Production process of 2, 6-dichloro-4-trifluoromethylaniline

Abstract

The invention discloses a production process of 2, 6-dichloro-4-trifluoromethylaniline, which comprises the following steps: 1) fluorination reaction, 2) ammonification reaction, and 3) chlorination reaction, the traditional ammonification reaction is divided into two steps of fluorination and ammonification to be completed through selection of a solvent and a catalyst, the raw material conversion rate is improved, the generation of solid waste in the reaction process is reduced, and the production cost is reduced. The method is high in process selectivity, high in economical efficiency, environmentally friendly, easy and convenient to operate, low in safety risk and suitable for industrial production, and the market competitiveness of the 2, 6-dichloro-4-trifluoromethylaniline product is improved.

Description

Technical Field

[0001] The invention belongs to the field of fine chemical production, and specifically relates to a production process of 2,6-dichloro-4-trifluoromethylaniline. Background Art

[0002] 2,6-Dichloro-4-trifluoromethylaniline is an important intermediate for medicine and pesticides because of its unique biological activity of fluorinated aromatic compounds and its easy combination with acid to form corresponding salts. Its diazonium salt can condense itself or with other compounds to generate many useful dyes, new high-efficiency insecticides and herbicides, such as fipronil, fluvalinate, flubendiamide and other pesticides.

[0003] At present, the mainstream industrial process of 2,6-dichloro-4-trifluoromethylaniline reported in the literature uses para-chlorotrifluorotoluene as raw material, and obtains 2,6-dichloro-4-trifluoromethylaniline through ammoniation and chlorination.

[0004] 1) Amination: p-Chlorotrifluorotoluene is used as the raw material, and liquid ammonia is reacted with solvent and catalyst under high temperature and high pressure to obtain p-trifluoromethylaniline.

[0005] For example, Chinese patent CN102643202A discloses a "method for producing p-trifluoromethylaniline", in which trifluorotoluene is used as raw material, the solvent is ethanol, and the catalyst is composed of cuprous chloride and potassium fluoride, which react with ammonia gas under high temperature and high pressure to obtain p-trifluoromethylaniline. The conversion rate of p-chlorotrifluorotoluene in the amination reaction of this route is about 50%, and the insoluble matter of amination is a mixture of potassium fluoride, potassium chloride, ammonium chloride, ammonium fluoride, cuprous chloride, etc., which makes it difficult to treat the solid waste.

[0006] 2) Chlorination: Add solvent to trifluoromethylaniline and pass chlorine gas intermittently to obtain 2,6-dichloro-4-trifluoromethylaniline.

[0007] For example, Chinese patent CN100534975C discloses a "method for producing 2,6-dichloro-4-trifluoromethylaniline". In this patent, a trifluoromethylaniline raw material is added to a solvent, wherein the reaction solvent is ethylene dichloride. Chlorine is introduced into a reactor for chlorination reaction to generate a mixture of 2,6-dichloro-4-trifluoromethylaniline. After the solvent is removed, an alkali is added for neutralization to obtain a crude 2,6-dichloro-4-trifluoromethylaniline, which is then refined by vacuum distillation to obtain a finished product with a purity of more than 99.5%. Part of the solvent is lost during the reaction desolventizing, the cost of treating the chlorine-containing tail gas is high, and the intermittent reaction has a high safety risk.

[0008] At present, the industrial production process of 2,6-dichloro-4-trifluoromethylaniline is similar to the combined method of patents CN102643202A and CN100534975C. The high-temperature and high-pressure reaction conditions of amination are relatively harsh; the conversion rate of p-chlorotrifluorotoluene during the reaction is about 50%, and the selectivity of p-trifluoromethylaniline is about 90%; after the reaction, the filter cake is a mixture of potassium salt, ammonium salt, cuprous chloride, etc., which can only be treated as solid waste; the filtrate needs to be distilled in turn for ethanol, remaining p-chlorotrifluorotoluene and p-trifluoromethylaniline, which is cumbersome. Chlorination is a high-risk reaction, and the safety risk of chlorine intermittent reaction is high. The post-reaction treatment and desolventizing lose part of the solvent, and the cost of tail gas treatment is high. Therefore, it is necessary to develop a production process of 2,6-dichloro-4-trifluoromethylaniline with high selectivity, strong economy, environmental friendliness, safety and simple operation. Summary of the invention

[0009] The invention aims to provide a production process of 2,6-dichloro-4-trifluoromethylaniline, which improves the conversion rate of the raw material para-chlorotrifluorotoluene, reduces the generation of solid waste and chlorine-containing tail gas in the reaction process, has high process selectivity, strong economy, is environmentally friendly, is simple to operate, has low safety risks, is suitable for industrial production, and improves the market competitiveness of 2,6-dichloro-4-trifluoromethylaniline products.

[0010] To achieve the above purpose, the technical solution of the present invention is as follows:

[0011] A production process of 2,6-dichloro-4-trifluoromethylaniline comprises the following steps:

[0012] 1) Fluorination reaction

[0013] Taking para-chlorobenzotrifluoride as a raw material, adding a pyrrolidone solvent, potassium fluoride and a phase transfer catalyst, mixing evenly, heating to 180-200° C., keeping the temperature for reaction for 10-15 hours, sampling and testing the gas phase qualitative content of para-chlorobenzotrifluoride in the reaction liquid to be less than 1% to terminate the reaction, filtering to obtain a filtrate and a filter cake respectively;

[0014] The pyrrolidone solvent is at least one of N-methylpyrrolidone, N-propylpyrrolidone and N-butylpyrrolidone; the amount of the pyrrolidone solvent is 2 to 5 times the weight of parachlorotrifluorotoluene;

[0015] The molar ratio of parachlorobenzotrifluoride to potassium fluoride is 1:2.1-2.5;

[0016] The phase transfer catalyst is at least one of bis-(N,N'-1,3-dimethyl-2-imidazolinyl)-ammonium chloride or bis-(N-bis(dimethylamino)methylene)-immonium chloride, and the amount of the phase transfer catalyst is 0.5-2.5wt% of the weight of para-chlorotrifluorotoluene;

[0017] 2) Amination

[0018] The filtrate obtained in step 1) is mixed with cuprous chloride and added to an autoclave, ammonia is introduced, the temperature is increased, and the reaction is carried out at a temperature of 170-190° C. and a pressure of 7-10 MPa for 8-12 hours. The reaction is terminated by sampling and testing the gas phase qualitative content of para-fluorotrifluorotoluene in the reaction liquid to be less than 1%. After the reaction is completed, the pressure is released, the obtained reaction liquid is filtered, and the obtained filtrate is concentrated and recovered to obtain a concentrated liquid and a solvent respectively;

[0019] The amount of cuprous chloride used is 0.5wt% to 2.5wt% of the weight of para-chlorobenzotrifluoride;

[0020] The molar ratio of parachlorobenzotrifluoride to ammonia is 1:15-20;

[0021] 3) Chlorination

[0022] The concentrated liquid obtained in step 2) and chlorine gas are simultaneously introduced into a microchannel reactor, and a sample is taken to detect the gas phase qualitative content of trifluoromethylaniline in the reaction liquid to be less than 0.5% to terminate the reaction, and the chlorinated material after the reaction is completed is collected and distilled to obtain a 2,6-dichloro-4-trifluoromethylaniline product with a purity of more than 99wt%;

[0023] The molar ratio of parachlorotrifluorotoluene to chlorine is 1:2-5;

[0024] The material stays in the microchannel reactor for 30 to 60 seconds;

[0025] The reaction temperature is 80-120°C.

[0026] Preferably, in step 1), the filter cake obtained is subjected to drying, water dissolution, activated carbon adsorption, concentration, drying and other operations to recover the by-products potassium chloride and potassium fluoride.

[0027] Preferably, in step 1), the amount of water required to dissolve the filter cake is 2 to 5 times the total weight of the filter cake after drying.

[0028] Preferably, in step 2), ammonia gas is collected during the pressure release process and compressed for reuse.

[0029] Preferably, in step 2), the obtained solvent is used as a pyrrolidone solvent in step 1.

[0030] Preferably, in step 2), the filter cake obtained after filtering the reaction solution is dried, dissolved in water, and filtered to obtain cuprous chloride and a dissolving solution, the obtained cuprous chloride is dried and reused, and the obtained dissolving solution is subjected to activated carbon adsorption, concentration, drying, and other operations to obtain by-product ammonium fluoride.

[0031] Preferably, in step 3), the tail gas generated during the reaction is first absorbed by water to obtain by-product hydrochloric acid, and then the chlorine is compressed and reused through drying and compression operations.

[0032] Preferably, in step 3), the concentration of the byproduct hydrochloric acid is 28wt% to 31wt%.

[0033] The present invention selects pyrrolidone solvents in the fluorination reaction to increase the solubility of potassium fluoride in the solvent, and simultaneously adds a catalyst bis-(N,N'-1,3-dimethyl-2-imidazoline)-ammonium chloride salt or bis-(N-bis(dimethylamino)methylene)-immonium chloride salt, so that the reaction material para-chlorobenzotrifluoride can be fully contacted with potassium fluoride, and the reaction activity of para-chlorobenzotrifluoride can be improved, and not only the reaction conversion rate of para-chlorobenzotrifluoride is increased to 99%, but also the reaction temperature is reduced to 180-200°C to obtain para-fluorobenzotrifluoride. After the reaction is completed, the reaction is filtered, and the fluorination filter cake is dried, dissolved, adsorbed, concentrated and crystallized, spray-dried, and other operations are performed to obtain byproduct potassium chloride and recyclable potassium fluoride.

[0034] The method is to carry out an ammoniation reaction on the obtained para-fluorobenzotrifluoride. During the ammoniation reaction, since potassium fluoride is not present, the para-fluorobenzotrifluoride and cuprous chloride can be fully contacted, and the conversion rate of the para-fluorobenzotrifluoride is increased to 99%. After the reaction is completed, the excess ammonia gas is dried and compressed for reuse. After the reaction is completed, the ammoniation filter cake is dried, the solid is dissolved in water, and the filter cake is filtered again. The cuprous chloride of the filter cake can be used for the ammoniation reaction after drying. The by-product ammonium fluoride is recovered by the dissolving liquid through operations such as adsorption, concentration crystallization, and drying.

[0035] In the final chlorination reaction process, the ammoniated concentrate and chlorine are directly subjected to a solvent-free microchannel continuous chlorination reaction to reduce the safety risk of the chlorination reaction. The reaction tail gas is first absorbed by water to obtain the by-product hydrochloric acid, and then dried and compressed to recover the chlorine for reuse. After the reaction, the chlorinated material is directly distilled to obtain the 2,6-dichloro-4-trifluoromethylaniline product, avoiding post-processing operations, no solvent loss and high-salt wastewater generation, simple operation, and low raw material and waste treatment costs.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention uses para-chlorobenzotrifluoride as a raw material, and sequentially undergoes fluorination, ammoniation, and chlorination to obtain 2,6-dichloro-4-trifluoromethylaniline. In the fluorination process, by adding a catalyst bis-(N,N'-1,3-dimethyl-2-imidazoline)-ammonium chloride salt or bis-(N-bis(dimethylamino)methylene)-immonium chloride salt, the reaction activity of para-chlorobenzotrifluoride is increased, the reaction temperature is reduced, and the conversion rate of para-chlorobenzotrifluoride is increased; and the process divides the original ammoniation reaction into two steps of fluorination and ammoniation, which further increases the conversion rate of para-chlorobenzotrifluoride. The existing mainstream process uses p-chlorobenzotrifluoride as raw material, cuprous chloride and potassium fluoride as catalysts, and ethanol as reaction solvent to synthesize p-trifluoromethylaniline in one step. Potassium fluoride is almost insoluble in ethanol. p-chlorobenzotrifluoride reacts with potassium fluoride in solid-liquid two-phase. The reaction activity of p-chlorobenzotrifluoride is low, and part of p-chlorobenzotrifluoride reacts to produce p-fluorobenzotrifluoride. Cuprous chloride is wrapped by a large amount of potassium fluoride, potassium chloride and ammonium chloride and ammonium fluoride produced by the reaction. It is difficult for ammonia to replace fluorine and chlorine, which ultimately results in a conversion rate of p-chlorobenzotrifluoride of only about 50%.

[0038] The products produced in the fluorination and amination reaction process of the present invention have relatively simple components and can be recycled after simple treatment, which saves production costs and avoids the generation of solid hazardous waste. However, the amination filter cake of the mainstream production process is a mixture of potassium fluoride, potassium chloride, ammonium chloride, ammonium fluoride, cuprous chloride, etc., and the single-component by-product cannot be recycled and can only be treated as hazardous waste.

[0039] The 2,6-dichloro-4-trifluoromethylaniline product obtained by the production process of the invention has a purity of more than 99wt%, a total yield of about 65% to 70%, and a yield that is about 20% higher than that of the mainstream industrial process. No solid waste is generated, no chlorine-containing tail gas and wastewater are generated, the comprehensive cost is low, and the reaction safety is strong. The invention is a green process with high selectivity, strong economy, and environmental friendliness, and has great guiding significance for industrial production. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with examples. For ease of understanding the present invention, the present invention lists examples as follows. Those skilled in the art should understand that the examples are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0041] Example 1

[0042] A production process of 2,6-dichloro-4-trifluoromethylaniline, the specific steps comprising:

[0043] 1) Fluorination: 350.00 g N-methylpyrrolidone, 100.00 g p-chlorotrifluorotoluene (0.55 mol), 73.00 g potassium fluoride (1.23 mol), and 0.75 g catalyst bis-(N,N'-1,3-dimethyl-2-imidazolinyl)-ammonium chloride salt were added to a reaction flask, mixed evenly, and then heated to 190°C. The reaction was kept warm for 12.0 hours, and the p-chlorotrifluorotoluene gas phase qualitative content in the reaction solution was 0.70% after sampling and detection. The reaction was completed, filtered, and the obtained fluorination filtrate was used for standby; the obtained filter cake was dried to recover N-methylpyrrolidone, and the dried filter cake was dissolved in water twice its weight, and then organic matter was first adsorbed with activated carbon, and then concentrated and evaporated to remove 70 wt% of water, and the concentrated filtrate was filtered. The obtained concentrated filter cake was dried to obtain a byproduct potassium chloride with a content of 98.5 wt%, and the obtained concentrated residual filtrate was spray-dried to obtain a usable potassium fluoride with a content of 90 wt%;

[0044] 2) Ammoniation: the fluorinated filtrate obtained in step 1) and 0.75 g of cuprous chloride are added to an autoclave, which is sealed well, and 150.00 g of ammonia (8.81 mol) is introduced, and the temperature is raised to 190° C. and 7.0 MPa for reaction for 7.0 hours. The gas phase qualitative content of para-fluorotrifluorotoluene in the reaction solution is sampled and detected to be 0.60% and the reaction is completed. After the reaction is completed, the pressure is released and the ammonia is compressed and reused; the obtained ammoniation solution is filtered to obtain an ammoniation filtrate and an ammoniation filter cake;

[0045] The obtained amination filtrate is concentrated to obtain N-methylpyrrolidone and a concentrated solution, respectively. The obtained N-methylpyrrolidone is used for fluorination reaction, and the obtained concentrated solution (0.40 mol of p-trifluoromethylaniline) is stored for later use;

[0046] The ammoniated filter cake is dried to recover the N-methylpyrrolidone sleeve for fluorination reaction, and the dried filter cake is dissolved in water twice its weight, filtered, and the obtained filter cake is dried to obtain the cuprous chloride sleeve for ammoniating reaction, and the obtained filtrate is firstly adsorbed with activated carbon for organic matter, and then concentrated, filtered, dried, etc. to obtain the byproduct ammonium fluoride with a content of 99wt%;

[0047] 3) Chlorination: the concentrated solution in step 2) and 110.00 g of chlorine (1.53 mol) are introduced into a 100° C. microchannel reactor at a proportional rate, and the material residence time is 45 s. The gas phase qualitative content of trifluoromethylaniline in the reaction solution is 0.40% by a time-dependent sample detection. The reaction tail gas is first absorbed by water to obtain a byproduct hydrochloric acid with a content of 30 wt%, and then the chlorine is compressed and reused by drying and compressing operations. The chlorinated material after the reaction is collected and distilled to obtain 82.72 g of 2,6-dichloro-4-trifluoromethylaniline product with a purity of 99.1 wt%, and the total yield is about 65%.

[0048] Example 2

[0049] A production process of 2,6-dichloro-4-trifluoromethylaniline, the specific steps comprising:

[0050] 1) Fluorination: 400.00 g N-methylpyrrolidone, 100.00 g p-chlorotrifluorotoluene (0.55 mol), 78.00 g potassium fluoride (1.32 mol), and 1.50 g catalyst bis-(N,N'-1,3-dimethyl-2-imidazolinyl)-ammonium chloride salt were added to a reaction flask, mixed evenly, and heated to 185°C. The reaction was kept warm for 11.0 hours. The p-chlorotrifluorotoluene gas phase qualitative content in the reaction solution was 0.65% after sampling and detection. The reaction was completed, filtered, and the obtained fluorination filtrate was used for standby; the obtained filter cake was dried to recover N-methylpyrrolidone, and the dried filter cake was dissolved in water twice its weight, and then organic matter was first adsorbed with activated carbon, and then concentrated and evaporated to remove 70 wt% of water, and the concentrated filtrate was filtered. The obtained concentrated filter cake was dried to obtain a byproduct potassium chloride with a content of 98.5 wt%, and the obtained concentrated residual filtrate was spray-dried to obtain a usable potassium fluoride with a content of 90 wt%;

[0051] 2) Amination: Add the fluorinated filtrate obtained in step 1) and 1.00 g of cuprous chloride to an autoclave, seal it well, introduce 177.40 g of ammonia (10.42 mol), raise the temperature to 185° C. and 9.5 MPa, react for 8.5 hours, sample and detect the gas phase qualitative content of para-fluorotrifluorotoluene in the reaction solution to be 0.45%, and the reaction is completed. After the reaction is completed, release the pressure, and compress the ammonia for reuse; filter the obtained ammoniated solution to obtain an ammoniated filtrate and an ammoniated filter cake;

[0052] The obtained amination filtrate is concentrated to obtain N-methylpyrrolidone and a concentrated solution, respectively. The obtained N-methylpyrrolidone is used for fluorination reaction, and the obtained concentrated solution (0.43 mol of p-trifluoromethylaniline) is stored for later use;

[0053] The ammoniated filter cake is dried to recover the N-methylpyrrolidone sleeve for fluorination reaction, and after drying, the filter cake is dissolved by adding water 3 times its weight, filtered, and the obtained filter cake is dried to obtain the cuprous chloride sleeve for ammoniating reaction, and the obtained filtrate is firstly adsorbed with activated carbon for organic matter, and then concentrated, filtered, dried, etc. to obtain the byproduct ammonium fluoride with a content of 99wt%;

[0054] 3) Chlorination: the concentrated solution in step 2) and 98.50 g of chlorine (1.37 mol) are introduced into a 95° C. microchannel reactor at a proportional rate, with a material residence time of 50 s. The gas phase qualitative content of p-trifluoromethylaniline in the reaction solution is 0.35% according to the time-dependent sample detection. The reaction tail gas is firstly absorbed by water to obtain a byproduct hydrochloric acid with a content of 30 wt %, and then the chlorine is compressed and reused by drying and compressing operations. The chlorinated material after the reaction is collected and distilled to obtain 82.99 g of 2,6-dichloro-4-trifluoromethylaniline product with a purity of 99.2 wt %, and the total yield is about 70%.

[0055] Example 3

[0056] A production process of 2,6-dichloro-4-trifluoromethylaniline, the specific steps comprising:

[0057] 1) Fluorination: 450.00 g N-propylpyrrolidone, 100.00 g p-chlorotrifluorotoluene (0.55 mol), 79.50 g potassium fluoride (1.34 mol), and 2.25 g catalyst bis-(N,N'-1,3-dimethyl-2-imidazolinyl)-ammonium chloride salt were added to a reaction flask, mixed evenly, and then heated to 185°C. The reaction was kept warm for 15.0 hours. The p-chlorotrifluorotoluene gas phase qualitative content in the reaction solution was 0.85% after sampling and detection. The reaction was completed, filtered, and the obtained fluorination filtrate was used for standby; the obtained filter cake was dried to recover N-propylpyrrolidone, and the dried filter cake was dissolved in water twice its weight, and then organic matter was first adsorbed with activated carbon, and then concentrated and evaporated to remove 70 wt% of water, and the concentrated filtrate was filtered. The obtained concentrated filter cake was dried to obtain a byproduct potassium chloride with a content of 98.5 wt%, and the obtained concentrated residual filtrate was spray-dried to obtain a usable potassium fluoride with a content of 90 wt%;

[0058] 2) Amination: Add the fluorinated filtrate obtained in step 1) and 1.50g of cuprous chloride into an autoclave, seal it well, introduce 158.80g of ammonia (9.32mol), raise the temperature to 190°C and 8.5MPa, react for 11.0 hours, sample and detect the gas phase qualitative content of para-fluorotrifluorotoluene in the reaction solution to be 0.60%, and the reaction is completed. After the reaction is completed, release the pressure, and recycle the ammonia after compression; filter the obtained ammoniated solution to obtain an ammoniated filtrate and an ammoniated filter cake;

[0059] The obtained amination filtrate is concentrated to obtain N-propyl pyrrolidone and a concentrated solution, respectively. The obtained propyl-methyl pyrrolidone is used for fluorination reaction, and the obtained concentrated solution (0.41 mol of p-trifluoromethylaniline) is stored for later use;

[0060] The ammoniated filter cake is dried to recover the N-propylpyrrolidone jacket for fluorination reaction, and after drying, 2.5 times of its weight of water is added to the filter cake to dissolve it, and filtered. After the obtained filter cake is dried, the cuprous chloride jacket is obtained for ammoniating reaction, and the obtained filtrate is firstly adsorbed with activated carbon for organic matter, and then concentrated, filtered, dried, etc. to obtain a byproduct ammonium fluoride with a content of 99wt%;

[0061] 3) Chlorination: the concentrated solution in step 2) and 118.00 g of chlorine (1.65 mol) are introduced into a 95° C. microchannel reactor at a proportional rate, and the material residence time is 60 s. The gas phase qualitative content of trifluoromethylaniline in the reaction solution is 0.25% according to the time-dependent sample detection. The reaction tail gas is first absorbed by water to obtain a byproduct hydrochloric acid with a content of 30 wt%, and then the chlorine is compressed and reused by drying and compressing operations. The chlorinated material after the reaction is collected and distilled to obtain 85.27 g of 2,6-dichloro-4-trifluoromethylaniline product with a purity of 99.1 wt%, and the total yield is about 67%.

[0062] Example 4

[0063] A production process of 2,6-dichloro-4-trifluoromethylaniline, the specific steps comprising:

[0064] 1) Fluorination: 300.00 g N-propylpyrrolidone, 100.00 g p-chlorotrifluorotoluene (0.55 mol), 70.00 g potassium fluoride (1.18 mol), and 1.00 g catalyst bis-(N-bis(dimethylamino)methylene)-immonium chloride were added to a reaction flask, mixed evenly, and then heated to 180° C., and kept warm for reaction for 13.5 hours. The p-chlorotrifluorotoluene gas phase qualitative content in the reaction solution was sampled and tested to be 0.55% at the end of the reaction, filtered, and the obtained fluorination filtrate was used for standby; the obtained filter cake was dried to recover N-propylpyrrolidone, and the dried filter cake was dissolved in water twice its weight, and then organic matter was first adsorbed with activated carbon, and then concentrated and evaporated to remove 70 wt % of water, and the concentrated filtrate was filtered, and the concentrated filter cake was dried to obtain a byproduct potassium chloride with a content of 98.5 wt %, and the concentrated residual filtrate was spray-dried to obtain a usable potassium fluoride with a content of 90 wt %;

[0065] 2) Amination: Add the fluorinated filtrate obtained in step 1) and 2.25g of cuprous chloride to an autoclave, seal it well, introduce 168.10g of ammonia (9.87mol), raise the temperature to 180°C and 8.0MPa, react for 9.5 hours, sample and detect the gas phase qualitative content of para-fluorotrifluorotoluene in the reaction solution to be 0.80%, and the reaction is completed. After the reaction is completed, release the pressure, and compress the ammonia for reuse; filter the obtained ammoniated solution to obtain an ammoniated filtrate and an ammoniated filter cake;

[0066] The obtained amination filtrate is concentrated to obtain N-propyl pyrrolidone and a concentrated solution, respectively. The obtained N-propyl pyrrolidone is used for fluorination reaction, and the obtained concentrated solution (0.41 mol of p-trifluoromethylaniline) is stored for later use;

[0067] The ammoniated filter cake is dried to recover the N-propylpyrrolidone sleeve for fluorination reaction, and after drying, the filter cake is dissolved in water 3 times its weight, filtered, and the obtained filter cake is dried to obtain the cuprous chloride sleeve for ammoniating reaction, and the obtained filtrate is firstly adsorbed with activated carbon for organic matter, and then concentrated, filtered, dried, etc. to obtain the byproduct ammonium fluoride with a content of 99wt%;

[0068] 3) Chlorination: the concentrated solution in step 2) and 157.20 g of chlorine (2.19 mol) are introduced into a 95° C. microchannel reactor at a proportional rate, and the material residence time is 40 s. The gas phase qualitative content of trifluoromethylaniline in the reaction solution is 0.30% by the time-dependent sample detection. The reaction tail gas is first absorbed by water to obtain a byproduct hydrochloric acid with a content of 30 wt%, and then the chlorine is compressed and reused by drying and compressing operations. The chlorinated material after the reaction is collected and distilled to obtain 83.91 g of 2,6-dichloro-4-trifluoromethylaniline product with a purity of 99.20 wt%, and the total yield is about 66%.

[0069] Example 5

[0070] A production process of 2,6-dichloro-4-trifluoromethylaniline, the specific steps comprising:

[0071] 1) Fluorination: add 500.00g N-butylpyrrolidone, 100.00g p-chlorotrifluorotoluene (0.55mol), 74.80g potassium fluoride (1.26mol), and 1.50g catalyst bis-(N-bis(dimethylamino)methylene)-immonium chloride to a reaction flask, mix well, heat to 200°C, keep warm for reaction for 10.0 hours, sample and detect the p-chlorotrifluorotoluene gas phase qualitative content in the reaction solution to be 0.40% after the reaction is completed, filter, and use the obtained fluorination filtrate for standby use; the obtained filter cake is dried to recover N-butylpyrrolidone, and the dried filter cake is dissolved by adding water twice its weight, then organic matter is first adsorbed by activated carbon, and then concentrated and evaporated to remove 70wt% of water, to obtain a concentrated filtrate for filtration, and the obtained concentrated filter cake is dried to obtain a byproduct potassium chloride with a content of 98.5wt%, and the obtained concentrated residual filtrate is spray-dried to obtain a usable potassium fluoride with a content of 90wt%;

[0072] 2) Ammoniation: the fluorinated filtrate obtained in step 1) and 2.50 g of cuprous chloride are added to an autoclave, which is sealed well, and 144.80 g of ammonia (8.50 mol) is introduced, and the temperature is raised to 190° C. and 7.0 MPa for reaction for 12.0 hours. The gas phase qualitative content of para-fluorotrifluorotoluene in the reaction solution is sampled and detected to be 0.75% and the reaction is completed. After the reaction is completed, the pressure is released and the ammonia is compressed and reused; the obtained ammoniation solution is filtered to obtain an ammoniation filtrate and an ammoniation filter cake;

[0073] The obtained amination filtrate is concentrated to obtain N-butylpyrrolidone and a concentrated solution, respectively. The obtained N-butylpyrrolidone is used for fluorination reaction, and the obtained concentrated solution (0.41 mol of p-trifluoromethylaniline) is stored for later use;

[0074] The ammoniated filter cake is dried to recover the N-butylpyrrolidone jacket for fluorination reaction, and after drying, the filter cake is dissolved in 2.5 times of its weight of water, filtered, and the obtained filter cake is dried to obtain the cuprous chloride jacket for ammoniating reaction, and the obtained filtrate is firstly adsorbed with activated carbon for organic matter, and then concentrated, filtered, dried, etc. to obtain the byproduct ammonium fluoride with a content of 99wt%;

[0075] 3) Chlorination: the concentrated solution in step 2) and 194.50 g of chlorine (2.71 mol) are introduced into a 120° C. microchannel reactor at a proportional rate, the material residence time is 30 s, and the gas phase qualitative content of trifluoromethylaniline in the reaction solution is 0.15% by the time-based sample detection. The reaction tail gas is first absorbed by water to obtain a byproduct hydrochloric acid with a content of 30 wt%, and then the chlorine is compressed and reused by drying and compression operations. The chlorinated material after the reaction is collected and distilled to obtain 86.41 g of 2,6-dichloro-4-trifluoromethylaniline product with a purity of 99.25 wt%, and the total yield is about 68%.

[0076] Example 6

[0077] A production process of 2,6-dichloro-4-trifluoromethylaniline, the specific steps comprising:

[0078] 1) Fluorination: 450.00 g N-butylpyrrolidone, 100.00 g p-chlorotrifluorotoluene (0.55 mol), 72.00 g potassium fluoride (1.21 mol), and 2.00 g catalyst bis-(N-bis(dimethylamino)methylene)-immonium chloride were added to a reaction flask, mixed evenly, and then heated to 185° C., and kept warm for reaction for 14.0 hours. The p-chlorotrifluorotoluene gas phase qualitative content in the reaction solution was sampled and tested to be 0.75% at the end of the reaction, filtered, and the obtained fluorination filtrate was used for standby; the obtained filter cake was dried to recover N-butylpyrrolidone, and the dried filter cake was dissolved in water 3 times its weight, and then organic matter was first adsorbed with activated carbon, and then concentrated and evaporated to remove 70 wt % of water, and the concentrated filtrate was filtered, and the concentrated filter cake was dried to obtain a byproduct potassium chloride with a content of 98.5 wt %, and the concentrated residual filtrate was spray-dried to obtain a usable potassium fluoride with a content of 90 wt %;

[0079] 2) Ammoniation: the fluorinated filtrate obtained in step 1) and 2.25 g of cuprous chloride are added to an autoclave, which is sealed well, and 168.00 g of ammonia (9.86 mol) is introduced, and the temperature is raised to 185° C. and 7.5 MPa for reaction for 11.5 hours. The gas phase qualitative content of para-fluorotrifluorotoluene in the reaction solution is sampled and detected to be 0.55% and the reaction is completed. After the reaction is completed, the pressure is released and the ammonia is compressed and reused; the obtained ammoniation solution is filtered to obtain an ammoniation filtrate and an ammoniation filter cake;

[0080] The obtained amination filtrate is concentrated to obtain N-butylpyrrolidone and a concentrated solution, respectively. The obtained N-butylpyrrolidone is used for fluorination reaction, and the obtained concentrated solution (0.42 mol of p-trifluoromethylaniline) is stored for later use;

[0081] The ammoniated filter cake is dried to recover the N-butylpyrrolidone jacket for fluorination reaction, and after drying, 2.0 times of its weight of water is added to the filter cake to dissolve it, and filtered. After the obtained filter cake is dried, the cuprous chloride jacket is obtained for ammoniating reaction, and the obtained filtrate is firstly adsorbed with organic matter by activated carbon, and then concentrated, filtered, dried, etc. to obtain a byproduct ammonium fluoride with a content of 99wt%;

[0082] 3) Chlorination: the concentrated solution in step 2) and 140.00 g of chlorine (1.95 mol) are introduced into a 105° C. microchannel reactor at a proportional rate, and the material residence time is 45 s. The gas phase qualitative content of trifluoromethylaniline in the reaction solution is 0.28% by the time-dependent sample detection. The reaction tail gas is first absorbed by water to obtain a byproduct hydrochloric acid with a content of 30 wt%, and then the chlorine is compressed and reused by drying and compressing operations. The chlorinated material after the reaction is collected and distilled to obtain 87.68 g of 2,6-dichloro-4-trifluoromethylaniline product with a purity of 99.25 wt%, and the total yield is about 69%.

[0083] Comparative Example 1

[0084] Referring to patents CN102643202A and CN100534975C, a production process of 2,6-dichloro-4-trifluoromethylaniline, the specific steps include:

[0085] 1) Ammoniation: 300.00g ethanol, 100.00g p-chlorobenzotrifluoride (0.55mol), 80.50g potassium fluoride (1.36mol), and 3.00g cuprous chloride were added to the autoclave in sequence, and the autoclave was sealed well. 200.00g ammonia (11.74mol) was introduced, and the temperature was raised to 210°C and 12MPa for reaction for 53 hours. The gas phase qualitative content of p-fluorobenzotrifluoride was 55.70% when the sample was taken for detection. The pressure was released and the ammoniation filtrate and ammoniation filter cake were obtained by filtration; the ammoniation filtrate was 435.50g, and the p-trifluoromethylaniline content was about 8.25wt%, and the synthesis yield of p-trifluoromethylaniline was about 61.30% calculated based on the p-chlorobenzotrifluoride reacted. The ammoniation filtrate was sequentially rectified to recover ethanol and excess p-chlorobenzotrifluoride, and the concentrated solution was stored for standby use; the ammoniation filter cake was dried and treated as solid waste;

[0086] 2) Chlorination: add 200.00 g of ethylene dichloride to the concentrated solution obtained in step 1), raise the temperature to 60° C., start passing chlorine gas, and pass 215.00 g of chlorine gas for about 8.5 hours. Take samples to detect the gas phase qualitative content of trifluoromethylaniline, which is 0.25%. The reaction tail gas is absorbed by water and sodium hydroxide solution in sequence to obtain by-products of hydrochloric acid and sodium hypochlorite solution. The reaction solution is first distilled to recover ethylene dichloride, and then rectified to obtain about 57.1 g of 2,6-dichloro-4-trifluoromethylaniline product with a purity of 99.2 wt%, and the total yield is about 44.9%.

[0087] The mainstream production process ammoniated filter cake is a mixture of potassium fluoride, potassium chloride, ammonium chloride, ammonium fluoride, cuprous chloride, etc. It is impossible to recover the single component by-product and it can only be treated as hazardous waste; the total yield is about 45%, which is about 20% lower than the yield of the present invention.

[0088] Comparative Example 2

[0089] Compared with Comparative Example 1, a production process of 2,6-dichloro-4-trifluoromethylaniline is prepared by adding a catalyst, bis-(N-bis(dimethylamino)methylene)-immonium chloride, and the specific steps include:

[0090] 1) Amination: 300.00 g ethanol, 100.00 g p-chlorotrifluorotoluene (0.55 mol), 80.50 g potassium fluoride (1.36 mol), 3.00 g cuprous chloride, 2.00 g bis-(N-bis(dimethylamino)methylene)-immonium chloride were added to the autoclave in sequence, the autoclave was sealed, 200.00 g ammonia (11.74 mol) was introduced, the temperature was raised, the reaction was carried out at 190°C and 10 MPa for 22 hours, and sampling was performed. The qualitative content of p-fluorobenzotrifluoride in the gas phase is detected to be about 45.4%, the pressure is released, and the aminated filtrate and the aminated filter cake are obtained by filtration; the aminated filtrate is 472.50 g, the p-trifluoromethylaniline content is about 6.75wt%, and the synthesis yield of p-trifluoromethylaniline is about 71.40% calculated based on the p-chlorobenzotrifluoride reacted; the aminated filtrate is sequentially distilled to recover ethanol and excess p-chlorobenzotrifluoride, and the concentrated solution is used for chlorination reaction; the aminated filter cake is dried to recover ethanol and then treated as solid waste;

[0091] 2) Chlorination: 200.00 g of ethylene dichloride is added to the concentrated solution obtained in step 1), the temperature is raised to 60° C., chlorine gas is introduced, and 215.00 g of chlorine gas is introduced in about 8.5 hours. The gas phase qualitative content of trifluoromethylaniline is sampled and detected to be 0.20%. The reaction tail gas is absorbed by water and sodium hydroxide solution in sequence to obtain by-products of hydrochloric acid and sodium hypochlorite solution. The reaction solution is first distilled to recover ethylene dichloride, and then rectified to obtain about 66.5 g of 2,6-dichloro-4-trifluoromethylaniline product with a purity of 99.1 wt%, and the total yield is about 52.3%.

[0092] The addition of the catalyst bis-(N-bis(dimethylamino)methylene)-immonium chloride improves the activity of p-chlorotrifluorotoluene and the selectivity of p-trifluoromethylaniline in the amination reaction. However, due to the one-step synthesis of p-trifluoromethylaniline, the components in the reaction system are complex, and the catalyst effect fails to achieve the effect of the present invention. The amination synthesis yield is only increased by 10%, and the total yield is about 10% lower than that of the present invention, but the reaction temperature is reduced from 210°C to 190°C.

[0093] Comparative Example 3

[0094] Compared with Comparative Example 1, N-methylpyrrolidone is used instead of ethanol. A production process of 2,6-dichloro-4-trifluoromethylaniline comprises the following specific steps:

[0095] 1) Amination: Add 300.00 g of N-methylpyrrolidone, 100.00g of p-chlorobenzotrifluoride (0.55mol), 80.50g of potassium fluoride (1.36mol), 3.00g of cuprous chloride, sealed well, introduced 200.00g of ammonia (11.74mol), heated to 190°C, 10.5MPa for 30 hours, sampled and tested the p-fluorobenzotrifluoride gas phase qualitative content of 42.80%, released the pressure, filtered to obtain an aminated filtrate and an aminated filter cake; the aminated filtrate 450.30g, the p-trifluoromethylaniline content was about 7.60wt%, and the p-trifluoromethylaniline synthesis yield was about 73.30% calculated based on the p-chlorobenzotrifluoride reacted, the aminated filtrate was sequentially rectified for excess p-chlorobenzotrifluoride and N-methylpyrrolidone, and the concentrated solution was used for chlorination reaction; the aminated filter cake was dried to recover N-methylpyrrolidone and then treated as solid waste;

[0096] 2) Chlorination: 200.00 g of ethylene dichloride is added to the concentrated solution obtained in step 1), the temperature is raised to 60° C., chlorine gas is introduced, and 215.00 g of chlorine gas is introduced in about 8.5 hours. The gas phase qualitative content of trifluoromethylaniline is sampled and tested to be 0.25%. The reaction tail gas is absorbed by water and sodium hydroxide solution in sequence to obtain by-products of hydrochloric acid and sodium hypochlorite solution. The reaction solution is first distilled to recover ethylene dichloride, and then rectified to obtain about 68.3 g of 2,6-dichloro-4-trifluoromethylaniline product with a purity of 99.1 wt%, and the total yield is about 53.7%.

[0097] After ethanol was replaced with N-methylpyrrolidone, the amination conversion rate was improved, and the total yield increased from 45% to 54%. However, due to the problem of the one-step reaction, the total yield was about 10% lower than that of the present invention.

Claims

1. A production process of 2,6-dichloro-4-trifluoromethylaniline, characterized in that: The process comprises the following steps: 1) fluorination reaction Taking para-chlorobenzotrifluoride as a raw material, adding a pyrrolidone solvent, potassium fluoride and a phase transfer catalyst, mixing evenly, heating to 180-200° C., keeping the temperature for reaction for 10-15 hours, sampling and testing the gas phase qualitative content of para-chlorobenzotrifluoride in the reaction liquid to be less than 1%, ending the reaction, filtering to obtain a filtrate and a filter cake respectively; The pyrrolidone solvent is at least one of N-methylpyrrolidone, N-propylpyrrolidone and N-butylpyrrolidone; the amount of the pyrrolidone solvent is 2 to 5 times the weight of parachlorotrifluorotoluene; The molar ratio of parachlorobenzotrifluoride to potassium fluoride is 1:2.1-2.5; The phase transfer catalyst is at least one of bis-(N,N'-1,3-dimethyl-2-imidazolinyl)-ammonium chloride or bis-(N-bis(dimethylamino)methylene)-immonium chloride, and the amount of the phase transfer catalyst is 0.5-2.5wt% of the weight of para-chlorotrifluorotoluene; 2) Amination reaction The filtrate obtained in step 1) is mixed with cuprous chloride and added to an autoclave, ammonia is introduced, the temperature is increased, and the reaction is carried out at a temperature of 170-190° C. and a pressure of 7-10 MPa for 8-12 hours. The reaction is terminated by sampling and testing the gas phase qualitative content of para-fluorotrifluorotoluene in the reaction liquid to be less than 1%. After the reaction is completed, the pressure is released, the reaction liquid is filtered, and the filtrate is concentrated and recovered to obtain a concentrated liquid and a solvent respectively; The amount of cuprous chloride used is 0.5wt% to 2.5wt% of the weight of para-chlorobenzotrifluoride; The molar ratio of parachlorobenzotrifluoride to ammonia is 1:15-20; 3) Chlorination reaction The concentrated liquid obtained in step 2) and chlorine gas are simultaneously introduced into a microchannel reactor, and a sample is taken to detect the gas phase qualitative content of trifluoromethylaniline in the reaction liquid to be less than 0.5% to terminate the reaction, and the chlorinated material after the reaction is completed is collected and distilled to obtain a 2,6-dichloro-4-trifluoromethylaniline product with a purity of more than 99wt%; The molar ratio of parachlorotrifluorotoluene to chlorine is 1:2-5; The material stays in the microchannel reactor for 30 to 60 seconds; The reaction temperature is 80-120°C.

2. The production process according to claim 1, characterized in that: In step 1), the filter cake is dried, dissolved in water, adsorbed on activated carbon, concentrated, dried, and other operations to recover byproducts of potassium chloride and potassium fluoride.

3. The production process according to claim 2, characterized in that: In step 1), the amount of water required to dissolve the filter cake is 2 to 5 times the total weight of the filter cake after drying.

4. The production process according to claim 1, characterized in that: In step 2), ammonia gas is collected during the pressure release process and compressed for reuse.

5. The production process according to claim 1, characterized in that: In step 2), the obtained solvent is used as a pyrrolidone solvent in step 1).

6. The production process according to claim 1, characterized in that: In step 2), the filter cake obtained after filtering the reaction solution is dried, dissolved in water, and filtered to obtain cuprous chloride and a dissolving solution, the obtained cuprous chloride is dried and reused, and the obtained dissolving solution is subjected to activated carbon adsorption, concentration, drying, and other operations to obtain by-product ammonium fluoride.

7. The production process according to claim 1, characterized in that: In step 3), the tail gas generated during the reaction is first absorbed by water to obtain by-product hydrochloric acid, and then the chlorine is compressed and reused through drying and compression operations.

8. The production process according to claim 7, characterized in that: In step 3), the concentration of the byproduct hydrochloric acid is 28wt% to 31wt%.