Continuous preparation method of 6-chloro-2, 4-dinitroaniline and diazonium salt thereof and equipment for implementing continuous preparation method

Abstract

The invention provides a continuous preparation method of 6-chloro-2, 4-dinitroaniline and diazonium salt of 6-chloro-2, 4-dinitroaniline and equipment for implementing the continuous preparation method. The preparation method of the 6-chloro-2, 4-dinitroaniline comprises the following steps: dissolving o-chloro-p-nitroaniline in a sulfuric acid solution to obtain a sulfuric acid solution of the o-chloro-p-nitroaniline; the method comprises the following steps: conveying a sulfuric acid solution of o-chloro-p-nitroaniline and a nitric acid solution or a mixed acid solution into a first micro-channel reactor for nitration reaction to obtain a nitro compound; wherein the mixed acid solution comprises nitric acid and sulfuric acid. According to the preparation method of the 6-chloro-2, 4-dinitroaniline, waste salt and / or waste water are / is not generated, and a chlorinating agent is not introduced in the nitration process, so that the preparation method is more environment-friendly; a large amount of explosive dust and dry tail gas cannot be generated, and safety risks such as dust pollution and dust explosion do not exist. The preparation method of the 6-chloro-2, 4-dinitroaniline can be carried out in a micro-channel reactor, and the intrinsic safety degree is high.

Description

Technical Field

[0001] The invention relates to a continuous preparation method of 6-chloro-2,4-dinitroaniline and its diazonium salt and equipment for implementing the continuous preparation method, belonging to the field of fine chemicals. Background Art

[0002] 6-Chloro-2,4-dinitroaniline is an important dye intermediate with large domestic production and sales. It is mainly used as the diazo component of disperse dyes to react with other coupling components to produce dyes. It plays an important role in disperse dye intermediates. At present, the production process of domestic manufacturers is basically based on the chlorination reaction of 2,4-dinitroaniline and a chlorinating agent (such as chlorine, hydrochloric acid, etc.) in the presence of an oxidant. In essence, it is obtained by the chlorination reaction of 2,4-dinitroaniline and chlorine. The reaction principle and chemical reaction formula are as follows:

[0003]

[0004] After the chlorination is completed, the product is separated to obtain a wet product, which is then dried. The dried 6-chloro-2,4-dinitroaniline is subjected to a diazotization reaction with nitrosyl sulfuric acid in a sulfuric acid medium to obtain 6-chloro-2,4-dinitroaniline hydrochloride, and the reaction formula is as follows:

[0005]

[0006] In the production process of chlorination synthesis of 6-chloro-2,4-dinitroaniline, chlorine must be excessive, which can easily generate byproducts such as dichlorobenzene, trichlorobenzene, tetrachlorobenzene, as well as dichlorophenol, trichlorophenol and polychlorophenol. These byproducts are chemical substances that cause cancer, mutation and allergies, and are indicators of strict content control in Europe and the United States. With the improvement of international and domestic textile industry standards, the residual content of such polychlorobenzenes or polychlorophenols is required to be very low. Some commodity dyes even require the content of some of the above harmful substances to be less than 1ppm (one part per million).

[0007] However, from the above reaction principle, it can be seen that the subsequent diazotization reaction and azotization reaction will not introduce chlorine atoms into this molecule, so the main source of these harmful substances in commercial dyes is the corresponding dye intermediates. In the chlorination step of 6-chloro-2,4-dinitroaniline synthesis, not only a large amount of wastewater, waste salt, and dry waste gas dust are produced, but also the post-processing needs to be treated according to environmental protection indicators before it can meet the export or synthesis needs of certain high-end dyes.

[0008] Therefore, it is an urgent technical problem to study a continuous preparation method of 6-chloro-2,4-dinitroaniline and its diazonium salt which does not produce waste salt and / or wastewater, is environmentally friendly, has a high safety factor and low production cost, and an equipment for implementing the continuous preparation method. Summary of the invention

[0009] Problem that the invention aims to solve

[0010] In view of the technical problems existing in the prior art, for example, a large amount of salt-containing wastewater is generated during the production process of 6-chloro-2,4-dinitrophenyl aniline, the prepared 6-chloro-2,4-dinitrophenyl aniline needs to be dried before being put into the subsequent diazotization reaction, and the drying process inevitably generates a large amount of explosive dust and drying tail gas, which poses safety risks such as environmental pollution and dust explosion, and a chlorine chlorination method generates a large amount of by-products such as polychlorinated benzenes or polychlorinated phenols, resulting in unqualified environmental protection indicators of the product, requiring additional other treatment methods to treat impurities, and high production costs, etc., and the solid-liquid-gas three-phase reaction of the chlorination process is difficult to be prepared using a microchannel or tubular reactor, and the production process has high safety risks. The present invention first provides a safe continuous preparation method for 6-chloro-2,4-dinitroaniline.

[0011] The preparation method of 6-chloro-2,4-dinitroaniline of the present invention does not generate waste salt and / or waste water, and does not introduce a chlorinating agent during the nitration process, which is more environmentally friendly; it does not generate a large amount of explosive dust and dry tail gas, and does not have safety risks such as dust pollution and dust explosion. The preparation method of 6-chloro-2,4-dinitroaniline of the present invention can be carried out in a microchannel reactor, and has a high degree of intrinsic safety.

[0012] The present invention also provides a continuous preparation method of 6-chloro-2,4-dinitroaniline diazonium salt. The preparation method of 6-chloro-2,4-dinitroaniline diazonium salt can be carried out in a microchannel reactor and has a high intrinsic safety level.

[0013] The invention also provides equipment for implementing the continuous preparation method of 6-chloro-2,4-dinitroaniline and its diazonium salt.

[0014] Solutions for solving problems

[0015] The present invention provides a method for preparing 6-chloro-2,4-dinitroaniline, which comprises the following steps:

[0016] dissolving o-chloro-p-nitroaniline in a sulfuric acid solution to obtain a sulfuric acid solution of o-chloro-p-nitroaniline;

[0017] The sulfuric acid solution and nitric acid solution or mixed acid solution of o-chloro-p-nitroaniline are transported to the first microchannel reactor for nitration reaction to obtain a nitro product; wherein,

[0018] The mixed acid solution includes nitric acid and sulfuric acid.

[0019] According to the method for preparing 6-chloro-2,4-dinitroaniline of the present invention, the mass concentration of the sulfuric acid solution is 85-100%, and in the sulfuric acid solution of o-chloro-p-nitroaniline, the molar ratio of the o-chloro-p-nitroaniline to the sulfuric acid is 1:6-15;

[0020] The temperature for dissolving the o-chloro-p-nitroaniline is below 65°C.

[0021] According to the method for preparing 6-chloro-2,4-dinitroaniline of the present invention, the mass concentration of the nitric acid solution is 90-98%; in the mixed acid solution, the mass concentration of sulfuric acid is 0.1-90%; and the mass concentration of nitric acid is 5-98%;

[0022] The molar ratio of o-chloro-p-nitroaniline to nitric acid is 1:1.01-1.15, and the temperature of the nitration reaction is 5-35°C.

[0023] The present invention also provides a method for preparing 6-chloro-2,4-dinitroaniline diazonium salt, which comprises the following steps:

[0024] transporting a sulfuric acid solution of 6-chloro-2,4-dinitroaniline and nitrosyl sulfuric acid to a second microchannel reactor for diazotization reaction to obtain a diazonium salt;

[0025] Wherein, the 6-chloro-2,4-dinitroaniline is prepared by the preparation method according to any one of claims 1 to 3.

[0026] According to the method for preparing 6-chloro-2,4-dinitroaniline diazonium salt of the present invention, the mass concentration of nitrosyl sulfuric acid in the sulfuric acid solution of nitrosyl sulfuric acid is 25-43%;

[0027] The molar ratio of o-chloro-p-nitroaniline to nitrosyl sulfuric acid is 1:(1.0-1.10); and the temperature of the diazotization reaction is 30-60°C.

[0028] The present invention also provides an apparatus for implementing the method for preparing 6-chloro-2,4-dinitroaniline according to the present invention, comprising: an o-chloro-p-nitroaniline dissolving kettle, a first microchannel reactor and a mixed acid kettle; wherein:

[0029] The first microchannel reactor is connected to the o-chloro-p-nitroaniline dissolving kettle and the mixed acid kettle respectively.

[0030] According to the equipment of the present invention, the first microchannel reactor is also connected to a nitro compound transfer kettle, and the nitro compound transfer kettle is used to store the nitro compound.

[0031] The present invention also provides an apparatus for implementing the method for preparing 6-chloro-2,4-dinitroaniline diazonium salt, comprising the apparatus for implementing the method for preparing 6-chloro-2,4-dinitroaniline according to claim 6 or 7 and a second microchannel reactor; wherein the second microchannel reactor is connected to the nitro compound transfer kettle.

[0032] According to the device of the present invention, the device further comprises a heat exchanger connected to the second microchannel reactor for cooling the diazonium salt.

[0033] According to the equipment of the present invention, the heat exchanger is connected to a diazonium salt transfer kettle.

[0034] Effects of the Invention

[0035] The preparation method of 6-chloro-2,4-dinitroaniline of the present invention does not generate waste salt and / or waste water, and does not introduce a chlorinating agent during the nitration process, which is more environmentally friendly; it does not generate a large amount of explosive dust and dry tail gas, and does not have safety risks such as dust pollution and dust explosion. The preparation method of 6-chloro-2,4-dinitroaniline of the present invention can be carried out in a microchannel reactor, and has a high degree of intrinsic safety.

[0036] The continuous preparation method of 6-chloro-2,4-dinitroaniline diazonium salt of the present invention can be carried out in a microchannel reactor and has a high intrinsic safety level.

[0037] The equipment for implementing the continuous preparation method of 6-chloro-2,4-dinitroaniline and its diazonium salt is simple and can be used for the continuous preparation of 6-chloro-2,4-dinitroaniline and its diazonium salt. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The present invention shows a process flow chart of a continuous preparation method of 6-chloro-2,4-dinitroaniline and its diazonium salt according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] Various exemplary embodiments, features and aspects of the present invention will be described in detail below. The word "exemplary" used here means "used as an example, embodiment or illustrative". Any embodiment described here as "exemplary" is not necessarily interpreted as being superior or better than other embodiments.

[0040] In addition, in order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can be implemented without certain specific details. In other examples, methods, means, equipment and steps well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present invention.

[0041] Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0042] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0043] In this specification, the references to "some specific / preferred embodiments", "other specific / preferred embodiments", "embodiments", etc., mean that the specific elements (e.g., features, structures, properties and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein, and may or may not exist in other embodiments. In addition, it should be understood that the elements may be combined in various embodiments in any suitable manner.

[0044] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints numerical values ​​A and B.

[0045] <First aspect>

[0046] like Figure 1 As shown, the present invention first provides a method for preparing 6-chloro-2,4-dinitroaniline, which comprises the following steps:

[0047] dissolving o-chloro-p-nitroaniline in a sulfuric acid solution to obtain a sulfuric acid solution of o-chloro-p-nitroaniline;

[0048] The sulfuric acid solution and nitric acid solution or mixed acid solution of o-chloro-p-nitroaniline are transported to the first microchannel reactor for nitration reaction to obtain a nitro product; wherein,

[0049] The mixed acid solution includes nitric acid and sulfuric acid.

[0050] The preparation method of 6-chloro-2,4-dinitroaniline of the present invention does not generate waste salt and / or waste water, and does not introduce a chlorinating agent during the nitration process, which is more environmentally friendly; it does not generate a large amount of explosive dust and dry tail gas, and does not have safety risks such as dust pollution and dust explosion. The preparation method of 6-chloro-2,4-dinitroaniline of the present invention can be carried out in a microchannel reactor, and has a high degree of intrinsic safety.

[0051] o-chloro-p-nitroaniline is dissolved in a sulfuric acid solution to obtain a sulfuric acid solution of o-chloro-p-nitroaniline. o-chloro-p-nitroaniline is solid, and dissolving it in a sulfuric acid solution can facilitate microchannel feeding, and the nitration reaction of the present invention needs to be carried out in a sulfuric acid medium.

[0052] In some specific embodiments, the mass concentration of the sulfuric acid solution is 85-100%, for example: 88%, 90%, 92%, 94%, 96%, 98%, etc.

[0053] In the present invention, in the sulfuric acid solution of o-chloro-p-nitroaniline, the molar ratio of o-chloro-p-nitroaniline to sulfuric acid is 1:6-15, for example, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, etc. When the molar ratio of o-chloro-p-nitroaniline to sulfuric acid is 1:6-15, it is beneficial to the subsequent reaction.

[0054] In the present invention, the temperature at which o-chloro-p-nitroaniline is dissolved is not particularly limited and can be set as needed. Specifically, the temperature at which o-chloro-p-nitroaniline is dissolved is 5-65°C, for example, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, etc.

[0055] In some specific embodiments, the mass concentration of the nitric acid solution is 90-98%, for example: 92%, 94%, 96%, 98% and the like; in the mixed acid solution, the mass concentration of nitric acid is 5-98%, for example: 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and the like; the mass concentration of sulfuric acid is 0.1-90%, for example: 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% and the like.

[0056] Further, in the present invention, the molar ratio of o-chloro-p-nitroaniline to nitric acid is 1:1.01-1.15, for example: 1:1.02, 1:1.04, 1:1.06, 1:1.08, 1:1.1, 1:1.12, 1:1.14, etc.; when the molar ratio of o-chloro-p-nitroaniline to nitric acid is 1:1.01-1.15, the reaction can be carried out effectively.

[0057] Further, in the present invention, the temperature of the nitration reaction is 5-35°C, for example, 10°C, 15°C, 20°C, 25°C, 30°C, etc. When the temperature of the nitration reaction is 5-35°C, the desired 6-chloro-2,4-dinitroaniline can be prepared.

[0058] Furthermore, the reaction residence time in the first microchannel reactor is 1s to 120s, for example: 10s, 20s, 30s, 40s, 50s, 60s, 70s, 80s, 90s, 100s, 110s, etc.

[0059] The first aspect of the present invention also provides a method for preparing 6-chloro-2,4-dinitroaniline diazonium salt, which comprises the following steps:

[0060] The nitro compound and the sulfuric acid solution of nitrosyl sulfuric acid are transported to the second microchannel reactor for diazotization reaction to obtain a diazonium salt; wherein the nitro compound is prepared by the above-mentioned preparation method.

[0061] The continuous preparation method of 6-chloro-2,4-dinitroaniline diazonium salt of the present invention can also be carried out in a microchannel reactor, and has a high intrinsic safety level.

[0062] In some specific embodiments, it is characterized in that the mass concentration of nitrosyl sulfuric acid in the sulfuric acid solution of nitrosyl sulfuric acid is 25-43%, for example: 28%, 20%, 32%, 35%, 38%, 40%, 42%, etc. In the present invention, the amount of nitrosyl sulfuric acid added can be determined by the molar amount of o-chloro-p-nitroaniline. Specifically, the molar ratio of o-chloro-p-nitroaniline to nitrosyl sulfuric acid is 1:1.0-1.10, for example: 1:1.02, 1:1.04, 1:1.06, 1:1.08, etc.

[0063] In the present invention, the temperature of the diazotization reaction is 30-60° C., for example, 35° C., 40° C., 45° C., 50° C., 55° C., etc. When the temperature of the diazotization reaction is 30-60° C., the desired diazonium salt can be prepared.

[0064] Furthermore, the reaction residence time in the second microchannel reactor is 1s to 120s, for example: 10s, 20s, 30s, 40s, 50s, 60s, 70s, 80s, 90s, 100s, 110s, etc.

[0065] The preparation method of 6-chloro-2,4-dinitroaniline and its diazonium salt of the present invention does not produce polychlorinated benzene or environmentally prohibited impurities such as polychlorinated benzene, reduces a large amount of acid waste water and solid dry tail gas compared with the traditional process, further improves the safety of the reaction, and is a safe and environmentally friendly new process.

[0066] <Second Aspect>

[0067] The second aspect of the present invention provides an apparatus for implementing the method for preparing 6-chloro-2,4-dinitroaniline according to the first aspect of the present invention, comprising: an o-chloro-p-nitroaniline dissolving kettle, a first microchannel reactor, and a mixed acid kettle or a nitric acid kettle; wherein:

[0068] The first microchannel reactor is connected to the o-chloro-p-nitroaniline dissolving kettle and the mixed acid kettle or the nitric acid kettle respectively.

[0069] The equipment for implementing the continuous preparation method of 6-chloro-2,4-dinitroaniline and its diazonium salt is simple and can be used for the continuous preparation of 6-chloro-2,4-dinitroaniline and its diazonium salt.

[0070] In some specific embodiments, the first microchannel reactor is further connected to a nitro compound transfer kettle, which is used to store the nitro compound. In the present invention, the nitro compound transfer kettle is a stirring device with a jacket or coil heat exchange method; the temperature of the nitro compound transfer kettle can be controlled at 5-35°C.

[0071] The second aspect of the present invention also provides an apparatus for implementing the method for preparing 6-chloro-2,4-dinitroaniline diazonium salt, which comprises the apparatus for implementing the method for preparing 6-chloro-2,4-dinitroaniline according to the present invention and a second microchannel reactor; wherein the second microchannel reactor is connected to the nitro compound transfer kettle.

[0072] In some specific embodiments, the device further comprises a heat exchanger connected to the second microchannel reactor for cooling the diazonium salt.

[0073] Specifically, the heat exchanger is connected to a diazonium salt transfer kettle.

[0074] In the present invention, the material enters the heat exchanger for cooling after passing through the second microchannel reactor, and then is transported to the diazonium salt transfer kettle. The diazonium salt passing through the heat exchanger is quickly cooled, and the outlet material temperature of the diazonium salt is controlled at 15-30°C after passing through the heat exchanger and then is transported to the diazonium salt transfer kettle; the material temperature in the diazonium salt transfer kettle is also controlled at 15-30°C; the refrigerant medium of the heat exchanger is low-temperature cold water or low-temperature frozen brine or other low-temperature fluids, and the inlet temperature of the cooling medium is lower than 7°C.

[0075] The equipment for implementing the method for preparing 2,4-dinitroaniline of the present invention simplifies and reduces the size of the reaction device, making the production safer and the production cost lower.

[0076] Example

[0077] The embodiments of the present invention will be described in detail below in conjunction with the examples, but those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific conditions are specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0078] Example 1

[0079] At room temperature, 25 grams (0.1448 mol) of o-chloro-p-nitroaniline is dissolved in 200 grams of 91% sulfuric acid, and 25 grams of 98% sulfuric acid and 9.68 grams of 98% nitric acid are mixed to prepare a mixed acid solution, and then the o-chloro-p-nitroaniline and the mixed acid solution are simultaneously transported to a first microchannel reactor in a molar ratio of o-chloro-p-nitroaniline to nitric acid of 1:1.05 for nitration reaction, the reaction temperature is controlled to be about 12°C, the reaction residence time is 25 seconds, the material is discharged into a four-necked flask with stirring, the temperature is controlled to be about 12°C, and the nitro product is obtained for standby use. The purity of the nitro product can be obtained by high performance liquid chromatography detection of 98.47%, and the yield of the nitro product can be obtained by calculation of 99.4%.

[0080] At the same time, 46.7 grams of a 41% nitrosyl sulfuric acid solution was prepared, and then the solution in the above four-necked flask and the nitrosyl sulfuric acid solution were simultaneously transported to the second microchannel reactor for diazotization reaction, so that the molar ratio of o-chloro-p-nitroaniline to nitrosyl sulfuric acid was 1:1.10, the temperature in the second microchannel reactor was controlled at about 48° C., the residence time was 30 seconds, the discharge was cooled to about 18° C. through a condenser, and then entered into a four-necked flask with stirring, the temperature was controlled at about 18° C., and the diazonium salt yield was 98.14%.

[0081] Example 2

[0082] At room temperature, 250 grams of o-chloro-p-nitroaniline is added to 1750 grams of 93% sulfuric acid, stirred and dissolved, and set aside; at the same time, 98% concentrated nitric acid and 40% nitrosyl sulfuric acid are prepared for use; at the same time, the sulfuric acid solution of o-chloro-p-nitroaniline and 98% nitric acid are transported to the first microchannel reactor for nitration reaction, so that the molar ratio of o-chloro-p-nitroaniline and nitric acid is 1:1.08, the temperature of the first microchannel reactor is controlled at about 12°C, the residence time is 25 seconds, the material is discharged into a four-mouth flask with stirring, and the temperature of the nitration material is controlled at about 18°C ​​in a water bath to obtain a nitro compound for use. The purity of the nitro compound is 98.05% as detected by high performance liquid chromatography, and the yield of the nitro compound is 99.02% as calculated.

[0083] At the same time, the nitro compound and a solution of nitrosyl sulfuric acid with a mass concentration of 42% are transported to the second microchannel reactor for diazotization reaction, so that the molar ratio of o-chloro-p-nitroaniline and nitrosyl sulfuric acid is 1:1.10, the temperature of the second microchannel reactor is controlled at about 48°C, the residence time is 30 seconds, the temperature of the discharge material drops to about 18°C ​​after passing through the condenser, and then flows into the four-necked flask, and the temperature is controlled at about 18°C. The calculated diazonium salt yield is 97.85%.

[0084] Example 3

[0085] In a 500-liter enamel kettle, 400 kg of 91% sulfuric acid is added, stirring is started, 50 kg of o-chloro-p-nitroaniline is added, the temperature is controlled not to exceed 60°C, stirring for 1 hour to dissolve, and the mixture is set aside; 100 kg of 98% concentrated nitric acid is injected into the concentrated nitric acid metering tank, and the mixture is put into the mixed acid kettle for standby use; 100 kg of 40% nitrosyl sulfuric acid is injected into the nitrosyl sulfuric acid solution metering tank; two metering pumps are used to simultaneously transport the sulfuric acid solution and nitric acid solution of o-chloro-p-nitroaniline to the first microchannel reactor, so that the molar ratio of o-chloro-p-nitroaniline to nitric acid is 1:1.03, the temperature of the first microchannel reactor is controlled at about 12°C, the residence time is 30 seconds, and the nitro compound is discharged for standby use. The purity of the nitro compound is 97.21% as detected by high performance liquid chromatography, and the yield of the nitro compound is 98.65% as calculated.

[0086] The nitro compound solution is transported to a 500L nitro compound transfer kettle, and then two metering pumps are used to simultaneously transport the nitro compound and a nitrosyl sulfuric acid solution with a mass concentration of 40% in the nitro compound transfer kettle to the second microchannel reactor, and the molar ratio of o-chloro-p-nitroaniline to nitrosyl sulfuric acid is controlled to be 1:1.10; the temperature of the second microchannel reactor is controlled to be around 52°C, the residence time is 25 seconds, the discharge is cooled to around 25°C through a shell and tube heat exchanger, and then flows into the diazonium salt transfer kettle, and the temperature of the diazonium salt transfer kettle is controlled to be around 20°C. The calculated diazonium salt yield is 98.21%.

[0087] Example 4

[0088] In a 1000L enamel kettle, 1400 kg of 88% sulfuric acid is added, stirring is started, 200 kg of o-chloro-p-nitroaniline is added, the temperature is controlled not to exceed 60°C, stirring is performed for 1 hour to dissolve, and the mixture is set aside; in another 500L enamel kettle, 250 kg of 98% sulfuric acid is added, and then the jacket water is turned on and stirred, the temperature is controlled not to exceed 45°C, 79.7 kg of 98% nitric acid is added, and mixed to obtain a mixed acid solution for use. Then two metering pumps are used to simultaneously transport the above o-chloro-p-nitroaniline and the mixed acid solution to the first microchannel reactor for nitration reaction, the molar ratio of o-chloro-p-nitroaniline to nitric acid is controlled to be 1:1.08, the temperature of the first microchannel reactor is controlled to be about 18°C, the residence time is 35 seconds, and the nitro product is obtained by discharging for use; the purity of the nitro product can be obtained by high performance liquid chromatography detection to be 97.95%, and the yield of the nitro product can be obtained by calculation to be 98.75%.

[0089] The nitro substance solution was transported to a 500L nitro substance transfer kettle, and the temperature in the kettle was controlled at about 18°C; then the nitro substance and nitrosyl sulfuric acid with a mass concentration of 40% in the nitro substance transfer kettle were simultaneously transported to the second microchannel reactor for diazotization using two metering pumps, the molar ratio of o-chloro-p-nitroaniline to nitrosyl sulfuric acid was controlled to be 1:1.06, the temperature of the second microchannel reactor was controlled to be about 48°C, the residence time was 30 seconds, the discharge from the second microchannel reactor was cooled to about 22°C through a condenser, and then entered the diazonium salt transfer kettle, and the temperature of the diazonium salt transfer kettle was controlled to be about 18°C; the diazonium salt yield was calculated to be 98.17%.

[0090] It should be noted that, although the technical solution of the present invention is introduced with specific examples, those skilled in the art will appreciate that the present invention should not be limited thereto.

[0091] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing 6-chloro-2,4-dinitroaniline, characterized in that: The following steps are involved: dissolving o-chloro-p-nitroaniline in a sulfuric acid solution to obtain a sulfuric acid solution of o-chloro-p-nitroaniline; The sulfuric acid solution and nitric acid solution or mixed acid solution of o-chloro-p-nitroaniline are transported to the first microchannel reactor for nitration reaction to obtain a nitro product; wherein, The mixed acid solution includes nitric acid and sulfuric acid.

2. The method for preparing 6-chloro-2,4-dinitroaniline according to claim 1, characterized in that: The mass concentration of the sulfuric acid solution is 85-100%, and in the sulfuric acid solution of o-chloro-p-nitroaniline, the molar ratio of the o-chloro-p-nitroaniline to the sulfuric acid is 1:6-15; The temperature for dissolving the o-chloro-p-nitroaniline is below 65°C.

3. The method for preparing 6-chloro-2,4-dinitroaniline according to claim 1 or 2, characterized in that: The mass concentration of the nitric acid solution is 90-98%; in the mixed acid solution, the mass concentration of sulfuric acid is 0.1-90%; and the mass concentration of nitric acid is 5-98%; The molar ratio of o-chloro-p-nitroaniline to nitric acid is 1:1.01-1.15, and the temperature of the nitration reaction is 5-35°C.

4. A method for preparing 6-chloro-2,4-dinitroaniline diazonium salt, characterized in that: The following steps are involved: transporting a sulfuric acid solution of 6-chloro-2,4-dinitroaniline and nitrosyl sulfuric acid to a second microchannel reactor for diazotization reaction to obtain a diazonium salt; Wherein, the 6-chloro-2,4-dinitroaniline is prepared by the preparation method according to any one of claims 1 to 3.

5. The method for preparing 6-chloro-2,4-dinitroaniline diazonium salt according to claim 4, characterized in that: The mass concentration of nitrosyl sulfuric acid in the sulfuric acid solution of nitrosyl sulfuric acid is 25-43%; The molar ratio of o-chloro-p-nitroaniline to the nitrosyl sulfuric acid is 1:(1.0-1.10); and the temperature of the diazotization reaction is 30-60°C.

6. An apparatus for implementing the method for preparing 6-chloro-2,4-dinitroaniline according to any one of claims 1 to 3, characterized in that: include: o-chloro-p-nitroaniline dissolving kettle, first microchannel reactor and mixed acid kettle; wherein, The first microchannel reactor is connected to the o-chloro-p-nitroaniline dissolving kettle and the mixed acid kettle respectively.

7. The device according to claim 6, characterized in that The first microchannel reactor is also connected to a nitro compound transfer kettle, and the nitro compound transfer kettle is used to store the nitro compound.

8. An apparatus for implementing a method for preparing 6-chloro-2,4-dinitroaniline diazonium salt, characterized in that: It comprises the equipment for implementing the method for preparing 6-chloro-2,4-dinitroaniline according to claim 6 or 7 and a second microchannel reactor; wherein the second microchannel reactor is connected to the nitro product transfer kettle.

9. The device according to claim 8, characterized in that The device also includes a heat exchanger connected to the second microchannel reactor, which is used to cool the diazonium salt.

10. The device according to claim 9, characterized in that The heat exchanger is connected with a diazonium salt transfer kettle.

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