Continuous production method of ultraviolet light absorber intermediate

Abstract

The invention belongs to the field of fine chemical engineering, and particularly relates to a continuous production method of an ultraviolet light absorber intermediate. 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 the UV-234 intermediate product. According to the method provided by the invention, the diazotization and coupling reaction time for preparing the UV-234 intermediate is effectively shortened, the decomposition of diazonium salt is reduced, the product quality is improved, the raw material solution does not need to be beaten, the material is uniform and stable for a long time, the amplification effect is basically avoided, the loss of equipment is low, the operation is simple, industrial amplification is facilitated, and the method has a good industrial application prospect.

Description

Technical Field

[0001] The invention relates to the field of fine chemicals, in particular to a continuous production method and system for an ultraviolet absorber intermediate. Background Art

[0002] UV absorbers are a class of vital light stabilizers that play an irreplaceable role in protecting materials from UV damage. These compounds can efficiently and selectively absorb UV rays in the wavelength range of 290 to 400 nanometers from sunlight and other light sources, especially short-wave ultraviolet rays that are harmful to humans and materials. By absorbing these harmful rays, UV absorbers not only protect their own structures from damage, but also effectively slow down the aging process of polymer materials such as plastics, coatings, and textiles in the sun, extending their service life and maintaining stable performance.

[0003] According to the different molecular structures, UV absorbers can be divided into several categories, such as benzophenones, benzotriazoles, salicylates and triazines. Among them, benzotriazoles have become one of the most widely used and produced UV absorbers on the market due to their good compatibility with polymer materials, stable performance, low toxicity, strong absorption capacity, oil resistance and discoloration resistance. They are widely used in various synthetic materials, providing a solid guarantee for the sun protection and anti-aging of products. Among them, UV-234, also known as 2-(2'-hydroxy-3',5'bis(a,a-dimethylbenzyl)phenyl)benzotriazole, is an excellent UV absorber with 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, obtain azo intermediates through diazo and coupling reactions, and then synthesize the target product through closed-loop reduction reaction. This synthesis method has low cost, easy-to-obtain raw materials, and simple process, but the yield is relatively low. Among them, the diazo and coupling reactions generate the intermediate of UV-324, also known as 2-(2'-hydroxy-3', 5'-dicumylphenyl) phenyltriazole.

[0005] In traditional diazotization and coupling reactions, both diazotization and coupling reactions are accompanied by the release of heat and are exothermic reactions. Since diazonium salts have significant thermal sensitivity and are easily affected by temperature and decomposed, the temperature control must be extremely precise and strict when performing the diazotization and coupling steps, and it is often necessary to maintain a low temperature environment of 0 to 5°C. In traditional industrial practice, the production of UV-234 intermediates is mostly carried out in intermittent kettle reactors. Under this production mode, when the raw material liquid is mixed at different temperatures and pH values ​​in the reactor, it often faces the challenge of uneven mass transfer and heat transfer efficiency, which in turn causes fluctuations and deviations in temperature, pH value and chemical composition in local areas. These unfavorable factors will significantly aggravate the occurrence of side reactions, ultimately affecting the overall yield and quality of the product, leading to a decrease in production efficiency and economic benefits. The continuous production of UV-234 intermediates can solve such problems very well. At present, the following relevant information is available on the continuous production of diazotization and coupling:

[0006] A Chinese patent (CN 116969856A) reported a method for continuously synthesizing diazonium salts of weakly alkaline aromatic amines. The invention uses the combined action of "ultrasound + microbubbles" to react in a tubular microreactor. Although the diazonium salt yield is high, the reaction device is complex, the operation is difficult, and a large amount of water is wasted, which is not in line with green production.

[0007] Chinese patent (CN 116283650A) reports a method of spraying a molten solution of o-amine and acid into water or an organic solvent to obtain a slurry containing o-amine acid salt, and then subjecting the slurry to a diazotization reaction with a diazotizing agent through a multi-stage pipeline reactor, and then coupling with a phenolic substance. However, the reaction raw material of this method is a slurry, and the operation is prone to cause blockage of the pipeline reactor.

[0008] A Chinese patent (CN 118084718 A) reports a continuous synthesis method for preparing azobenzene intermediate compounds and 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 an azobenzene intermediate compound through a coupling reaction; however, the preparation of the diazonium salt in this method still adopts intermittent operation, which is time-consuming and unsafe.

[0009] Yang Shulin and others from Shenyang Institute of Chemical Industry used diversified microreactors to realize continuous production of diazo coupling reaction, which significantly broadened the synthesis range of azo pigments (see "Dyeing and Coloring" Volume 54, Issue 2, April 2017). However, unfortunately, the literature did not describe in detail the specific experimental conditions and microchannel fine design parameters. In this synthesis process, the mixing method is collision or laminar contact mixing, which may cause the pigment particle size to increase and the uniformity to decrease compared with micron-level dispersion mixing, thereby affecting the conversion rate of the reactants.

[0010] Micro-reaction continuous synthesis is a technology that mixes and reacts in micron to millimeter-scale pipeline systems. This technology leads to a new era of chemical and drug production. Relying on high-efficiency continuous flow microchannel reaction devices, this technology achieves fine dynamic control of reaction conditions with its excellent heat and mass transfer performance and low liquid retention. This innovation not only improves the safety and environmental protection standards of production, but also significantly improves reaction efficiency and ensures precise control of reaction conditions. At the same time, it effectively reduces energy consumption and contributes to the green and sustainable development of the chemical industry. For reports on microreactors, relevant information includes:

[0011] A Chinese invention patent (CN101224405B) reported a reactor / mixer with a micro-sieve structure, which integrates continuous phase and dispersed phase inlet pipes, mixed solution outlet pipes, and 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 the collection chamber and other structures are prone to cause reactants and pigments to accumulate and precipitate, blocking the channel, interfering with the continuous synthesis process, and affecting production efficiency and product quality.

[0012] At present, the continuous synthesis technology of diazo coupling still has limitations in the mixing principle, and has not yet fully utilized the micron-level dispersion mixing process 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 high-viscosity azo pigment synthesis, and lacks 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. Summary of the invention

[0013] In view of the above shortcomings, the present invention aims to provide a continuous production method for ultraviolet absorber intermediates to solve the problems of diazotization blockage, heat dissipation, low yield, easy encapsulation of raw materials, aggregation and precipitation, and channel blockage faced in the continuous synthesis of UV-234 intermediates.

[0014] To achieve the above purpose, the technical solution provided by the present invention is as follows:

[0015] A method for continuous production of ultraviolet absorber intermediates, comprising a system for continuous production of ultraviolet absorber intermediates, wherein the system comprises a continuous diazotization device and a continuous coupling reaction device; the continuous diazotization device comprises a first miniaturized segmented flow reactor and a first microreactor, and the continuous coupling device comprises a second miniaturized segmented flow reactor and a second microreactor;

[0016] The method comprises the following steps:

[0017] 1) the amine solution and the sodium nitrite solution are respectively and continuously introduced into the first micro-scale split flow reactor at a rate of 5 ml to 40 ml / min to mix and react to obtain a mixed reaction solution A, and the mixed reaction solution A is then introduced into the first micro-reactor to react to obtain a diazonium salt solution;

[0018] 2) the diazonium salt solution and the phenol solution are respectively and continuously introduced into the second micro-scale split flow reactor at a rate of 5 ml to 60 ml / min to mix and react to obtain a mixed reaction solution B, and the mixed reaction solution B is then introduced into the second micro-reactor to undergo a coupling reaction to generate a crude UV-234 intermediate product;

[0019] 3) The crude UV-234 intermediate product is filtered and washed to obtain a UV-234 intermediate product;

[0020] Wherein: the amine solution is a homogeneous solution of concentrated sulfuric acid, m-nitroaniline and water;

[0021] The phenol solution is a homogeneous solution of methanol, surfactant, sodium hydroxide and 2,4-dicumylphenol.

[0022] Furthermore, in the above-mentioned continuous production method of ultraviolet absorber intermediates, the molar ratio of the amine solution to concentrated sulfuric acid, water and m-nitroaniline is 1-4:100-400:1; preferably 3-4:100-150:1.

[0023] Furthermore, in the above-mentioned continuous production method of ultraviolet absorber intermediates, the molar ratio of sodium nitrite to water in the sodium nitrite solution is 1:0.73-6.05.

[0024] Furthermore, in the above-mentioned continuous production method of ultraviolet absorber intermediates, the molar ratio of methanol, sodium hydroxide and 2,4-dicumylphenol is 250-1500:5.5-8:1.

[0025] Furthermore, in the above-mentioned continuous production method of ultraviolet absorber intermediates, the surfactant is one of sodium dodecylbenzene sulfonate, polyethylene glycol, and hexadecyltrimethylammonium bromide, and 2 to 9 g of the surfactant is added per mole of 2,4-dicumylphenol.

[0026] The mixed reaction solution A is kept in the first microreactor at 5-50° C. for 10-50 seconds; and the mixed reaction solution B is kept in the second microreactor at 5-50° C. for 4-20 seconds.

[0027] Furthermore, in the above-mentioned continuous production method of ultraviolet absorber intermediates, 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 thermostatic tank;

[0028] The amine solution storage tank, the first metering pump and the first miniaturized split flow reactor are connected in series via a first pipeline;

[0029] The sodium nitrite aqueous solution storage tank, the second metering pump and the first miniaturized split flow reactor are connected in series via a second pipeline;

[0030] The first micro-scale segmented flow reactor is connected to the first micro-reactor, the first micro-reactor is connected to the diazonium salt solution buffer storage tank through a third pipeline, and the first micro-scale segmented flow reactor and the first micro-reactor are placed in a first thermostatic bath;

[0031] The continuous coupling device comprises 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 tank;

[0032] The phenol solution storage tank, the third metering pump and the second miniaturized split flow reactor are connected in series via a fourth pipeline;

[0033] The diazonium salt solution buffer storage tank, the fourth metering pump and the second miniaturized split flow reactor are connected in series via a third pipeline;

[0034] The second micro-scale segmented flow reactor is connected to the second micro-reactor, the second micro-reactor is connected to the UV-intermediate storage tank through a fifth pipeline, and the second micro-scale segmented flow reactor and the second micro-reactor are placed in a second thermostatic bath.

[0035] Furthermore, in the above-mentioned continuous production method of ultraviolet absorber intermediates, 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.

[0036] The second pipeline is provided with a second back pressure valve, and the second back pressure valve is arranged on the pipeline between the second metering pump and the first miniaturized split flow reactor;

[0037] The third pipeline is provided with a third back pressure valve, and the third back pressure valve is arranged on the pipeline between the third metering pump and the second miniaturized split flow reactor;

[0038] The fourth pipeline is provided with a fourth back pressure valve, and the fourth back pressure valve is arranged on the pipeline between the fourth metering pump and the second miniaturized split flow reactor;

[0039] Furthermore, in the above-mentioned continuous production method of ultraviolet absorber intermediates, the first miniaturized segmented flow reactor and the second miniaturized segmented flow reactor have the same structure, and include, from left to right, a first connecting part, a miniaturized liquid separation clamp, a mixing and separation reaction piece, and a second connecting part.

[0040] Furthermore, in the above-mentioned continuous production method of the ultraviolet absorber intermediate, the first connecting portion is provided with a first liquid inlet pipe and a second liquid inlet pipe;

[0041] The miniaturized liquid separation clamp is provided with two rows of rectangular micro-channels on the left and right sides, and the tail ends of the rectangular micro-channels in the two rows are arranged alternately, and the feed port of the left rectangular micro-channel is connected to the first liquid inlet pipe; the feed port of the right rectangular micro-channel is connected to the second liquid inlet pipe;

[0042] The mixing and splitting reaction piece is provided with a mixed liquid reaction groove, and the mixed liquid reaction groove is tightly connected to the tail end tip;

[0043] The outlet end of the liquid reaction tank is communicated with the liquid outlet arranged on the second connecting part.

[0044] Furthermore, in the above-mentioned continuous production method of ultraviolet absorber intermediates, the first microreactor or the second microreactor is a spiral reaction microtube.

[0045] The microreactor can be various microtube reactors including microreaction tubes. Preferably, the inner diameter of the microreaction 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 microreactor can be determined by changing the tube length.

[0046] The micro-reaction tubes described in the present application may be in the form of tubes of various shapes, such as straight tubes, curved tubes, U-shaped tubes, ring tubes, spiral tubes, etc. Preferably, in order to save space and installation, the micro-reaction tubes are micro-tube spiral reaction tubes.

[0047] The system works as follows:

[0048] During continuous production, the thermostatic bath and the thermostatic bath are turned on. When the system stabilizes to the required temperature, the pressure of each back pressure valve is adjusted to the required pressure value, and then the first and second metering pumps are turned on to extract the homogeneous solutions of the amine solution storage tank and the sodium nitrite aqueous solution storage tank respectively, and transport them into the miniaturized split flow reactor for uniform mixing and preliminary diazotization, and then transport them into the microreactor for further reaction, and then the diazotization solution after the complete reaction 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, the third metering pump is turned on, and the fourth metering pump extracts the homogeneous solutions of the phenol solution storage tank and the diazonium salt solution buffer storage tank respectively, and transports them into the miniaturized split flow reactor for uniform mixing and preliminary coupling, and then transports them into the microreactor for further reaction, and finally the crude UV-234 intermediate product obtained after the complete reaction is stored in the UV-234 intermediate storage tank. The crude UV-234 intermediate product is then filtered, washed, and dried to obtain the final product UV-234 intermediate.

[0049] Among them, the pressures of the first back-pressure valve, the second back-pressure valve, the third back-pressure valve, and the fourth back-pressure valve are 0.8 MPa to 10 MPa.

[0050] Preferably, the molar ratio of methanol-sodium hydroxide-2,4-dicumylphenol is 500-1000:5.5-8:1, and 3-5 g of surfactant is added per 1 mol of 2,4-dicumylphenol.

[0051] Preferably, the added surfactant is sodium dodecylbenzene sulfonate.

[0052] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:

[0053] 1. The technical solution provided by the present invention adopts a microreactor for continuous synthesis of UV-234 intermediates, effectively controls the speed of the reaction liquid in the system, the feed amount of the reactants, so that the reaction liquid can be divided into dozens of fine fluids in a miniaturized split flow reactor for contact and mixing to perform a preliminary reaction, and then enter the coil-type microreactor for full reaction. It has a compact structure, a large specific surface area, and excellent heat transfer performance per unit volume. It can quickly and effectively export the heat generated during the reaction through a heat exchange mechanism, thereby ensuring the safety of production operations while increasing the feeding rate. In addition, the diazonium salt yield is high. In the coupling reaction stage, the efficient mixing effect ensures the uniform distribution of the coupling components, effectively prevents the precipitation of the components, thereby greatly improving the conversion rate of the coupling components, and significantly improving the quality of the final product.

[0054] 2. The technical solution provided by the present invention implements precise control of the raw material ratio, ensuring that the main raw material feed ratio 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.

[0055] 3. The technical solution provided by the present invention adjusts the raw material composition ratio. The continuous synthesis raw material liquid is a homogeneous solution system, which does not require slurrying and will not cause particle precipitation in the solution in the micro-reaction system, thereby clogging the micro-reactor and affecting subsequent production. The whole set of equipment is easy to disassemble and assemble, which is conducive to subsequent cleaning and maintenance after the reaction is stopped.

[0056] 4. The technical solution provided by the present invention has low requirements for temperature control, does not require additional low-temperature cooling equipment, and saves energy significantly. At the same time, it avoids excessive use of sodium nitrite and coupling phenol components, saves raw materials and reduces the burden of wastewater treatment, which is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a schematic diagram of the process device structure of the present invention;

[0058] Figure 2 It is an overall schematic diagram of the miniaturized segmented reactor device of the present invention;

[0059] Figure 3 This is a schematic structural diagram of the first connecting portion of the miniaturized segmented reactor of the present invention;

[0060] Figure 4 It is a schematic diagram of the miniaturized liquid separation structure clip of the miniaturized segmented reactor of the present invention;

[0061] Figure 5 It is a schematic diagram of a mixing and splitting reaction piece of a miniaturized splitting reactor of the present invention;

[0062] Figure 6 It is a schematic diagram of the second connection part of the miniaturized segmented reactor of the present invention;

[0063] Figure 7 It is the liquid chromatogram of the UV-234 intermediate of the present invention.

[0064] The names of the components in the accompanying drawings are as follows:

[0065] 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 thermostatic 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 14; fourth back pressure valve 15; second thermostatic bath 16; second miniaturized split flow reactor 17; second microreactor 18; UV-234 intermediate storage tank 19; first pipeline 20; second pipeline 21; third pipeline 22; third pipeline 23; fourth pipeline 24; first connecting part A; first liquid inlet pipe A1; second liquid inlet pipe A2; miniaturized liquid separation clip B; mixing reaction piece C; second connecting part D; rectangular microchannel B1, tail end tip B11; mixed liquid reaction tank C1, liquid outlet D1. DETAILED DESCRIPTION

[0066] The present invention will be further described below through specific examples. These examples and descriptions are intended to clearly illustrate the concept of the present invention rather than to limit the scope of application of the present invention.

[0067] In the following examples and comparative examples, unless otherwise specified, all reagents and raw materials used are commercially available products.

[0068] Example 1

[0069] This embodiment provides a continuous production system for ultraviolet absorber intermediates. Figure 1-Figure 6 , including a continuous diazotization device and a continuous coupling reaction device;

[0070] The continuous diazotization device comprises 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 thermostatic tank 9;

[0071] The amine solution storage tank 1, the first metering pump 3 and the first miniaturized split flow reactor 7 are connected in series through a 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.

[0072] 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; 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.

[0073] The first micro-scale segmented flow reactor 7 is connected to the first micro-reactor 8 of the spiral reaction micro-tube, the first micro-reactor 8 is connected to the diazonium salt solution buffer storage tank 10 through the third pipeline 22, and the first micro-scale segmented flow reactor 7 and the first micro-reactor 8 are placed in a first thermostatic bath 9;

[0074] The continuous coupling device comprises 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 split flow reactor 17, a second microreactor 18, a UV-234 intermediate storage tank 19 and a second thermostatic bath 16;

[0075] The phenol solution storage tank 11, the third metering pump 12 and the second miniaturized split flow reactor 17 are connected in series through a fourth pipeline 24; a fourth back pressure valve 15 is provided on the fourth pipeline 23, and the fourth back pressure valve 15 is arranged on the pipeline between the fourth metering pump 13 and the second miniaturized split flow reactor 17;

[0076] 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 a third pipeline 23; a third back pressure valve 14 is provided on the third pipeline 23, and the third back pressure valve 14 is arranged on the pipeline between the third metering pump 12 and the second miniaturized split flow reactor 17;

[0077] The second micro-reactor 17 is connected to the second micro-reactor 18 of the spiral reaction micro-tube, and the second micro-reactor 18 is connected to the UV-234 intermediate storage tank 9 through the fifth pipeline 24. The second micro-reactor 17 and the second micro-reactor 18 are placed in the second thermostatic bath 16.

[0078] More specifically, the first micronized segmented flow reactor 7 has the same structure as the first micronized segmented flow reactor 17, and includes, from left to right, a first connecting portion A, a micronized liquid separation clamp B, a mixing and separation reaction plate C, and a second connecting portion D, and each component is sealed by a sealing gasket.

[0079] In order to facilitate liquid inlet, the first connecting portion A is provided with a first liquid inlet pipe A1 and a second liquid inlet pipe A2;

[0080] The miniaturized liquid separation clamp B is provided with two rows of rectangular microchannels B1 on the left and right sides, and the tail end sharp openings B11 of the two rows of rectangular microchannels B1 are arranged alternately, and the feed port of the left rectangular microchannel B1 is connected to the first liquid inlet pipe A1; the feed port of the right rectangular microchannel B1 is connected to the second liquid inlet pipe A2; the mixing and separation reaction plate 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 connected to the upper liquid outlet D1 arranged on the second connecting part D.

[0081] When the system provided by the present invention is in continuous production, the first thermostatic bath 9 and the second thermostatic bath 16 are turned on, and when the system is stabilized to 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, and then the first metering pump 3 is turned on, and the second metering pump 4 respectively accurately extracts the homogeneous solutions of the amine solution storage tank 1 and the sodium nitrite aqueous solution storage tank 2 and transports them into the first miniaturized split flow reactor 7, and the two raw material solutions are divided into dozens of fine fluids in the miniaturized liquid separation clamp B, contact each other, and then enter the mixing reaction piece C for full mixing and preliminary diazotization, and then the diazotization reaction liquid enters the first microreactor 8 to continue the reaction, and then the diazotization solution after the reaction is completely transported to the diazonium salt solution buffer storage tank 10 for storage. When the solution of the diazonium salt solution buffer storage tank 10 reaches a certain value, the third metering pump 12 is turned on, and the fourth metering pump 13 extracts the homogeneous solution of the phenol solution storage tank 11 and the diazonium salt solution buffer storage tank 10 respectively, and transports them into the second micro-scale split flow reactor 17 for uniform mixing and preliminary coupling, and then transports them into the second microreactor 18 for further reaction, and finally the crude product of UV-234 intermediate obtained by the complete reaction enters the UV-234 intermediate storage tank 19 for storage. Subsequently, the crude product of UV-234 intermediate is filtered, washed, and dried to obtain the final product UV-234 intermediate.

[0082] The present invention adopts a metering pump to implement precise regulation of the raw material ratio, ensuring that the main raw material feed ratio is close to the optimal value of the chemical reaction theory, and strictly controls the reaction temperature and reaction pressure through the automatic control system constant temperature tank and back pressure valve, thereby improving the reaction efficiency and product quality and reducing the generation of by-products.

[0083] In the diazotization reaction carried out in the continuous diazotization device, the miniaturized segmented flow reactor adopted by the system of the present invention can make the amine solution and the sodium nitrite solution be divided into dozens of fine fluids in the miniaturized liquid separation clip B, contact each other and then enter the mixed reaction plate C for preliminary reaction, and then enter the spiral reaction microtube for the next step of full reaction. With its small size, large specific surface area and excellent unit volume heat transfer performance, this technology can quickly and effectively conduct a large amount of heat generated by the diazotization reaction during the reaction through the heat exchange mechanism, avoiding the decomposition and explosion of the diazonium salt caused by the high temperature of the system, thereby ensuring the safety of production operation while improving the feeding rate, and the diazonium salt yield is high.

[0084] In the coupling reaction carried out by the continuous coupling device, the efficient mixing reaction effect of the miniaturized split flow reactor ensures the uniform distribution of the coupling components, effectively prevents the precipitation of the components, thereby greatly improving the conversion rate of the coupling components. At the same time, through the huge specific surface area and excellent unit volume heat transfer performance in the system, a large amount of energy generated by the coupling reaction can be quickly removed from the reaction, avoiding the decomposition of the reaction raw material diazonium salt. 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 diazonium salt that is easy to decompose can react with the phenol coupling in time after being generated. Compared with the intermittent reaction, the present invention greatly reduces the loss of diazonium salt.

[0085] Example 2

[0086] This embodiment provides a method for continuous production of ultraviolet absorber intermediates, which is carried out using the system provided in Example 1. The specific method is as follows:

[0087] 1) At room temperature (25°C), dissolve 34.52g of m-nitroaniline, 75g of water and 75g of 98% concentrated sulfuric acid in a 250ml beaker and stir to obtain a homogeneous amine solution;

[0088] 2) Dissolve 18.95 g of sodium nitrite in 250 g of water and stir to obtain a homogeneous sodium nitrite solution;

[0089] 3) 82.615 g of 2,4-dicumylphenol, 61 g of sodium hydroxide, 1.5 g of sodium dodecylbenzene sulfonate and 750 ml of methanol were mixed in a 1000 ml beaker to obtain a homogeneous phenol solution;

[0090] 4) At room temperature, the metering pump is turned on to control the flow rate of the amine solution to 12 ml / min, and the flow rate of the sodium nitrite solution is controlled to 20 ml / min. The two solutions simultaneously and continuously enter the first micro-split flow reactor 7 for rapid mixing and preliminary reaction to obtain a mixed reaction solution A; the mixed reaction solution A then enters the first micro-reactor 8 for a reaction residence time of 40 s, a reaction temperature of 20° C., and a reaction pressure of 3 MPa; then the diazotized solution that has reacted completely is transported to the diazonium salt solution buffer storage tank 10, and the metering pump is turned on to control the flow rate of the phenol solution to 64 ml / min, and the flow rate of the diazonium salt solution to 32 ml / min. The two solutions simultaneously and continuously enter The mixed reaction solution B was then introduced into the second micro-scale split flow reactor 17 for rapid mixing and preliminary reaction to obtain a mixed reaction solution B. The mixed reaction solution B was again introduced into the second micro-reactor 18 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 a crude UV-234 intermediate product. After filtration, a crude UV-234 intermediate product was obtained. The crude UV-234 intermediate product was first washed and filtered with a mixed detergent of methanol: water in a ratio of 1:1, and the washing and filtering were repeated three times; then the crude UV-234 intermediate product was washed and filtered with pure water, and the washing and filtering were repeated three times; then it was dried at 70° C. for 12 h, and the yield was 90.94%. The chromatogram thereof can be found at Figure 7 .

[0091] Example 3

[0092] This embodiment provides a method for continuous production of ultraviolet absorber intermediates, which is carried out using the system provided in Example 1. The specific method is as follows:

[0093] 1) At room temperature (25°C), dissolve 13.808g of m-nitroaniline, 30g of water and 30g of 98% concentrated sulfuric acid in a 100ml beaker and stir to obtain a homogeneous amine solution;

[0094] 2) Dissolve 7.38 g of sodium nitrite in 100 g of water and stir to obtain a homogeneous sodium nitrite solution;

[0095] 3) 33.046 g of 2,4-dicumylphenol, 24.20 g of sodium hydroxide, 0.6 g of sodium dodecylbenzene sulfonate and 300 ml of methanol were mixed in a 500 ml beaker to obtain a homogeneous phenol solution;

[0096] 4) At room temperature, the metering pump is turned on to control the flow rate of the amine solution to 15 ml / min, and the flow rate of the sodium nitrite solution to 25 ml / min. The two solutions simultaneously and continuously enter the first miniaturized split flow reactor 7 for rapid mixing and preliminary reaction to obtain a mixed reaction solution A; the mixed reaction solution A enters the first microreactor 8 for a reaction residence time of 45 s, a reaction temperature of 20° C., and a reaction pressure of 3 MPa. Subsequently, the completely reacted diazotized solution is transported to the diazonium salt solution buffer storage tank 10. At the same time, the metering pump is turned on to control the flow rate of the phenol solution to 64 ml / min, and the flow rate of the diazonium salt solution is controlled to 32 ml / min. The two solutions simultaneously and continuously enter the second miniaturized split flow reactor (17) for rapid mixing and preliminary reaction to obtain a mixed reaction solution B. The mixed reaction solution B enters the second microreactor 18 for a reaction residence time of 15 s, a reaction temperature of 20°C, and a reaction pressure of 5 MPa to obtain a UV-234 intermediate crude product solid-liquid mixture. After filtering, a UV-234 intermediate crude product is obtained. The UV-234 intermediate crude product is first washed and filtered with a mixed detergent of methanol: water in a ratio of 1:1, and the washing is repeated three times; then the UV-234 intermediate crude product is washed and filtered with pure water, and the washing is repeated three times; then it is dried at 70°C for 12 hours to obtain a yield of 91.48%.

[0097] Example 4

[0098] This embodiment provides a method for continuous production of ultraviolet absorber intermediates, which is carried out using the system provided in Example 1. The specific method is as follows:

[0099] 1) At room temperature (25°C), dissolve 20.112g of m-nitroaniline, 45g of water and 45g of 98% concentrated sulfuric acid in a 100ml beaker and stir to obtain a homogeneous amine solution;

[0100] 2) Dissolve 11.37 g of sodium nitrite in 150 g of water and stir to obtain a homogeneous sodium nitrite solution;

[0101] 3) 49.569 g of 2,4-dicumylphenol, 36.60 g of sodium hydroxide, 0.9 g of sodium dodecylbenzene sulfonate and 450 ml of methanol were mixed in a 500 ml beaker to obtain a homogeneous phenol solution;

[0102] 4) At room temperature, the metering pump is turned on to control the flow rate of the amine solution to 20 ml / min, and the flow rate of the sodium nitrite solution to 33.3 ml / min. The two solutions simultaneously and continuously enter the first miniaturized split flow reactor 7 for rapid mixing and preliminary reaction to obtain a mixed reaction solution A. The mixed reaction solution A 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 diazotized solution is transported to the diazonium salt solution buffer storage tank 10. At the same time, the metering pump is turned on to control the flow rate of the phenol solution to 60 ml / min, and the flow rate of the diazonium salt solution is controlled to 30 ml / min. The two solutions simultaneously and continuously enter the second miniaturized split flow reactor 17 for rapid mixing and preliminary reaction to obtain a mixed reaction solution B. The mixed reaction solution B enters the second microreactor 18 for a reaction residence time of 14 s, a reaction temperature of 20°C, and a reaction pressure of 5 MPa to obtain a solid-liquid mixture of a crude UV-234 intermediate product. After filtration, a crude UV-234 intermediate product is obtained. The crude UV-234 intermediate product is first washed and filtered with a mixed detergent of methanol: water in a ratio of 1:1, and the washing is repeated three times; then the crude UV-234 intermediate product is washed and filtered with pure water, and the washing is repeated three times; then it is dried at 70°C for 12 hours to obtain a yield of 92.29%.

[0103] Comparative Example 1

[0104] 1) Using the existing autoclave reaction technology, 34.52 g of m-nitroaniline, 75 g of water and 75 g of 98% concentrated sulfuric acid were dissolved in a 250 ml three-necked flask at room temperature (25° C.), and stirred evenly to obtain a homogeneous amine solution;

[0105] 2) Dissolve 18.95 g of sodium nitrite in 250 g of water and stir to obtain a homogeneous sodium nitrite solution;

[0106] 3) Under continuous stirring, at a reaction temperature of 20° C. and normal pressure, the sodium nitrite solution was completely added to the amine solution in step 1 within 10 min, and the reaction time was 2 h to obtain a diazonium salt solution;

[0107] 4) 82.615 g of 2,4-dicumylphenol, 61 g of sodium hydroxide, 1.5 g of sodium dodecylbenzene sulfonate and 750 ml of methanol were mixed in a 1000 ml beaker to obtain a homogeneous phenol solution.

[0108] 5) Under continuous stirring, the reaction temperature is 20°C, and under normal pressure, the diazonium salt solution obtained in step 3 is completely added to the phenol solution in step 4 within 1 hour, and the reaction is continued for 1 hour after the addition to obtain a solid-liquid mixture of a crude UV-234 intermediate product. After filtering, a crude UV-234 intermediate product is obtained. The crude UV-234 intermediate product is first washed and filtered with a mixed detergent of methanol: water in a ratio of 1:1, and the result is repeated three times; then the crude UV-234 intermediate product is washed and filtered with pure water, and the result is repeated three times; then dried at 70°C for 12 hours to obtain a yield of 64.32%.

[0109] In the following examples and comparative examples:

[0110] UV-234 intermediate yield = UV-234 intermediate product solid amount × concentration of UV-234 intermediate product detected by liquid chromatography / feed amount of m-nitroaniline × 100% (by mass).

[0111] The preferred implementation process conditions and methods of the present invention are described in detail above, but the present invention is not limited to the specific details in the above-mentioned implementation process conditions and methods. Within 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.

[0112] In addition, the various implementation methods of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the disclosed content of the present invention and be protected.

Claims

1. A method for continuous production of ultraviolet absorber intermediates, characterized in that: The invention relates to a system for continuous production of ultraviolet absorber intermediates, wherein the system for continuous production of ultraviolet absorber intermediates comprises a continuous diazotization device and a continuous coupling reaction device; the continuous diazotization device comprises a first miniaturized segmented flow reactor and a first microreactor, and the continuous coupling device comprises a second miniaturized segmented flow reactor and a second microreactor; The method comprises the following steps: 1) the amine solution and the sodium nitrite solution are respectively and continuously introduced into the first micro-scale split flow reactor at a rate of 5 ml to 40 ml / min to mix and react to obtain a mixed reaction solution A, and the mixed reaction solution A is then introduced into the first micro-reactor to react to obtain a diazonium salt solution; 2) the diazonium salt solution and the phenol solution are respectively and continuously introduced into the second micro-scale split flow reactor at a rate of 5 ml to 60 ml / min to mix and react to obtain a mixed reaction solution B, and the mixed reaction solution B is then introduced into the second micro-reactor to undergo a coupling reaction to generate a crude UV-234 intermediate product; 3) The crude UV-234 intermediate product is filtered and washed to obtain a UV-234 intermediate product; Wherein: the amine solution is a homogeneous solution of concentrated sulfuric acid, m-nitroaniline and water; The phenol solution is a homogeneous solution of methanol, surfactant, sodium hydroxide and 2,4-dicumylphenol.

2. The method for continuous production of ultraviolet absorber intermediate according to claim 1, characterized in that: The amine solution comprises concentrated sulfuric acid, water and m-nitroaniline in a molar ratio of 1-4:100-400:

1.

3. The method for continuous production of ultraviolet absorber intermediate according to claim 1, characterized in that: The molar ratio of sodium nitrite to water in the sodium nitrite solution is 1:0.73-6.

05.

4. The method for continuous production of ultraviolet absorber intermediate according to claim 1, characterized in that: The molar ratio of the methanol, sodium hydroxide and 2,4-dicumylphenol is 250-1500:5.5-8:

1.

5. The method for continuous production of ultraviolet absorber intermediate according to claim 1, characterized in that: The surfactant is one of sodium dodecylbenzene sulfonate, polyethylene glycol and hexadecyltrimethylammonium bromide, and 2 to 9 g of the surfactant is added to each mole of 2,4-dicumylphenol.

6. The method for continuous production of ultraviolet absorber intermediates according to claim 1, characterized in that: The mixed reaction solution A is kept in the first microreactor at 5-50° C. for 10-50 seconds; and the mixed reaction solution B is kept in the second microreactor at 5-50° C. for 4-20 seconds.

7. The method for continuous production of ultraviolet absorber intermediate according to claim 1, characterized in that: The continuous diazotization device comprises 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 thermostatic bath (9); The amine solution storage tank (1), the first metering pump (3) and the first miniaturized split flow reactor (7) are connected in series via a first pipeline (20); 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 via a second pipeline (21); The first micro-scale segmented flow reactor (7) is connected to the first micro-reactor (8), the first micro-reactor (8) is connected to the diazonium salt solution buffer storage tank (10) via a third pipeline (22), and the first micro-scale segmented flow reactor (7) and the first micro-reactor (8) are placed in a first thermostatic bath (9); The continuous coupling device comprises 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 split flow reactor (17), a second microreactor (18), a UV-234 intermediate storage tank (19) and a second thermostatic bath (16); The phenol solution storage tank (11), the third metering pump (12) and the second miniaturized split flow reactor (17) are connected in series via a fourth pipeline (24); 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 via a third pipeline (23); The second micro-scale segmented flow reactor (17) is connected to the second micro-reactor (18), and the second micro-reactor (18) is connected to the UV-234 intermediate storage tank (9) through a fifth pipeline (24). The second micro-scale segmented flow reactor (17) and the second micro-reactor (18) are placed in a second thermostatic bath (16).

8. The method for continuous production of ultraviolet absorber intermediates according to claim 7, characterized in that: The first pipeline (20) is provided with a first back pressure valve (5), 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). The second pipeline (21) is provided with a second back pressure valve (6), 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); The third pipeline (23) is provided with a third back pressure valve (14), and the third back pressure valve (14) is arranged on the pipeline between the third metering pump (12) and the second miniaturized split flow reactor (17); The fourth pipeline (23) is provided with a fourth back pressure valve (15), and the fourth back pressure valve (15) is arranged on the pipeline between the fourth metering pump (13) and the second miniaturized split flow reactor (17).

9. The method for continuous production of ultraviolet absorber intermediate according to claim 7, characterized in that: The first micronized segmented flow reactor (7) and the second micronized segmented flow reactor (17) have the same structure, and include, from left to right, a first connecting portion (A), a micronized liquid separation clamp (B), a mixing and separation reaction plate (C), and a second connecting portion (D). The first connecting portion (A) is provided with a first liquid inlet pipe (A1) and a second liquid inlet pipe (A2); The miniaturized liquid separation clamp (B) is provided with two rows of rectangular micro-channels (B1) on the left and right sides, and the tail ends (B11) of the rectangular micro-channels (B1) in the two rows on the left and right sides are arranged in a staggered manner, and the feed port of the left rectangular micro-channel (B1) is connected to the first liquid inlet pipe (A1); the feed port of the right rectangular micro-channel (B1) is connected to the second liquid inlet pipe (A2); The mixing and splitting reaction piece (C) is provided with a mixed liquid reaction groove (C1), and the mixed liquid reaction groove (C1) is tightly connected to the tail end tip (B11); The outlet end of the liquid reaction tank (C1) is connected to the liquid outlet (D1) arranged on the second connecting part (D).

10. The method for continuous production of ultraviolet absorber intermediate according to claim 6, characterized in that: The first microreactor (8) and the second microreactor (18) are both spiral reaction microtubes.

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