Et3NHCl-FeCl3 ionic liquid catalyst for synthesizing triazine ultraviolet light absorber

Abstract

The invention discloses an Et3NHCl-FeCl3 ionic liquid catalyst for synthesizing a triazine ultraviolet light absorber, and relates to the technical field of catalysts, the catalyst is prepared by mixing and reacting triethylamine hydrochloride, ferric trichloride and a third component; the catalytic performance of the catalyst is remarkably improved by constructing a ternary eutectic system comprising triethylamine hydrochloride, ferric trichloride and a third component, the ternary components have a synergistic effect to form a multi-element active center, triethylamine hydrochloride provides a Bronsted acid site, ferric trichloride contributes Lewis acid activity, and the catalytic performance of the catalyst is remarkably improved. The third component synergistically improves the efficiency and selectivity of the nucleophilic substitution reaction of cyanuric chloride and aromatic amine by enhancing proton transfer and chelating metal to inhibit hydrolysis or expand acidic sites, and the preparation process adopts premixing, step-by-step feeding and precise dehydration strategies, so that the structural stability and batch consistency of the catalyst can be ensured, and the preparation process is suitable for industrial production. The excellent cyclic regeneration capability is endowed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, in particular to an Et3NHCl-FeCl3 ionic liquid catalyst for synthesizing triazine ultraviolet absorbers. BACKGROUND

[0002] Et3NHCl-FeCl3 is a mixed system composed of triethylamine hydrochloride (Et3NHCl) and ferric chloride (FeCl3), which plays a dual role in chemistry. On the one hand, it can form a eutectic solvent, which is essentially a unique ionic environment formed by hydrogen bonding and other interactions, which can replace traditional volatile organic solvents as a green reaction medium for electrochemical deposition or material synthesis. On the other hand, FeCl3 as a strong Lewis acid core endows the system with excellent catalytic ability, which can efficiently promote key organic transformations such as Friedel-Crafts reaction. In this medium, the solubility and stability of FeCl3 are often enhanced, while Et3NHCl helps to stabilize active intermediates and promote mass transfer.

[0003] Triazine ultraviolet absorbers are a class of high-performance organic ultraviolet absorbers, named for their molecular structure containing a triazine ring. They can effectively absorb ultraviolet rays with a wavelength of 290-400 nanometers and convert them into harmless heat energy, thereby protecting high molecular materials (such as plastics, coatings, fibers) from photo-degradation. Compared with traditional benzotriazole absorbers, triazine products generally have higher molar extinction coefficients and more excellent ultraviolet absorption capacity, especially in the long-wave UVA region, thus providing more durable and comprehensive protection. In the synthesis of triazine ultraviolet absorbers (especially hydroxyphenyl triazines such as the core structure of the Tinuvin® series), Et3NHCl-FeCl3 ionic liquid catalyst is a highly efficient and green catalytic system.

[0004] Existing Et3NHCl-FeCl3 ionic liquid catalysts mostly adopt a two-component mechanism, which provides only limited active sites (such as Brønsted acid and Lewis acid), lacks dynamic regulation of the third component, and cannot balance proton transfer, metal stability and acid strength in coordination, resulting in easy decay of activity, increased side reactions, and limited efficiency and selectivity. Therefore, the present application proposes an Et3NHCl-FeCl3 ionic liquid catalyst for synthesizing triazine ultraviolet absorbers to solve the problems existing in the prior art. SUMMARY

[0005] In view of the above problems, the purpose of the present application is to provide an Et3NHCl-FeCl3 ionic liquid catalyst for synthesizing triazine ultraviolet absorbers, which solves the problem that existing Et3NHCl-FeCl3 ionic liquid catalysts mostly adopt a two-component mechanism and have a single synergistic mechanism and limited catalytic efficiency and selectivity.

[0006] To achieve the purpose of the present application, the present application is implemented by the following technical solutions: an Et3NHCl-FeCl3 ionic liquid catalyst for synthesizing triazine ultraviolet absorbers, which is a ternary eutectic system containing a third component, is prepared by mixing reaction of triethylamine hydrochloride, iron trichloride and the third component in a molar ratio of 1:1.5-2.2:0.05-0.5, and the third component is selected from one of C1-C6 carboxylic acids, C2-C6 polyols and metal chlorides, and the ternary eutectic system is prepared by pre-mixing triethylamine hydrochloride and the third component, then adding iron trichloride, and reacting and dehydrating under an inert atmosphere.

[0007] Further improvement lies in that the molar ratio of the triethylamine hydrochloride, the iron trichloride and the third component is 1:1.8:0.3.

[0008] Further improvement lies in that the third component is a C1-C6 carboxylic acid, the C1-C6 carboxylic acid is selected from one of lactic acid, oxalic acid and acetic acid, and the molar proportion in the Et3NHCl-FeCl3 ionic liquid catalyst is 0.1-0.3 parts.

[0009] Further improvement lies in that the third component is a C2-C6 polyol, the C2-C6 polyol is selected from one of ethylene glycol, propylene glycol and glycerol, and the molar proportion in the Et3NHCl-FeCl3 ionic liquid catalyst is 0.08-0.4 parts.

[0010] Further improvement lies in that the third component is a metal chloride, the metal chloride is selected from one of AlCl3, ZnCl2 and CuCl2, and the molar proportion in the Et3NHCl-FeCl3 ionic liquid catalyst is 0.05-0.2 parts.

[0011] Further improvement lies in that the preparation method of the Et3NHCl-FeCl3 ionic liquid catalyst comprises the following steps:

[0012] S1. The triethylamine hydrochloride and the third component after drying treatment are added to a reactor in a predetermined molar ratio, stirred and mixed for 30-60 min to form a uniform transparent liquid;

[0013] S2. The iron trichloride after drying treatment is added to the uniform transparent liquid obtained in step S1 in a predetermined molar ratio in 3-5 batches under the protection of an inert atmosphere.

[0014] S3. After the addition of iron chloride in step S2 is completed, the temperature is raised to 80-100℃, the vacuum system is opened, and stirring is continued for 2-6h to obtain a dark brown viscous liquid, which is the finished product of the Et3NHCl-FeCl3 ionic liquid catalyst.

[0015] Further improvement lies in that in step S1, after the triethylamine hydrochloride and the third component are added into the reactor, they are stirred and mixed at a temperature of 40-70℃, and the stirring rate is 200-400rpm.

[0016] Further improvement lies in that in step S2, the addition of the iron trichloride is controlled at a temperature ≤50℃, the interval time of each batch of addition is 10-15min, and the addition amount of each batch is the same.

[0017] The beneficial effects of the present application are that: the present application realizes significant improvement of the catalytic performance of the catalyst by constructing a ternary eutectic system including triethylamine hydrochloride, iron trichloride and a third component, wherein the ternary components form multiple active centers through synergistic effect, the triethylamine hydrochloride provides Brønsted acid sites, the iron trichloride contributes Lewis acid activity, and the third component (carboxylic acid, polyol or metal chloride) respectively enhances proton transfer, chelates metal to inhibit hydrolysis or expands acid sites, thereby synergistically improving the efficiency and selectivity of the nucleophilic substitution reaction of cyanuric chloride and aromatic amine, and the preparation process adopts the strategies of premixing, stepwise addition and precise dehydration, which can ensure the stability of the catalyst structure and batch consistency, endow the catalyst with excellent recycling ability, and finally make the catalyst have the advantages of efficient catalysis, strong substrate adaptability and simple operation, thereby providing a reliable scheme for the green synthesis of triazine ultraviolet absorbers. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the preparation method flowchart of the Et3NHCl-FeCl3 ionic liquid catalyst for synthesizing triazine ultraviolet absorbers according to the present application. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0020] Triazine UV absorbers are widely used in sunscreen cosmetics, anti-aging plastics, and protective coatings due to their highly efficient UV shielding properties. Their mainstream synthetic route involves the nucleophilic substitution reaction of cyanuric chloride with aromatic amines. This reaction requires a catalyst to activate the chlorine atom of the cyanuric chloride to improve the reaction rate and selectivity. Traditional catalysts, such as Lewis acids (AlCl3) and protic acids (H2SO4), suffer from problems such as strong corrosivity and complex post-processing. Ionic liquid catalysts have become a research hotspot due to their green and recyclable advantages; however, existing systems are mostly two-component (such as quaternary ammonium salts and metal chlorides), and their catalytic performance and stability are still insufficient, hindering industrial applications.

[0021] Existing binary ionic liquid catalysts (such as the Et3NHCl-FeCl3 binary system) rely solely on Brønsted acids (Et3NH3). + Limited synergy between FeCl3 and Lewis acid (FeCl3), lack of a third component to dynamically regulate acid strength and metal ion stability, easily leads to insufficient active sites and Fe... 3+ Hydrolysis deactivation and increased side reactions result in low catalytic efficiency and poor product selectivity. Furthermore, the crude preparation process leads to poor batch stability of the catalyst, making recycling and regeneration difficult and increasing operating costs. Therefore, developing novel ionic liquid catalysts with diverse synergistic mechanisms and stable performance is crucial to overcoming the synthesis bottleneck.

[0022] It should be noted that the technical means not described in detail in the embodiments of the present invention can be implemented by conventional means and are not the key points of the invention, so they will not be elaborated upon.

[0023] Example 1

[0024] This embodiment provides an Et3NHCl-FeCl3 ionic liquid catalyst for synthesizing triazine-based ultraviolet absorbers. This Et3NHCl-FeCl3 ionic liquid catalyst is a ternary eutectic system containing a third component, namely triethylamine hydrochloride (Et3NHCl, providing Brønsted acid sites Et3NH). + ), ferric chloride (FeCl3, providing Lewis acid sites Fe), 3+ The mixture is prepared by reacting a C1-C6 carboxylic acid (selected from lactic acid, oxalic acid, and acetic acid; lactic acid is selected in this example) with a third component in a molar ratio of 1:1.5:0.1. The third component is prepared by premixing triethylamine hydrochloride with the third component (to form a preliminary interaction), then adding ferric chloride (to avoid excessive local concentration and agglomeration), and reacting and dehydrating under an inert atmosphere. It has the activity of catalyzing the nucleophilic substitution reaction of cyanuric chloride with aromatic amines.

[0025] See Figure 1 This embodiment also provides a method for preparing an Et3NHCl-FeCl3 ionic liquid catalyst, including the following steps:

[0026] S1, the dry treated hydrochloric acid triethylamine (purity ≥ 98%, water content < 0.05%) and the third component are added to the reactor, stirred at a stirring speed of 200 rpm for 30 min in a temperature environment of 40°C to form a uniform transparent liquid;

[0027] S2, under the protection of inert atmosphere (nitrogen, purity ≥ 99.9%), the dry treated ferric chloride (purity ≥ 99%, pre-ground to 100 mesh) is added to the uniform transparent liquid obtained in step S1 in 3 batches, the feeding temperature is controlled ≤ 50°C, the interval time of each batch is 10 min, and the feeding amount of each batch is the same;

[0028] S3, after the ferric chloride feeding is completed, the temperature is raised to 80°C, the vacuum system (vacuum degree 5 kPa) is started, and the stirring is continued for 2 h (to the system water content < 0.01%, detected by Karl Fischer titration method), a dark brown viscous liquid (25°C viscosity 500 mPa·s) is obtained, which is the Et3NHCl-FeCl3 ionic liquid catalyst product (the catalytic performance parameters of the catalyst are: in the synthesis of triazine ultraviolet absorber reaction, the cyanuric chloride conversion rate is ≥ 95%, the selectivity of the target product is ≥ 92%, and the activity retention rate is ≥ 85% after 5 times of recycling).

[0029] The Et3NHCl-FeCl3 ionic liquid catalyst prepared in this embodiment is used to catalyze the nucleophilic substitution reaction of cyanuric chloride and aromatic amine compounds to synthesize triazine ultraviolet absorber, wherein:

[0030] The aromatic amine compound is a monoamino aromatic hydrocarbon (such as methyl p-aminobenzoate, m-aminophenol, p-methoxyaniline, and methyl aminobenzoate is selected in this embodiment);

[0031] The reaction adopts gradient temperature rising step feeding process, specifically:

[0032] First stage: cyanuric chloride and Et3NHCl-FeCl3 ionic liquid catalyst are added to the reactor, heated to 80°C, and stirred for 10 min;

[0033] Second stage: the aromatic amine compound is added in 2 batches (each batch accounts for 50% of the total amount, and the batch interval is 30 min), and the molar ratio of the total aromatic amine to cyanuric chloride is controlled to be 3.0:1 (for trifunctional substitution target product);

[0034] Third stage: heat to 120°C and keep for 1 h to complete the reaction.

[0035] After the reaction is completed, the liquid phase containing the catalyst is separated (the solid product is removed by filtration), and the following methods are selected for regeneration:

[0036] HCl gas regeneration: dry HCl gas was bubbled into the liquid phase (flow rate 10 mL / min) at 50℃ for 1-3 h, and then dehydrated under vacuum (vacuum degree ≤10 kPa) for 1 h before reuse.

[0037] The structure of the Et3NHCl-FeCl3 ionic liquid catalyst prepared in this example was confirmed by the following characterization:

[0038] Infrared spectrum (IR): N-H stretching vibration peak at 3200 cm -1 , C=N stretching vibration peak (from Et3NH + ) at 1600 cm -1 , and Fe-Cl characteristic peak at 1100 cm -1 ;

[0039] X-ray diffraction (XRD): broad diffraction peaks in the range of 2θ = 10-30°, indicating that it is an amorphous eutectic ionic liquid.

[0040] Example 2

[0041] This example provides an Et3NHCl-FeCl3 ionic liquid catalyst for synthesizing triazine ultraviolet absorbers, which is a ternary eutectic system containing a third component, prepared by mixing hydrochloric acid triethylamine (Et3NHCl, providing Brønsted acid site Et3NH + ), iron trichloride (FeCl3, providing Lewis acid site Fe 3+ ), and a third component in a molar ratio of 1:1.8:0.3, the third component being a C2-C6 polyhydric alcohol (selected from one of ethylene glycol, propylene glycol, and glycerol, and ethylene glycol is selected in this example), by pre-mixing hydrochloric acid triethylamine with the third component (forming a preliminary interaction), then adding iron trichloride (to avoid local concentration and agglomeration), and reacting and dehydrating under an inert atmosphere to obtain an active catalyst for the nucleophilic substitution reaction of cyanuric chloride and aromatic amine.

[0042] Referring to Figure 1 , this example also provides a method for preparing an Et3NHCl-FeCl3 ionic liquid catalyst, comprising the following steps:

[0043] S1, dry hydrochloric acid triethylamine (purity ≥98%, water content <0.05%) and a third component are added to a reactor, stirred and mixed at a stirring rate of 300 rpm for 45 min in a temperature environment of 55℃ to form a uniform transparent liquid;

[0044] S2, under the protection of inert atmosphere (argon, purity ≥ 99.9%), the dry treated ferric chloride (purity ≥ 99%, pre-ground to 150 mesh) was added into the uniform transparent liquid obtained in step S1 in 4 batches, the feeding temperature was controlled to be ≤ 50℃, the interval time of each batch was 12 min, and the feeding amount of each batch was the same;

[0045] S3, after the ferric chloride feeding was completed, the temperature was increased to 90℃, the vacuum system (vacuum degree 8 kPa) was started, and the dehydration was continued for 4 h (until the water content of the system was < 0.01%, detected by Karl Fischer titration), a dark brown viscous liquid (viscosity 1000 mPa·s at 25℃) was obtained, which was the Et3NHCl-FeCl3 ionic liquid catalyst product (the catalytic performance parameters of the catalyst were: in the synthesis of triazine ultraviolet absorber reaction, the cyanuric chloride conversion rate was ≥ 95%, the selectivity of the target product was ≥ 92%, and the activity retention rate was ≥ 85% after 5 cycles).

[0046] The Et3NHCl-FeCl3 ionic liquid catalyst prepared in this example was used to catalyze the nucleophilic substitution reaction of cyanuric chloride and aromatic amine compounds to synthesize triazine ultraviolet absorbers, wherein:

[0047] The aromatic amine compound was a diaminobenzene (such as m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, and m-phenylenediamine was selected in this example);

[0048] The reaction adopted a gradient temperature rising step feeding process, specifically:

[0049] First stage: cyanuric chloride and catalyst were added to the reactor, and the temperature was increased to 90℃, and stirred for 15 min;

[0050] Second stage: the aromatic amine compound was added in 3 batches (the amount of each batch was one third of the total amount, and the batch interval was 45 min), and the total molar amount of the aromatic amine was controlled to be 1:1 (for single functional group substitution target product) with the molar ratio of cyanuric chloride;

[0051] Third stage: the temperature was increased to 130℃, and the reaction was completed after 2 h of heat preservation.

[0052] After the reaction was completed, the liquid phase containing the catalyst was separated (the solid product was removed by centrifugation), and the following methods were selected for regeneration:

[0053] H2O2 oxidation regeneration: 0.5% of 30% hydrogen peroxide solution was added to the liquid phase, and stirred at 50℃ for 1 h, and then cooled and separated, and the lower ionic liquid catalyst was reused.

[0054] The structure of the Et3NHCl-FeCl3 ionic liquid catalyst prepared in this example was confirmed by the following characterization:

[0055] Infrared spectrum (IR): there is N-H stretching vibration peak at 3300 cm -1 -1 + -1

[0056] X-ray diffraction (XRD): there are broadened diffraction peaks in the range of 2θ=10-30°, indicating that it is an amorphous eutectic ionic liquid.

[0057] Example 3

[0058] The present example provides an Et3NHCl-FeCl3 ionic liquid catalyst for synthesizing triazine ultraviolet absorber, which is a ternary eutectic system containing a third component, prepared by mixing reaction of triethylamine hydrochloride (Et3NHCl, providing Brønsted acid site Et3NH + ), iron trichloride (FeCl3, providing Lewis acid site Fe 3+ ) and a third component in a molar ratio of 1:2.2:0.2, the third component being a metal chloride (selected from one of AlCl3, ZnCl2, CuCl2, and AlCl3 is selected in the present example), by pre-mixing (forming a preliminary interaction) triethylamine hydrochloride with the third component, then adding iron trichloride (to avoid local concentration and agglomeration), and reacting under inert atmosphere to remove water, having the activity of catalyzing the nucleophilic substitution reaction of cyanuric chloride and aromatic amine.

[0059] Referring to Figure 1 , the present example also provides a preparation method of the Et3NHCl-FeCl3 ionic liquid catalyst, comprising the following steps:

[0060] S1, dry treated triethylamine hydrochloride (purity≥98%, water content<0.05%) and a third component are added to a reactor, stirred and mixed at a stirring speed of 400 rpm for 60 min in a temperature environment of 70°C to form a uniform transparent liquid;

[0061] S2, under the protection of inert atmosphere (nitrogen, purity≥99.9%), dry treated iron trichloride (purity≥99%, pre-ground to 200 mesh) is added to the uniform transparent liquid obtained in step S1 in 5 batches, the feeding temperature is controlled to be≤50°C, the interval time of each batch is 15 min, and the feeding amount of each batch is the same;

[0062] ​​​​S3, after the addition of ferric chloride is completed, the temperature is raised to 100℃, the vacuum system (vacuum degree 10kPa) is opened, and the stirring is continued for 6h (to the system moisture content <0.01%, detected by Karl Fischer titration), a dark brown viscous liquid (25℃ viscosity 2000mPa·s) is obtained, which is the Et3NHCl-FeCl3 ionic liquid catalyst product (the catalytic performance parameters of the catalyst are: in the synthesis of triazine ultraviolet absorber reaction, the cyanuric chloride conversion rate is ≥95%, the selectivity of the target product is ≥92%, and the activity retention rate is ≥85% after 5 times of recycling).

[0063] The Et3NHCl-FeCl3 ionic liquid catalyst prepared in this example is used to catalyze the nucleophilic substitution reaction of cyanuric chloride and aromatic amine compounds to synthesize triazine ultraviolet absorbers, wherein:

[0064] The aromatic amine compound is triaminobenzene (1,3,5-triaminobenzene);

[0065] The reaction adopts a gradient temperature rising stepwise feeding process, specifically:

[0066] First stage: cyanuric chloride and catalyst are added to the reactor, and the temperature is raised to 100℃, and stirred for 20min;

[0067] Second stage: the aromatic amine compound is added in two batches (the amount of each batch is 50% of the total amount, and the batch interval is 60min), and the total molar amount of aromatic amine and the molar ratio of cyanuric chloride are controlled to be 3.3:1 (for tri-functional group substitution target product);

[0068] Third stage: the temperature is raised to 140℃, and the reaction is completed after 3h of incubation.

[0069] After the reaction is completed, the liquid phase containing the catalyst is separated (the solid product is removed by filtration or centrifugation), and the following methods are selected for regeneration:

[0070] HCl gas regeneration: dry HCl gas is introduced into the liquid phase (flow rate 20mL / min), and the bubble treatment is carried out at 80℃ for 3h, and then vacuum dehydration (vacuum degree ≤10kPa) for 1h.

[0071] The structure of the Et3NHCl-FeCl3 ionic liquid catalyst prepared in this example is confirmed by the following characterization:

[0072] Infrared spectrum (IR): there is a N-H stretching vibration peak at 3400cm -1 , a C=N stretching vibration peak (from Et3NH -1 ) at 1650cm + , and a Fe-Cl characteristic peak at 1150cm -1 ;

[0073] X-ray diffraction (XRD): a broadened diffraction peak in the range of 2θ = 10-30°, indicating that it is an amorphous eutectic ionic liquid.

[0074] The above description is merely preferred embodiments of the present application, but not to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall fall within the scope of protection of the present application.

Claims

1. An Et3NHCl-FeCl3 ionic liquid catalyst for the synthesis of triazine-based ultraviolet absorbers, characterized in that: The Et3NHCl-FeCl3 ionic liquid catalyst is a ternary eutectic system containing a third component, which is prepared by mixing triethylamine hydrochloride, ferric chloride and the third component in a molar ratio of 1:1.5-2.2:0.05-0.5, wherein the third component is selected from one of C1-C6 carboxylic acid, C2-C6 polyhydric alcohol and metal chloride, and the ternary eutectic system is prepared by pre-mixing triethylamine hydrochloride and the third component, then adding ferric chloride, and reacting and dehydrating under an inert atmosphere.

2. The Et3NHCl-FeCl3 ionic liquid catalyst for the synthesis of triazine-based UV absorbers according to claim 1, characterized by: The molar ratio of the triethylamine hydrochloride, ferric chloride and the third component is 1:1.8:0.

3.

3. The Et3NHCl-FeCl3 ionic liquid catalyst for the synthesis of triazine-based UV absorbers according to claim 1, characterized by: The third component is C1-C6 carboxylic acid, and the C1-C6 carboxylic acid is selected from one of lactic acid, oxalic acid and acetic acid, and the molar ratio in the Et3NHCl-FeCl3 ionic liquid catalyst is 0.1-0.3 parts.

4. The Et3NHCl-FeCl3 ionic liquid catalyst for the synthesis of triazine-based UV absorbers according to claim 1, characterized by: The third component is C2-C6 polyhydric alcohol, and the C2-C6 polyhydric alcohol is selected from one of ethylene glycol, propylene glycol and glycerol, and the molar ratio in the Et3NHCl-FeCl3 ionic liquid catalyst is 0.08-0.4 parts.

5. The Et3NHCl-FeCl3 ionic liquid catalyst for the synthesis of triazine-based UV absorbers according to claim 1, characterized by: The third component is metal chloride, and the metal chloride is selected from one of AlCl3, ZnCl2 and CuCl2, and the molar ratio in the Et3NHCl-FeCl3 ionic liquid catalyst is 0.05-0.2 parts.

6. The Et3NHCl-FeCl3 ionic liquid catalyst for the synthesis of triazine-based UV absorbers according to claim 1, characterized by: The preparation method of the Et3NHCl-FeCl3 ionic liquid catalyst comprises the following steps: S1. The triethylamine hydrochloride and the third component after drying treatment are added to a reactor in a preset molar ratio, and stirred and mixed for 30-60 min to form a uniform transparent liquid; S2. The ferric chloride after drying treatment is added to the uniform transparent liquid obtained in step S1 in a preset molar ratio in 3-5 batches under the protection of an inert atmosphere; S3. After the addition of ferric chloride in step S2 is completed, the temperature is raised to 80-100℃, the vacuum system is started, and the stirring is continued for 2-6 h to obtain a dark brown viscous liquid, which is the finished product of the Et3NHCl-FeCl3 ionic liquid catalyst.

7. The Et3NHCl-FeCl3 ionic liquid catalyst for the synthesis of triazine-based UV absorbers according to claim 6, characterized by: In step S1, after the triethylamine hydrochloride and the third component are added to the reactor, they are stirred and mixed at a temperature of 40-70℃, and the stirring rate is 200-400 rpm.

8. The Et3NHCl-FeCl3 ionic liquid catalyst for synthesis of triazine-based UV absorbers according to claim 6, characterized by: In step S2, the addition temperature of the ferric chloride is controlled to ≤50℃, the interval time of each batch is 10-15 min, and the addition amount of each batch is the same.

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