92.5% as determined by liquid chromatography external standard method.

[0025] Example 4 A method for preparing 3,4,5-trichlorobenzonitrile, using p-hydroxybenzonitrile and chlorine as raw materials, under the joint action of Lewis acid catalyst and phenyl phosphonic acid dialkyl ester co-catalyst, includes the following steps: In a 1000 mL four-necked flask with mechanical stirring, thermometer, gas inlet tube and reflux condenser, 121.55 g (98%, 1 mol) of p-hydroxybenzonitrile, 200.66 g (97%, 1.2 mol) of anhydrous ferric chloride, 364.65 g of o-dichlorobenzene and 6.08 g of phenyl phosphonic acid diethyl ester were added and mixed uniformly. First, the temperature was raised to 60°C, and then 177.5 g (2.5 mol) of chlorine was introduced within 3 h. Then the temperature was raised to 140°C, and 106.5 g (1.5 mol) of chlorine was introduced within 2 h. The reaction was monitored until the raw material p-hydroxybenzonitrile and the intermediate state 3,5-dichloro-4-hydroxybenzonitrile were completely reacted. After the reaction was completed, the reaction liquid was cooled to room temperature, filtered, and the filtrate was washed with water. The residue obtained by vacuum desorption was recrystallized in a methanol-water solution (the volume fraction of methanol in the solution was 90%, and the volume fraction of water was 10%). After filtration and drying, 193.87 g of white solid was obtained, which was 3,4,5-trichlorobenzonitrile of the present application.

[0026] The content of 3,4,5-trichlorophenyl cyanide is 97.5% and the yield is 94.3% by liquid chromatography external standard method.

[0027] Example 5 A preparation method of 3,4,5-trichlorophenyl cyanide, which uses p-hydroxyphenyl cyanide and chlorine as raw materials, and prepares 3,4,5-trichlorophenyl cyanide under the joint action of a Lewis acid catalyst and a phenyl phosphonic acid dialkyl ester co-catalyst, and includes the following steps: In a 1000 mL four-necked flask with mechanical stirring, a thermometer, a gas inlet tube and a reflux condenser, 121.55 g (98%, 1 mol) of p-hydroxyphenyl cyanide, 148.16 g (99%, 1.1 mol) of anhydrous aluminum chloride, 486.2 g of o-dichlorobenzene and 6.08 g of phenyl phosphonic acid diisopropyl ester are added and uniformly mixed, first heated to 70°C, 177.5 g (2.5 mol) of chlorine is introduced within 3 h, then heated to 160°C, 106.5 g (1.5 mol) of chlorine is introduced within 2 h, and the complete reaction of the raw material p-hydroxyphenyl cyanide and the intermediate state 3,5-dichloro-4-hydroxyphenyl cyanide is monitored. After the reaction is completed, the reaction liquid is cooled to room temperature, filtered, the filtrate is washed with water, and the residue obtained by desolventizing under reduced pressure is recrystallized in a methanol-water solution (the volume fraction of methanol in the solution is 90% and the volume fraction of water is 10%), filtered and dried to obtain 197.87 g of white solid, which is 3,4,5-trichlorophenyl cyanide of the present application.

[0028] The content of 3,4,5-trichlorophenyl cyanide is 98.6% and the yield is 94.5% by liquid chromatography external standard method.

[0029] Example 6 A preparation method of 3,4,5-trichlorophenyl cyanide, which uses p-hydroxyphenyl cyanide and chlorine as raw materials, and prepares 3,4,5-trichlorophenyl cyanide under the joint action of a Lewis acid catalyst and a phenyl phosphonic acid dialkyl ester co-catalyst, and includes the following steps: Into a 1000 mL four-necked flask with mechanical stirring, thermometer, gas inlet tube and reflux condenser, 121.55 g (98%, 1 mol) of p-hydroxybenzonitrile, 161.62 g (99%, 1.2 mol) of anhydrous aluminum chloride, 486.2 g of o-dichlorobenzene and 6.08 g of phenylphosphonic acid diisopropyl ester were added and mixed uniformly, heated to 70°C, 177.5 g (2.5 mol) of chlorine was introduced within 2 h, then heated to 170°C, 106.5 g (1.5 mol) of chlorine was introduced within 2 h, and the reaction of the raw material p-hydroxybenzonitrile and the intermediate 3,5-dichloro-4-hydroxybenzonitrile was monitored until completion. After the reaction was completed, the reaction liquid was cooled to room temperature, filtered, the filtrate was washed with water, and the solvent was removed under reduced pressure. The obtained residue was recrystallized in a methanol-water solution (the volume fraction of methanol in the solution was 90%, and the volume fraction of water was 10%), filtered, and dried to obtain 196.36 g of white solid, which was 3,4,5-trichlorobenzonitrile of the present application.

[0030] The content of 3,4,5-trichlorobenzonitrile was 98.2% and the yield was 93.4% as determined by liquid chromatography external standard method.

[0031] Example 7 A method for preparing 3,4,5-trichlorobenzonitrile, which uses p-hydroxybenzonitrile and chlorine as raw materials, and a Lewis acid catalyst and a phenylphosphonic acid dialkyl ester co-catalyst to prepare 3,4,5-trichlorobenzonitrile, comprising the following steps: Into a 1000 mL four-necked flask with mechanical stirring, thermometer, gas inlet tube and reflux condenser, 121.55 g (98%, 1 mol) of p-hydroxybenzonitrile, 152.99 g (98%, 1.1 mol) of anhydrous zinc chloride, 486.2 g of m-dichlorobenzene and 6.08 g of phenylphosphonic acid dibutyl ester were added and mixed uniformly, heated to 80°C, 213 g (3 mol) of chlorine was introduced within 2 h, then heated to 180°C, 71 g (1 mol) of chlorine was introduced within 1 h, and the reaction of the raw material p-hydroxybenzonitrile and the intermediate 3,5-dichloro-4-hydroxybenzonitrile was monitored until completion. After the reaction was completed, the reaction liquid was cooled to room temperature, filtered, the filtrate was washed with water, and the solvent was removed under reduced pressure. The obtained residue was recrystallized in a methanol-water solution (the volume fraction of methanol in the solution was 90%, and the volume fraction of water was 10%), filtered, and dried to obtain 194.44 g of white solid, which was 3,4,5-trichlorobenzonitrile of the present application.

[0032] The content of 3,4,5-trichlorobenzonitrile was 98% and the yield was 92.3% as determined by liquid chromatography external standard method.

[0033] Example 8 A preparation method of 3,4,5-trichlorobenzonitrile, which comprises the following steps of: taking p-hydroxybenzonitrile and chlorine as raw materials, and preparing 3,4,5-trichlorobenzonitrile under the joint action of a Lewis acid catalyst and a phenyl phosphonic acid dialkyl ester co-catalyst. In a 1000 mL four-necked flask with mechanical stirring, a thermometer, a gas inlet tube and a reflux condenser, 121.55 g (98%, 1 mol) of p-hydroxybenzonitrile, 166.9 g (98%, 1.2 mol) of anhydrous zinc chloride, 486.2 g of m-dichlorobenzene and 12.16 g of dibutyl phenyl phosphonate were added and uniformly mixed, and then heated to 80°C, 213 g (3 mol) of chlorine was introduced within 2 h, and then heated to 180°C, 71 g (1 mol) of chlorine was introduced within 1 h, and the complete reaction of the raw material p-hydroxybenzonitrile and the intermediate 3,5-dichloro-4-hydroxybenzonitrile was monitored. After the reaction was completed, the reaction liquid was cooled to room temperature, filtered, the filtrate was washed with water, and then desolved under reduced pressure, and the obtained residue was recrystallized in a methanol-water solution (the volume fraction of methanol in the solution was 90% and the volume fraction of water was 10%), filtered and dried to obtain 190.84 g of white solid, which was 3,4,5-trichlorobenzonitrile of the present application.

[0034] The content of 3,4,5-trichlorobenzonitrile determined by liquid chromatography external standard method was 97.9%, and the yield was 90.5%.

[0035] Comparative Example 1 A preparation method of 3,4,5-trichlorobenzonitrile, which is basically the same as that of Example 2, and the only difference is that no dimethyl phenyl phosphonate is added in Comparative Example 1.

[0036] The results show that the main product in the liquid chromatography control analysis is the intermediate 3,5-dichloro-4-hydroxybenzonitrile, and only a small amount of 3,4,5-trichlorobenzonitrile is generated. After drying, 183.51 g of solid is obtained, and the content of 3,4,5-trichlorobenzonitrile determined by liquid chromatography external standard method is 0.9%, and the yield is 0.8%.

[0037] Comparative Example 2 A preparation method of a benzaldehyde compound, which is basically the same as that of Example 2, and the only difference is that, after being uniformly mixed, 284 g (4 mol) of chlorine is introduced within 7 h in Comparative Example 2.

[0038] The results show that most of the products in the control analysis are the intermediate 3,5-dichloro-4-hydroxybenzonitrile, and only a small amount of 3,4,5-trichlorobenzonitrile is generated. After drying, 188.1 g of solid is obtained, and the content of 3,4,5-trichlorobenzonitrile determined by liquid chromatography external standard method is 9%, and the yield is 8.2%.

[0039] Comparative Example 3 A preparation method of a benzaldehyde compound is basically the same as that in Example 2, with the difference that in Comparative Example 2, after being mixed uniformly, the temperature is raised to 180℃, and 284 g (4 mol) of chlorine is introduced within 7 h.

[0040] The results show that 182.11 g of solid is obtained after drying, the content of 3,4,5-trichlorophenyl cyanide is 96.7% as determined by liquid chromatography external standard method, and the yield is 85.3%.

[0041] Comparative Example 4: A preparation method of a benzaldehyde compound is basically the same as that in Example 2, with the difference that in Comparative Example 2, after being mixed uniformly, the temperature is raised to 90℃ first, 142 g (2 mol) of chlorine is introduced within 4 h, then the temperature is raised to 130℃, and 142 g (2 mol) of chlorine is introduced within 3 h.

[0042] The results show that 175.54 g of solid is obtained after drying, the content of 3,4,5-trichlorophenyl cyanide is 97.5% as determined by liquid chromatography external standard method, and the yield is 82.9%.

[0043] Comparative Example 5: A preparation method of a benzaldehyde compound is basically the same as that in Example 2, with the difference that in Comparative Example 2, after being mixed uniformly, the temperature is raised to 50℃ first, 142 g (2 mol) of chlorine is introduced within 4 h, then the temperature is raised to 200℃, and 142 g (2 mol) of chlorine is introduced within 3 h.

[0044] The results show that 181.83 g of solid is obtained after drying, the content of 3,4,5-trichlorophenyl cyanide is 98.1% as determined by liquid chromatography external standard method, and the yield is 86.4%.

[0045] From the above results, it can be seen that if no catalyst is added, the main product is intermediate 3,5-dichloro-4-hydroxyphenyl cyanide, and only a small amount of 3,4,5-trichlorophenyl cyanide is generated. At the same time, the reaction process and reaction conditions are extremely important for improving the yield and purity of the product. In addition, in addition to p-hydroxyphenyl cyanide, other hydroxyphenyl cyanides cannot be used to synthesize 3,4,5-trichlorophenyl cyanide. In addition, in addition to chlorobenzene organic solvents, other organic solvents cannot be used to synthesize 3,4,5-trichlorophenyl cyanide.

[0046] Compared with conventional preparation methods, the preparation method of 3,4,5-trichlorophenyl cyanide in the present application fundamentally improves the raw materials and synthesis route from the design of the reaction path, and has the following obvious advantages: (1) The synthesis steps are less, and 3,4,5-trichlorophenyl cyanide can be synthesized from bulk raw material p-hydroxyphenyl cyanide in one pot reaction.

[0047] (2) high yield and high purity, wherein the product yield is 90.5%-94.8%, and the content is 97.5%-98.6%.

[0048] (3) the raw materials, catalysts, co-catalysts and solvents are all cheap and easy-to-obtain bulk chemical raw materials, and the production is not limited by raw materials.

[0049] (4) the process is simple, which is conducive to industrialized production.

[0050] (5) high safety, and in the reaction process, there is no risk of decomposition out of control of raw materials.

[0051] Therefore, the preparation method of 3,4,5-trichlorobenzonitrile of the present application uses p-hydroxybenzonitrile as raw material, and under the joint action of Lewis acid catalyst and phenyl phosphonic acid dialkyl ester co-catalyst, 3,4,5-trichlorobenzonitrile can be generated by optimizing the reaction temperature with high selectivity and high yield, which has the advantages of simple process, easy operation, easy-to-obtain raw materials, low cost, high safety, high yield, less pollution, etc., is convenient for large-scale preparation, is conducive to industrialized application, and can meet the demand of different fields for 3,4,5-trichlorobenzonitrile.

[0052] The above examples are only preferred embodiments of the present application, and the protection scope of the present application is not limited to the above examples. Any technical scheme falling within the idea of the present application belongs to the protection scope of the present application. It should be pointed out that, for ordinary skilled persons in the technical field, the improvements and decorations without departing from the principle of the present application should also be considered as the protection scope of the present application.

Claims

1. A process for the preparation of 3,4,5-trichloronitrile, characterized in that, The method comprises the following steps: S1, mixing p-hydroxybenzonitrile, a Lewis acid catalyst, a phenyl phosphonic acid dialkyl ester co-catalyst, and chlorobenzene organic solvent to obtain a mixed solution A; S2, heating the mixed solution A obtained in step S1 to 40-80℃, and introducing chlorine to perform chlorination reaction to obtain a mixed solution B; S3, heating the mixed solution B obtained in step S2 to 120-180℃, and introducing chlorine to perform chlorination reaction to obtain 3,4,5-trichlorobenzonitrile.

2. The production method according to claim 1, characterized by, In step S1, the Lewis acid catalyst is at least one of anhydrous ferric chloride, anhydrous aluminum chloride, and anhydrous zinc chloride; the molar ratio of the Lewis acid catalyst to the p-hydroxybenzonitrile is 1-1.2:

1.

3. The production method according to claim 1, characterized by, In step S1, the phenyl phosphonic acid dialkyl ester co-catalyst is at least one of dimethyl phenyl phosphonate, diethyl phenyl phosphonate, diisopropyl phenyl phosphonate, and dibutyl phenyl phosphonate; the mass ratio of the phenyl phosphonic acid dialkyl ester co-catalyst to the p-hydroxybenzonitrile is 0.01-0.1:

1.

4. The method of claim 1, wherein, In step S1, the chlorobenzene organic solvent is at least one of chlorobenzene, o-dichlorobenzene, and m-dichlorobenzene; the mass ratio of the chlorobenzene organic solvent to the p-hydroxybenzonitrile is 3-6:

1.

5. The production method according to any one of claims 1 to 4, characterized by, In step S2, the molar ratio of the chlorine to the p-hydroxybenzonitrile is 2-3:

1.

6. The production method according to claim 5, characterized by, In step S2, the chlorine is introduced within 2-4 hours.

7. The production method according to any one of claims 1 to 4, characterized by, In step S3, the molar ratio of the chlorine to the p-hydroxybenzonitrile is 1-2:

1.

8. The production method according to claim 7, characterized by, In step S3, the chlorine is introduced within 1-3 hours.

9. The production method according to claim 8, characterized by, In step S3, after the chlorination reaction is completed, the following treatment is further included: cooling the reaction solution to room temperature, filtering, collecting the filtrate, washing the filtrate with water, desolventizing under reduced pressure, collecting the residue, recrystallizing with a methanol-water solution, filtering, and drying to obtain 3,4,5-trichlorobenzonitrile.

10. The method of claim 9, wherein, The volume ratio of methanol to water in the methanol-water solution is 9:1.