Continuous production system for ultraviolet light absorber intermediates

Abstract

The utility model belongs to the field of fine chemical engineering, and particularly relates to a continuous production system for an ultraviolet light absorber intermediate. The system comprises a continuous diazotization device and a continuous coupling reaction device, the continuous coupling reaction device comprises a first miniaturized split flow reactor, a first microreactor, a second miniaturized split flow reactor and a second microreactor; the method comprises the following steps: carrying out diazotization reaction on an amine acidic solution and a sodium nitrite solution in a microreactor to generate a diazonium salt solution, then carrying out coupling reaction on the diazonium salt solution and a phenol alkaline solution in a split flow reactor to generate a UV-234 intermediate crude product, and finally filtering and washing to obtain a UV-234 intermediate product; the UV-234 intermediate is prepared by adopting the system, the reaction time is short, the decomposition of diazonium salt is reduced, the product quality is improved, the raw material liquid does not need to be beaten, the material is uniform and stable for a long time, the amplification effect is basically avoided, the equipment loss is low, the operation is simple, the industrial amplification is facilitated, and the system has a good industrial application prospect.

Description

Technical Field

[0001] The utility model relates to the field of fine chemical industry, and particularly relates to a continuous production system for an ultraviolet absorber intermediate and the system. Background Technique

[0002] Ultraviolet absorbers are a crucial type of light stabilizer, which play an irreplaceable role in protecting materials from ultraviolet damage. These compounds can efficiently and selectively absorb ultraviolet light with wavelengths in the range of 290 to 400 nanometers in sunlight and other light sources, especially the short-wave ultraviolet light that is harmful to humans and materials. By absorbing these harmful rays, ultraviolet absorbers not only protect their own structures from being damaged, but also effectively slow down the aging process of polymer materials such as plastics, coatings, textiles, etc. under sunlight, extend their service life and maintain stable performance.

[0003] According to different molecular structures, ultraviolet absorbers can be divided into multiple categories, such as benzophenone type, benzotriazole type, salicylate type, and triazine type, etc. Among them, benzotriazole type has become one of the ultraviolet absorbers with the largest output and the widest application in the market due to its good compatibility with polymer materials, stable performance, low toxicity, strong absorption ability, and oil and discoloration resistance. They are widely used in various synthetic materials, providing a solid guarantee for the sun protection and anti-aging of products. And among them, UV-234, also known as 2-(2'-hydroxy-3',5-bis(a,a-dimethylbenzyl)phenyl)benzotriazole, is an ultraviolet absorber with excellent performance and has broad application prospects and market value.

[0004] At present, the main industrial synthesis route of UV-234 is to use aromatic amine and alkylphenol as raw materials, and obtain an azo intermediate through diazotization and coupling reactions, and then synthesize the target product through a ring-closure reduction reaction. This synthesis method has low cost, easily available raw materials, and simple process, but the yield is relatively low. Among them, the diazotization and coupling reactions generate an intermediate of UV-324, also known as 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole.

[0005] In traditional diazotization coupling reactions, both the diazotization and coupling reactions are accompanied by heat release and are exothermic reactions. Since diazonium salts are significantly thermosensitive and prone to decomposition under the influence of temperature, when performing the diazotization and coupling steps, the temperature control needs to be extremely precise and strict, often requiring maintenance in a low-temperature environment of 0 - 5°C. In traditional industrial practices, the production of UV-234 intermediates mostly uses batch kettle reactors. In this production mode, when the raw material liquid is mixed in the reactor at different temperatures and pH values, it often faces the challenge of uneven mass transfer and heat transfer efficiency, thereby triggering fluctuations and deviations in temperature, pH value, and chemical composition in local areas. These adverse factors will significantly exacerbate the occurrence of side reactions, ultimately affecting the overall yield and quality of the product, resulting in a decline in production efficiency and economic benefits. The continuous production of UV-234 intermediates can well solve such problems. Currently, the following relevant information is available regarding the continuous production of diazotization coupling:

[0006] Chinese Patent (CN 116969856A) reports a method for continuously synthesizing diazonium salts of weak basic aromatic amines. This utility model conducts the reaction in a tubular microreactor through the combined action of "ultrasound + microbubbles". Although the yield of diazonium salts is high, the reaction device is complex, the operation difficulty is high, and it causes a large amount of water waste, which does not conform to green production.

[0007] Chinese Patent (CN 116283650A) reports a method of atomizing and spraying a solution of molten o-amine and acid into water or an organic solvent to obtain a slurry containing o-amine salt. The slurry undergoes a diazotization reaction with a diazotizing reagent through a multi-stage pipe reactor and then undergoes a coupling reaction with phenolic substances. However, in this method, the reaction raw material is a slurry, and the operation is prone to clogging the pipe reactor.

[0008] Chinese Patent (CN 118084718 A) reports a method for continuously preparing azobenzene intermediate compounds and synthesizing benzotriazole light stabilizers. The continuous method includes mixing a diazonium salt solution and a phenolic compound solution in a mixer based on the Venturi effect to prepare a mixed fluid; passing the mixed fluid into a continuous reactor to prepare azobenzene intermediate compounds through a coupling reaction; however, the preparation of diazonium salts in this method still uses batch operation, which is time-consuming and unsafe.

[0009] Yang Shulin et al. from Shenyang Research Institute of Chemical Industry achieved continuous production of diazotization coupling reactions using a diversified microreactor, significantly broadening the synthesis range of azo pigments (see "Dyeing and Finishing" Vol. 54, No. 2, April 2017). However, unfortunately, the specific experimental conditions and fine design parameters of the microchannels were not detailed in the literature. In this synthesis process, the mixing method is collision-based or laminar contact mixing. Compared with micron-scale dispersion mixing, it may cause an increase in pigment particle size and a decrease in uniformity, thereby affecting the conversion rate of reactants.

[0010] Microreactor continuous synthesis is a technology for mixing and reacting in a pipeline system with a scale ranging from micrometers to millimeters. This technology has led to a new era in the production of chemicals and drugs. Relying on an efficient continuous-flow microchannel reaction device, with excellent heat and mass transfer performance and low liquid holdup, it enables fine dynamic control of reaction conditions. This innovation not only improves the safety and environmental protection standards of production but also significantly enhances reaction efficiency, ensuring precise control of reaction conditions. At the same time, it effectively reduces energy consumption, contributing to the green and sustainable development of the chemical industry. Regarding reports on microreactors, relevant materials include:

[0011] Chinese Utility Model Patent (CN101224405B) reports a reactor / mixer with a micro-screen hole structure, integrating continuous and dispersed phase inlet pipes, a mixed solution outlet pipe, a distribution chamber at the inlet, and a product collection chamber at the outlet. This design is suitable for the synthesis of low-viscosity products, such as the preparation of inorganic nanoparticles, but is limited in the synthesis of high-viscosity pigments. Because structures such as the collection chamber are prone to causing the accumulation and precipitation of reactants and pigments, blocking the channels, interfering with the continuous synthesis process, and affecting production efficiency and product quality.

[0012] Currently, there are still limitations in the mixing principle of the continuous synthesis technology of diazotization coupling. The micron-scale dispersion mixing process has not been fully utilized to achieve more efficient mixing enhancement. At the same time, the existing microreactor structure design has not fully considered and adapted to the special system requirements of the synthesis of high-viscosity azo pigments, lacking targeted optimization and improvement, which to a certain extent limits the wide application and performance improvement of this technology in the field of pigment synthesis. Utility Model Content

[0013] Aiming at the above deficiencies, the present utility model aims to provide a continuous production system for ultraviolet absorber intermediates, to solve the problems of diazotization blockage, heat dissipation, low yield, and easy encapsulation of raw materials, aggregation and precipitation, and channel blockage in the continuous synthesis of UV-234 intermediates.

[0014] To achieve the above object, the technical solution provided by the present utility model is as follows:

[0015] A continuous production system for ultraviolet absorber intermediates includes a continuous diazotization device and a continuous coupling reaction device; the continuous diazotization device includes a first miniaturized split-flow reactor and a first microreactor, and the continuous coupling device includes a second miniaturized split-flow reactor and a second microreactor.

[0016] Further, in the above continuous production system of the ultraviolet absorber intermediate, the continuous diazotization device includes an amine solution storage tank, a sodium nitrite aqueous solution storage tank, a first metering pump, a second metering pump, a first miniaturized split-flow reactor, a first microreactor, a diazonium salt solution buffer storage tank, and a first constant temperature bath;

[0017] The amine solution storage tank, the first metering pump and the first miniaturized split-flow reactor are connected in series through a first pipeline;

[0018] The sodium nitrite aqueous solution storage tank, the second metering pump and the first miniaturized split-flow reactor are connected in series through a second pipeline;

[0019] The first miniaturized split-flow reactor is connected to the first microreactor, the first microreactor is connected to the diazonium salt solution buffer storage tank through a sixth pipeline, and the first miniaturized split-flow reactor and the first microreactor are placed in the first constant temperature bath;

[0020] The continuous coupling device includes a diazonium salt solution buffer storage tank, a phenol solution storage tank, a third metering pump, a fourth metering pump, a second miniaturized split-flow reactor, a second microreactor, a UV-intermediate storage tank, and a second constant temperature bath;

[0021] The phenol solution storage tank, the third metering pump and the second miniaturized split-flow reactor are connected in series through a fourth pipeline;

[0022] Further, in the above continuous production system of the ultraviolet absorber intermediate, the diazonium salt solution buffer storage tank, the fourth metering pump and the second miniaturized split-flow reactor are connected in series through a third pipeline;

[0023] The second miniaturized split-flow reactor is connected to the second microreactor, the second microreactor is connected to the UV-intermediate storage tank through a fifth pipeline, and the second miniaturized split-flow reactor and the second microreactor are placed in the second constant temperature bath.

[0024] Further, in the above continuous production system of the ultraviolet absorber intermediate, a first back pressure valve is provided on the first pipeline, and the first back pressure valve is arranged on the pipeline between the first metering pump and the first miniaturized split-flow reactor.

[0025] A second back pressure valve is provided on the second pipeline, and the second back pressure valve is arranged on the pipeline between the second metering pump and the first miniaturized split-flow reactor;

[0026] A fourth back pressure valve is provided on the third pipeline, and the fourth back pressure valve is arranged on the pipeline between the third metering pump and the second miniaturized split-flow reactor;

[0027] A third back-pressure valve is provided on the fourth pipeline, and the third back-pressure valve is arranged on the pipeline between the fourth metering pump and the second miniaturized divided-flow reactor;

[0028] Furthermore, in the above-mentioned continuous production system of ultraviolet absorber intermediates, the first miniaturized divided-flow reactor and the second miniaturized divided-flow reactor have the same structure, and successively include a first connection part, a miniaturized liquid separation clip, a mixing and reaction sheet, and a second connection part from left to right.

[0029] Furthermore, in the above-mentioned continuous production system of ultraviolet absorber intermediates, a first liquid inlet pipe and a second liquid inlet pipe are provided on the first connection part;

[0030] The miniaturized liquid separation clip is provided with two rows of left and right, a number of rectangular micro-channels. The tail ends of the rectangular micro-channels in the two rows on the left and right are arranged in an interlaced manner, and the feed port of the rectangular micro-channel on the left is communicated with the first liquid inlet pipe; the feed port of the rectangular micro-channel on the right is communicated with the second liquid inlet pipe;

[0031] A mixed liquid reaction tank is provided on the mixing and reaction sheet, and the mixed liquid reaction tank is closely connected to the tail end sharp mouth;

[0032] The outlet end of the liquid reaction tank is communicated with the liquid outlet provided on the second connection part.

[0033] Furthermore, in the above-mentioned continuous production system of ultraviolet absorber intermediates, the first micro-reactor or the second micro-reactor is a spiral reaction micro-tube.

[0034] The micro-reactor can be various micro-tube reactors including micro-reaction tubes. Preferably, the inner diameter of the micro-reaction tube is 0.5 - 10.0 mm, preferably 1.0 - 4.5 mm, more preferably 1.0 - 3.0 mm; the outer diameter is 1.5 - 14.0 mm, preferably 1.5 - 7.5 mm, more preferably 1.5 - 5.0 mm, preferably 10.0 - 50.0 m, more preferably 10.0 - 30.0 m. The reaction time of the micro-reactor can be determined by changing the tube length dimension.

[0035] The micro-reaction tube in this application can be in various tube forms, such as straight tubes, bent tubes, U-shaped tubes, loop tubes, spiral tubes, etc. Preferably, in order to save space and installation, the micro-reaction tube is a micro-tube spiral reaction tube.

[0036] The working principle of this system is:

[0037] During continuous production, turn on the constant temperature bath and the constant temperature bath. When the system stabilizes to the required temperature, adjust the pressure of each backpressure valve to the required pressure value. Subsequently, turn on the first and second metering pumps to respectively extract the homogeneous solutions from the amine solution storage tank and the sodium nitrite aqueous solution storage tank and transport them into the miniaturized split-flow reactor for uniform mixing and preliminary diazotization, and then transport them into the microreactor for continuous reaction. Subsequently, the completely reacted diazotization solution is transported into the diazonium salt solution buffer storage tank for storage. When the solution in the diazonium salt solution buffer storage tank reaches a certain value, turn on the third metering pump and the fourth metering pump to respectively extract the homogeneous solutions from the phenolic solution storage tank and the diazonium salt solution buffer storage tank and transport them into the miniaturized split-flow reactor for uniform mixing and preliminary coupling, and then transport them into the microreactor for continuous reaction. Finally, the crude product of the UV-234 intermediate obtained from the complete reaction enters the UV-234 intermediate storage tank for storage. Subsequently, the crude product of the UV-234 intermediate is filtered, washed, and dried to obtain the final product, the UV-234 intermediate.

[0038] Among them, the pressures of the first backpressure valve, the second backpressure valve, the third backpressure valve, and the fourth backpressure valve are 0.8 MPa to 10 MPa.

[0039] Compared with the prior art, the beneficial effects of the present utility model are mainly reflected in:

[0040] 1. The technical solution provided by the present utility model adopts a microreactor for the continuous synthesis of the UV-234 intermediate, effectively controlling the speed of the reaction liquid and the feeding amount of the reactants in the system, enabling the reaction liquid to be divided into dozens of fine fluids in the miniaturized split-flow reactor to contact and mix with each other for preliminary reaction, and then entering the coiled microreactor for full reaction. Its structure is small and delicate, with a large specific surface area and excellent heat transfer performance per unit volume, and can quickly and effectively export the heat generated during the reaction through the heat exchange mechanism. Therefore, while increasing the feeding rate, the safety of production operations is ensured. Moreover, the diazonium salt yield is high. In the coupling reaction stage, the efficient mixing effect ensures the uniform distribution of the coupling components, effectively preventing the precipitation of the components, thus greatly improving the conversion rate of the coupling components and significantly enhancing the quality of the final product.

[0041] 2. The technical solution provided by the present utility model precisely regulates the raw material ratio, ensures that the feeding ratio of the main raw materials is close to the theoretical optimal value, and strictly follows the preset optimal reaction conditions through the automatic control system, thereby improving the reaction efficiency and product quality and reducing the generation of by-products; optimizing the mass transfer and heat transfer effects and further promoting the accuracy of temperature control.

[0042] 3. The technical solution provided by the present utility model adjusts the proportion of raw material composition. The continuous synthesis raw material liquid is a homogeneous solution system, without pulping, and will not cause particle precipitation in the solution to block the microreactor and affect subsequent production. Moreover, the whole set of devices is easy to disassemble and assemble, which is beneficial to cleaning and maintenance after the reaction stops.

[0043] 4. The process of the technical solution provided by the present utility model has low requirements for temperature control, without additional low-temperature cooling equipment, and has significant energy saving. At the same time, it avoids excessive use of sodium nitrite and coupling phenolic components, saves raw materials and reduces the burden of wastewater treatment, which is green and environmentally friendly. Brief Description of the Drawings

[0044] Figure 1 It is a schematic structural diagram of the process flow device of the present utility model;

[0045] Figure 2 It is an overall schematic diagram of the miniaturized segmented reactor device of the present utility model;

[0046] Figure 3 It is a schematic structural diagram of the first connecting part of the miniaturized segmented reactor of the present utility model;

[0047] Figure 4 It is a schematic diagram of the miniaturized liquid separation structure clip of the miniaturized segmented reactor of the present utility model;

[0048] Figure 5 It is a schematic diagram of the mixing and reaction sheet of the miniaturized segmented reactor of the present utility model;

[0049] Figure 6 It is a schematic diagram of the second connecting part of the miniaturized segmented reactor of the present utility model;

[0050] Figure 7 It is a liquid chromatogram of the UV-234 intermediate of the present utility model.

[0051] The names of the various components in the drawings are as follows:

[0052] Amine solution storage tank 1; Sodium nitrite aqueous solution storage tank 2; First metering pump 3; Second metering pump 4; First back pressure valve 5; Second back pressure valve 6; First miniaturized split flow reactor 7; First microreactor 8; First constant temperature bath 9; Diazonium salt solution buffer storage tank 10; Phenol solution storage tank 11; Third metering pump 12; Fourth metering pump 13; Third back pressure valve 15; Fourth back pressure valve 14; Second constant temperature bath 16; Second miniaturized split flow reactor 17; Second microreactor 18; UV-234 intermediate storage tank 19; First pipeline 20; Second pipeline 21; Sixth pipeline 22; Third pipeline 23; Fourth pipeline 24; Fifth pipeline 25; First connection part A; First liquid inlet pipe A1; Second liquid inlet pipe A2; Miniaturized liquid separation clip B; Mixing and reaction sheet C; Second connection part D; Cuboid microchannel B1, with a sharp end B11; Mixed liquid reaction tank C1, liquid outlet D1. Detailed implementation mode

[0053] The following will deeply elaborate on the present utility model through specific examples. These examples and descriptions are intended to clearly show the concept of the present utility model, rather than limiting the application scope of the present utility model.

[0054] In the following examples and comparative examples, without special instructions, various reagents and raw materials used are commercially available products.

[0055] Example 1

[0056] A continuous production system for an ultraviolet absorber intermediate provided in this example is referred to Figures 1-6 , and includes a continuous diazotization device and a continuous coupling reaction device;

[0057] The continuous diazotization device includes an amine solution storage tank 1, a sodium nitrite aqueous solution storage tank 2, a first metering pump 3, a second metering pump 4, a first miniaturized split flow reactor 7, a first microreactor 8, a diazonium salt solution buffer storage tank 10, and a first constant temperature bath 9;

[0058] The amine solution storage tank 1, the first metering pump 3 and the first miniaturized split flow reactor 7 are connected in series through the first pipeline 20; A first back pressure valve 5 is provided on the first pipeline 20, and the first back pressure valve 5 is arranged on the pipeline between the first metering pump 3 and the first miniaturized split flow reactor 7.

[0059] The sodium nitrite aqueous solution storage tank 2, the second metering pump 4 and the first miniaturized split flow reactor 7 are connected in series through the second pipeline 21; A second back pressure valve 6 is provided on the second pipeline 21, and the second back pressure valve 6 is arranged on the pipeline between the second metering pump 4 and the first miniaturized split flow reactor 7.

[0060] The first miniaturized split-flow reactor 7 is connected to the first micro-reactor 8 of the spiral reaction microtube. The first micro-reactor 8 is connected to the diazonium salt solution buffer storage tank 10 through the sixth pipeline 22. The first miniaturized split-flow reactor 7 and the first micro-reactor 8 are placed in the first constant temperature bath 9;

[0061] The continuous coupling device includes a diazonium salt solution buffer storage tank 10, a phenolic solution storage tank 11, a third metering pump 12, a fourth metering pump 13, a second miniaturized split-flow reactor 17, a second micro-reactor 18, a UV-234 intermediate storage tank 19, and a second constant temperature bath 16;

[0062] The phenolic solution storage tank 11, the third metering pump 12 and the second miniaturized split-flow reactor 17 are connected in series through the fourth pipeline 24. A fourth back pressure valve 14 is provided on the fourth pipeline 24, and the fourth back pressure valve 14 is arranged on the pipeline between the third metering pump 12 and the second miniaturized split-flow reactor 17;

[0063] The diazonium salt solution buffer storage tank 10, the fourth metering pump 13 and the second miniaturized split-flow reactor 17 are connected in series through the third pipeline 23. A third back pressure valve 15 is provided on the third pipeline 23, and the third back pressure valve 15 is arranged on the pipeline between the fourth metering pump 13 and the second miniaturized split-flow reactor 17;

[0064] The second miniaturized split-flow reactor 17 is connected to the second micro-reactor 18 of the spiral reaction microtube. The second micro-reactor 18 is connected to the UV-234 intermediate storage tank 19 through the fifth pipeline 25. The second miniaturized split-flow reactor 17 and the second micro-reactor 18 are placed in the second constant temperature bath 16.

[0065] More specifically, the first miniaturized split-flow reactor 7 and the second miniaturized split-flow reactor 17 have the same structure, and successively include a first connection part A, a miniaturized liquid separation clip B, a mixing and reaction sheet C, and a second connection part D from left to right. Each component is sealed by a sealing gasket in the middle.

[0066] For the convenience of liquid inlet, a first liquid inlet pipe A1 and a second liquid inlet pipe A2 are provided on the first connection part A;

[0067] The described miniaturized liquid separation clip B is provided with two rows on the left and right and a number of cuboid micro-channels B1. The tail end sharp openings B11 of the cuboid micro-channels B1 in the two rows on the left and right are arranged in an interleaved manner, and the feed inlet of the left cuboid micro-channel B1 is communicated with the first liquid inlet pipe A1; the feed inlet of the right cuboid micro-channel B1 is communicated with the second liquid inlet pipe A2; the mixing and reaction sheet C is provided with a mixed liquid reaction tank C1, and the mixed liquid reaction tank C1 is tightly connected to the tail end sharp opening B11; the outlet end of the liquid reaction tank C1 is communicated with the upper liquid outlet D1 provided on the second connecting part D.

[0068] When the system provided by the present utility model conducts continuous production, the first constant temperature bath 9 and the second constant temperature bath 16 are turned on. When the system is stable at the required temperature, the back pressure valve pressures of the first pipeline 20, the second pipeline 21, the third pipeline 23 and the fourth pipeline 24 are adjusted to the required pressure values. Subsequently, the first metering pump 3 and the second metering pump 4 are turned on to accurately extract the homogeneous solutions in the amine solution storage tank 1 and the sodium nitrite aqueous solution storage tank 2 and transport them into the first miniaturized split-flow reactor 7. The two raw material solutions are divided into dozens of fine fluids in the miniaturized liquid separation clip B and come into contact with each other, and then enter the mixing and reaction sheet C for full mixing and preliminary diazotization. Subsequently, the diazotization reaction solution enters the first micro-reactor 8 to continue the reaction. Subsequently, the fully reacted diazotization solution is transported into the diazonium salt solution buffer storage tank 10 for storage. When the solution in the diazonium salt solution buffer storage tank 10 reaches a certain value, the third metering pump 12 and the fourth metering pump 13 are turned on to extract the homogeneous solutions in the phenol solution storage tank 11 and the diazonium salt solution buffer storage tank 10 respectively and transport them into the second miniaturized split-flow reactor 17 for uniform mixing and preliminary coupling, and then transported into the second micro-reactor 18 to continue the reaction. Finally, the UV-234 intermediate crude product obtained by the complete reaction enters the UV-234 intermediate storage tank 19 for storage. Subsequently, the UV-234 intermediate crude product is filtered, washed and dried to obtain the final product UV-234 intermediate.

[0069] The present utility model adopts metering pumps to precisely control the raw material ratio, ensuring that the feeding ratio of the main raw materials is close to the optimal value of the chemical reaction theory. By means of the automatic control system of the constant temperature bath and the back pressure valve, the reaction temperature and reaction pressure are strictly controlled, thereby improving the reaction efficiency and product quality and reducing the generation of by-products.

[0070] In the diazotization reaction carried out in the continuous diazotization device, the miniaturized split-flow reactor adopted by the system of the present utility model enables the amine solution and the sodium nitrite solution to be respectively divided into dozens of fine fluids in the miniaturized liquid separation clip B and come into contact with each other, and then enter the mixing and splitting reaction sheet C for preliminary reaction, and then enter the spiral reaction microtube for further full reaction. With its small volume, large specific surface area and excellent heat transfer performance per unit volume, this technology can effectively export a large amount of heat generated by the diazotization reaction during the reaction process through the heat exchange mechanism, avoiding the decomposition and explosion of diazonium salts caused by the high temperature of the system. Thus, while increasing the feeding rate, the safety of production operation is ensured, and the yield of diazonium salts is high.

[0071] In the coupling reaction carried out in the continuous coupling device, the efficient mixing reaction effect of the miniaturized split-flow reactor ensures the uniform distribution of coupling components, effectively preventing the precipitation of components, thereby greatly improving the conversion rate of coupling components. At the same time, in the system, through the large specific surface area and excellent heat transfer performance per unit volume, a large amount of energy generated by the coupling reaction can be quickly removed from the reaction, avoiding the decomposition of the diazonium salt, the reaction raw material. This improvement not only significantly improves the quality of the final UV-234 intermediate product. At the same time, by connecting the continuous diazotization device and the continuous coupling device, the easily decomposed diazonium salt can react with phenols in a timely manner after being generated. Compared with the batch reaction, the present utility model greatly reduces the loss of diazonium salts.

[0072] In order to better use the technical solution provided by this application, the following gives a method for preparing an ultraviolet absorber by using the continuous production system of the ultraviolet absorber intermediate provided by this application. The specific method is as follows:

[0073] 1) At room temperature (25 °C), take 34.52 g of m-nitroaniline, 75 g of water and 75 g of 98% concentrated sulfuric acid and dissolve them in a 250 ml beaker, and stir evenly to obtain a homogeneous amine solution;

[0074] 2) Take 18.95 g of sodium nitrite and dissolve it in 250 g of water, and stir evenly to obtain a homogeneous sodium nitrite solution;

[0075] 3) Take 82.615 g of 2,4-dicumylphenol, 61 g of sodium hydroxide, 1.5 g of sodium dodecylbenzenesulfonate and 750 ml of methanol in a 1000 ml beaker and stir evenly to obtain a homogeneous phenol solution;

[0076] 4) At room temperature, start the metering pump to control the flow rate of the amine solution at 12 ml / min and the flow rate of the sodium nitrite solution at 20 ml / min. The two solutions enter the first miniaturized segmented flow reactor 7 simultaneously and continuously for rapid mixing and preliminary reaction to obtain the mixed reaction solution A. The mixed reaction solution A then enters the first microreactor 8 for a reaction residence time of 40 s, a reaction temperature of 20 °C, and a reaction pressure of 3 MPa. Subsequently, the completely reacted diazotization solution is transported into the diazonium salt solution buffer storage tank 10. At the same time, start the metering pump to control the flow rate of the phenolic solution at 64 ml / min and the flow rate of the diazonium salt solution at 32 ml / min. The two solutions enter the second miniaturized segmented flow reactor 17 simultaneously and continuously for rapid mixing and preliminary reaction to obtain the mixed reaction solution B. The mixed reaction solution B enters the second microreactor 18 again for a reaction residence time of 12 s, a reaction temperature of 20 °C, and a reaction pressure of 5 MPa to obtain a solid-liquid mixture of the crude product of the UV-234 intermediate. After filtration, the crude product of the UV-234 intermediate is obtained. First, use a mixed detergent with methanol:water = 1:1 to wash and filter the crude product of the UV-234 intermediate, repeating three times; then use pure water to wash and filter the crude product of the UV-234 intermediate, repeating three times; then dry at 70 °C for 12 h to obtain a yield of 90.94%; the chromatogram is referred to Figure 7 。

[0077] The preferred implementation process conditions and methods of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above implementation process conditions and methods. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical process conditions of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0078] In addition, any combination can be made between various different implementation methods of the present invention, as long as it does not violate the idea of the present invention, it should also be regarded as the content disclosed by the present invention and be protected.

Claims

1. A continuous production system for an ultraviolet absorber intermediate, characterized in that: It includes a continuous diazotization device and a continuous coupling reaction device; the continuous diazotization device includes a first miniaturized segmented flow reactor (7) and a first microreactor (8), and the continuous coupling reaction device includes a second miniaturized segmented flow reactor (17) and a second microreactor (18).

2. The continuous production system of the ultraviolet absorber intermediate according to claim 1, wherein: The continuous diazotization device includes an amine solution storage tank (1), a sodium nitrite aqueous solution storage tank (2), a first metering pump (3), a second metering pump (4), a first miniaturized segmented flow reactor (7), a first microreactor (8), a diazonium salt solution buffer storage tank (10), and a first constant temperature bath (9); The amine solution storage tank (1), the first metering pump (3) and the first miniaturized segmented flow reactor (7) are connected in series through a first pipeline (20); The sodium nitrite aqueous solution storage tank (2), the second metering pump (4) and the first miniaturized segmented flow reactor (7) are connected in series through a second pipeline (21); The first miniaturized segmented flow reactor (7) is connected to the first microreactor (8), the first microreactor (8) is connected to the diazonium salt solution buffer storage tank (10) through a sixth pipeline (22), and the first miniaturized segmented flow reactor (7) and the first microreactor (8) are placed in the first constant temperature bath (9).

3. The continuous production system of the ultraviolet absorber intermediate according to claim 2, wherein: The continuous coupling reaction device includes a diazonium salt solution buffer storage tank (10), a phenol solution storage tank (11), a third metering pump (12), a fourth metering pump (13), a second miniaturized segmented flow reactor (17), a second microreactor (18), a UV-234 intermediate storage tank (19), and a second constant temperature bath (16); The phenol solution storage tank (11), the third metering pump (12) and the second miniaturized segmented flow reactor (17) are connected in series through a fourth pipeline (24); The diazonium salt solution buffer storage tank (10), the fourth metering pump (13) and the second miniaturized segmented flow reactor (17) are connected in series through a third pipeline (23); The second miniaturized segmented flow reactor (17) is connected to the second microreactor (18), the second microreactor (18) is connected to the UV-234 intermediate storage tank (19) through a fifth pipeline (25), and the second miniaturized segmented flow reactor (17) and the second microreactor (18) are placed in the second constant temperature bath (16).

4. The continuous production system of the ultraviolet absorber intermediate according to claim 3, wherein: A first back pressure valve (5) is provided on the first pipeline (20), and the first back pressure valve (5) is arranged on the pipeline between the first metering pump (3) and the first miniaturized segmented flow reactor (7); A second back pressure valve (6) is provided on the second pipeline (21), and the second back pressure valve (6) is arranged on the pipeline between the second metering pump (4) and the first miniaturized segmented flow reactor (7); A third back pressure valve (15) is provided on the third pipeline (23), and the third back pressure valve (15) is arranged on the pipeline between the fourth metering pump (13) and the second miniaturized segmented flow reactor (17); A fourth back-pressure valve (14) is provided on the fourth pipeline (24), and the fourth back-pressure valve (14) is arranged on the pipeline between the third metering pump (12) and the second miniaturized split-flow reactor (17).

5. The continuous production system of the ultraviolet absorber intermediate according to claim 3, characterized in that: The first miniaturized split-flow reactor (7) and the second miniaturized split-flow reactor (17) have the same structure and sequentially include a first connection part (A), a miniaturized liquid separation clip (B), a mixing and reaction sheet (C), and a second connection part (D) from left to right.

6. The continuous production system of the ultraviolet absorber intermediate according to claim 5, characterized in that: A first liquid inlet pipe (A1) and a second liquid inlet pipe (A2) are provided on the first connection part (A).

7. The continuous production system of the ultraviolet absorber intermediate according to claim 6, wherein: On the miniaturized liquid separation clip (B), there are two rows of left and right, a number of rectangular micro-channels (B1). The tail end pointed openings (B11) of the two rows of left and right rectangular micro-channels (B1) are arranged staggeredly, and the feed port of the left rectangular micro-channel (B1) is communicated with the first liquid inlet pipe (A1); the feed port of the right rectangular micro-channel (B1) is communicated with the second liquid inlet pipe (A2).

8. The continuous production system of the ultraviolet absorber intermediate according to claim 7, characterized in that: A mixed liquid reaction tank (C1) is provided on the mixing and reaction sheet (C), and the mixed liquid reaction tank (C1) is tightly connected to the tail end pointed opening (B11).

9. The continuous production system of the ultraviolet absorber intermediate according to claim 8, wherein: The outlet end of the liquid reaction tank (C1) is communicated with the liquid outlet (D1) provided on the second connection part (D).

10. The continuous production system of the ultraviolet absorber intermediate according to claim 1, wherein: The first micro-reactor (8) and the second micro-reactor (18) are both spiral reaction micro-tubes.

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