A pipe reactor, and an apparatus and method for preparing 3,5-dichloronitrobenzene

Abstract

The application belongs to the technical field of fine chemical industry, and particularly relates to a pipeline reactor and a device and method for preparing 3,5-dichloronitrobenzene. The pipeline reactor comprises a reactor main body which is a pipeline structure arranged in a vertical direction; a feed inlet and an exhaust outlet are arranged at the upper part of the reactor main body, and a liquid return inlet and a liquid discharge outlet are arranged at the lower part of the reactor main body; reactant materials enter the reactor main body from the upper part of the reactor main body through the feed inlet; the gas generated in the reaction process is discharged through the exhaust outlet, and then is subjected to cooling and gas-liquid separation treatment; the liquid obtained through the gas-liquid separation treatment is injected into the reactor main body again through the liquid return inlet; and the reaction completion liquid after the reaction is completed is discharged from the reactor main body through the liquid discharge outlet. The pipeline reactor and the device and method for preparing 3,5-dichloronitrobenzene have the advantages of high production efficiency, good safety, and continuous production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fine chemical industry, and particularly relates to a pipeline reactor and a device and method for preparing 3,5-dichloronitrobenzene. BACKGROUND

[0002] 3,5-dichloronitrobenzene, molecular formula: C6H3Cl2NO2, CAS number: 618-62-2, appearance: orange to brown crystal, melting point: 64-65℃, boiling point: 247.4℃, is an important pesticide and pharmaceutical intermediate. In the field of fine chemical industry, 3,5-dichloronitrobenzene is often used to prepare 3,5-dichloroaniline, which can be used as a raw material for agricultural insecticides, and from which dimethachlone, dimethachlon, iprodione and mycostop can be prepared, which are effective for sclerotinia, sheath blight and botrytis cinerea. At the same time, 3,5-dichloroaniline can also be used to synthesize herbicides, plant growth regulators and the like. In addition, in the pharmaceutical industry, 3,5-dichloroaniline is often used to manufacture quinoline derivatives for treating malaria. In the dye industry, 3,5-dichloroaniline can be used to manufacture azo dyes and pigments. Among the many methods for synthesizing 3,5-dichloroaniline, the catalytic hydrogenation reduction method is the most widely used method for synthesizing 3,5-dichloroaniline at present, which uses 3,5-dichloronitrobenzene as raw material, and reduces 3,5-dichloronitrobenzene to 3,5-dichloroaniline by hydrogenation. Therefore, the demand for 3,5-dichloronitrobenzene in China is very large.

[0003] At present, the synthesis of 3,5-dichloronitrobenzene is mostly carried out in a tank reactor. On the one hand, the process of preparing 3,5-dichloronitrobenzene in a tank reactor is discontinuous, in order to improve the preparation efficiency, the volume of the tank reactor used at present is very large, such as the most commonly used tank reactor with a volume of 16000L, which results in a large liquid holdup of the tank reactor and difficulty in controlling the temperature. On the other hand, a large amount of gas is generated in the synthesis process of 3,5-dichloronitrobenzene, therefore, the risk of using a tank reactor to prepare 3,5-dichloronitrobenzene is very high, especially for a large-capacity tank reactor, and accidents have occurred in similar reactions at home and abroad.

[0004] Therefore, it is one of the technical problems to be solved by those skilled in the art to develop a preparation device and method for 3,5-dichloronitrobenzene which has high production efficiency, good safety and can be produced continuously. SUMMARY

[0005] The present application aims to solve the above technical problems, and provides a pipeline reactor and a device and method for preparing 3,5-dichloronitrobenzene which have high production efficiency, good safety and can be produced continuously.

[0006] In view of the above, the present application provides a pipeline reactor, which comprises:

[0007] a reactor body in a pipeline structure arranged along a vertical direction;

[0008] a feed inlet and an exhaust outlet are arranged at the upper part of the reactor body, and a liquid return inlet and a liquid discharge outlet are arranged at the lower part of the reactor body; the reactant material enters the reactor body from the upper part of the reactor body through the feed inlet; the gas generated in the reaction process is discharged through the exhaust outlet, and then is subjected to cooling and gas-liquid separation treatment; the liquid obtained through the gas-liquid separation treatment is injected into the reactor body again through the liquid return inlet; and the reaction completion liquid after the reaction is completed is discharged from the reactor body through the liquid discharge outlet.

[0009] Further, the reactor body is in a double-layer pipeline structure arranged along a vertical direction, and comprises:

[0010] an outer tube and an inner tube arranged in the outer tube, both of which are in a pipeline structure arranged along a vertical direction, and the outer tube and the inner tube are coaxially arranged, a reaction cavity is formed in the inner tube, and a heat exchange medium containing cavity is formed between the outer tube and the inner tube.

[0011] Further, a heat exchange medium inlet is arranged at the upper end of the reactor body, and a heat exchange medium outlet is arranged at the lower end of the reactor body; the heat exchange medium inlet and the heat exchange medium outlet are respectively communicated with the heat exchange medium containing cavity; and the heat exchange medium flows through the heat exchange medium containing cavity from top to bottom, so as to regulate the temperature of the reactant material in the reaction cavity.

[0012] Further, a cooling and heating all-in-one machine is arranged outside the pipeline reactor; the inlet of the cooling and heating all-in-one machine is connected with the heat exchange medium outlet; the outlet of the cooling and heating all-in-one machine is connected with the heat exchange medium inlet; the heat exchange medium in the heat exchange medium containing cavity can be discharged into the cooling and heating all-in-one machine through the heat exchange medium outlet, and then re-enters the heat exchange medium containing cavity after heat exchange.

[0013] Further, the height of the exhaust outlet on the reactor body is 85% to 92% of the total height of the reactor body; and in the working process, the liquid level height of the reactant material in the reactor body is controlled to be lower than the height of the exhaust outlet.

[0014] A device for preparing 3,5-dichloronitrobenzene, comprising:

[0015] a reaction liquid A conveying unit, a sodium nitrite solution conveying unit, a reaction unit, a heat exchange unit, and a gas treatment unit; the reaction unit comprises the above-mentioned pipeline reactor, wherein:

[0016] The reaction liquid A conveying unit is connected with the feeding port on the pipeline reactor, and is used for injecting the reaction liquid A into the reaction cavity;

[0017] The sodium nitrite solution conveying unit is connected with the feeding port on the pipeline reactor, and is used for injecting the sodium nitrite solution into the reaction cavity;

[0018] The heat exchange unit is connected with the heat exchange medium inlet and outlet on the pipeline reactor, and is used for circulating and injecting the heat exchange medium into the heat exchange medium containing cavity;

[0019] The gas treatment unit is connected with the exhaust port on the pipeline reactor, and is used for treating the gas discharged from the pipeline reactor.

[0020] A method for preparing 3,5-dichloronitrobenzene, which uses the above device to prepare 3,5-dichloronitrobenzene, and comprises the following steps:

[0021] S1, configuring the reaction liquid A and the sodium nitrite solution;

[0022] S2, closing the liquid outlet of the reactor main body, injecting isopropyl alcohol accounting for 80% to 94% of the total volume of the reaction cavity, heating the isopropyl alcohol to 75 to 85℃, then opening the liquid outlet of the reactor main body, and continuously injecting the reaction liquid A and the sodium nitrite solution into the pipeline reactor respectively;

[0023] S3, controlling the temperature in the reaction cavity in the pipeline reactor to be 70 to 85℃ by the heat exchange unit, and keeping the exhaust port of the pipeline reactor open during the reaction, so that the gas in the reaction cavity can be discharged to the heat exchanger in time through the exhaust port;

[0024] S4, controlling the residence time of the material in the reaction cavity in the pipeline reactor to be 25 to 35 min, and then discharging through the liquid outlet in the pipeline reactor to obtain the reaction completion liquid.

[0025] Further, the reaction liquid A is a mixture of 2,6-dichloro-4-nitroaniline, isopropyl alcohol, sulfuric acid, water and copper sulfate, and the content of each component in the reaction liquid A is 12 to 17 parts of 2,6-dichloro-4-nitroaniline, 45 to 50 parts of isopropyl alcohol, 8 to 13 parts of sulfuric acid, 10 to 14 parts of water and 0.05 to 0.2 parts of copper sulfate by weight; the sodium nitrite solution is an aqueous solution of sodium nitrite, and the concentration of the sodium nitrite solution is 25 to 37 g / L.

[0026] Further, in the step S2, the flow ratio of the reaction liquid A and the sodium nitrite solution is controlled to be (3 to 5) : 1.

[0027] Further, the holdup volume of the pipeline reactor is 300-480L, the flow rate of the reaction liquid A is 490-780L / h, and the flow rate of the sodium nitrite solution is 110-170L / h.

[0028] In the present application, by using the pipeline reactor, the volume of the reaction equipment is reduced (by about 40 times), and the holdup volume is reduced. Meanwhile, by regulating the heat exchange medium, the temperature control of the pipeline reactor is accurate. In addition, by multi-point exhaust at the upper part of the pipeline reactor, the gas in the pipeline reactor can be quickly discharged, and the operation safety of the reaction equipment is greatly improved. Furthermore, in the process of preparing 3,5-dichloronitrobenzene, by feeding two parts of materials, i.e., the reaction liquid A and the sodium nitrite solution, and combining with the pipeline reactor, the continuous production of 3,5-dichloronitrobenzene is realized. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is the device and flow diagram for preparing 3,5-dichloronitrobenzene according to the present application.

[0030] The marks in the figure represent:

[0031] 101, reaction liquid A delivery pump; 102, reaction liquid A filter; 103, reaction liquid A flow meter; 201, sodium nitrite solution delivery pump; 202, sodium nitrite solution filter; 203, sodium nitrite solution flow meter; 3, pipeline reactor; 301, reactor main body; 302, gas discharge pipe; 303, liquid return pipe; 304, liquid discharge pipe; 305, heat exchange medium input pipe; 306, heat exchange medium output pipe; 307, inner pipe; 308, outer pipe; 4, heat exchanger; 5, gas-liquid separation tank. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be clearly described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present application.

[0033] In the description of the present application, it should be noted that the terms used herein are merely for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. For the purpose of description, the dimensions of the various parts shown in the drawings are not drawn to scale. The techniques, methods, and devices known to those of ordinary skill in the relevant art can not be discussed in detail, but should be considered part of the specification when appropriate. In all examples shown and discussed herein, any specific value should be interpreted as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments can have different values. It should be noted that like reference numerals and letters refer to like items in the following drawings, and thus, once an item is defined in one drawing, it need not be discussed further in subsequent drawings.

[0034] It should be noted that the terms "first", "second", and the like in the description and claims of the present application are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the use of such terms is not made with the intention of limiting the scope of the embodiments of the present application to the particular embodiments that are described in the examples, and that "first", "second", and the like can be interchanged under appropriate circumstances such that the embodiments of the present application are, therefore, capable of use in other sequences than the one that is described in the examples. Furthermore, the terms "comprise", "comprising", "include", "including", and the like are used herein to indicate the presence of stated features, integers, steps, or components but not to the exclusion of the presence or addition of one or more other features, integers, steps, components, or groups thereof. In addition, the terms "and / or" and "one or more" are used in the present application to mean either "and" or "or", but not necessarily both, unless explicitly stated otherwise.

[0035] It should be noted that in the description of the present application, the orientation or positional relationships indicated by the terms such as "front", "back", "upper", "lower", "left", "right", "horizontal", "vertical", "top", and "bottom" are generally based on the orientation or positional relationships shown in the drawings, and are merely for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore should not be construed as limiting the scope of protection of the present application. The terms "inner" and "outer" refer to the inner and outer relative to the outline of the parts themselves.

[0036] It should be noted that in this application, the terms "comprising", "including", or any other variant thereof are intended to cover a non-exclusive inclusion, so that a process, method, article, or apparatus that includes a series of elements not only includes those elements, but also includes other elements not explicitly listed, or inherent to such process, method, article, or apparatus. Without more limitations, the element defined by the statement "including a" does not exclude the presence of additional identical elements in the process, method, article, or apparatus including the element. In addition, it should be pointed out that the scope of the methods and apparatus in the embodiments of the present application is not limited to performing functions in the order shown or discussed, but can also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method can be performed in an order different from that described, and various steps can also be added, omitted, or combined. In addition, the features described with reference to certain examples can be combined in other examples.

[0037] As shown in Figure 1 A pipe reactor, the pipe reactor 3 includes:

[0038] A reactor body 301, which is a pipe structure arranged in a vertical direction;

[0039] A feed inlet and an exhaust outlet are arranged at the upper part of the reactor body 301, and a liquid return inlet and a liquid outlet are arranged at the lower part; the reactant material enters the reactor body 301 from the upper part of the reactor body 301 through the feed inlet; the gas generated during the reaction is discharged through the exhaust outlet, and then subjected to cooling and gas-liquid separation treatment, and the liquid obtained by the gas-liquid separation treatment is injected into the reactor body 301 again through the liquid return inlet; the reaction completion liquid after the reaction is completed is discharged from the reactor body 301 through the liquid outlet.

[0040] Further, the reactor body 301 is a double-layer pipe structure arranged in a vertical direction, which includes:

[0041] An outer pipe 308 and an inner pipe 307 arranged therein, both of which are pipe structures arranged in a vertical direction, and the outer pipe 308 and the inner pipe 307 are coaxially arranged, forming a reaction cavity in the inner pipe 307 and a heat exchange medium containing cavity between the outer pipe 308 and the inner pipe 307.

[0042] Further, a heat exchange medium inlet is arranged at the upper end of the reactor body 301, and a heat exchange medium outlet is arranged at the lower end, the heat exchange medium inlet and the heat exchange medium outlet are respectively communicated with the heat exchange medium containing cavity, and the heat exchange medium flows through the heat exchange medium containing cavity from top to bottom to regulate the temperature of the reactant material in the reaction cavity.

[0043] As some embodiments of the present application, a cold and heat all-in-one machine is arranged outside the pipe reactor 3, the inlet of the cold and heat all-in-one machine is connected with the heat exchange medium outlet, the outlet of the cold and heat all-in-one machine is connected with the heat exchange medium inlet, the heat exchange medium after heat exchange of the reactant in the reaction cavity can be discharged to the cold and heat all-in-one machine through the heat exchange medium outlet, and then enters the heat exchange medium containing cavity again after temperature regulation and control by the cold and heat all-in-one machine.

[0044] Further, the heat exchange medium is heat conducting oil, and the temperature of the heat conducting oil is controlled by the cold and heat all-in-one machine.

[0045] As some embodiments of the present application, the number of the feeding port and the exhaust port on the reactor body 301 can be one or multiple.

[0046] Preferably, the number of the feeding port on the reactor body 301 is at least two.

[0047] Preferably, the number of the exhaust port on the reactor body 301 is 2-6, and more preferably, the number of the exhaust port on the reactor body 301 is 4, and each exhaust port is arranged uniformly and spaced along the circumference of the reactor body 301.

[0048] Preferably, in working, the liquid level height of the reactant in the reactor body 301 should be controlled, and it is appropriate that the liquid level height of the reactant is not higher than, preferably lower than the height of the exhaust port.

[0049] More preferably, the height of the exhaust port is 85%-92% of the total height of the reactor body 301, so that in the process of preparing 3,5-dichloronitrobenzene, the upper 8%-15% of the volume in the reactor body 301 is in gas phase, and the lower 85%-92% of the volume is in liquid phase.

[0050] It should be noted that in addition to the process of preparing 3,5-dichloronitrobenzene described in the present application, the pipe reactor 3 can also be used in other reaction processes with a large amount of gas generated.

[0051] In addition, the present application also provides a device for preparing 3,5-dichloronitrobenzene, which comprises:

[0052] a reaction liquid A conveying unit, a sodium nitrite solution conveying unit, a reaction unit, a heat exchange unit, and a gas treatment unit, the reaction unit comprises the above-mentioned pipe reactor 3, wherein:

[0053] the reaction liquid A conveying unit is connected with the feeding port on the pipe reactor 3, and is used for injecting the reaction liquid A into the reaction cavity;

[0054] The sodium nitrite solution delivery unit is connected with the feeding port on the pipeline reactor 3, and is used for injecting the sodium nitrite solution into the reaction cavity;

[0055] The heat exchange unit is connected with the heat exchange medium inlet and the heat exchange medium outlet on the pipeline reactor 3, and is used for circulating injection of the heat exchange medium into the heat exchange medium containing cavity.

[0056] The gas treatment unit is connected with the exhaust port on the pipeline reactor 3, and is used for treating the gas discharged from the pipeline reactor 3.

[0057] Further, the reaction liquid A is a mixture of 2, 6-dichloro-4-nitroaniline, isopropyl alcohol, sulfuric acid, water and copper sulfate.

[0058] Further, the sodium nitrite solution is an aqueous solution of sodium nitrite.

[0059] Specifically, the reaction liquid A delivery unit comprises:

[0060] A reaction liquid A supply device capable of outputting reaction liquid A;

[0061] A reaction liquid A delivery pump 101 connected with the reaction liquid A supply device, and used for pumping out the reaction liquid A in the reaction liquid A supply device;

[0062] A reaction liquid A filter 102 located at the rear end of the reaction liquid A delivery pump 101, and used for filtering the reaction liquid A pumped out by the reaction liquid A delivery pump 101;

[0063] A reaction liquid A flow meter located at the rear end of the reaction liquid A filter 102, and used for metering the reaction liquid A injected into the pipeline reactor 3;

[0064] The reaction liquid A in the reaction liquid A supply device is pumped out by the reaction liquid A delivery pump 101, filtered by the reaction liquid A filter 102, and then injected into the reaction cavity through the metering of the reaction liquid A flow meter.

[0065] Specifically, the sodium nitrite solution delivery unit comprises:

[0066] A sodium nitrite solution supply device capable of outputting sodium nitrite solution;

[0067] A sodium nitrite solution delivery pump 201 connected with the sodium nitrite solution supply device, and used for pumping out the sodium nitrite solution in the sodium nitrite solution supply device;

[0068] A sodium nitrite solution filter 202 located at the rear end of the sodium nitrite solution delivery pump 201, and used for filtering the sodium nitrite solution pumped out by the sodium nitrite solution delivery pump 201;

[0069] a sodium nitrite solution flow meter 203, which is located at the rear end of the sodium nitrite solution filter 202, for metering the sodium nitrite solution injected into the pipeline reactor 3;

[0070] The sodium nitrite solution in the sodium nitrite solution supply device is pumped out by the sodium nitrite solution delivery pump 201, filtered by the sodium nitrite solution filter 202, and injected into the reaction cavity through the metering of the sodium nitrite solution flow meter 203.

[0071] Preferably, the reaction liquid A delivery pump 101 and the sodium nitrite solution delivery pump 201 are three-pump-head hydraulic diaphragm pumps, and the pump head material is HC-276.

[0072] Further, the gas treatment unit comprises:

[0073] a heat exchanger 4 connected to the exhaust port of the pipeline reactor 3, wherein the high-temperature gas discharged from the exhaust port of the pipeline reactor 3 is cooled in the heat exchanger 4, and the high-temperature gas exchanges heat with the low-temperature medium in the heat exchanger 4 as a high-temperature medium, so that the temperature of the gas discharged from the pipeline reactor 3 is reduced and condensed, and liquid is separated out;

[0074] a gas-liquid separation tank 5, wherein the high-temperature gas cooled by the heat exchanger 4 is introduced into the gas-liquid separation tank 5 for gas-liquid separation.

[0075] Further, the upper end of the gas-liquid separation tank 5 is provided with a tail gas discharge port, and the lower end is provided with a condensed liquid discharge port, wherein the gas separated by the gas-liquid separation tank 5 is discharged through the tail gas discharge port, and the liquid separated by the gas-liquid separation tank 5 is discharged through the condensed liquid discharge port.

[0076] Preferably, the condensed liquid discharge port is connected to the liquid return port in the pipeline reactor 3 through a liquid return pipe 303, and the liquid discharged from the condensed liquid discharge port is returned to the reaction cavity of the pipeline reactor 3.

[0077] As some embodiments of the present application, the main component of the tail gas discharged from the tail gas discharge port of the gas-liquid separation tank 5 is hydrogen, and the tail gas discharge port can be connected to a discharge main pipe, and the generated tail gas can be discharged into the discharge main pipe, and then transported to a waste gas treatment device together with other waste gas for treatment and emptying. Alternatively, the tail gas can be treated or discharged separately.

[0078] Further, the reaction unit further comprises:

[0079] a gas discharge pipe 302, which is provided and connected to the exhaust port in the pipeline reactor 3 one by one.

[0080] Preferably, the gas discharge pipe 302 is arranged around the pipe reactor 3 in a vertical manner, one end of the gas discharge pipe 302 is connected with the exhaust port in the pipe reactor 3, and the other end is connected with the high-temperature medium inlet of the gas-liquid separation tank 5.

[0081] Further, the reaction unit further comprises:

[0082] a liquid discharge pipe 304 connected with the liquid discharge port in the pipe reactor 3, for discharging the reaction completion liquid after the reaction is completed;

[0083] a heat exchange medium input pipe 305 connected with the heat exchange medium inlet in the pipe reactor 3, for injecting the heat exchange medium into the heat exchange medium containing cavity;

[0084] a heat exchange medium output pipe 306 connected with the heat exchange medium outlet in the pipe reactor 3, for discharging the heat exchange medium after being exchanged with the reaction material in the heat exchange medium containing cavity.

[0085] In addition, the application also provides a method for preparing 3,5-dichloronitrobenzene, which is prepared by using the device for preparing 3,5-dichloronitrobenzene described above, and the method comprises the following steps:

[0086] S1, configuring the reaction liquid A and the sodium nitrite solution;

[0087] S2, closing the liquid discharge port of the reactor body, injecting isopropyl alcohol accounting for 80% to 94% of the total volume of the reaction cavity, heating the isopropyl alcohol to 75 to 85°C, then opening the liquid discharge port of the reactor body, and continuously injecting the reaction liquid A and the sodium nitrite solution into the pipe reactor at the same time;

[0088] S3, controlling the temperature in the reaction cavity in the pipe reactor 3 to be 70 to 85°C by the heat exchange unit, and keeping the exhaust port in the pipe reactor 3 open during the reaction, so that the gas in the reaction cavity can be discharged to the heat exchanger 4 in time through the exhaust port;

[0089] S4, controlling the residence time of the material in the reaction cavity in the pipe reactor 3 to be 25 to 35 min, and then discharging through the liquid discharge port in the pipe reactor 3 to obtain the reaction completion liquid.

[0090] As some embodiments of the application, after obtaining the reaction completion liquid, the 3,5-dichloronitrobenzene product can be obtained by distillation treatment.

[0091] Preferably, in the step S3, the gas in the reaction cavity can be discharged to the heat exchanger 4, cooled to below 20°C through the heat exchanger 4, and then injected into the gas-liquid separation tank 5 for gas-liquid separation treatment.

[0092] Preferably, the liquid holdup of the pipeline reactor 3 is 300-480 L, and the operating pressure is normal pressure.

[0093] More preferably, when the liquid holdup of the pipeline reactor 3 is 300-480 L, in the step S2, the flow rate of the reaction liquid A outputted by the reaction liquid A delivery unit is controlled to be 490-780 L / h, and the flow rate of the sodium nitrite solution outputted by the sodium nitrite solution delivery unit is controlled to be 110-170 L / h.

[0094] Further, in the step S2, the flow rate ratio of the reaction liquid A to the sodium nitrite solution is controlled to be (3-5) : 1.

[0095] Preferably, when the liquid holdup of the pipeline reactor 3 is 300-480 L, in the step S3, the heat exchange area of the heat exchanger 4 is 1-1.5 m 2 , and the operating pressure is normal pressure.

[0096] Preferably, when the liquid holdup of the pipeline reactor 3 is 300-480 L, in the step S3, the volume of the gas-liquid separation tank 5 is 120-180 L, and the operating pressure is normal pressure.

[0097] Preferably, in the reaction liquid A, the content of each component is respectively 2,6-dichloro-4-nitroaniline 12-17 parts by weight, isopropyl alcohol 45-50 parts by weight, sulfuric acid 8-13 parts by weight, water 10-14 parts by weight, and copper sulfate 0.05-0.2 parts by weight. Among them, the sulfuric acid is an aqueous solution of sulfuric acid with a concentration greater than or equal to 70%.

[0098] Preferably, the concentration of the sodium nitrite solution is 25-37 g / L.

[0099] The device and method for preparing 3,5-dichloronitrobenzene according to the present application are illustrated by specific examples as follows:

[0100] Example 1

[0101] A 400 L pipeline reactor is used to prepare 3,5-dichloronitrobenzene:

[0102] S1, configure the reaction liquid A and the sodium nitrite solution, wherein the weight parts of each component in the reaction liquid A are respectively 2,6-dichloro-4-nitroaniline 12 parts, isopropyl alcohol 45 parts, sulfuric acid 8 parts, water 10 parts, and copper sulfate 0.05 parts; the concentration of the sodium nitrite solution is 25 g / L;

[0103] S2, close the liquid outlet of the reactor body, inject isopropyl alcohol into the reaction cavity, which accounts for 80% of the total volume of the reaction cavity, heat the isopropyl alcohol to 75℃, then open the liquid outlet of the reactor body, and continuously inject the reaction liquid A and the sodium nitrite solution into the pipeline reactor at the same time; wherein the flow rate of the reaction liquid A is 500 L / h, and the flow rate of the sodium nitrite solution is 110 L / h;

[0104] S3, control the temperature in the reaction cavity of the pipeline reactor to be 70℃ through the heat exchange unit, and keep the exhaust port of the pipeline reactor open at all times during the reaction, so that the gas in the reaction cavity can be discharged to the heat exchanger through the exhaust port in time.

[0105] S4, control the residence time of the material in the reaction cavity of the pipeline reactor to be 35 min, then discharge through the liquid outlet of the pipeline reactor, and obtain the reaction completion liquid.

[0106] The reaction completion liquid is detected to obtain that the effective conversion rate of 3,5-dichloronitrobenzene is 95.42%.

[0107] Example 2

[0108] A 400L pipeline reactor is used to prepare 3,5-dichloronitrobenzene:

[0109] S1, configure the reaction liquid A and the sodium nitrite solution, wherein the weight parts of each component in the reaction liquid A are as follows: 2,6-dichloro-4-nitroaniline 14.85 parts, isopropyl alcohol 47.54 parts, sulfuric acid 10.84 parts, water 11.88 parts, and copper sulfate 0.1 part; the concentration of the sodium nitrite solution is 33.3g / L;

[0110] S2, close the liquid outlet of the reactor body, inject isopropyl alcohol into the reaction cavity, which accounts for 80% of the total volume of the reaction cavity, heat the isopropyl alcohol to 75℃, then open the liquid outlet of the reactor body, and continuously inject the reaction liquid A and the sodium nitrite solution into the pipeline reactor at the same time; wherein the flow rate of the reaction liquid A is 500 L / h, and the flow rate of the sodium nitrite solution is 110 L / h;

[0111] S3, control the temperature in the reaction cavity of the pipeline reactor to be 70℃ through the heat exchange unit, and keep the exhaust port of the pipeline reactor open at all times during the reaction, so that the gas in the reaction cavity can be discharged to the heat exchanger through the exhaust port in time.

[0112] S4, control the residence time of the material in the reaction cavity of the pipeline reactor to be 35 min, then discharge through the liquid outlet of the pipeline reactor, and obtain the reaction completion liquid.

[0113] The reaction completion liquid is detected to obtain that the effective conversion rate of 3,5-dichloronitrobenzene is 95.77%.

[0114] Example 3

[0115] The 3,5-dichloronitrobenzene is prepared by using a pipeline reactor with a capacity of 400L.

[0116] S1, a reaction liquid A and a sodium nitrite solution are configured, wherein the weight parts of each component in the reaction liquid A are respectively 17 parts of 2,6-dichloro-4-nitroaniline, 50 parts of isopropyl alcohol, 13 parts of sulfuric acid, 14 parts of water and 0.2 parts of copper sulfate; the concentration of the sodium nitrite solution is 37g / L;

[0117] S2, the liquid outlet of the reactor body is closed, and isopropyl alcohol accounting for 94% of the total volume of the reaction cavity is injected into the reaction cavity, and then the isopropyl alcohol is heated to 85°C, and then the liquid outlet of the reactor body is opened, and the reaction liquid A and the sodium nitrite solution are continuously injected into the pipeline reactor at the same time; wherein the flow rate of the reaction liquid A is 510L / h, and the flow rate of the sodium nitrite solution is 170L / h;

[0118] S3, the temperature in the reaction cavity of the pipeline reactor is controlled to be 85°C by a heat exchange unit, and at the same time, the exhaust port of the pipeline reactor is kept open during the reaction, so that the gas in the reaction cavity can be discharged to the heat exchanger in time through the exhaust port.

[0119] S4, the residence time of the material in the reaction cavity of the pipeline reactor is controlled to be 35min, and then the reaction completion liquid is discharged through the liquid outlet of the pipeline reactor.

[0120] The reaction completion liquid is detected to obtain that the effective conversion rate of 3,5-dichloronitrobenzene is 96.31%.

[0121] In the present application, by using the pipeline reactor, the volume of the reaction equipment is reduced (reduced by about 40 times), the liquid holding capacity is reduced, and at the same time, the temperature control of the pipeline reactor is accurate by adjusting the heat exchange medium, in addition, the gas in the pipeline reactor can be quickly discharged through the multi-point exhaust at the upper part of the pipeline reactor, and the operation safety of the reaction equipment is greatly improved. Furthermore, in the process of preparing 3,5-dichloronitrobenzene, two parts of material feeding, i.e. the reaction liquid A and the sodium nitrite solution, are combined with the pipeline reactor to realize the continuous production of 3,5-dichloronitrobenzene.

[0122] The embodiments of the present application are described above with reference to the drawings, and the embodiments and features in the embodiments of the present application can be combined with each other without conflict, and the present application is not limited to the above-described specific embodiments, and the above-described specific embodiments are only illustrative but not restrictive, and a person of ordinary skill in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, and all belong to the protection of the present application.

Claims

1. A process for the preparation of 3,5-dichloronitrobenzene, characterized in that, The method adopts a device for preparing 3,5-dichloronitrobenzene, and the device comprises: a reaction liquid A conveying unit, a sodium nitrite solution conveying unit, a reaction unit, a heat exchange unit, and a gas treatment unit, wherein the reaction unit comprises a pipeline reactor (3), and wherein: the pipeline reactor (3) comprises: a reactor main body (301) in a pipeline structure arranged in a vertical direction; a feed inlet and a gas outlet are arranged at an upper portion of the reactor main body (301), and a liquid return inlet and a liquid discharge outlet are arranged at a lower portion of the reactor main body (301); a reactant is introduced into the reactor main body (301) from the upper portion of the reactor main body (301) through the feed inlet; gas generated in a reaction process is discharged through the gas outlet and then subjected to cooling and gas-liquid separation treatment; liquid obtained through the gas-liquid separation treatment is injected into the reactor main body (301) again through the liquid return inlet; and a reaction completion liquid after the reaction is completed is discharged from the reactor main body (301) through the liquid discharge outlet; the reactor main body (301) is in a double-pipeline structure arranged in a vertical direction, and the reactor main body (301) comprises: an outer pipe (308) and an inner pipe (307) arranged in the outer pipe (308); the outer pipe (308) and the inner pipe (307) are both in a pipeline structure arranged in a vertical direction; the outer pipe (308) and the inner pipe (307) are coaxially arranged, a reaction cavity is formed in the inner pipe (307), and a heat exchange medium containing cavity is formed between the outer pipe (308) and the inner pipe (307); the reaction liquid A conveying unit is connected with the feed inlet of the pipeline reactor (3) and used for injecting the reaction liquid A into the reaction cavity; the sodium nitrite solution conveying unit is connected with the feed inlet of the pipeline reactor (3) and used for injecting the sodium nitrite solution into the reaction cavity; the heat exchange unit is connected with a heat exchange medium inlet and a heat exchange medium outlet of the pipeline reactor (3) and used for circulating and injecting a heat exchange medium into the heat exchange medium containing cavity; the gas treatment unit is connected with the gas outlet of the pipeline reactor (3) and used for treating the gas discharged from the pipeline reactor (3); the method comprises the following steps: S1, configuring a reaction liquid A and a sodium nitrite solution; S2, closing the liquid discharge outlet of the reactor main body, injecting isopropyl alcohol accounting for 80% to 94% of the total volume of the reaction cavity, heating the isopropyl alcohol to 75 to 85 ℃, then opening the liquid discharge outlet of the reactor main body, and continuously injecting the reaction liquid A and the sodium nitrite solution into the pipeline reactor; S3, controlling the temperature in the reaction cavity of the pipeline reactor to be 70 to 85 ℃ through the heat exchange unit, and keeping the gas outlet of the pipeline reactor open at all times during the reaction, so that the gas in the reaction cavity can be discharged to the heat exchanger in time; S4, controlling the residence time of the material in the reaction cavity of the pipeline reactor to be 25 to 35 min, and then discharging the reaction completion liquid through the liquid discharge outlet of the pipeline reactor. The reaction liquid A is a mixture of 2,6-dichloro-4-nitroaniline, isopropyl alcohol, sulfuric acid, water and copper sulfate, and the content of each component in the reaction liquid A is 2,6-dichloro-4-nitroaniline 12-17 parts, isopropyl alcohol 45-50 parts, sulfuric acid 8-13 parts, water 10-14 parts, and copper sulfate 0.05-0.2 parts by weight.

2. The process for the production of 3,5-dichloronitrobenzene according to claim 1, characterized in that, A heat exchange medium inlet is arranged at the upper end of the reactor body (301), and a heat exchange medium outlet is arranged at the lower end of the reactor body (301), the heat exchange medium inlet and the heat exchange medium outlet are respectively communicated with the heat exchange medium containing cavity, and the heat exchange medium flows from top to bottom through the heat exchange medium containing cavity to regulate the temperature of the reaction material in the reaction cavity.

3. The process for the production of 3,5-dichloronitrobenzene according to claim 2, characterized in that, A cold and hot all-in-one machine is arranged outside the pipeline reactor (3), the inlet of the cold and hot all-in-one machine is connected with the heat exchange medium outlet, the outlet of the cold and hot all-in-one machine is connected with the heat exchange medium inlet, the heat exchange medium in the heat exchange medium containing cavity can be discharged to the cold and hot all-in-one machine through the heat exchange medium outlet, and then re-enters the heat exchange medium containing cavity after heat exchange.

4. The method of claim 1, wherein the 3,5-dichloronitrobenzene is prepared by the process of claim 1, wherein the process is carried out at a temperature of from 20 °C to 30 °C. The height of the exhaust port on the reactor body (301) is 85%-92% of the total height of the reactor body (301), and the liquid level height of the reaction material in the reactor body (301) is controlled to be lower than the height of the exhaust port during work.

5. The method of claim 1, wherein the 3,5-dichloronitrobenzene is prepared by the process of claim 1, wherein the process is carried out at a temperature of from 20 °C to 30 °C. In step S2, the flow ratio of the reaction liquid A and the sodium nitrite solution is controlled to be (3-5):

1.

6. The method of claim 1, wherein the 3,5-dichloronitrobenzene is produced by the process of claim 1, wherein the process is carried out at a temperature of from 20 °C to 30 °C. The liquid holding capacity of the pipeline reactor is 300-480L, the flow rate of the reaction liquid A is 490-780L / h, and the flow rate of the sodium nitrite solution is 110-170L / h.

Images