Continuous photochemical reaction system for preparing 2, 4-disubstituted benzyl bromide by using 2, 4-disubstituted toluene

Abstract

The utility model provides a continuous photochemical reaction system for preparing 2, 4-disubstituted benzyl bromide by adopting 2, 4-disubstituted toluene. The continuous photochemical reaction system comprises a photocatalytic reaction device, a feeding device, a post-treatment device, a product receiving device and a heat exchange device. According to the system, 2, 4-disubstituted toluene and dibromohydantoin can be subjected to continuous bromination reaction to realize photochemical reaction, continuous feeding and continuous discharging are realized, and the reaction process is uninterrupted. The structure of the heat exchange device is improved, for example, the heat exchange device is controlled to be a corrugated pipe, the corrugation distance and the pipe diameter of the corrugated pipe are controlled, particularly, baffle plates are arranged on the inner wall of the corrugated pipe at intervals, and the size of the baffle plates and the distance between every two adjacent baffle plates are controlled to be within a certain range value; therefore, the heat transfer coefficient of the heat exchange device is high, the temperature control effect is better, and the efficiency of the continuous photochemical reaction and the purity of the 2, 4-disubstituted benzyl bromide product are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of photochemical reactions, in particular to a continuous photochemical reaction system for preparing 2,4-disubstituted benzyl bromide by adopting 2,4-disubstituted toluene. Background Art

[0002] Currently, most reactors used for continuous photochemical reactions have coils wrapped around the outside of a quartz barrel. The light intensity will be lost by about 10% when it passes through the quartz glass. In addition, quartz glass is fragile, posing safety risks during installation or use.

[0003] Moreover, the existing technology mostly uses a method of winding a temperature-control tube around the coil to cool down. The outer layer of the reactor is blocked, and only a cylindrical light source in the inner layer can be used to illuminate the reaction. Moreover, this method (interlayer heat exchange) has poor temperature control effect and cannot be used for reactions with large heat release. The LED light source is inside the reactor, and the light radiates outward, which will cause the risk of some ultraviolet light leakage and light pollution.

[0004] In addition, the photochemical reactor used in the prior art has no automatic control and feedback system, and cannot achieve precise feeding, especially for the reaction of preparing 2,4-disubstituted benzyl bromide from 2,4-disubstituted toluene, which cannot achieve continuous automatic production. Utility Model Content

[0005] The main purpose of the utility model is to provide a continuous photochemical reaction system for preparing 2,4-disubstituted benzyl bromide by using 2,4-disubstituted toluene, so as to solve the problem that the method of preparing 2,4-disubstituted benzyl bromide by using continuous photocatalysis of 2,4-disubstituted toluene in the prior art cannot achieve continuous automatic production.

[0006] In order to achieve the above-mentioned object, according to one aspect of the utility model, a continuous photochemical reaction system for preparing 2,4-disubstituted benzyl bromide using 2,4-disubstituted toluene is provided. The continuous photochemical reaction system includes a photocatalytic reaction device for continuously brominating 2,4-disubstituted toluene with dibromohydantoin, a feeding device connected to the photocatalytic reaction device and used to continuously transport 2,4-disubstituted toluene and dibromohydantoin to the photocatalytic reaction device, a post-processing device connected to the photocatalytic reaction device and used to continuously post-process the crude 2,4-disubstituted benzyl bromide product, a product receiving device connected to the post-processing device and used to continuously receive the 2,4-disubstituted benzyl bromide product, and a heat exchange device. The crude 2,4-disubstituted benzyl bromide product obtained in the photocatalytic reaction device The invention relates to a method for preparing a photocatalytic reaction device comprising: a feeding device connected to a 2,4-disubstituted toluene source and a dibromohydantoin source, respectively; a 2,4-disubstituted benzyl bromide product is obtained in a post-processing device; a feeding device, a product receiving device and a heat exchange device are all connected to a photocatalytic reaction device, and the heat exchange device is used to adjust the temperature of the materials in the feeding device, the product receiving device and the photocatalytic reaction device; wherein the heat exchange device is a tubular heat exchanger structure, the heat exchange device includes a shell, a temperature control medium and a pipe for storing the temperature control medium, the pipe is a corrugated pipe, the corrugation shape of the corrugated pipe is U-shaped, and the corrugation spacing of the corrugated pipe is 6-8 mm; the diameter of the corrugated pipe is 10-25 mm; baffles are arranged on the inner wall of the shell at intervals, the spacing between adjacent baffles is 20-30% of the shell diameter, and the height of the baffles along the radial direction of the shell is 15-20% of the shell diameter.

[0007] Furthermore, the above-mentioned post-processing device includes a continuous extraction device and a continuous concentration device, the continuous extraction device includes an extraction device inlet and an extraction device outlet, the extraction device inlet is connected to the outlet of the photocatalytic reaction device, and the continuous extraction device continuously extracts the crude 2,4-disubstituted benzyl bromide product to obtain an extracted product system; the extraction device inlet is provided with a deflector, which is used to guide the crude 2,4-disubstituted benzyl bromide product into the continuous extraction device, the deflector is a spiral coil, and the spiral angle of the spiral coil is 5~30 degrees; the spiral coil is provided on the pipeline The invention discloses a method for preparing a continuous extraction device comprising a continuous extraction device and a continuous concentration device. The continuous extraction device comprises a continuous extraction device and a continuous concentration device. The continuous concentration device comprises a continuous concentration device and a continuous concentration device for continuously concentrating a product system after extraction to obtain a 2,4-disubstituted benzyl bromide product. The method comprises a method for preparing a continuous extraction device and a continuous concentration device. The method comprises a method for preparing a continuous extraction device and a continuous concentration device for continuously concentrating a product system after extraction to obtain a 2,4-disubstituted benzyl bromide product. The method comprises a method for preparing a continuous extraction device and a continuous concentration device for continuously concentrating a product system along an axial direction of the spiral coil. The method comprises a method for preparing a continuous extraction device and a continuous concentration device for continuously concentrating a product system after extraction to obtain a 2,4-disubstituted benzyl bromide product.

[0008] Furthermore, the above-mentioned continuous photochemical reaction system also includes a PLC control device, one end of the PLC control device is electrically connected to the feeding device, and the other end is electrically connected to the product receiving device.

[0009] Furthermore, a pressure transmitter is provided on the pipeline connecting the PLC control device and the feeding device.

[0010] Furthermore, a temperature transmitter is provided on the pipeline connecting the PLC control device and the product receiving device; and a back pressure valve is provided on the pipeline between the temperature transmitter and the continuous extraction device.

[0011] Furthermore, the feeding device includes an electronic scale, a feeding tank, and a plunger pump, and the feeding tank is arranged on the electronic scale; the plunger pump is connected to the outlet of the feeding tank and is connected to the photocatalytic reaction device through a pressure transmitter.

[0012] Furthermore, the above-mentioned photocatalytic reaction device includes an internal light source, a transparent coil reactor, and an external light source. The transparent coil reactor includes an internal coil and an external coil arranged outside the internal coil. The internal coil is used to pass the temperature control medium, and the external coil is used to pass the reaction raw materials. The internal coil is arranged outside the internal light source and extends along its axial direction. The external light source is arranged in a ring around the external coil on the circumferential outside away from the internal light source; the center of the external light source overlaps with the center of the internal light source; the inner diameter ratio of the internal coil to the external coil is 1:1.5~1:3.

[0013] Furthermore, the irradiation range of the external light source and the internal light source covers 100% of the transparent coil reactor.

[0014] Furthermore, the above-mentioned photocatalytic reaction device also includes a plurality of hollow coil supports, which are fixed on the outside of the external coil; the number of the hollow coil supports is 6 to 12, and the plurality of hollow coil supports are arranged at equal intervals.

[0015] Furthermore, the above-mentioned internal light source and external light source adopt a modular design, the internal light source is a columnar light source, and the internal light source and the external light source are independently selected from one or more of LED, mercury lamp, xenon lamp, and laser.

[0016] By applying the technical solution of the present utility model and the system of the present application, a photochemical reaction can be continuously generated, and continuous feeding and discharging can be achieved without interruption during the reaction process. Specifically, the present application improves the structure of the heat exchange device, such as controlling the heat exchange device to be a bellows, controlling the spacing of the corrugations and the diameter of the bellows, especially providing baffles on the inner wall of the bellows, and controlling the size of the baffles and the spacing between adjacent baffles within a certain range of values, thereby making the heat transfer coefficient of the heat exchange device high and the temperature control effect better, thereby better regulating the continuous photochemical reaction temperature of 2,4-disubstituted toluene and dibromohydantoin and the temperature of the 2,4-disubstituted benzyl bromide product, further improving the efficiency of the above continuous photochemical reaction and the purity of the 2,4-disubstituted benzyl bromide product. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting part of this application are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0018] Figure 1 A top view of a photocatalytic reaction device provided according to an embodiment of the present utility model is shown;

[0019] Figure 2 A cross-sectional view of a photocatalytic reaction device provided according to an embodiment of the present invention is shown;

[0020] Figure 3 A schematic structural diagram of a continuous photochemical reaction system according to an embodiment of the present invention is shown;

[0021] Figure 4 Shown according to the utility model Figure 3 Schematic diagram of the structure of the heat exchange device in the continuous photochemical reaction system shown.

[0022] The above drawings include the following reference numerals:

[0023] 01. Photocatalytic reaction device; 02. Feeding device; 03. Post-processing device; 04. Product receiving device; 05. Heat exchange device; 06. PLC control device; 11. Internal light source; 12. Transparent coil reactor; 13. External light source; 14. Hollow coil bracket; 21. Electronic scale; 22. Feed tank; 23. Plunger pump; 31. Continuous extraction device; 32. Continuous concentration device; 33. Back pressure valve; 51. Shell; 52. Bellows; 53. Baffle; 61. Pressure transmitter; 62. Temperature transmitter; 121. Internal coil; 122. External coil. DETAILED DESCRIPTION

[0024] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0025] As analyzed in the background technology of the present invention, the existing technology has the problem that the method of preparing 2,4-disubstituted benzyl bromide by continuous photocatalysis of 2,4-disubstituted toluene cannot achieve continuous automatic production. The present invention provides a continuous photochemical reaction system for preparing 2,4-disubstituted benzyl bromide by using 2,4-disubstituted toluene.

[0026] In a typical embodiment of the present application, a continuous photochemical reaction system for preparing 2,4-disubstituted benzyl bromide using 2,4-disubstituted toluene is provided, such as Figure 3As shown, the continuous photochemical reaction system includes: a photocatalytic reaction device 01 (its top view is Figure 1 , its cross-sectional view is Figure 2 ), a feeding device 02 connected to the photocatalytic reaction device 01 for continuously conveying 2,4-disubstituted toluene and dibromohydantoin to the photocatalytic reaction device 01, a post-processing device 03 connected to the photocatalytic reaction device 01 for continuously post-processing the crude 2,4-disubstituted benzyl bromide product, a product receiving device 04 connected to the post-processing device 03 for continuously receiving the 2,4-disubstituted benzyl bromide product, and a heat exchange device 05, wherein the crude 2,4-disubstituted benzyl bromide product is obtained in the photocatalytic reaction device 01; the feeding device 02 is connected to the 2,4-disubstituted toluene source and the dibromohydantoin source respectively; the 2,4-disubstituted benzyl bromide product is obtained in the post-processing device 03; the feeding device 02, the product receiving device 04 and the heat exchange device 05 are all connected to the photocatalytic reaction device 01, and the heat exchange device 05 is used to adjust the temperature of the materials in the feeding device 02, the product receiving device 04 and the photocatalytic reaction device 01; wherein the heat exchange device 05 is a tubular heat exchanger structure, such as Figure 4 As shown, the heat exchange device 05 includes a shell 51, a temperature control medium and a pipe for storing the temperature control medium. The pipe is a bellows 52. The corrugation shape of the bellows 52 is U-shaped, and the corrugation spacing of the bellows 52 is 6~8mm; the diameter of the bellows 52 is 10~25mm; baffles 53 are arranged at intervals on the inner wall of the shell 51, and the spacing between adjacent baffles 53 is 20~30% of the diameter of the shell 51. The height of the baffles 53 along the radial direction of the shell 51 is 15~20% of the diameter of the shell 51.

[0027] The system of the present application can realize continuous photochemical reaction, continuous feeding and continuous discharging, and no interruption during the reaction process. Specifically, the present application improves the structure of the heat exchange device, such as controlling the heat exchange device to be a bellows, controlling the corrugation spacing and the diameter of the bellows, especially providing baffles on the inner wall of the bellows, and controlling the size of the baffles and the spacing between adjacent baffles within a certain range of values, so that the heat transfer coefficient of the heat exchange device is high and the temperature control effect is better, thereby better regulating the continuous photochemical reaction temperature of 2,4-disubstituted toluene and dibromohydantoin and the temperature of the 2,4-disubstituted benzyl bromide product, further improving the efficiency of the above continuous photochemical reaction and the purity of the 2,4-disubstituted benzyl bromide product.

[0028] In addition, the wall thickness of the bellows is 1.5-3 mm. By controlling the relevant parameters of the bellows within the above range, the heat transfer coefficient of the heat exchange device 05 is increased by 15%-25%, and the shell-side fluid Reynolds number is ≥5000.

[0029] This application uses 2,4-disubstituted toluene and dibromohydantoin as raw materials. Light acts as a catalyst to activate dibromohydantoin to produce Br·, which selectively removes the benzylic hydrogen atoms of the 2,4-disubstituted toluene, generating stable benzyl radicals. Br· then combines with the benzyl radicals to produce the target product, 2,4-disubstituted benzyl bromide. (The 2,4-substituent in the 2,4-disubstituted toluene synergistically controls the regioselectivity of the reaction through electronic and steric effects.) Compared to traditional benzylic bromination (such as the NBS / peroxide system), the continuous photochemical reaction system used in this application to prepare 2,4-disubstituted benzyl bromide from 2,4-disubstituted toluene does not require an initiator and operates under mild conditions.

[0030] In one embodiment of the present application, the post-processing device 03 includes a continuous extraction device 31 and a continuous concentration device 32. The continuous extraction device 31 includes an extraction device inlet and an extraction device outlet. The extraction device inlet is connected to the outlet of the photocatalytic reaction device 01. The continuous extraction device 31 continuously extracts the crude 2,4-disubstituted benzyl bromide product to obtain an extracted product system; the extraction device inlet is provided with a deflector for directing the crude 2,4-disubstituted benzyl bromide product into the continuous extraction device 31. The deflector is a spiral coil with a spiral angle of 5 to 30 degrees; the spiral A deflection baffle is provided on the coil pipeline, and the cross-sectional area of the deflection baffle along the axial direction of the spiral coil is 20% to 80% of the axial cross-sectional area of the spiral coil; the pitch of the spiral coil is 10 to 100 mm; a deflection baffle is provided at every 90° interval along the axial winding angle of each spiral ring of the spiral coil, and there is only one deflection baffle at the highest point and the lowest point of each spiral ring; the continuous concentrator 32 is connected to the extraction device outlet of the continuous extraction device 31, and the continuous concentrator 32 is used to continuously concentrate the extracted product system to obtain a 2,4-disubstituted benzyl bromide product.

[0031] A spiral coil design is used as a flow guide. Compared to traditional straight tube flow guides, the spiral coil increases material turbulence and contact surface area, thereby improving extraction efficiency. The spiral angle is optimized between 5° and 30°, ensuring smooth material flow while increasing residence time and ensuring sufficient extraction. Furthermore, baffles are installed on the spiral coil to further increase turbulence, prevent short-circuiting, and ensure effective contact between the material and the extractant. The cross-sectional area of the baffles accounts for 20% to 80% of the cross-sectional area of the spiral coil, balancing material flowability and extraction efficiency. The spiral coil pitch ranges from 10 to 100 mm, and baffles are placed at every 90° of the spiral, ensuring thorough mixing of the material within each spiral loop. The combined design of the spiral coil and baffles increases the contact area and time between the extractant and the crude 2,4-disubstituted benzyl bromide product, significantly improving extraction efficiency. Compared to traditional static extraction, the continuous extraction apparatus 31 enables more thorough continuous extraction of the crude 2,4-disubstituted benzyl bromide product.

[0032] Directly following the continuous extraction unit 31, it is used to concentrate the extracted 2,4-disubstituted benzyl bromide, further increasing its concentration and purity, and accelerating the subsequent purification and recovery of the product. The continuous concentration design reduces the intermediate waiting time and energy consumption of batch operations, improving the production efficiency of the entire system.

[0033] In one embodiment of the present application, the above-mentioned continuous photochemical reaction system further includes a PLC control device 06 , one end of the PLC control device 06 is electrically connected to the feeding device 02 , and the other end of the PLC control device 06 is electrically connected to the product receiving device 04 .

[0034] Specifically, one end of the PLC control device 06 of the present application is connected to the electronic scale 21, the plunger pump 23, and the pressure transmitter 61 in sequence, and the other end is connected to the temperature transmitter 62. The present application adopts a PLC control system, which can automatically control the feed rate of the reaction raw materials by connecting to the electronic scale 21, and can control the flow rate and flow rate of the reaction raw materials by connecting to the plunger pump 23, thereby ensuring the stable feeding of each reaction raw material; at the same time, the PLC control device 06 can automatically collect important parameters of each part of the reaction, such as temperature and pressure, by connecting to the pressure transmitter 61 and the temperature transmitter 62, and control the pressure and temperature during the reaction process, thereby accurately controlling the equipment and simplifying operation.

[0035] In order to more conveniently control the pressure of the above-mentioned continuous photochemical reaction, in one embodiment of the present application, a pressure transmitter 61 is provided on the pipeline connecting the above-mentioned PLC control device 06 and the feeding device 02.

[0036] In one embodiment of the present application, a temperature transmitter 62 is provided on the pipeline connecting the PLC control device 06 and the product receiving device 04 ; a back pressure valve 33 is provided on the pipeline between the temperature transmitter 62 and the continuous extraction device 31 .

[0037] Some reactions release heat violently, and excessively high temperatures will increase the impurity content. Therefore, strict temperature control is required throughout the reaction. The temperature transmitter 62 can control the temperature more accurately.

[0038] In one embodiment of the present application, the above-mentioned feeding device 02 includes an electronic scale 21, a feeding tank 22 and a plunger pump 23, and the feeding tank 22 is arranged on the electronic scale 21; the plunger pump 23 is connected to the outlet of the feeding tank 22, and is connected to the photocatalytic reaction device 01 through a pressure transmitter 61.

[0039] The electronic scale 21 reflects the remaining weight in the feed tank in real time, the pumping speed of the plunger pump 23 controls the feed speed, and the reaction pressure is controlled by the pressure transmitter 61.

[0040] In one embodiment of the present application, the above-mentioned photocatalytic reaction device 01 includes an internal light source 11, a transparent coil reactor 12 and an external light source 13. The transparent coil reactor 12 includes an internal coil 121 and an external coil 122 arranged outside the internal coil 121. The internal coil 121 is used to pass the temperature control medium, and the external coil 122 is used to pass the reaction raw materials. The internal coil 121 is arranged outside the internal light source 11 and extends along its axial direction. The external light source 13 is arranged in a ring around the external coil 122 on the circumferential outside away from the internal light source 11; the center of the external light source 13 overlaps with the center of the internal light source 11; the inner diameter ratio of the internal coil 121 to the external coil 122 is 1:1.5~1:3.

[0041] Because the continuous photochemical reaction system of the present application includes the aforementioned continuous photochemical reaction unit, an internal light source 11 and an external light source 13 are disposed on both the inside and outside of the transparent coil reactor 12, allowing both the inside and outside of the transparent coil reactor 12 to receive light. Furthermore, there is no quartz glass blocking the internal and external light sources from the transparent coil reactor 12, allowing light to directly penetrate the transparent coil reactor 12. This reduces light loss through the quartz glass, thereby increasing light intensity and improving light utilization.

[0042] In order to improve the light transmittance of the transparent coil reactor 12, in some embodiments, the material of the transparent coil reactor 12 is preferably one or more of PFA, FEP, PCTFE, quartz and Pyrex glass. The above materials have good light transmittance, and the UV light source transmittance is above 97%. In addition, the transparent coil reactor 12 made of the above materials can withstand high temperatures and high pressures, and has good corrosion resistance. The above transparent coil reactor 12 has a wide range of applications. The materials of the internal coil 121 and the external coil 122 in the transparent coil reactor 12 can be the same or different, and the materials of the internal coil 121 and the external coil 122 can be one or more of PFA, FEP, PCTFE, quartz and Pyrex glass.

[0043] The temperature control method utilizes direct-contact tube-in-tube heat exchange. Specifically, the reaction raw materials are introduced into the outer coil 122, while the temperature-control medium is introduced into the inner coil 121. The outer surface of the inner coil 121 (i.e., the temperature-control pipe) is in direct contact with the reaction raw materials, resulting in a high heat transfer coefficient and excellent temperature control. This method is particularly suitable for the continuous photocatalytic production of 2,4-disubstituted benzyl bromide products from 2,4-disubstituted toluene and dibromohydantoin. Furthermore, because the temperature-control pipe (inner coil 121) is encased within the outer coil 122, the pipe does not block light, allowing light to directly strike the outer coil 122. This eliminates any loss in light intensity and further improves light energy utilization.

[0044] The present invention's design arranges the center of the external light source 13 to overlap with the center of the internal light source 11. This design maximizes the illumination range of the light source and avoids uneven light intensity distribution. Furthermore, the overlapping center-of-center arrangement allows the light from the internal and external light sources to complement each other, enhancing the light intensity within the reactor, particularly in the reactor's center, where light intensity is typically most needed. Furthermore, this overlapping center-of-center arrangement helps reduce the footprint of the photochemical reactor, making it more compact and suitable for industrial applications.

[0045] Controlling the inner diameter ratio of the inner coil 121 to the outer coil 122 within the above range helps optimize heat exchange efficiency and illumination. A smaller inner diameter ratio (approximately 1:1.5) improves heat exchange efficiency because a smaller inner coil diameter means a larger heat exchange area per unit volume, enabling more effective control of reaction temperature and making it suitable for reactions requiring precise temperature control. A larger inner diameter ratio (approximately 1:3) facilitates illumination because the larger diameter of the outer coil provides a wider illumination path, making it suitable for reactions requiring extensive illumination. The design of the above inner diameter ratio of the inner coil 121 to the outer coil 122 takes into account the dual requirements of temperature control and illumination efficiency in photochemical reactions. By adjusting the coil size ratio, the optimal balance can be found under different reaction conditions, which is crucial for improving the yield and selectivity of photochemical reactions.

[0046] In some embodiments, during the reaction process, the internal light source 11 can be controlled to illuminate alone, the external light source 13 can be controlled to illuminate alone, or the internal light source 11 and the external light source 13 can be controlled to illuminate simultaneously. When the internal light source 11 and the external light source 13 illuminate simultaneously, the light intensity per unit volume of the transparent coil reactor 12 can be more than doubled. When the production capacity demand is relatively small, using only a single light source can meet production requirements.

[0047] In order to fully irradiate the reactants and further improve the light intensity and light utilization rate, in one embodiment of the present application, the irradiation range of the external light source 13 and the internal light source 11 covers 100% of the transparent coil reactor 12.

[0048] In order to support the transparent coil reactor 12 and fix the transparent coil reactor 12 between the internal light source 11 and the external light source 13, in one embodiment of the present application, the above-mentioned photocatalytic reaction device 01 also includes a plurality of hollow coil supports 14, and the hollow coil supports 14 are fixed on the outside of the external coil 122; the number of the hollow coil supports 14 is 6 to 12, and the plurality of hollow coil supports 14 are arranged at equal intervals.

[0049] The hollow coil support 14 can be a skeleton-type support made of steel pipe. The coil is fixed to the hollow coil support 14, without blocking the internal light source and with minimal blocking of the external light source. Furthermore, to better balance cost and stability of the photocatalytic reaction device 01, the number of hollow coil supports 14 is selected to be 6 to 12.

[0050] The internal light source 11 and external light source 13 in this application utilize specially customized ultra-high-intensity light sources, including but not limited to LEDs, mercury lamps, xenon lamps, lasers, and other light sources. In some embodiments, the internal light source 11 and external light source 13 utilize a modular design, allowing for flexible configuration of light source specifications and quantity based on different reaction requirements. To increase illumination intensity, in some embodiments, the internal light source 11 is preferably a cylindrical light source, and the internal light source 11 and external light source 13 are independently selected from one or more of LEDs, mercury lamps, xenon lamps, and lasers.

[0051] In some embodiments, the internal light source 11 and the external light source 13 adopt a modular design. The internal light source 11, the external light source 13, and the transparent coil reactor 12 are independently designed, and their respective functions and structures are independent, and are assembled into a whole. Each module can be flexibly disassembled, and the modules can be replaced individually or the module combination can be changed according to different usage requirements.

[0052] The beneficial effects of the present application will be described below with reference to specific embodiments.

[0053] Example 1

[0054] 2-Chloro-4-fluorotoluene and dibromohydantoin were used as raw materials for a photocatalytic bromination reaction. The reaction formula of the bromination reaction is as follows:

[0055]

[0056] use Figure 3 The continuous photochemical reaction system shown in FIG. 1 includes a feeding device 02 and a photocatalytic reaction device 01 (the top view of which is Figure 1 , its cross-sectional view is Figure 2 ), post-processing device 03, product receiving device 04, the post-processing device 03 includes a continuous extraction device 31 and a continuous concentration device 32, the continuous extraction device 31 includes an extraction device inlet and an extraction device outlet, the extraction device inlet is connected to the outlet of the photocatalytic reaction device 01, the extraction device inlet is provided with a spiral coil, the spiral angle of the spiral coil is 20°; a deflection baffle is provided on the pipeline of the spiral coil, the cross-sectional area of the deflection baffle along the axial direction of the spiral coil is 60% of the axial cross-sectional area of the spiral coil, the pitch of the spiral coil is 60mm, and each spiral ring of the spiral coil is provided with a deflection baffle every 90° along the axial winding angle of the spiral coil, and there is only one deflection baffle at the highest point and the lowest point of each spiral ring; the continuous concentration device 32 is connected to the extraction device outlet of the continuous extraction device 31.

[0057] The photocatalytic reaction device 01 comprises an internal light source 11, a transparent coil reactor 12, and an external light source 13. The internal and external light sources 11 and 13 utilize a modular design. The internal light source 11 is a cylindrical light source. Both are 365nm LED lamps with a power of 25kW. The transparent coil reactor 12 comprises an internal coil 121 and an external coil 122, which is sleeved outside the internal coil 121. The internal coil 121 is used to pass a temperature-controlled medium, while the external coil 122 is used to pass the reaction raw materials. The internal coil 121 sleeves outside the internal light source 11 and extends along its axial direction. The external light source 13 is arranged in an annular manner around the external coil 122, circumferentially away from the internal light source 11. The center of the external light source 13 overlaps with the center of the internal light source 11. The inner diameter ratio of the internal coil 121 to the outer coil 122 is 1:2. The irradiation range of the external light source 13 and the internal light source 11 fully covers the transparent coil reactor 12. The photocatalytic reaction device 01 further includes 8 hollow coil supports 14 , which are fixed to the outside of the external coil 122 , and the multiple hollow coil supports 14 are arranged at equal intervals.

[0058] The feeding device 02 includes an electronic scale 21 , a feeding tank 22 and a plunger pump 23 . The feeding tank 22 is arranged on the electronic scale 21 . The plunger pump 23 is connected to the outlet of the feeding tank 22 and is connected to the photocatalytic reaction device 01 through a pressure transmitter 61 .

[0059] The continuous photochemical reaction system also includes a heat exchanger 05. The feeder 02, product receiving device 04, and heat exchanger 05 are all connected to the photocatalytic reaction device 01. Heat exchanger 05 is used to regulate the temperature of the materials in the feeder 02, product receiving device 04, and photocatalytic reaction device 01. Heat exchanger 05 is a tubular heat exchanger structure, comprising a shell 51, a temperature control medium, and a pipe for storing the temperature control medium. The pipe is a bellows 52, with a U-shaped corrugation and a corrugation pitch of 7 mm. The diameter of the bellows 52 is 15 mm. Baffles 53 are spaced apart on the inner wall of the shell 51. The spacing between adjacent baffles 53 is 25% of the diameter of the shell 51, and the height of the baffles 53 along the radial direction of the shell 51 is 18% of the diameter of the shell 51.

[0060] The continuous photochemical reaction system also includes a PLC control device 06, one end of which is electrically connected to the feeding device 02, and the other end is electrically connected to the product receiving device 04. A pressure transmitter 61 is provided on the pipeline connecting the PLC control device 06 and the feeding device 02, a temperature transmitter 62 is provided on the pipeline connecting the PLC control device 06 and the product receiving device 04, and a back pressure valve 33 is provided on the pipeline between the temperature transmitter 62 and the continuous extraction device 31.

[0061] The 2,4-disubstituted toluene source and the dibromohydantoin source are respectively connected to the feeding device 02, and the 2,4-disubstituted toluene and the dibromohydantoin are continuously transported to the photocatalytic reaction device 01 through the feeding device 02. After the 2,4-disubstituted toluene and the dibromohydantoin in the photocatalytic reaction device 01 undergo continuous bromination reaction, a crude 2,4-disubstituted benzyl bromide product is obtained. An electronic scale 21 and a PLC control device 06 are used to precisely control the feed rates of 2,4-disubstituted toluene and dibromohydantoin to 1 L / min, respectively. A temperature control medium is introduced into the internal coil 121 of the transparent coil reactor made of PFA, and the reaction raw materials are introduced into the external coil 122 of PFA. The temperature of the internal coil 121 is controlled to stably control the reaction temperature at 20°C. The crude 2,4-disubstituted benzyl bromide product is directed to the continuous extraction device 31 through a spiral coil provided at the inlet of the extraction device. The crude 2,4-disubstituted benzyl bromide product is continuously extracted in the continuous extraction device 31 to obtain an extracted product system; the extracted product system is continuously concentrated in the continuous concentrator 32 to obtain a 2,4-disubstituted benzyl bromide product. The outlet sample is taken for HPLC analysis, and the product purity is 98%. The outflowing system is concentrated under vacuum to remove the solvent to obtain a product yield of 95%. The output can reach 160 kg / day, and the continuous reaction equipment can operate continuously for 20,000 hours.

[0062] Example 2

[0063] 2-Chloro-4-fluorotoluene and dibromohydantoin were used as raw materials for a photocatalytic bromination reaction. The reaction formula of the bromination reaction is as follows:

[0064]

[0065] use Figure 3 The continuous photochemical reaction system shown in FIG. 1 includes a feeding device 02 and a photocatalytic reaction device 01 (the top view of which is Figure 1 , its cross-sectional view is Figure 2 ), post-processing device 03, product receiving device 04, the post-processing device 03 includes a continuous extraction device 31 and a continuous concentration device 32, the continuous extraction device 31 includes an extraction device inlet and an extraction device outlet, the extraction device inlet is connected to the outlet of the photocatalytic reaction device 01, the extraction device inlet is provided with a spiral coil, the spiral angle of the spiral coil is 5°; a deflection baffle is provided on the pipeline of the spiral coil, the cross-sectional area of the deflection baffle along the axial direction of the spiral coil is 20% of the axial cross-sectional area of the spiral coil, the pitch of the spiral coil is 10mm, and each spiral ring of the spiral coil is provided with a deflection baffle every 90° along the axial winding angle of the spiral coil, and there is only one deflection baffle at the highest point and the lowest point of each spiral ring; the continuous concentration device 32 is connected to the extraction device outlet of the continuous extraction device 31.

[0066] The photocatalytic reaction device 01 comprises an internal light source 11, a transparent coil reactor 12, and an external light source 13. The internal and external light sources 11 and 13 utilize a modular design. The internal light source 11 is a cylindrical light source. Both are 365nm LED lamps with a power of 25kW. The transparent coil reactor 12 comprises an internal coil 121 and an external coil 122, which is sleeved outside the internal coil 121. The internal coil 121 is used to pass a temperature-controlled medium, while the external coil 122 is used to pass the reaction raw materials. The internal coil 121 sleeves outside the internal light source 11 and extends along its axial direction. The external light source 13 is arranged in an annular manner around the external coil 122, circumferentially away from the internal light source 11. The center of the external light source 13 overlaps with the center of the internal light source 11. The inner diameter ratio of the internal coil 121 to the outer coil 122 is 1:1.5. The irradiation range of the external and internal light sources 13 and 11 fully covers the transparent coil reactor 12. The photocatalytic reaction device 01 further includes 6 hollow coil supports 14 , which are fixed to the outside of the external coil 122 , and the multiple hollow coil supports 14 are arranged at equal intervals.

[0067] The feeding device 02 includes an electronic scale 21 , a feeding tank 22 and a plunger pump 23 . The feeding tank 22 is arranged on the electronic scale 21 . The plunger pump 23 is connected to the outlet of the feeding tank 22 and is connected to the photocatalytic reaction device 01 through a pressure transmitter 61 .

[0068] The continuous photochemical reaction system also includes a heat exchanger 05. The feeder 02, product receiving device 04, and heat exchanger 05 are all connected to the photocatalytic reaction device 01. Heat exchanger 05 is used to regulate the temperature of the materials in the feeder 02, product receiving device 04, and photocatalytic reaction device 01. Heat exchanger 05 is a tubular heat exchanger structure, comprising a shell 51, a temperature control medium, and a pipe for storing the temperature control medium. The pipe is a bellows 52, with a U-shaped corrugation and a corrugation pitch of 6 mm. The diameter of the bellows 52 is 10 mm. Baffles 53 are spaced apart on the inner wall of the shell 51. The spacing between adjacent baffles 53 is 20% of the diameter of the shell 51, and the height of the baffles 53 along the radial direction of the shell 51 is 15% of the diameter of the shell 51.

[0069] The continuous photochemical reaction system also includes a PLC control device 06, one end of which is electrically connected to the feeding device 02, and the other end is electrically connected to the product receiving device 04. A pressure transmitter 61 is provided on the pipeline connecting the PLC control device 06 and the feeding device 02, a temperature transmitter 62 is provided on the pipeline connecting the PLC control device 06 and the product receiving device 04, and a back pressure valve 33 is provided on the pipeline between the temperature transmitter 62 and the continuous extraction device 31.

[0070] The 2,4-disubstituted toluene source and the dibromohydantoin source are respectively connected to the feeding device 02, and the 2,4-disubstituted toluene and the dibromohydantoin are continuously transported to the photocatalytic reaction device 01 through the feeding device 02. After the 2,4-disubstituted toluene and the dibromohydantoin in the photocatalytic reaction device 01 undergo continuous bromination reaction, a crude 2,4-disubstituted benzyl bromide product is obtained. An electronic scale 21 and a PLC control device 06 are used to precisely control the feed rates of 2,4-disubstituted toluene and dibromohydantoin to 0.1 L / min, respectively. A temperature control medium is introduced into the inner coil 121 of the transparent coil reactor made of PFA, and the reaction raw materials are introduced into the outer coil 122 of the PFA material. The reaction temperature is stably controlled at 20°C by controlling the temperature of the inner coil 121. The crude 2,4-disubstituted benzyl bromide product is directed to the continuous extraction device 31 through a spiral coil provided at the inlet of the extraction device. The crude 2,4-disubstituted benzyl bromide product is continuously extracted in the continuous extraction device 31 to obtain an extracted product system; the extracted product system is continuously concentrated in the continuous concentrator 32 to obtain a 2,4-disubstituted benzyl bromide product. The outlet sample is taken for HPLC analysis, and the product purity is 96%. The outflowing system is concentrated under vacuum to remove the solvent to obtain a product yield of 94%. The output can reach 161 kg / day, and the continuous reaction equipment can operate continuously for 20,000 hours.

[0071] Example 3

[0072] 2-Chloro-4-fluorotoluene and dibromohydantoin were used as raw materials for a photocatalytic bromination reaction. The reaction formula of the bromination reaction is as follows:

[0073]

[0074] use Figure 3 The continuous photochemical reaction system shown in FIG. 1 includes a feeding device 02 and a photocatalytic reaction device 01 (the top view of which is Figure 1 , its cross-sectional view is Figure 2 ), post-processing device 03, product receiving device 04, the post-processing device 03 includes a continuous extraction device 31 and a continuous concentration device 32, the continuous extraction device 31 includes an extraction device inlet and an extraction device outlet, the extraction device inlet is connected to the outlet of the photocatalytic reaction device 01, the extraction device inlet is provided with a spiral coil, the spiral angle of the spiral coil is 30°; a deflection baffle is provided on the pipeline of the spiral coil, the cross-sectional area of the deflection baffle along the axial direction of the spiral coil is 80% of the axial cross-sectional area of the spiral coil, the pitch of the spiral coil is 100mm, and each spiral ring of the spiral coil is provided with a deflection baffle every 90° along the axial winding angle of the spiral coil, and there is only one deflection baffle at the highest point and the lowest point of each spiral ring; the continuous concentration device 32 is connected to the extraction device outlet of the continuous extraction device 31.

[0075] The photocatalytic reaction device 01 comprises an internal light source 11, a transparent coil reactor 12, and an external light source 13. The internal and external light sources 11 and 13 utilize a modular design. The internal light source 11 is a cylindrical light source. Both are 365nm LED lamps with a power of 25kW. The transparent coil reactor 12 comprises an internal coil 121 and an external coil 122, which is sleeved outside the internal coil 121. The internal coil 121 is used to pass a temperature-controlled medium, while the external coil 122 is used to pass the reaction raw materials. The internal coil 121 sleeves outside the internal light source 11 and extends along its axial direction. The external light source 13 is arranged in an annular manner around the external coil 122, circumferentially away from the internal light source 11. The center of the external light source 13 overlaps with the center of the internal light source 11. The inner diameter ratio of the internal coil 121 to the outer coil 122 is 1:3. The irradiation range of the external and internal light sources 13 and 11 fully covers the transparent coil reactor 12. The photocatalytic reaction device 01 further includes 12 hollow coil supports 14 , which are fixed to the outside of the external coil 122 , and the plurality of hollow coil supports 14 are arranged at equal intervals.

[0076] The feeding device 02 includes an electronic scale 21 , a feeding tank 22 and a plunger pump 23 . The feeding tank 22 is arranged on the electronic scale 21 . The plunger pump 23 is connected to the outlet of the feeding tank 22 and is connected to the photocatalytic reaction device 01 through a pressure transmitter 61 .

[0077] The continuous photochemical reaction system also includes a heat exchanger 05. The feeder 02, product receiving device 04, and heat exchanger 05 are all connected to the photocatalytic reaction device 01. Heat exchanger 05 is used to regulate the temperature of the materials in the feeder 02, product receiving device 04, and photocatalytic reaction device 01. Heat exchanger 05 is a tubular heat exchanger structure, comprising a shell 51, a temperature control medium, and a pipe for storing the temperature control medium. The pipe is a bellows 52, with a U-shaped corrugation and an 8mm corrugation pitch. The diameter of the bellows 52 is 25mm. Baffles 53 are spaced apart on the inner wall of the shell 51. The spacing between adjacent baffles 53 is 30% of the diameter of the shell 51, and the height of the baffles 53 along the radial direction of the shell 51 is 20% of the diameter of the shell 51.

[0078] The continuous photochemical reaction system also includes a PLC control device 06, one end of which is electrically connected to the feeding device 02, and the other end is electrically connected to the product receiving device 04. A pressure transmitter 61 is provided on the pipeline connecting the PLC control device 06 and the feeding device 02, a temperature transmitter 62 is provided on the pipeline connecting the PLC control device 06 and the product receiving device 04, and a back pressure valve 33 is provided on the pipeline between the temperature transmitter 62 and the continuous extraction device 31.

[0079] The 2,4-disubstituted toluene source and the dibromohydantoin source are respectively connected to the feeding device 02, and the 2,4-disubstituted toluene and the dibromohydantoin are continuously transported to the photocatalytic reaction device 01 through the feeding device 02. After the 2,4-disubstituted toluene and the dibromohydantoin in the photocatalytic reaction device 01 undergo continuous bromination reaction, a crude 2,4-disubstituted benzyl bromide product is obtained. An electronic scale 21 and a PLC control device 06 are used to precisely control the feed rates of 2,4-disubstituted toluene and dibromohydantoin to 2 L / min, respectively. A temperature control medium is introduced into the internal coil 121 of the transparent coil reactor made of PFA, and the reaction raw materials are introduced into the external coil 122 of PFA. The reaction temperature is stably controlled at 20°C by controlling the temperature of the internal coil 121. The crude 2,4-disubstituted benzyl bromide product is directed to the continuous extraction device 31 through a spiral coil provided at the inlet of the extraction device. The crude 2,4-disubstituted benzyl bromide product is continuously extracted in the continuous extraction device 31 to obtain an extracted product system; the extracted product system is continuously concentrated in the continuous concentrator 32 to obtain a 2,4-disubstituted benzyl bromide product. The outlet sample is taken for HPLC analysis, and the product purity is 99%. The outflowing system is concentrated under vacuum to remove the solvent to obtain a product yield of 98%, and the output can reach 165 kg / day. The continuous reaction equipment operates continuously for 21,000 hours.

[0080] Example 4

[0081] The difference from Example 1 is that no baffle is provided on the spiral coil pipeline, and 2,4-disubstituted benzyl bromide product is finally obtained. The outlet sample is analyzed by HPLC, and the product purity is 90%. The outflow system is concentrated under vacuum to remove the solvent to obtain a product yield of 90%, and the output can reach 150 kg / day. The continuous reaction equipment continues to operate for 18000 h.

[0082] Comparative Example 1

[0083] The difference from Example 1 is that the baffle 53 is not provided on the inner wall of the shell 51, and the final 2,4-disubstituted benzyl bromide product is obtained. The outlet sample is analyzed by HPLC, and the product purity is 70%. The outflow system is concentrated under vacuum to remove the solvent to obtain a product yield of 80%. The output can reach 160 kg / day, and the continuous reaction equipment operates continuously for 10,000 h.

[0084] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0085] The system of the present application can realize continuous photochemical reaction, continuous feeding and continuous discharging, and no interruption during the reaction process. Specifically, the present application improves the structure of the heat exchange device, such as controlling the heat exchange device to be a bellows, controlling the corrugation spacing and the diameter of the bellows, especially providing baffles on the inner wall of the bellows, and controlling the size of the baffles and the spacing between adjacent baffles within a certain range of values, so that the heat transfer coefficient of the heat exchange device is high and the temperature control effect is better, thereby better regulating the continuous photochemical reaction temperature of 2,4-disubstituted toluene and dibromohydantoin and the temperature of the 2,4-disubstituted benzyl bromide product, further improving the efficiency of the above continuous photochemical reaction and the purity of the 2,4-disubstituted benzyl bromide product.

[0086] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A continuous photochemical reaction system for preparing 2,4-disubstituted benzyl bromide using 2,4-disubstituted toluene, characterized in that: The continuous photochemical reaction system comprises: A photocatalytic reaction device (01) for continuously performing a bromination reaction of 2,4-disubstituted toluene with dibromohydantoin, wherein a crude 2,4-disubstituted benzyl bromide product is obtained in the photocatalytic reaction device (01); A feeding device (02) connected to the photocatalytic reaction device (01) and used for continuously conveying the 2,4-disubstituted toluene and the dibromohydantoin to the photocatalytic reaction device (01), wherein the feeding device (02) is connected to a 2,4-disubstituted toluene source and a dibromohydantoin source, respectively; A post-processing device (03) connected to the photocatalytic reaction device (01) for continuously post-processing the crude 2,4-disubstituted benzyl bromide product, wherein the post-processing device (03) obtains a 2,4-disubstituted benzyl bromide product; A product receiving device (04) connected to the post-processing device (03) for continuously receiving the 2,4-disubstituted benzyl bromide product; a heat exchange device (05), wherein the feeding device (02), the product receiving device (04), and the heat exchange device (05) are all in communication with the photocatalytic reaction device (01), and the heat exchange device (05) is used to adjust the temperature of materials in the feeding device (02), the product receiving device (04), and the photocatalytic reaction device (01); The heat exchange device (05) is a tubular heat exchanger structure, comprising a shell (51), a temperature control medium, and a pipe for storing the temperature control medium. The pipe is a bellows (52), the bellows (52) has a U-shaped corrugation, and the corrugation spacing of the bellows (52) is 6 to 8 mm. The diameter of the bellows (52) is 10 to 25 mm. Baffles (53) are arranged at intervals on the inner wall of the shell (51), the spacing between adjacent baffles (53) is 20-30% of the diameter of the shell (51), and the height of the baffles (53) along the radial direction of the shell (51) is 15-20% of the diameter of the shell (51).

2. The continuous photochemical reaction system according to claim 1, characterized in that: The post-processing device (03) comprises: A continuous extraction device (31) comprising an extraction device inlet and an extraction device outlet, wherein the extraction device inlet is connected to the outlet of the photocatalytic reaction device (01), and the continuous extraction device (31) continuously extracts the crude 2,4-disubstituted benzyl bromide product to obtain an extracted product system; The inlet of the extraction device is provided with a flow guide, which is used to guide the crude 2,4-disubstituted benzyl bromide product into the continuous extraction device (31), and the flow guide is a spiral coil, and the spiral angle of the spiral coil is 5-30 degrees; The spiral coil is provided with a baffle, wherein the cross-sectional area of the baffle along the axial direction of the spiral coil is 20-80% of the cross-sectional area of the spiral coil; the pitch of the spiral coil is 10-100 mm; Each spiral ring of the spiral coil is provided with a deflection baffle at every 90° interval along the axial winding angle of the spiral coil, and there is only one deflection baffle at the highest point and the lowest point of each spiral ring; A continuous concentration device (32) is connected to the extraction device outlet of the continuous extraction device (31), and the continuous concentration device (32) is used to continuously concentrate the extracted product system to obtain the 2,4-disubstituted benzyl bromide product.

3. The continuous photochemical reaction system according to claim 1, characterized in that: The continuous photochemical reaction system further comprises a PLC control device (06), one end of the PLC control device (06) being electrically connected to the feeding device (02), and the other end of the PLC control device (06) being electrically connected to the product receiving device (04).

4. The continuous photochemical reaction system according to claim 3, characterized in that: A pressure transmitter (61) is provided on the pipeline connecting the PLC control device (06) and the feeding device (02).

5. The continuous photochemical reaction system according to claim 3, characterized in that: A temperature transmitter (62) is provided on the pipeline connecting the PLC control device (06) and the product receiving device (04); A back pressure valve (33) is provided on the pipeline between the temperature transmitter (62) and the continuous extraction device (31).

6. The continuous photochemical reaction system according to any one of claims 1 to 5, characterized in that: The feeding device (02) comprises: Electronic scales (21), A feeding tank (22), wherein the feeding tank (22) is arranged on the electronic scale (21); A plunger pump (23), the plunger pump (23) is connected to the outlet of the feed tank (22), and is connected to the photocatalytic reaction device (01) through a pressure transmitter (61).

7. The continuous photochemical reaction system according to any one of claims 1 to 5, characterized in that: The photocatalytic reaction device (01) comprises: Internal light source (11), A transparent coil reactor (12), comprising an inner coil (121) and an outer coil (122) sleeved outside the inner coil (121), the inner coil (121) being used to introduce a temperature control medium, the outer coil (122) being used to introduce reaction raw materials, the inner coil (121) being sleeved outside the inner light source (11) and extending along its axial direction, an external light source (13), the external light source (13) being arranged in an annular manner around the external coil (122) and away from the internal light source (11); The center of the external light source (13) overlaps with the center of the internal light source (11); The inner diameter ratio of the inner coil (121) to the outer coil (122) is 1:1.5 to 1:

3.

8. The continuous photochemical reaction system according to claim 7, characterized in that: The irradiation ranges of the external light source (13) and the internal light source (11) cover 100% of the transparent coil reactor (12).

9. The continuous photochemical reaction system according to claim 7, characterized in that: The photocatalytic reaction device (01) further comprises a plurality of hollow coil supports (14), wherein the hollow coil supports (14) are fixed on the outside of the external coil (122); the number of the hollow coil supports (14) is 6 to 12, and the plurality of hollow coil supports (14) are arranged at equal intervals.

10. The continuous photochemical reaction system according to claim 7, characterized in that: The internal light source (11) and the external light source (13) are modularly designed. The internal light source (11) is a columnar light source. The internal light source (11) and the external light source (13) are independently selected from one or more of LED, mercury lamp, xenon lamp, and laser.

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