Preparation method of 1, 2, 3-trichloro-4, 6-dinitrobenzene

Abstract

The invention discloses a preparation method of 1, 2, 3-trichloro-4, 6-dinitrobenzene, which comprises the following steps: (1) sequentially adding sulfuric acid and 1, 2, 3-trichlorobenzene into a batching kettle, uniformly mixing, and heating to 60-75 DEG C to obtain a mixture A; (2) sequentially adding nitric acid and sulfuric acid into another batching kettle, and uniformly mixing to obtain nitric acid and sulfuric acid mixed acid; (3) respectively feeding the mixture A obtained in the step (1) and the mixed nitric acid and sulfuric acid obtained in the step (2) into a secondary tubular reactor with the diameter of 10mm through a pump by adopting a two-stream feeding mode, and carrying out nitration reaction; and (4) after the nitration reaction is completed, conveying a reaction solution obtained in the secondary tubular reactor into a receiving tank, separating out waste acid and an organic phase, neutralizing the residual waste acid in the organic phase, and washing to be neutral to obtain the 1, 2, 3-trichloro-4, 6-dinitrobenzene. The conversion rate of the 1, 2, 3-trichlorobenzene is greater than 99%, the yield of the obtained product 1, 2, 3-trichloro-4, 6-dinitrobenzene is greater than 98%, and the purity is gt; the content is 99.5%.

Description

Technical Field

[0001] The invention belongs to the technical field of organic chemical synthesis, and specifically relates to a method for preparing 1,2,3-trichloro-4,6-dinitrobenzene. Background Art

[0002] PBO fiber is known as the king of fibers due to its good performance. PBO fiber is prepared by polymerization of terephthalic acid and 4,6-diaminoresorcinol (DAR) hydrochloride. The preparation methods of DAR hydrochloride are mainly divided into 1,2,3-trichlorobenzene method and resorcinol method according to the raw materials. The trichlorobenzene process is the process of preparing 4,6-diaminoresorcinol hydrochloride by nitration, hydrolysis, hydrogenation and other processes of trichlorobenzene.

[0003] At present, 1,2,3-trichloro-4,6-dinitrobenzene is an important intermediate for preparing 4,6-diaminoresorcinol hydrochloride. It is usually prepared by nitrating 1,2,3-trichlorobenzene with nitric acid and sulfuric acid. In order to ensure the high conversion rate of trichlorobenzene and the yield of 1,2,3-trichloro-4,6-dinitrobenzene in the nitration process, the dehydration value of sulfuric acid is required to be high, and the amount of sulfuric acid is large. In the actual application process, the ratio of sulfuric acid to trichlorobenzene molar number reaches more than 10, resulting in a large amount of waste acid generated at the end of the reaction, thereby increasing the production cost of 1,2,3-trichloro-4,6-dinitrobenzene. However, if the amount of sulfuric acid is reduced, not only will the conversion rate of trichlorobenzene and the yield of 1,2,3-trichloro-4,6-dinitrobenzene be reduced, but also the purity of the obtained 1,2,3-trichloro-4,6-dinitrobenzene will be low, which cannot meet the actual production needs. Summary of the invention

[0004] The invention aims to solve the technical problem that in the prior art, if the amount of sulfuric acid is reduced in the process of preparing 1,2,3-trichloro-4,6-dinitrobenzene by nitration reaction of 1,2,3-trichlorobenzene, not only the conversion rate of trichlorobenzene and the yield of 1,2,3-trichloro-4,6-dinitrobenzene will be reduced, but also the purity of the obtained 1,2,3-trichloro-4,6-dinitrobenzene will be low and the actual production demand cannot be met; a preparation method of 1,2,3-trichloro-4,6-dinitrobenzene is proposed to achieve the technical effect of effectively ensuring a high conversion rate of trichlorobenzene, a high yield of 1,2,3-trichloro-4,6-dinitrobenzene and a high purity of 1,2,3-trichloro-4,6-dinitrobenzene under the premise of effectively reducing the amount of sulfuric acid.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene comprises the following steps:

[0007] (1) adding sulfuric acid and 1,2,3-trichlorobenzene into a batching kettle in sequence, mixing them evenly and heating them to 60-75° C. to obtain a mixture A; wherein the molar ratio of sulfuric acid to 1,2,3-trichlorobenzene is 1.6-3.2;

[0008] (2) adding nitric acid and sulfuric acid into another batching kettle in sequence and mixing them evenly to obtain nitric-sulfur mixed acid; wherein the molar ratio of sulfuric acid to nitric acid is 1.5-2.0;

[0009] (3) using a two-stream feeding method, respectively pumping the mixture A obtained in step (1) and the nitric acid-sulfuric acid mixture obtained in step (2) into a two-stage tubular reactor with a diameter of 10 mm for nitration reaction; wherein the molar ratio of nitric acid in the nitric acid-sulfuric acid mixture to 1,2,3-trichlorobenzene in the mixture A is 2.1-2.3;

[0010] (4) After the nitration reaction is completed, the reaction liquid obtained in the secondary tubular reactor is transported to a receiving tank, and the waste acid and the organic phase are separated. The waste acid remaining in the organic phase is neutralized and washed to neutrality to obtain 1,2,3-trichloro-4,6-dinitrobenzene.

[0011] Furthermore, the mass concentration of sulfuric acid in step (1) and step (2) is not less than 98%, and the mass concentration of nitric acid in step (2) is not less than 65%.

[0012] Furthermore, the interior of the batching kettle in step (1) and step (2) is coated with an acid-resistant coating.

[0013] Furthermore, in step (2), the mixing temperature of nitric acid and sulfuric acid is 60-80° C., and the mixing time is 8-12 min.

[0014] Furthermore, in the step (3), the molar ratio of sulfuric acid to 1,2,3-trichlorobenzene in the mixture A and the mixture of nitric and sulfuric acid added to the secondary tubular reactor is 6.0-6.5.

[0015] Furthermore, in the step (3), the reaction temperature of the first stage reactor of the two-stage tubular reactor is 55-75°C, and the reaction temperature of the second stage reactor is 60-90°C.

[0016] Furthermore, the reaction time of the nitration reaction in step (3) is 3 to 8 minutes.

[0017] Furthermore, in step (3), the molar ratio of nitric acid in the nitric-sulfuric acid mixture to 1,2,3-trichlorobenzene in the mixture A is 2.1-2.2.

[0018] Furthermore, in the preparation method, the conversion rate of the 1,2,3-trichlorobenzene is greater than 99%, the yield of the 1,2,3-trichloro-4,6-dinitrobenzene is greater than 98%, and the purity is greater than 99.5%.

[0019] The beneficial effects of the present invention are:

[0020] The present invention reduces the total molar ratio of sulfuric acid to 1,2,3-trichlorobenzene in the raw material to 6.0-6.5 under the premise of ensuring that the conversion rate of 1,2,3-trichlorobenzene is greater than 99% and the yield of 1,2,3-trichloro-4,6-dinitrobenzene is greater than 98%, thereby effectively reducing the amount of waste acid after the reaction.

[0021] Since 1,2,3-trichlorobenzene is in the form of small particles, after mixing with concentrated sulfuric acid, the viscosity of the concentrated sulfuric acid is relatively large, which is not conducive to the mixing and reaction mass transfer between substances during the nitration reaction. The present invention uses a tubular reactor with a diameter of 10 mm, which can effectively improve the uniform mixing degree between substances, thereby improving the efficiency of the nitration reaction and reducing the generation of by-products during the reaction. At the same time, the temperature of the first-stage reactor in the secondary tubular reactor of the present invention is set to 55-75°C, at which temperature the main reaction can be better controlled and the occurrence of side reactions can be reduced; the temperature of the second-stage reactor is set to 60-90°C, which is conducive to the reaction of dinitration and further reduces the occurrence of subsequent side reactions of dinitration. Finally, the purity of the obtained 1,2,3-trichloro-4,6-dinitrobenzene is >99.5%. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be described more clearly and completely below. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meaning understood by people with general skills in the field to which the present invention belongs.

[0023] The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "one", "an" or "the" and similar words do not indicate a quantitative limitation, but indicate the existence of at least one. Words such as "include" or "comprise" mean that the elements or objects appearing before "include" or "comprise" cover the features, wholes, steps, operations, elements and / or components listed after "include" or "comprise", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0024] Example 1

[0025] A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene comprises the following steps:

[0026] 98% concentrated sulfuric acid and 1,2,3-trichlorobenzene were added to a reaction kettle respectively and mixed evenly, the molar ratio of concentrated sulfuric acid to 1,2,3-trichlorobenzene was adjusted to 3.0:1, and the mixture was heated to 75°C to obtain a mixture A for standby use; 98% concentrated sulfuric acid and 65% concentrated nitric acid were added to another reaction kettle respectively, the molar ratio of concentrated sulfuric acid to concentrated nitric acid was adjusted to 1.5:1, and the mixture was stirred at 80°C for 10 minutes to obtain a nitric-sulfuric acid mixed acid for standby use;

[0027] The nitric acid-sulfuric acid mixture and mixture A were fed into a 2-stage tubular reactor with an inner diameter of 10 mm by a two-stream feeding method. The heat transfer oil temperature of the 2-stage reactor was set to 75°C and 90°C, respectively. The flow rates of the 2-stream feed pumps were adjusted to control the molar ratio of nitric acid to trichlorobenzene to be 2.1:1, and the residence time was 3 min. The reaction liquid from the 2-stage tubular reactor was received in a liquid separation tank, the organic phase was separated, washed to neutrality, and the sample was analyzed.

[0028] Among them, the conversion rate of 1,2,3-trichlorobenzene is 99.5%, the yield of 1,2,3-trichloro-4,6-dinitrobenzene is 98.1%, and the purity of 1,2,3-trichloro-4,6-dinitrobenzene is 99.6%.

[0029] Example 2

[0030] A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene comprises the following steps:

[0031] 98% concentrated sulfuric acid and 1,2,3-trichlorobenzene were added to a reaction kettle respectively, mixed evenly, the molar ratio of concentrated sulfuric acid to 1,2,3-trichlorobenzene was adjusted to 3.2:1, and the mixture was heated to 70°C to obtain a mixture A for standby use; 98% concentrated sulfuric acid and 65% concentrated nitric acid were added to another reaction kettle respectively, the molar ratio of concentrated sulfuric acid to concentrated nitric acid was adjusted to 1.8:1, and the mixture was stirred at 70°C for 10 minutes to obtain a nitric-sulfuric acid mixed acid for standby use;

[0032] The nitric acid-sulfuric acid mixture and mixture A were fed into a 2-stage tubular reactor with an inner diameter of 10 mm by a two-stream feeding method. The heat transfer oil temperature of the 2-stage reactor was set to 70°C and 85°C, respectively. The flow rates of the 2-stream feed pumps were adjusted to control the molar ratio of nitric acid to trichlorobenzene to be 2.3:1, and the residence time was 5 min. The reaction liquid from the 2-stage reactor was received in a liquid separation tank, the organic phase was separated, washed to neutrality, and the sample was analyzed.

[0033] Among them, the conversion rate of 1,2,3-trichlorobenzene is 99.5%, the yield of 1,2,3-trichloro-4,6-dinitrobenzene is 98.2%, and the purity of 1,2,3-trichloro-4,6-dinitrobenzene is 99.5%.

[0034] Example 3

[0035] A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene comprises the following steps:

[0036] 98% concentrated sulfuric acid and 1,2,3-trichlorobenzene were added to a reaction kettle respectively and mixed evenly, the molar ratio of concentrated sulfuric acid to 1,2,3-trichlorobenzene was adjusted to 2.8:1, and the mixture was heated to 70°C to obtain a mixture A for standby use; 98% concentrated sulfuric acid and 65% concentrated nitric acid were added to another reaction kettle respectively, the molar ratio of concentrated sulfuric acid to concentrated nitric acid was adjusted to 2.0:1, and the mixture was stirred at 80°C for 10 minutes to obtain a nitric-sulfuric acid mixed acid for standby use;

[0037] The nitric acid-sulfuric acid mixture and mixture A were fed into a 2-stage tubular reactor with an inner diameter of 10 mm by a two-stream feeding method. The heat transfer oil temperature of the 2-stage reactor was set to 55°C and 80°C, respectively. The flow rates of the 2-stream feed pumps were adjusted to control the molar ratio of nitric acid to trichlorobenzene to be 2.2:1, and the residence time was 7 minutes. The reaction liquid from the 2-stage tubular reactor was received in a liquid separation tank, the organic phase was separated, washed to neutrality, and the sample was analyzed.

[0038] Among them, the conversion rate of 1,2,3-trichlorobenzene is 99.4%, the yield of 1,2,3-trichloro-4,6-dinitrobenzene is 98.2%, and the purity of 1,2,3-trichloro-4,6-dinitrobenzene is 99.5%.

[0039] Example 4

[0040] A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene comprises the following steps:

[0041] 98% concentrated sulfuric acid and 1,2,3-trichlorobenzene were added to a reaction kettle respectively and mixed evenly, the molar ratio of concentrated sulfuric acid to 1,2,3-trichlorobenzene was adjusted to 2.6:1, and the mixture was heated to 60°C to obtain a mixture A for standby use; 98% concentrated sulfuric acid and 65% concentrated nitric acid were added to another reaction kettle respectively, the molar ratio of concentrated sulfuric acid to concentrated nitric acid was adjusted to 1.6:1, and the mixture was stirred at 80°C for 10 minutes to obtain a nitric-sulfuric acid mixed acid for standby use;

[0042] The nitric acid-sulfuric acid mixture and mixture A were fed into a two-stage tubular reactor with an inner diameter of 10 mm by a two-stream feeding method. The heat transfer oil temperature of the two-stage reactor was set to 60°C and 75°C, respectively. The flow rates of the two feed pumps were adjusted to control the molar ratio of nitric acid to trichlorobenzene to be 2.2:1, and the residence time was 7 minutes. The reaction liquid from the two-stage tubular reactor was received in a liquid separation tank, the organic phase was separated, washed to neutrality, and the sample was analyzed.

[0043] Among them, the conversion rate of 1,2,3-trichlorobenzene is 99.1%, the yield of 1,2,3-trichloro-4,6-dinitrobenzene is 98.0%, and the purity of 1,2,3-trichloro-4,6-dinitrobenzene is 99.5%.

[0044] Example 5

[0045] A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene comprises the following steps:

[0046] 98% concentrated sulfuric acid and 1,2,3-trichlorobenzene were added to a reaction kettle respectively and mixed evenly, the molar ratio of concentrated sulfuric acid to 1,2,3-trichlorobenzene was adjusted to 2.4:1, and the mixture was heated to 60°C to obtain a mixture A for standby use; 98% concentrated sulfuric acid and 65% concentrated nitric acid were added to another reaction kettle respectively, the molar ratio of concentrated sulfuric acid to concentrated nitric acid was adjusted to 1.8:1, and the mixture was stirred at 80°C for 10 minutes to obtain a nitric-sulfuric acid mixed acid for standby use;

[0047] The nitric acid-sulfuric acid mixture and mixture A were fed into a two-stage tubular reactor with an inner diameter of 10 mm by a two-stream feeding method. The heat transfer oil temperature of the two-stage reactor was set to 70°C and 75°C, respectively. The flow rates of the two feed pumps were adjusted to control the molar ratio of nitric acid to trichlorobenzene to be 2.2:1, and the residence time was 7 minutes. The reaction liquid from the two-stage tubular reactor was received in a liquid separation tank, the organic phase was separated, washed to neutrality, and the sample was analyzed.

[0048] Among them, the conversion rate of 1,2,3-trichlorobenzene is 99.1%, the yield of 1,2,3-trichloro-4,6-dinitrobenzene is 98.0%, and the purity of 1,2,3-trichloro-4,6-dinitrobenzene is 99.5%.

[0049] Example 6

[0050] A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene comprises the following steps:

[0051] 98% concentrated sulfuric acid and 1,2,3-trichlorobenzene were added to a reaction kettle respectively and mixed evenly, the molar ratio of concentrated sulfuric acid to 1,2,3-trichlorobenzene was adjusted to 2.0:1, and the mixture was heated to 60°C to obtain a mixture A for standby use; 98% concentrated sulfuric acid and 65% concentrated nitric acid were added to another reaction kettle respectively, the molar ratio of concentrated sulfuric acid to concentrated nitric acid was adjusted to 2.0:1, and the mixture was stirred at 80°C for 10 minutes to obtain a nitric-sulfuric acid mixed acid for standby use;

[0052] The nitric acid-sulfuric acid mixture and mixture A were fed into a 2-stage tubular reactor with an inner diameter of 10 mm by a two-stream feeding method. The heat transfer oil temperature of the 2-stage reactor was set to 75°C and 70°C, respectively. The flow rates of the 2-stream feed pumps were adjusted to control the molar ratio of nitric acid to trichlorobenzene to be 2.1:1, and the residence time was 7 minutes. The reaction liquid from the 2-stage tubular reactor was received in a liquid separation tank, the organic phase was separated, washed to neutrality, and the sample was analyzed.

[0053] Among them, the conversion rate of 1,2,3-trichlorobenzene is 99.3%, the yield of 1,2,3-trichloro-4,6-dinitrobenzene is 98.0%, and the purity of 1,2,3-trichloro-4,6-dinitrobenzene is 99.5%.

[0054] Example 7

[0055] A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene comprises the following steps:

[0056] 98% concentrated sulfuric acid and 1,2,3-trichlorobenzene were added to a reaction kettle respectively and mixed evenly, the molar ratio of concentrated sulfuric acid to 1,2,3-trichlorobenzene was adjusted to 1.6:1, and the mixture was heated to 75°C to obtain a mixture A for standby use; 98% concentrated sulfuric acid and 65% concentrated nitric acid were added to another reaction kettle respectively, the molar ratio of concentrated sulfuric acid to concentrated nitric acid was adjusted to 1.5:1, and the mixture was stirred at 80°C for 10 minutes to obtain a nitric-sulfuric acid mixed acid for standby use;

[0057] The nitric acid-sulfuric acid mixture and mixture A were fed into a two-stage tubular reactor with an inner diameter of 10 mm by a two-stream feeding method. The heat transfer oil temperature of the two-stage reactor was set to 65°C and 60°C, respectively. The flow rates of the two feed pumps were adjusted to control the molar ratio of nitric acid to trichlorobenzene to be 2.3:1, and the residence time was 3 minutes. The reaction liquid from the two-stage tubular reactor was received in a liquid separation tank, the organic phase was separated, washed to neutrality, and the sample was analyzed.

[0058] Among them, the conversion rate of 1,2,3-trichlorobenzene is 99.2%, the yield of 1,2,3-trichloro-4,6-dinitrobenzene is 98.0%, and the purity of 1,2,3-trichloro-4,6-dinitrobenzene is 99.5%.

[0059] Comparative Example 1

[0060] A 500mL four-necked flask was connected with a speed-adjustable stirrer, a thermometer and a constant pressure dropping funnel. 60.5g of trichlorobenzene and 360g of 98% sulfuric acid were added to the four-necked flask. Under stirring, 57g of 65% nitric acid was added dropwise. The temperature was controlled at 80-85°C and the reaction was maintained for 5 hours. After the reaction was completed, the mixture was allowed to stand for 30 minutes. After standing, the waste acid layer was separated and the organic phase was sampled and analyzed. The content of 1,2,3-trichloro-4-nitrobenzene was 0.1% and the content of 1,2,3-trichloro-4,6-dinitrobenzene was 98.5%.

[0061] Comparative Example 2

[0062] A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene comprises the following steps:

[0063] 98% concentrated sulfuric acid and 1,2,3-trichlorobenzene were added to a reaction kettle respectively and mixed evenly, the molar ratio of concentrated sulfuric acid to 1,2,3-trichlorobenzene was adjusted to 3.0:1, and the mixture was heated to 75°C to obtain a mixture A for standby use; 98% concentrated sulfuric acid and 65% concentrated nitric acid were added to another reaction kettle respectively, the molar ratio of concentrated sulfuric acid to concentrated nitric acid was adjusted to 1.5:1, and the mixture was stirred at 80°C for 10 minutes to obtain a nitric-sulfuric acid mixed acid for standby use;

[0064] The nitric acid-sulfuric acid mixture and mixture A were fed into a three-stage tubular reactor with an inner diameter of 4 mm by a two-stream feeding method. The heat transfer oil temperatures of the three-stage tubular reactor were set to 75°C, 50°C, and 40°C, respectively. The flow rates of the two feed pumps were adjusted to control the molar ratio of nitric acid to trichlorobenzene to be 2.1:1, and the residence time was 3 min. The reaction liquid from the three-stage tubular reactor was received in a liquid separation tank, the organic phase was separated, washed to neutrality, and the sample was analyzed.

[0065] Among them, the conversion rate of 1,2,3-trichlorobenzene is 99.4%, the yield of 1,2,3-trichloro-4,6-dinitrobenzene is 98.0%, and the purity of 1,2,3-trichloro-4,6-dinitrobenzene is 98.1%.

[0066] The difference between this comparative example 2 and the above-mentioned embodiment 1 is that the 2-stage tubular reactor with an inner diameter of 10 mm is replaced with a 3-stage tubular reactor with an inner diameter of 4 mm, and the temperature of the heat transfer oil in the tubular reactor is changed. From the results of embodiment 1 and comparative example 2, it can be seen that increasing the inner diameter of the tubular reactor and increasing the temperature of the second-stage reactor can significantly improve the purity of the product (1,2,3-trichloro-4,6-dinitrobenzene).

[0067] Comparative Example 3

[0068] A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene comprises the following steps:

[0069] 98% concentrated sulfuric acid and 1,2,3-trichlorobenzene were added to a reaction kettle respectively and mixed evenly, the molar ratio of concentrated sulfuric acid to 1,2,3-trichlorobenzene was adjusted to 3.0:1, and the mixture was heated to 75°C to obtain a mixture A for standby use; 98% concentrated sulfuric acid and 65% concentrated nitric acid were added to another reaction kettle respectively, the molar ratio of concentrated sulfuric acid to concentrated nitric acid was adjusted to 1:1, and the mixture was stirred at 80°C for 10 minutes to obtain a nitric-sulfuric acid mixed acid for standby use;

[0070] The nitric acid-sulfuric acid mixture and mixture A were fed into a 2-stage tubular reactor with an inner diameter of 10 mm by a two-stream feeding method. The heat transfer oil temperature of the 2-stage reactor was set to 75°C and 90°C, respectively. The flow rates of the 2-stream feed pumps were adjusted to control the molar ratio of nitric acid to trichlorobenzene to be 2.1:1, and the residence time was 3 min. The reaction liquid from the 2-stage tubular reactor was received in a liquid separation tank, the organic phase was separated, washed to neutrality, and the sample was analyzed.

[0071] Among them, the conversion rate of 1,2,3-trichlorobenzene is 99.1%, the yield of 1,2,3-trichloro-4,6-dinitrobenzene is 97.6%, and the purity of 1,2,3-trichloro-4,6-dinitrobenzene is 99.0%.

[0072] The difference between this comparative example 3 and the above-mentioned example 1 is that the amount of sulfuric acid in the nitric-sulfuric acid mixture is reduced, that is, the amount of sulfuric acid in the nitration reaction is reduced. From the results of example 1 and comparative example 3, it can be seen that appropriately increasing the amount of sulfuric acid can increase the conversion rate of 1,2,3-trichlorobenzene and improve the purity of the product (1,2,3-trichloro-4,6-dinitrobenzene).

[0073] Finally, it should be noted that these embodiments are only used to illustrate the present invention and do not limit the scope of the present invention. In addition, for those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. The obvious changes or modifications derived from them are still within the scope of protection of the present invention.

Claims

1. A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene, characterized in that: The steps include: (1) adding sulfuric acid and 1,2,3-trichlorobenzene into a batching kettle in sequence, mixing them evenly and heating them to 60-75° C. to obtain a mixture A; wherein the molar ratio of sulfuric acid to 1,2,3-trichlorobenzene is 1.6-3.2; (2) adding nitric acid and sulfuric acid into another batching kettle in sequence and mixing them evenly to obtain nitric-sulfur mixed acid; wherein the molar ratio of sulfuric acid to nitric acid is 1.5-2.0; (3) using a two-stream feeding method, respectively pumping the mixture A obtained in step (1) and the nitric acid-sulfuric acid mixture obtained in step (2) into a two-stage tubular reactor with a diameter of 10 mm for nitration reaction; wherein the molar ratio of nitric acid in the nitric acid-sulfuric acid mixture to 1,2,3-trichlorobenzene in the mixture A is 2.1-2.3; (4) After the nitration reaction is completed, the reaction liquid obtained in the secondary tubular reactor is transported to a receiving tank, and the waste acid and the organic phase are separated. The waste acid remaining in the organic phase is neutralized and washed to neutrality to obtain 1,2,3-trichloro-4,6-dinitrobenzene.

2. A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene according to claim 1, characterized in that: The mass concentration of sulfuric acid in step (1) and step (2) is not less than 98%, and the mass concentration of nitric acid in step (2) is not less than 65%.

3. A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene according to claim 1, characterized in that: The interior of the batching kettle in step (1) and step (2) is coated with an acid-resistant coating.

4. A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene according to claim 1, characterized in that: In the step (2), the mixing temperature of nitric acid and sulfuric acid is 60-80° C., and the mixing time is 8-12 minutes.

5. A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene according to claim 1, characterized in that: In the step (3), the molar ratio of sulfuric acid to 1,2,3-trichlorobenzene in the mixture A and the mixture of nitric and sulfuric acid added to the secondary tubular reactor is 6.0-6.

5.

6. A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene according to claim 1, characterized in that: In the step (3), the reaction temperature of the first stage reactor of the two-stage tubular reactor is 55-75°C, and the reaction temperature of the second stage reactor is 60-90°C.

7. A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene according to claim 1, characterized in that: The reaction time of the nitration reaction in step (3) is 3 to 8 minutes.

8. A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene according to claim 1, characterized in that: In the step (3), the molar ratio of nitric acid in the nitric-sulfuric acid mixture to 1,2,3-trichlorobenzene in the mixture A is 2.1-2.

2.

9. A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene according to claim 1, characterized in that: The conversion rate of the 1,2,3-trichlorobenzene is greater than 99%, the yield of the 1,2,3-trichloro-4,6-dinitrobenzene is greater than 98%, and the purity of the 1,2,3-trichloro-4,6-dinitrobenzene is greater than 99.5%.