A process for the preparation of 1,2,3-trichloro-4,6-dinitrobenzene

Abstract

The application discloses a preparation method of 1,2,3-trichloro-4,6-dinitrobenzene, which comprises the following steps: (1) sulfuric acid and 1,2,3-trichlorobenzene are sequentially added into a batching kettle, mixed uniformly and heated to 60-75 DEG C to obtain a mixture A; (2) nitric acid and sulfuric acid are sequentially added into another batching kettle and mixed uniformly to obtain a nitrosulfur mixed acid; (3) two feed modes are adopted, the mixture A obtained in the step (1) and the nitrosulfur mixed acid obtained in the step (2) are pumped into a two-stage tubular reactor with a diameter of 10 mm respectively to carry out nitration reaction; (4) after the nitration reaction is completed, the reaction liquid obtained in the two-stage tubular reactor is transported into a receiving tank, waste acid and an organic phase are separated, the residual waste acid in the organic phase is neutralized and washed to neutral to obtain 1,2,3-trichloro-4,6-dinitrobenzene. According to the application, 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 greater than 99.5%.

Description

Technical Field

[0001] This invention belongs to the field of organic chemical synthesis technology, specifically relating to a method for preparing 1,2,3-trichloro-4,6-dinitrobenzene. Background Technology

[0002] PBO fiber, known as the "King of Fibers" due to its excellent properties, is prepared by the polymerization reaction of terephthalic acid and 4,6-diaminoresorcinol (DAR) hydrochloride. The preparation methods of DAR hydrochloride, based on the raw materials, mainly include the 1,2,3-trichlorobenzene method and the resorcinol method. The trichlorobenzene process involves nitrifying, hydrolyzing, and hydrogenating trichlorobenzene to prepare 4,6-diaminoresorcinol hydrochloride.

[0003] Currently, 1,2,3-trichloro-4,6-dinitrobenzene is an important intermediate in the preparation of 4,6-diaminoresorcinol hydrochloride. It is typically produced by nitration of 1,2,3-trichlorobenzene with nitric acid and sulfuric acid. To ensure high conversion rates of trichlorobenzene and a high yield of 1,2,3-trichloro-4,6-dinitrobenzene, the nitration process requires a high dehydration value of the sulfuric acid, resulting in a large amount of sulfuric acid used. In practical applications, the molar ratio of sulfuric acid to trichlorobenzene often exceeds 10, leading to a large amount of waste acid generated at the end of the reaction, thus increasing the production cost of 1,2,3-trichloro-4,6-dinitrobenzene. However, reducing the amount of sulfuric acid not only decreases the conversion rate of trichlorobenzene and the yield of 1,2,3-trichloro-4,6-dinitrobenzene, but also results in lower purity of the obtained 1,2,3-trichloro-4,6-dinitrobenzene, which cannot meet actual production requirements. Summary of the Invention

[0004] This invention addresses the technical problem in the prior art where reducing the amount of sulfuric acid used in the nitration reaction of 1,2,3-trichlorobenzene to prepare 1,2,3-trichloro-4,6-dinitrobenzene not only reduces the conversion rate of trichlorobenzene and the yield of 1,2,3-trichloro-4,6-dinitrobenzene, but also results in low purity of the obtained 1,2,3-trichloro-4,6-dinitrobenzene, failing to meet actual production requirements. The invention proposes a method for preparing 1,2,3-trichloro-4,6-dinitrobenzene that effectively reduces the amount of sulfuric acid used while maintaining a high conversion rate of trichlorobenzene, a high yield of 1,2,3-trichloro-4,6-dinitrobenzene, and high purity of 1,2,3-trichloro-4,6-dinitrobenzene.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

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

[0007] (1) Sulfuric acid and 1,2,3-trichlorobenzene are added to the mixing vessel in sequence, mixed evenly and heated to 60-75℃ to obtain mixture A; wherein, the molar ratio of sulfuric acid to 1,2,3-trichlorobenzene is 1.6-3.2;

[0008] (2) Nitric acid and sulfuric acid are added sequentially to another mixing vessel and mixed evenly to obtain a nitric acid-sulfuric acid mixture; wherein the molar ratio of sulfuric acid to nitric acid is 1.5-2.0;

[0009] (3) Using a two-feed method, the mixture A obtained in step (1) and the nitrate-sulfur mixed acid obtained in step (2) are pumped into a two-stage tubular reactor with a diameter of 10 mm for nitration reaction; wherein the molar ratio of nitric acid in the nitrate-sulfur mixed acid to 1,2,3-trichlorobenzene in mixture A is 2.1-2.3.

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

[0011] Furthermore, the mass concentration of sulfuric acid in both steps (1) and (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 mixing tank in steps (1) and (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 step (3), the molar ratio of sulfuric acid to 1,2,3-trichlorobenzene in the mixture A added to the secondary tubular reactor and the mixture of nitrate and sulfuric acid is 6.0-6.5.

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

[0016] Furthermore, the reaction time for 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 acid-sulfur mixture to 1,2,3-trichlorobenzene in mixture A is 2.1-2.2.

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

[0019] The beneficial effects of this invention are:

[0020] This invention involves mixing 1,2,3-trichlorobenzene and nitric acid with sulfuric acid separately, and then feeding the materials into a secondary reactor using a two-stream feeding method for nitration. This reduces the total molar ratio of sulfuric acid to 1,2,3-trichlorobenzene in the raw materials to 6.0-6.5, while ensuring a conversion rate of 1,2,3-trichlorobenzene >99% and a yield of 1,2,3-trichloro-4,6-dinitrobenzene >98%, thereby effectively reducing the amount of waste acid after the reaction.

[0021] Because 1,2,3-trichlorobenzene is in small particulate form, its mixing with concentrated sulfuric acid results in a high viscosity of the sulfuric acid, which is detrimental to the mixing and mass transfer of substances during the nitration reaction. This invention utilizes a tubular reactor with a diameter of 10 mm, which effectively improves the uniformity of mixing between substances, thereby increasing the efficiency of the nitration reaction and reducing the formation of byproducts during the reaction. Simultaneously, the temperature of the first stage reactor in this invention is set at 55-75℃, which allows for better control of the main reaction and reduces the occurrence of side reactions; the temperature of the second stage reactor is set at 60-90℃, which is conducive to the dinitration reaction and further reduces the occurrence of subsequent dinitration side reactions. Ultimately, the purity of the obtained 1,2,3-trichloro-4,6-dinitrobenzene is >99.5%. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be described more clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0023] The terms "first," "second," and similar words used in the specification and claims of this patent application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "an," "a," or "the," etc., do not indicate a quantity limitation, but rather indicate the presence of at least one. Terms such as "comprising" or "including" indicate that the element or object preceding "comprising" encompasses the features, integrals, steps, operations, elements, and / or components listed following "comprising" or "including," and do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0024] Example 1

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

[0026] 98% concentrated sulfuric acid and 1,2,3-trichlorobenzene were added separately to a reaction vessel and mixed thoroughly. 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 mixture A, which was set aside for later use. 98% concentrated sulfuric acid and 65% concentrated nitric acid were added separately to another reaction vessel. 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 nitrate-sulfur mixed acid, which was set aside for later use.

[0027] A two-feed system was used to feed the nitric acid-sulfur mixture and mixture A into a two-stage tubular reactor with an inner diameter of 10 mm. The heat transfer oil temperatures of the two reactors were set to 75℃ and 90℃, respectively. The flow rates of the two feed pumps were adjusted to control the molar ratio of nitric acid to trichlorobenzene at 2.1:1 and the residence time at 3 min. The reaction liquid exiting the two-stage tubular reactor was collected into a separatory tank, the organic phase was separated, washed until neutral, and the sample was analyzed.

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

[0029] Example 2

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

[0031] 98% concentrated sulfuric acid and 1,2,3-trichlorobenzene were added separately to a reaction vessel and mixed thoroughly. 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 mixture A, which was set aside for later use. 98% concentrated sulfuric acid and 65% concentrated nitric acid were added separately to another reaction vessel. 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 nitrate-sulfur mixed acid, which was set aside for later use.

[0032] A two-feed system was used to feed the nitric acid-sulfur mixture and mixture A into a two-stage tubular reactor with an inner diameter of 10 mm. The heat transfer oil temperatures of the two reactors were set to 70℃ and 85℃, respectively. The flow rates of the two feed pumps were adjusted to control the molar ratio of nitric acid to trichlorobenzene at 2.3:1, with a residence time of 5 min. The reaction liquid exiting the two reactors was collected into a separatory tank, the organic phase was separated, washed until neutral, and the sample was analyzed.

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

[0034] Example 3

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

[0036] 98% concentrated sulfuric acid and 1,2,3-trichlorobenzene were added separately to a reaction vessel and mixed thoroughly. 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 mixture A, which was set aside for later use. 98% concentrated sulfuric acid and 65% concentrated nitric acid were added separately to another reaction vessel. 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 nitrate-sulfur mixed acid, which was set aside for later use.

[0037] A two-feed system was used to feed the nitric acid-sulfur mixture and mixture A into a two-stage tubular reactor with an inner diameter of 10 mm. The heat transfer oil temperatures of the two reactors were set to 55℃ and 80℃, respectively. The flow rates of the two feed pumps were adjusted to control the molar ratio of nitric acid to trichlorobenzene at 2.2:1 and the residence time at 7 min. The reaction liquid exiting the two-stage tubular reactor was collected into a separatory tank, the organic phase was separated, washed until neutral, and the sample was analyzed.

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

[0039] Example 4

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

[0041] 98% concentrated sulfuric acid and 1,2,3-trichlorobenzene were added separately to a reaction vessel and mixed thoroughly. 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 mixture A, which was set aside for later use. 98% concentrated sulfuric acid and 65% concentrated nitric acid were added separately to another reaction vessel. 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 nitrate-sulfur mixed acid, which was set aside for later use.

[0042] A two-feed system was used to feed the nitric acid-sulfur mixture and mixture A into a two-stage tubular reactor with an inner diameter of 10 mm. The heat transfer oil temperatures of the two reactors were set to 60℃ and 75℃, respectively. The flow rates of the two feed pumps were adjusted to control the molar ratio of nitric acid to trichlorobenzene at 2.2:1 and the residence time at 7 min. The reaction liquid exiting the two-stage tubular reactor was collected into a separatory tank, the organic phase was separated, washed until neutral, and the sample was analyzed.

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

[0044] Example 5

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

[0046] 98% concentrated sulfuric acid and 1,2,3-trichlorobenzene were added separately to a reaction vessel and mixed thoroughly. 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 mixture A, which was set aside for later use. 98% concentrated sulfuric acid and 65% concentrated nitric acid were added separately to another reaction vessel. 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 nitrate-sulfur mixed acid, which was set aside for later use.

[0047] A two-feed system was used to feed the nitric acid-sulfur mixture and mixture A into a two-stage tubular reactor with an inner diameter of 10 mm. The heat transfer oil temperatures of the two reactors were set to 70℃ and 75℃, respectively. The flow rates of the two feed pumps were adjusted to control the molar ratio of nitric acid to trichlorobenzene at 2.2:1, with a residence time of 7 min. The reaction liquid exiting the two-stage tubular reactor was collected into a separatory tank, the organic phase was separated, washed until neutral, and the sample was analyzed.

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

[0049] Example 6

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

[0051] 98% concentrated sulfuric acid and 1,2,3-trichlorobenzene were added separately to a reaction vessel and mixed thoroughly. 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 mixture A, which was set aside for later use. 98% concentrated sulfuric acid and 65% concentrated nitric acid were added separately to another reaction vessel. 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 nitrate-sulfur mixed acid, which was set aside for later use.

[0052] A two-feed system was used to feed the nitric acid-sulfur mixture and mixture A into a two-stage tubular reactor with an inner diameter of 10 mm. The heat transfer oil temperatures of the two reactors were set to 75℃ and 70℃, respectively. The flow rates of the two feed pumps were adjusted to control the molar ratio of nitric acid to trichlorobenzene at 2.1:1 and the residence time at 7 min. The reaction liquid exiting the two-stage tubular reactor was collected into a separatory tank, the organic phase was separated, washed until neutral, and the sample was analyzed.

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

[0054] Example 7

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

[0056] 98% concentrated sulfuric acid and 1,2,3-trichlorobenzene were added separately to a reaction vessel and mixed thoroughly. 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 mixture A, which was set aside for later use. 98% concentrated sulfuric acid and 65% concentrated nitric acid were added separately to another reaction vessel. 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 nitrate-sulfur mixed acid, which was set aside for later use.

[0057] A two-feed system was used to feed the nitric acid-sulfur mixture and mixture A into a two-stage tubular reactor with an inner diameter of 10 mm. The heat transfer oil temperatures of the two reactors were set to 65℃ and 60℃, respectively. The flow rates of the two feed pumps were adjusted to control the molar ratio of nitric acid to trichlorobenzene at 2.3:1 and the residence time at 3 min. The reaction liquid exiting the two-stage tubular reactor was collected into a separatory tank, the organic phase was separated, washed until neutral, and the sample was analyzed.

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

[0059] Comparative Example 1

[0060] In a 500mL four-necked flask, a speed-controlled stirrer, thermometer, and constant-pressure dropping funnel were connected. 60.5g of trichlorobenzene and 360g of 98% sulfuric acid were added to the flask. While stirring, 57g of 65% nitric acid was added dropwise. The temperature was controlled at 80-85℃, 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 includes the following steps:

[0063] 98% concentrated sulfuric acid and 1,2,3-trichlorobenzene were added separately to a reaction vessel and mixed thoroughly. 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 mixture A, which was set aside for later use. 98% concentrated sulfuric acid and 65% concentrated nitric acid were added separately to another reaction vessel. 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 nitrate-sulfur mixed acid, which was set aside for later use.

[0064] A two-feed system was used to feed the nitric-sulfur mixed acid and mixture A into a three-stage tubular reactor with an inner diameter of 4 mm. The heat transfer oil temperatures of the three-stage tubular reactor were set to 75℃, 50℃, and 40℃, respectively. The flow rates of the two feed pumps were adjusted to control the molar ratio of nitric acid to trichlorobenzene at 2.1:1 and the residence time at 3 min. The reaction liquid exiting the three-stage tubular reactor was collected into a separatory tank, the organic phase was separated, washed until neutral, and the sample was analyzed.

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

[0066] The difference between Comparative Example 2 and Example 1 is that the two-stage tubular reactor with an inner diameter of 10 mm was replaced with a three-stage tubular reactor with an inner diameter of 4 mm, and the temperature of the heat transfer oil in the tubular reactor was also changed. The results from Example 1 and Comparative Example 2 show that increasing the inner diameter of the tubular reactor while simultaneously raising 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 includes the following steps:

[0069] 98% concentrated sulfuric acid and 1,2,3-trichlorobenzene were added separately to a reaction vessel and mixed thoroughly. 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 mixture A, which was set aside for later use. 98% concentrated sulfuric acid and 65% concentrated nitric acid were added separately to another reaction vessel. 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 min to obtain a nitrate-sulfur mixed acid, which was set aside for later use.

[0070] A two-feed system was used to feed the nitric acid-sulfur mixture and mixture A into a two-stage tubular reactor with an inner diameter of 10 mm. The heat transfer oil temperatures of the two reactors were set to 75℃ and 90℃, respectively. The flow rates of the two feed pumps were adjusted to control the molar ratio of nitric acid to trichlorobenzene at 2.1:1 and the residence time at 3 min. The reaction liquid exiting the two-stage tubular reactor was collected into a separatory tank, the organic phase was separated, washed until neutral, and the sample was analyzed.

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

[0072] The difference between Comparative Example 3 and Example 1 above is that the amount of sulfuric acid in the nitrate-sulfur mixture is reduced, which means the amount of sulfuric acid in the nitration reaction is reduced. The results from Example 1 and Comparative Example 3 show that appropriately increasing the amount of sulfuric acid can increase the conversion rate of 1,2,3-trichlorobenzene and simultaneously improve the purity of the product (1,2,3-trichloro-4,6-dinitrobenzene).

[0073] Finally, it should be noted that these embodiments are for illustrative purposes only and do not limit the scope of the invention. Furthermore, those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all embodiments here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing 1,2,3-trichloro-4,6-dinitrobenzene, characterized in that, Includes the following steps: (1) Sulfuric acid and 1,2,3-trichlorobenzene are added to the mixing vessel in sequence, mixed evenly and heated to 60-75℃ to obtain mixture A; wherein the molar ratio of sulfuric acid to 1,2,3-trichlorobenzene is 1.6-3.2; (2) Nitric acid and sulfuric acid are added sequentially to another mixing vessel and mixed evenly to obtain a nitric acid-sulfur mixture; wherein the molar ratio of sulfuric acid to nitric acid is 1.5-2.0; (3) Using a two-feed method, the mixture A obtained in step (1) and the nitrate-sulfur mixed acid obtained in step (2) are pumped into a two-stage tubular reactor with a diameter of 10 mm for nitration reaction; wherein the molar ratio of nitric acid in the nitrate-sulfur mixed acid to 1,2,3-trichlorobenzene in mixture A is 2.1-2.3; (4) After the nitration reaction is completed, the reaction liquid obtained from the two-stage tubular reactor is transported to the receiving tank, and the waste acid and organic phase are separated. The waste acid remaining in the organic phase is neutralized and washed until neutral to obtain 1,2,3-trichloro-4,6-dinitrobenzene. In both steps (1) and (2), the mass concentration of sulfuric acid is not less than 98%, and in step (2), the mass concentration of nitric acid is not less than 65%. In step (3), the reaction temperature of the first stage reactor of the two-stage tubular reactor is 55-75℃, and the reaction temperature of the second stage reactor is 60-90℃.

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

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

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

5.

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

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

2.

7. The 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 >99%, the yield of the 1,2,3-trichloro-4,6-dinitrobenzene is >98%, and the purity of the 1,2,3-trichloro-4,6-dinitrobenzene is >99.5%.