A continuous ammonolysis method for mixed nitrochlorobenzene

Abstract

The present invention relates to the technical field of fine chemical synthesis, and particularly discloses a continuous ammonolysis method for mixed nitrochlorobenzene. The continuous ammonolysis method for mixed nitrochlorobenzene is characterized in that: the mixed nitrochlorobenzene is continuously added to the primary ammonolysis kettle, and is mixed countercurrently with ammonia water and a catalyst from the subsequent ammonolysis kettle to carry out an ammonolysis reaction. The reaction liquid enters the separator at the upper part of the kettle through a lift. A part of the liquid material is refluxed into the reaction zone at the lower part of the kettle, and after the organic phase and the ammonia water phase are separated in the separator for the other part of the liquid material, the organic phase flows into the subsequent ammonolysis kettle to continue the ammonolysis reaction; until the reaction and separation are completed in the last ammonolysis kettle to obtain a crude product of mixed nitroaniline, which enters the refining section for refining. The present invention can reduce the consumption and circulation amount of concentrated ammonia water, realize the efficient conversion of mixed nitrochlorobenzene under relatively mild reaction conditions, effectively inhibit side reactions such as hydrolysis and coking, and at the same time reduce material consumption and energy consumption, and increase the economy of the reaction.

Description

Technical Field

[0001] The present invention relates to the technical field of fine chemical synthesis, and particularly relates to a method for continuous ammonolysis of mixed nitrochlorobenzenes. Background Art

[0002] o- and p-nitroanilines are important fine organic intermediates and are raw materials for catalytic hydrogenation to prepare o- and p-phenylenediamines. At present, the important synthesis method of o- and p-nitroanilines is to use the p-, o-, and m-mixed nitrochlorobenzenes obtained by nitrating chlorobenzene as raw materials, and concentrated ammonia water as the aminating agent, and prepare them through an ammonolysis reaction. Currently, the existing technical reports on the ammonolysis of nitrochlorobenzenes mainly focus on the individual ammonolysis reactions of o- or p-nitrochlorobenzene, and there is little research on the direct ammonolysis of mixed nitrochlorobenzenes; moreover, the existing technologies mainly focus on the optimization of basic process conditions, and there are few research reports on the control of side reactions in the ammonolysis reaction.

[0003] The ammonolysis reaction of nitrochlorobenzene belongs to a nucleophilic substitution reaction. The presence of the electron-withdrawing group - nitro on the benzene ring can reduce the electron cloud density of the o- and p-positions to a certain extent, which is beneficial to the progress of the ammonolysis reaction. However, as the reaction proceeds, the concentration of nitrochlorobenzene in the reaction system continuously decreases, and the reaction rate significantly slows down. Especially in the mixed nitrochlorobenzene system containing a small amount of m-nitrochlorobenzene, the difficulty of completely converting it through the ammonolysis rearrangement reaction is much higher than that of o- and p-nitrochlorobenzenes. In order to completely react the mixed nitrochlorobenzenes, it is necessary to increase the dosage of the aminating agent or raise the reaction temperature to strengthen the reaction conditions, which greatly increases the consumption and circulation amount of ammonia water, reduces the economy of the reaction, and the increase in the reaction temperature not only increases the energy consumption, but also induces side reactions such as hydrolysis and coking, significantly reducing the selectivity of the ammonolysis reaction. The hydrolysis side reaction of the reaction substrate at high temperature will generate nitro-phenolic substances, which will not only increase the treatment difficulty when mixed with the reaction products in the subsequent hydrogenation and rectification separation sections, but also pose a safety hazard. Summary of the Invention

[0004] In order to make up for the deficiencies of the existing technology, the present invention provides a method for continuous ammonolysis of mixed nitrochlorobenzenes with high conversion rate and high selectivity.

[0005] The present invention is achieved by the following technical solutions:

[0006] A method for continuous ammonolysis of mixed nitrochlorobenzenes, using the p-, o-, and m-mixed nitrochlorobenzenes obtained by nitrating chlorobenzene as raw materials, characterized in that: the ammonolysis of nitrochlorobenzene adopts a mode of connecting multiple ammonolysis reactors in series, and the nitrochlorobenzene and ammonia water are mixed and reacted countercurrently;

[0007] The molten raw material mixed nitrochlorobenzene is continuously added to the primary ammonolysis kettle, where it undergoes an ammonolysis reaction with the ammonia water from the subsequent ammonolysis kettle. The reaction liquid is lifted into the separator at the upper part of the kettle by the in-built elevator in the kettle. Part of the liquid material flows back into the reaction zone at the lower part of the kettle, and the other part of the liquid material is separated into an organic phase and an ammonia water phase in the separator. The organic phase is then transported into the next-level ammonolysis kettle to continue the ammonolysis reaction;

[0008] Part of the organic phase in the reaction liquid material also flows into the subsequent ammonolysis kettle after being separated by the elevator and separator in the kettle, until the reaction and separation are completed in the last-stage ammonolysis kettle to obtain the crude mixed nitroaniline, which then enters the refining section for refining;

[0009] The raw material concentrated ammonia water and the catalyst are continuously added to the last-stage ammonolysis kettle. After reaction, lifting, and separation in each ammonolysis kettle, they are transported into the previous-stage ammonolysis kettle to continue the reaction, until the reaction is completed in the primary ammonolysis kettle and then lifted and separated and removed from the reaction system.

[0010] In the long-term research on the ammonolysis reaction of p-nitrochlorobenzene, the inventor creatively found that from the initial stage to the middle stage of the ammonolysis reaction, the side reaction degree of the substrate hydrolysis to generate nitrophenols is very small. When the reaction enters the final stage, when the concentrations of nitroaniline and ammonia water both decrease to a certain range, the ammonolysis reaction rate significantly slows down. At this time, increasing the reaction temperature will cause the side reaction of hydrolysis to start intensifying. When the reaction temperature is too high, intermolecular condensation reactions will occur between amines and phenol compounds to generate tar-like by-products.

[0011] In addition, the mixed nitrochlorobenzene obtained from the mononitration reaction of chlorobenzene usually contains 0.5% - 2.5% of m-nitrochlorobenzene. Due to the ortho-para orientation effect of the nitro group, the chlorine in the meta position is difficult to be nucleophilically substituted by the amine agent, and more severe reaction conditions are required for its transposition reaction, which will therefore increase the possibility of side reactions occurring.

[0012] To specifically overcome the above problems, the present invention creatively develops a strategy of countercurrent mixing and contacting reaction between nitrochlorobenzene and the amine agent. The specific principle is as follows: The raw material mixed nitrochlorobenzene and the amine agent - concentrated ammonia water are respectively added from the primary and last-stage ammonolysis kettles, and the two materials are in countercurrent contact and mixed for reaction; the ammonia water has the highest concentration in the last-stage kettle, and as the reaction, separation, and flow to the previous-stage reaction kettle proceed, its concentration gradually decreases; the mixed nitrochlorobenzene has the highest concentration in the primary kettle, and as the reaction, separation, and flow to the last-stage reaction kettle proceed, its concentration gradually decreases; therefore, in the primary kettle, the high-concentration reaction substrate - nitrochlorobenzene can react with the relatively low-concentration ammonia water until the concentration of the unreacted nitrochlorobenzene in the last-stage kettle is relatively low, but the ammonia water concentration is the highest, and the conversion of the remaining nitrochlorobenzene can be achieved under a relatively mild reaction temperature, avoiding the influence of a large temperature increase in the final stage of the reaction on the reaction selectivity. At the same time, the consumption of concentrated ammonia water is saved, and no phase transfer catalyst needs to be added in the later stage of the reaction, significantly improving the economic efficiency of the process method.

[0013] The better technical solutions of the present invention are as follows:

[0014] In the raw material mixed nitrochlorobenzene, the mass ratios of p-nitrochlorobenzene, o-nitrochlorobenzene and m-nitrochlorobenzene are 55%-65%, 35%-45% and 0.5%-2.5% respectively.

[0015] The number of stages of the ammonolysis kettle is 2 or 3;

[0016] Further preferably, when the number of stages of the ammonolysis kettle is 2, the reaction temperatures of the primary and final stages are controlled at 130-160°C and 140-170°C respectively;

[0017] Further preferably, when the number of stages of the ammonolysis kettle is 3, the reaction temperatures of the primary, intermediate and final stages are controlled at 130-150°C, 140-160°C and 140-170°C respectively.

[0018] The total molar ratio of NH₃·H₂O in the concentrated ammonia water added to the final-stage ammonolysis kettle to the mixed nitrochlorobenzene added to the primary-stage ammonolysis kettle is 6:1-15:1, and the mass concentration of NH₃·H₂O in the concentrated ammonia water is 25%-40%.

[0019] The catalyst added together with the ammonia water is one or several of cuprous chloride, copper chloride, and copper sulfate, and the catalyst dosage is 0.1%-2% of the feeding mass of the mixed nitrochlorobenzene.

[0020] In each stage of the ammonolysis kettle, after the liquid material is lifted by the elevator, the mass ratio of the liquid material flowing back into the reaction zone to the liquid material entering the separator is 0.1:1-10:1.

[0021] The total residence time of the mixed nitrochlorobenzene reaction liquid material in the multi-stage ammonolysis kettle is 5h-10h, and nitrogen replacement is adopted in the ammonolysis kettle to isolate the entry of air.

[0022] In the crude product of the mixed nitroaniline, the sum of the contents of o-nitroaniline and p-nitroaniline is higher than 99.5%, the balance of aminobenzene chloride is less than 0.1%, and the contents of phenols and other by-products are less than 0.3%.

[0023] The beneficial effects of the present invention are mainly reflected in:

[0024] On the premise of ensuring the complete conversion of nitrochlorobenzene, the total consumption and circulation amount of concentrated ammonia water are reduced, the terminal reaction is carried out at a relatively mild temperature, the hydrolysis and coking side reactions are greatly inhibited, and at the same time, the material consumption and energy consumption are reduced;

[0025] In addition, no phase transfer catalyst needs to be added during the reaction process, which simplifies the post-treatment process and improves the economy of the process method. Brief Description of the Drawings

[0026] The present invention will be further described below in conjunction with the accompanying drawings.

[0027] Figure 1 It is the gas chromatogram of the crude product of mixed nitroaniline after the ammonolysis reaction in Example 1;

[0028] Figure 2 It is the gas chromatogram of the crude product of mixed nitroaniline after the ammonolysis reaction in Example 2;

[0029] Figure 3 It is the gas chromatogram of the crude product of mixed nitroaniline after the ammonolysis reaction in Example 4;

[0030] Figure 4 It is the gas chromatogram of the crude product of mixed nitroaniline after the ammonolysis reaction in Example 7 (Comparative Example 1);

[0031] Figure 5 It is the gas chromatogram of the crude product of mixed nitroaniline after the ammonolysis reaction in Example 8 (Comparative Example 2). Detailed Embodiments

[0032] The technical solution of the present invention will be described in detail below in conjunction with specific embodiments for the convenience of understanding the present invention, but it is not a limitation to the present invention.

[0033] Example 1: A method for continuous ammonolysis of mixed nitrochlorobenzene, the specific steps are as follows:

[0034] Using the mixed p-, o-, and m-nitrochlorobenzene obtained by the chlorobenzene mononitration reaction as the raw material for the ammonolysis reaction, and analyzing this raw material by gas chromatography. The mass contents of p-nitrochlorobenzene, o-nitrochlorobenzene, and m-nitrochlorobenzene are 61%, 38%, and 1% respectively.

[0035] The nitrochlorobenzene ammonolysis reaction is carried out in a series connection of 3 ammoniaolysis kettles with a volume of 10L each, equipped with a self-lifting device and a liquid-liquid separator. Nitrogen replacement is carried out in each stage of the ammoniaolysis kettle to isolate the entry of air. First, prepare 40% concentrated ammonia water, add copper chloride to dissolve and mix it evenly in the concentrated ammonia water. Add the above-prepared concentrated ammonia water with copper chloride catalyst from the third-stage ammoniaolysis kettle, and add the molten mixed nitrochlorobenzene from the first-stage ammoniaolysis kettle. The total molar ratio of concentrated ammonia water NH₃·H₂O to mixed nitrochlorobenzene is 10:1, and the dosage of copper chloride is 1% (by mass) of the feeding amount of mixed nitrochlorobenzene. The nitrochlorobenzene and ammonia water are mixed countercurrently for reaction. After the reaction materials complete the reaction, material lifting, separation of ammonia water and organic phase in each stage of the reaction kettle, the organic phase is transported into the next-stage reaction kettle, and the ammonia water phase is transported into the previous-stage reaction kettle.

[0036] During the reaction process, control the reaction temperatures of the first, second, and third-stage ammonolysis reactors to be 135°C, 140°C, and 160°C respectively; in each stage of the ammonolysis reactor, after the reaction feed liquid is lifted by the elevator, the mass ratio of the refluxed liquid into the reaction zone to the liquid entering the separator is 3:1; control the total residence time of the nitrochlorobenzene reaction feed liquid in the three-stage ammonolysis reactor to be 6 h.

[0037] After the above continuous reaction process reaches stability, sample from the mixed crude nitroaniline discharge of the separator of the third-stage ammonolysis reactor and analyze it by gas chromatography. In the mixed crude nitroaniline, the contents of o-nitroaniline and p-nitroaniline are 38.976% and 60.769% respectively, and the sum of their contents is 99.745%. The three kinds of o-, m-, and p-nitrochlorobenzenes are completely converted and cannot be detected in the mixed crude nitroaniline, and the content of phenols and other by-products is less than 0.23% (for the specific chromatogram, see the appendix Figure 1 )

[0038] The analysis method of the mixed crude nitroaniline involved in the above examples is as follows:

[0039] Gas chromatograph: Agilent 7820A; Detector: Flame ionization detector (FID); Chromatographic column: HP-5 (30 m × 0.32 mm × 0.25 μm); Detector temperature: 300°C; Vaporization chamber temperature: 280°C; Combustion gas (hydrogen) flow rate: 30 mL / min; Combustion-supporting gas (air) flow rate: 300 mL / min; Carrier gas (nitrogen) flow rate: 25 mL / min; Split ratio: 20:1; Injection volume: 1 μL; Solvent for sample preparation: Chromatographic methanol.

[0040] Programmed temperature rising conditions: Initial column temperature 70°C, hold for 5 min; Raise the temperature to 160°C at a heating rate of 10°C / min; Then raise the temperature to 190°C at a heating rate of 20°C / min; Hold for 20 min.

[0041] Under the above chromatographic conditions, the peak retention times of o-nitroaniline and p-nitroaniline are about 12.5 min and 15 min respectively.

[0042] Example 2: A method for continuous ammonolysis of mixed nitrochlorobenzene, the specific steps are as follows:

[0043] Use the same mixed nitrochlorobenzene as the ammonolysis reaction raw material as in Example 1 (the mass contents of p-nitrochlorobenzene, o-nitrochlorobenzene, and m-nitrochlorobenzene are 61%, 38%, and 1% respectively).

[0044] The ammonolysis reaction of nitrochlorobenzene is carried out in a series connection of three 10L ammonolysis kettles with self-lifting devices and liquid-liquid separators. Nitrogen replacement is used in each stage of the ammonolysis kettle to isolate the entry of air. First, 35% concentrated ammonia water is prepared as the aminating agent, and cuprous chloride is added to the concentrated ammonia water for dissolution and mixing evenly. The above-prepared concentrated ammonia water added with cuprous chloride catalyst is added from the third-stage ammonolysis kettle, and the molten mixed nitrochlorobenzene is added from the first-stage ammonolysis kettle. The total molar ratio of NH₃·H₂O in the concentrated ammonia water to the mixed nitrochlorobenzene is 12:1, and the dosage of cuprous chloride is 0.5% (by mass) of the feeding amount of the mixed nitrochlorobenzene. The nitrochlorobenzene and ammonia water are mixed countercurrently for reaction. After the reaction materials complete the reaction, material lifting, separation of ammonia water and organic phase in each stage of the reaction kettle, the organic phase is transported into the next-stage reaction kettle, and the ammonia water phase is transported into the previous-stage reaction kettle.

[0045] During the reaction process, the reaction temperatures of the first, second, and third-stage ammonolysis kettles are controlled at 140°C, 150°C, and 165°C respectively; in each stage of the ammonolysis kettle, after the reaction liquid is lifted by the lifter, the mass ratio of the refluxed liquid to the liquid entering the separator in the reaction zone is controlled at 4:1; the total residence time of the nitrochlorobenzene reaction liquid in the three-stage ammonolysis kettle is controlled at 8h.

[0046] After the above continuous reaction process tends to be stable, a sample is taken from the crude product of mixed nitroaniline discharged from the separator of the third-stage ammonolysis kettle and analyzed under the same gas chromatography analysis conditions as in Example 1. In the crude product of mixed nitroaniline, the contents of o-nitroaniline and p-nitroaniline are 38.751% and 60.995% respectively, and the sum of their contents is 99.746%. The three kinds of o-, m-, and p-nitrochlorobenzenes are completely converted and cannot be detected in the crude product of mixed nitroaniline, and the content of phenols and other by-products is less than 0.24% (see the chromatogram in the appendix Figure 2 )

[0047] Example 3: A continuous ammonolysis method for mixed nitrochlorobenzene, the specific steps are as follows:

[0048] The same mixed nitrochlorobenzene as in Example 1 is used as the raw material for the ammonolysis reaction (the mass contents of p-nitrochlorobenzene, o-nitrochlorobenzene, and m-nitrochlorobenzene are 61%, 38%, and 1% respectively).

[0049] The ammonolysis reaction of nitrochlorobenzene is carried out in a series connection of three 10L ammonolysis kettles with self-lifting devices and liquid-liquid separators. Nitrogen replacement is carried out in each stage of the ammonolysis kettle to isolate the entry of air. 30% concentrated ammonia water is prepared as the aminating agent, and copper sulfate is added to the concentrated ammonia water for dissolution and mixing evenly. The above-prepared concentrated ammonia water added with copper sulfate catalyst is added from the third-stage ammonolysis kettle, and the molten mixed nitrochlorobenzene is added from the first-stage ammonolysis kettle. The total molar ratio of NH₃·H₂O in the concentrated ammonia water to the mixed nitrochlorobenzene is 12.5:1, and the dosage of copper sulfate is 1.5% (by mass) of the feeding amount of the mixed nitrochlorobenzene. The nitrochlorobenzene and ammonia water are mixed countercurrently for reaction. After the reaction materials complete the reaction, material lifting, and separation of ammonia water and organic phase in each stage of the reaction kettle, the organic phase is transported into the next-stage reaction kettle, and the ammonia water phase is transported into the previous-stage reaction kettle.

[0050] During the reaction process, the reaction temperatures of the first, second, and third-stage ammonolysis kettles are controlled at 145°C, 155°C, and 165°C respectively; in each stage of the ammonolysis kettle, after the reaction liquid is lifted by the lifter, the mass ratio of the refluxed liquid into the reaction zone to the liquid entering the separator is controlled at 5:1; the total residence time of the nitrochlorobenzene reaction liquid in the three-stage ammonolysis kettle is controlled at 9.5 h.

[0051] After the above continuous reaction process tends to be stable, sampling is carried out from the crude product discharge of the mixed nitroaniline in the separator of the third-stage ammonolysis kettle, and analysis is carried out under the same gas chromatography analysis conditions as in Example 1. In the crude product of the mixed nitroaniline, the contents of o-nitroaniline and p-nitroaniline are 38.893% and 60.969% respectively, and the sum of their contents is 99.862%. The three kinds of o-, m-, and p-nitrochlorobenzenes are completely converted and cannot be detected in the crude product of the mixed nitroaniline, and the contents of phenols and other by-products are less than 0.13%.

[0052] Example 4: A continuous ammonolysis method for mixed nitrochlorobenzene, the specific steps are as follows:

[0053] The same mixed nitrochlorobenzene as in Example 1 is used as the raw material for the ammonolysis reaction (the mass contents of p-nitrochlorobenzene, o-nitrochlorobenzene, and m-nitrochlorobenzene are 61%, 38%, and 1% respectively).

[0054] The ammonolysis reaction of nitrochlorobenzene is carried out in series with two 10L ammonolysis kettles equipped with self-lifting devices and liquid-liquid separators. Nitrogen replacement is carried out in each stage of the ammonolysis kettle to isolate the entry of air. 39% concentrated ammonia water is prepared as the aminating agent, and copper chloride is added to the concentrated ammonia water for dissolution and mixing evenly. The above-prepared concentrated ammonia water added with copper chloride catalyst is added from the second-stage ammonolysis kettle, and the molten mixed nitrochlorobenzene is added from the first-stage ammonolysis kettle. The total molar ratio of NH₃·H₂O in the concentrated ammonia water to the mixed nitrochlorobenzene is 12:1, and the dosage of copper chloride is 1% (by mass) of the feeding amount of the mixed nitrochlorobenzene. The nitrochlorobenzene and ammonia water are mixed countercurrently for reaction. After the reaction materials complete the reaction, material lifting, and separation of ammonia water and organic phase in each stage of the reaction kettle, the organic phase is transported into the next-stage reaction kettle, and the ammonia water phase is transported into the previous-stage reaction kettle.

[0055] During the reaction process, the reaction temperatures of the first and second-stage ammonolysis kettles are controlled at 150°C and 165°C respectively; in each stage of the ammonolysis kettle, after the reaction liquid is lifted by the lifter, the mass ratio of the refluxed liquid into the reaction zone to the liquid entering the separator is controlled at 8:1; the total residence time of the nitrochlorobenzene reaction liquid in the two-stage ammonolysis kettles is controlled at 10h.

[0056] After the above continuous reaction process tends to be stable, samples are taken from the crude product discharge of the mixed nitroaniline in the separator of the second-stage ammonolysis kettle and analyzed under the same gas chromatography analysis conditions as in Example 1. In the crude product of the mixed nitroaniline, the contents of o-nitroaniline and p-nitroaniline are 38.848% and 60.963% respectively, and the sum of their contents is 99.811%. The three kinds of o-, m-, and p-nitrochlorobenzenes are completely converted and cannot be detected in the crude product of the mixed nitroaniline, and the content of phenols and other by-products is less than 0.17% (see the attached Figure 3 )

[0057] Example 5: A continuous ammonolysis method for mixed nitrochlorobenzene, the specific steps are as follows:

[0058] Using the mixed nitrochlorobenzene prepared by the mononitration reaction of chlorobenzene as the raw material for the ammonolysis reaction, this raw material is analyzed by gas chromatography. The mass contents of p-nitrochlorobenzene, o-nitrochlorobenzene, and m-nitrochlorobenzene are 60%, 38%, and 2% respectively.

[0059] Using the same continuous ammonolysis method as in Example 1, after the continuous reaction process tends to be stable, samples are taken from the crude product discharge of the mixed nitroaniline in the separator of the last-stage ammonolysis kettle and analyzed under the same gas chromatography analysis conditions as in Example 1. In the crude product of the mixed nitroaniline, the contents of o-nitroaniline and p-nitroaniline are 39.942% and 59.887% respectively, and the sum of their contents is 99.829%. The three kinds of o-, m-, and p-nitrochlorobenzenes are completely converted and cannot be detected in the crude product of the mixed nitroaniline, and the content of phenols and other by-products is less than 0.17%.

[0060] Example 6: A continuous ammonolysis method for mixed nitrochlorobenzene, the specific steps are as follows:

[0061] Use the same mixed nitrochlorobenzene as the raw material for the ammonolysis reaction as in Example 6 (the mass contents of p-nitrochlorobenzene, o-nitrochlorobenzene and m-nitrochlorobenzene are 60%, 38% and 2% respectively).

[0062] Refer to the continuous ammonolysis method of Example 1 for the reaction. Compared with the method provided in Example 1, the difference is that the reaction temperatures of the first, second and third stage ammonolysis reactors are all controlled at 150 °C. After the continuous reaction process tends to be stable, samples are taken from the crude product discharge of the mixed nitroaniline in the separator of the last stage ammonolysis reactor, and analyzed under the same gas chromatography analysis conditions as in Example 1. In the crude product of mixed nitroaniline, the contents of o-nitroaniline and p-nitroaniline are 39.851% and 59.893% respectively, and the sum of their contents is 99.744%. The three kinds of o-, m- and p-nitrochlorobenzenes are completely converted and cannot be detected in the crude product of mixed nitroaniline, and the content of phenols and other by-products is less than 0.25%.

[0063] Example 7 (Comparative Example 1):

[0064] Use the same mixed nitrochlorobenzene as the raw material for the ammonolysis reaction as in Example 1 (the mass contents of p-nitrochlorobenzene, o-nitrochlorobenzene and m-nitrochlorobenzene are 61%, 38% and 1% respectively).

[0065] The ammonolysis reaction of nitrochlorobenzene is carried out in series with 3 conventional 10 L ammonolysis reactors (without elevator and separator). The concentration of raw material concentrated ammonia water, the type and dosage of catalyst, the raw material ratio and various reaction conditions (the reaction temperature of each stage reactor, the total residence time of reaction materials, etc.) are the same as those in Example 1. The difference is that both the concentrated ammonia water phase and the mixed nitrochlorobenzene phase are added from the first stage reactor, and the two reaction liquid materials are mixed in a co-current manner for reaction. The reaction liquid materials maintain a liquid level height of 70% in each stage reactor and continuously flow to the next stage reactor until they are discharged and separated from the third stage reactor.

[0066] After the continuous reaction process tends to be stable, samples are taken from the crude product discharge of the mixed nitroaniline discharged from the third stage ammonolysis reactor, and analyzed under the same gas chromatography analysis conditions as in Example 1. In the crude product of mixed nitroaniline, the contents of o-nitroaniline and p-nitroaniline are 38.598% and 48.260% respectively, and the sum of their contents is only 86.858%. 10.836% of p-nitrochlorobenzene remains unreacted, and the content of phenols and other by-products is about 2.3% (for the specific chromatogram, see the appendix Figure 4 )

[0067] Example 8 (Comparative Example 2):

[0068] The same mixed nitrochlorobenzenes as in Example 1 were used as the raw materials for the ammonolysis reaction (the mass contents of p-nitrochlorobenzene, o-nitrochlorobenzene, and m-nitrochlorobenzene were 61%, 38%, and 1% respectively).

[0069] The ammonolysis reaction of the mixed nitrochlorobenzenes was carried out according to the method of Example 7 (Comparative Example 1). The difference was that the reaction temperatures of the first, second, and third reaction kettles were increased to 165 °C, 175 °C, and 185 °C respectively, and the total residence time of the reaction materials in the reaction system was extended to 9 h.

[0070] After the continuous reaction process became stable, samples were taken from the discharged crude product of the mixed nitroanilines from the third ammonolysis kettle and analyzed under the same gas chromatography analysis conditions as in Example 1. In the crude product of the mixed nitroanilines, the contents of o-nitroaniline and p-nitroaniline were 37.879% and 58.860% respectively, and the sum of their contents was only 96.739%. The sum of the contents of phenols and other by-products was as high as 3.25% (for the specific chromatogram, see the appendix Figure 5 )

[0071] Example 9 (Comparative Example 3):

[0072] The same mixed nitrochlorobenzenes as in Example 5 were used as the raw materials for the ammonolysis reaction (the mass contents of p-nitrochlorobenzene, o-nitrochlorobenzene, and m-nitrochlorobenzene were 60%, 38%, and 2% respectively).

[0073] The ammonolysis reaction of the mixed nitrochlorobenzenes was the same as the method of Example 8 (Comparative Example 2).

[0074] After the continuous reaction process became stable, samples were taken from the discharged crude product of the mixed nitroanilines from the third ammonolysis kettle and analyzed under the same gas chromatography analysis conditions as in Example 1. In the crude product of the mixed nitroanilines, the contents of o-nitroaniline and p-nitroaniline were 38.027% and 54.341% respectively, and the sum of their contents was only 92.368%. 4.722% of p-nitrochlorobenzene remained unreacted, and the content of phenols and other by-products was 2.9%.

[0075] Example 10 (Comparative Example 4):

[0076] The same mixed nitrochlorobenzenes as in Example 5 were used as the raw materials for the ammonolysis reaction (the mass contents of p-nitrochlorobenzene, o-nitrochlorobenzene, and m-nitrochlorobenzene were 60%, 38%, and 2% respectively).

[0077] The ammonolysis reaction of the mixed nitrochlorobenzenes was carried out in a single 5 L reaction kettle. The specific method was as follows: 1 kg of the molten above-mentioned mixed nitrochlorobenzenes and 3.7 kg of 30% ammonia water were added to the reaction kettle together, and the temperature was raised to 180 - 185 °C and reacted for 10 h.

[0078] After the reaction ended, samples were taken from the crude product of mixed nitroanilines and analyzed under the same gas chromatography analysis conditions as in Example 1. In the crude product of mixed nitroanilines, the contents of o-nitroaniline and p-nitroaniline were 38.354% and 57.072% respectively, and the sum of their contents was only 95.526%. 1.825% of p-nitrochlorobenzene was not completely reacted, and the sum of the contents of phenols and other by-products was approximately 2.75%.

[0079] In the above embodiments, the best implementation mode of the present invention has been described. Obviously, under the inventive concept of the present invention, many changes can still be made. Here, it should be noted that any changes made under the inventive concept of the present invention will fall within the protection scope of the present invention.

Claims

1. A continuous ammonolysis method for mixed nitrochlorobenzene, which uses the mixed para-, ortho-, and meta-nitrochlorobenzene obtained by nitrating chlorobenzene as the raw material, and is characterized in that: The ammonolysis of nitrochlorobenzene is carried out in a series connection of multiple ammonolysis reactors, and nitrochlorobenzene and ammonia water are mixed and reacted countercurrently; molten raw material mixed nitrochlorobenzene is continuously added to the primary ammonolysis reactor and undergoes an ammonolysis reaction with ammonia water from the subsequent ammonolysis reactor. The reaction liquid is lifted into the separator at the upper part of the reactor by a self - contained lifter in the reactor. Part of the liquid material flows back into the reaction zone at the lower part of the reactor, and after the organic phase and ammonia water phase are separated in the separator for the other part of the liquid material, the organic phase is transported into the next - level ammonolysis reactor to continue the ammonolysis reaction; part of the organic phase in the reaction liquid material also flows into the subsequent ammonolysis reactor after being separated by the lifter and separator in the reactor until the reaction and separation are completed in the last - level ammonolysis reactor, and then it is used as the crude product of mixed nitroaniline and enters the refining section for refining; concentrated ammonia water and catalyst are continuously added to the last - level ammonolysis reactor, and after reaction, lifting, and separation in each ammonolysis reactor, they are transported into the previous - level ammonolysis reactor to continue the reaction until the reaction is completed and lifted and separated in the primary ammonolysis reactor and then removed from the reaction system; The catalyst added together with ammonia water is one or more of cuprous chloride, copper chloride, and copper sulfate, and the catalyst dosage is 0.1% - 2% of the feeding mass of mixed nitrochlorobenzene.

2. The continuous ammonolysis method of mixed nitrochlorobenzene according to claim 1, characterized in that: In the raw material mixed nitrochlorobenzene, the mass ratios of para - nitrochlorobenzene, ortho - nitrochlorobenzene, and meta - nitrochlorobenzene are 60% - 61%, 38%, and 1% - 2% respectively.

3. The continuous ammonolysis method of mixed nitrochlorobenzene according to claim 1, characterized in that: The number of stages of the ammonolysis reactor is 2 or 3.

4. The continuous ammonolysis method of mixed nitrochlorobenzene according to claim 1, characterized in that: The total molar ratio of NH₃·H₂O in the concentrated ammonia water added to the last - level ammonolysis reactor to the mixed nitrochlorobenzene added to the primary ammonolysis reactor is 6:1 - 15:1, and the mass concentration of NH₃·H₂O in the concentrated ammonia water is 25% - 40%.

5. The continuous ammonolysis method of mixed nitrochlorobenzene according to claim 3, characterized in that: When the number of stages of the ammonolysis reactor is 2, the reaction temperatures of the primary and last - level reactors are controlled at 130 - 160 °C and 140 - 170 °C respectively.

6. The continuous ammonolysis method of mixed nitrochlorobenzene according to claim 3, characterized in that: When the number of stages of the ammonolysis reactor is 3, the reaction temperatures of the primary, intermediate, and last - level reactors are controlled at 130 - 150 °C, 140 - 160 °C, and 140 - 170 °C respectively.

7. The continuous ammonolysis method of mixed nitrochlorobenzene according to claim 1, characterized in that: In the ammonolysis reactor, after the liquid material is lifted by the lifter, the mass ratio of the liquid flowing back into the reaction zone to the liquid material entering the separator is 0.1:1 - 10:

1.

8. The continuous ammonolysis method of mixed nitrochlorobenzene according to claim 1, characterized in that, The total residence time of the reaction liquid in the multi - stage ammonolysis reactor is 5h - 10h, and nitrogen replacement is used in the ammonolysis reactor to isolate the entry of air.

9. The continuous ammonolysis method of mixed nitrochlorobenzene according to claim 1, characterized in that: In the crude product of mixed nitroaniline, the sum of the contents of ortho - nitroaniline and para - nitroaniline is higher than 99.5%, the remainder of aminobenzene chloride is less than 0.1%, and the contents of phenols and other by - products are less than 0.3%.

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