A method for preparing a benzotriazole ultraviolet absorber

Abstract

The application provides a preparation method of a benzotriazole compound, and comprises the following steps: reacting a compound shown in formula (I) with hydrogen in a solvent to generate a benzotriazole compound shown in formula (II), wherein the solvent comprises an ionic liquid, and R1 and R2 in the formula (I) and the formula (II) are each independently selected from H and an alkyl group with 1-10 carbon atoms. The preparation method of the application does not need to add an external base, the product has high purity, and the reaction has high selectivity.

Description

Technical Field

[0001] This invention relates to the field of polymer material additives, specifically to a method for preparing a benzotriazole-based ultraviolet absorber. Background Technology

[0002] Benzotriazole UV absorbers are a class of compounds with similar main structures and excellent UV absorption capabilities. Besides possessing physical properties such as light color, low toxicity, low volatility, good oil resistance, and good polymer compatibility, they also exhibit excellent photochemical properties, capable of absorbing ultraviolet light with wavelengths of 290–400 nm. While absorbing UV light, they transform into an excited state, releasing energy as heat and light, thus achieving their UV-blocking function. Benzotriazole UV absorbers can not only undergo condensation copolymerization reactions to generate high-molecular-weight light stabilizers, but also produce synergistic effects with hindered amine light stabilizers, thereby minimizing the oxidation of polymer materials.

[0003] Currently, the general preparation method for benzotriazole UV absorbers involves first preparing azobenzene as an intermediate, and then reducing and cyclizing the azobenzene to obtain the corresponding product. The reduction methods for the intermediate azobenzene mainly include: zinc powder reduction, hydrazine hydrate reduction, sulfide reduction, sulfide-zinc powder reduction, hydrazine hydrate-zinc powder reduction, hydrazine hydrate-hydrogenation reduction, hydrazine hydrate-sodium dithionite reduction, glucose-zinc powder reduction, and catalytic hydrogenation reduction. Zinc powder reduction inevitably generates large amounts of alkaline wastewater containing organic matter and difficult-to-treat waste residue, seriously hindering the development of my country's benzotriazole UV absorber industry.

[0004] Catalytic hydrogenation reduction uses hydrogen as a reducing agent to convert the azo intermediate HAB to benzotriazole under the action of a suitable catalyst. Hydrogen is inexpensive, and theoretically, the only byproduct of this method is water, making it environmentally friendly. Therefore, in the long run, this method is an economical, green, and promising synthetic route. Thus, catalytic hydrogenation is currently a highly regarded method in the synthesis of benzotriazole. White HL et al. reported a process for synthesizing UV-P using catalytic hydrogenation with Raney Ni as a catalyst, achieving a yield of up to 88%. Jancis EH et al. used Pd / C as a catalyst, achieving a UV-P yield of approximately 70%. However, the technology for preparing benzotriazole-based ultraviolet absorbers using this method is still immature; the selectivity of the reaction and the catalyst lifetime need improvement, and there are no reports of continuous production.

[0005] The catalytic hydrogenation of HAB to synthesize benzotriazole compounds is a highly complex process, accompanied by numerous side reactions, which hinders the industrialization of catalytic hydrogenation technology. The side reactions involved in the catalytic hydrogenation synthesis of benzotriazole-type UV absorbers include: the cleavage of the hydrazine bond after the reduction of the azo bond in HAB to form aromatic amine byproducts (I); excessive hydrogenation of the intramolecular benzene ring to form tetrahydrogen byproducts (III, IV); and the possibility of ring-opening to generate aromatic amine byproducts if nitrogen oxides cannot be rapidly hydrogenated to obtain the target product (II).

[0006]

[0007] Currently, the only way to suppress parallel competing side reactions and reduce the generation of aromatic amine byproducts is to add alkaline auxiliaries (such as NaOH solution, piperidine, and diethylamine) to the reaction system to promote the main reaction of intramolecular dehydration and cyclization to generate nitrogen oxides. Suppressing the formation of aromatic amine byproducts in reaction systems without added liquid alkali has become a recognized challenge in the industry, and no relevant research reports have been published to date. However, the addition of alkaline auxiliaries also leads to difficulties in product separation and purification, and the generation of alkaline waste liquid. Furthermore, the organic alkali added to the reaction system is difficult to process and has an unpleasant odor, while the added inorganic alkali can cause partial deactivation of the catalyst and make it non-renewable. In alkali-free systems, the lack of an alkaline environment results in very low solubility of azobenzene (the raw material) and nitrogen oxides (the product) in common solvents (methanol, ethanol, water, etc.), while solvents with high solubility (toluene, ethyl acetate, etc.) lead to high concentrations of reaction byproducts in the system, significantly reducing selectivity.

[0008] Therefore, developing an alkali-free system for the catalytic hydrogenation synthesis of benzotriazole UV absorbers is of great significance for improving reaction selectivity and reducing costs, and has a huge market prospect. The key technology lies in solvent design. Summary of the Invention

[0009] To address the aforementioned technical problems in the prior art, this invention provides a method for preparing benzotriazole-based ultraviolet absorbers. This method, by selecting a specific solvent, enables the hydrogenation of an azo intermediate into benzotriazole compounds in an alkali-free system. The solvent in this alkali-free system has low solubility for the product, causing the product to crystallize and precipitate, reducing the product concentration in the reaction solution and shifting the reaction towards product formation, thus significantly improving reaction selectivity. Furthermore, this invention further enhances the raw material conversion rate and reaction selectivity by selecting a specific catalyst.

[0010] The present invention adopts the following technical solution:

[0011] A method for preparing a benzotriazole compound includes: reacting a compound of formula (I) with hydrogen in a solvent to generate a benzotriazole compound of formula (II), wherein the solvent includes an ionic liquid.

[0012]

[0013] In formulas (I) and (II), R1 and R2 are each independently selected from H and alkyl groups having 1-10 carbon atoms.

[0014] This invention presents a method for synthesizing benzotriazole UV absorbers via catalytic hydrogenation in an alkali-free system. Furthermore, this method utilizes the low solubility of the product in specific solvents (such as ionic liquids). After the reaction begins, the product in the solution crystallizes out once a certain concentration is reached, thus reducing the product solubility in the solution. According to reaction kinetics, the reaction shifts towards the product formation direction, which can greatly improve the rate selectivity of the reaction.

[0015] In some embodiments, the volume fraction of the ionic liquid in the solvent is 10% to 100%, for example 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100% or any value between them, preferably 20% to 100%, more preferably 20% to 50%.

[0016] In this invention, ionic liquids can improve reaction selectivity; therefore, the amount of ionic liquid used should not be too small, as this will reduce reaction selectivity. Furthermore, this invention has found that when the volume fraction of the ionic liquid in the solvent is not less than 10%, the product selectivity can reach over 90%, especially when the volume fraction of the ionic liquid in the solvent is 20%, the product selectivity can reach over 95%. When the volume fraction of the ionic liquid in the solvent is higher than 20%, the product selectivity is not significantly different from that at 20%. Therefore, from a cost-saving perspective, the preferred volume percentage of the ionic liquid in the solvent is 20-50%.

[0017] In some embodiments, the solvent also includes water. Preferably, the volume fraction of water in the solvent is no more than 80%.

[0018] In some embodiments, the ionic liquid is selected from compounds of formula (III):

[0019]

[0020] R3 and R4 are each independently selected from alkyl groups having 1 to 10 carbon atoms.

[0021] In some specific embodiments, R3 and R4 are each independently selected from methyl, ethyl, propyl, isopropyl, butyl, and isobutyl.

[0022] In some specific embodiments, R3 is ethyl or butyl, and R4 is selected from methyl, ethyl, propyl, isopropyl, butyl, and isobutyl.

[0023] In some embodiments, X is a halogen, preferably chlorine or bromine.

[0024] In some preferred embodiments, the ionic liquid is 1-ethyl-3-methylimidazolium chloride and / or 1-butyl-3-methylimidazolium chloride, more preferably 1-butyl-3-methylimidazolium chloride.

[0025] In some embodiments, in formulas (I) and (II), R1 and R2 are each independently selected from H, methyl, ethyl, n-propyl, isopropyl, butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, n-octyl, isooctyl and tert-octyl, preferably H, methyl, tert-butyl, 1,1-dimethylpropyl and tert-octyl.

[0026] In some embodiments, the compound represented by formula (II) is selected from the following compounds:

[0027]

[0028] In the method for preparing benzotriazole compounds of the present invention, the reaction is carried out in a closed container, wherein the pressure of hydrogen gas in the container is 0.5-3 MPa, for example 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa or any value between them, preferably 1-3 MPa.

[0029] In the method for preparing benzotriazole compounds of the present invention, the reaction temperature is 30-80°C, for example 30°C, 40°C, 50°C, 60°C, 70°C, 80°C or any value between them, preferably 40-70°C.

[0030] In some embodiments, a catalyst is also added to the reaction, the catalyst being a Pt-containing bimetallic organic framework material.

[0031] In some specific embodiments, the catalyst is Pt@Mg-MOF-74.

[0032] The catalyst Pt@Mg-MOF-74 in this invention acts as a basic active center, further improving reaction selectivity. The Pt@Mg-MOF-74 catalyst encapsulates both metal Pt and a phenolic acid oxygen-based basic group formed by the deprotonation of hydroxyl groups. In this case, the catalytic active center is no longer a simple zero-valent metal particle, but rather a zero-valent metal particle acting as a hydrogenation active center. First, it dissociates H2 into active hydrogen, hydrogenating the N=N double bond in the azo intermediate to an NN single bond. Then, the basic active center provided by the phenolic acid oxygen group catalyzes an intramolecular dehydration and cyclization reaction to generate N-Oxide. Simultaneously, the presence of defect sites leads to coordination between the metal Pt and the central atom, effectively improving reaction selectivity. This invention utilizes the synergistic effect of hydrogenation-basic bifunctional catalysis to promote the main reaction, thereby effectively suppressing the NN single bond breaking side reaction without the addition of basic promoters such as NaOH. The reaction formula is shown below:

[0033]

[0034] In some preferred embodiments, the Pt loading in the catalyst is 1-5 wt%, for example 1%, 2%, 3%, 4%, 5% and any value between them.

[0035] In some embodiments, the amount of catalyst used is 1-10% of the mass of the compound shown in formula (I), for example 2%, 3%, 4%, 5%, 6%, 7%, 8% and any value between them, preferably 2-8%.

[0036] In some embodiments, the Pt-containing bimetallic organic framework material is prepared by the following method:

[0037] The salt of the second metal, the ligand and the solvent are mixed and then reacted with a Pt-containing compound. The reaction is preferably carried out at a temperature of 100-140°C. The reaction product is then reduced to obtain a Pt-containing bimetallic organic framework material.

[0038] Preferably, the molar ratio of the second metal salt to the Pt-containing compound is (55-275):1, for example, 55:1, 60:1, 70:1, 80:1, 90:1, 100:1, 105:1, 125:1, 155:1, 175:1, 205:1, 225:1, 255:1, 275:1 or any value between them.

[0039] The molar ratio of the ligand to the Pt-containing compound is (16-85):1, for example, 16:1, 17:1, 20:1, 22:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1, 85:1 or any value between them.

[0040] In some embodiments, the salt of the second metal is selected from the acetate, hydrochloride, sulfate, or nitrate of the second metal.

[0041] In some preferred embodiments, the second metal is Mg and the ligand is 2,5-dihydroxyterephthalic acid.

[0042] In some preferred embodiments, the salt of the second metal is selected from magnesium acetate, magnesium chloride, magnesium sulfate, or magnesium nitrate.

[0043] In some embodiments, the solvent is an organic solvent, preferably N,N-dimethylformamide.

[0044] In some embodiments, the Pt-containing compound is chloroplatinic acid.

[0045] In some embodiments, the reducing agent used for the reduction is selected from at least one of hydrazine hydrate, hydrogen, and sodium borohydride.

[0046] In some embodiments, the mass ratio of the compound represented by formula (I) to the volume ratio of the solvent is 1 g:(2-6) mL, for example 1 g:2 mL, 1 g:2.5 mL, 1 g:3 mL, 1 g:3.5 mL, 1 g:4 mL, 1 g:4.5 mL, 1 g:5 mL, 1 g:5.5 mL, 1 g:6 mL or any value between them, preferably 1 g:(4-6) mL.

[0047] Compared with the prior art, the present invention has the following advantages:

[0048] (1) By using a solvent containing ionic liquid, the solubility of the reaction product in the solvent is reduced, the product concentration in the solvent is low, the reaction moves forward, the final product yield is high, and the reaction selectivity is high.

[0049] (2) The method for catalytic hydrogenation synthesis of benzotriazole ultraviolet absorbers provided by the present invention does not require the addition of an external alkali, thus reducing the occurrence of side reactions.

[0050] (3) The present invention uses Pt@Mg-MOF-74 as a catalyst for the reaction in the alkali-free system, which can further improve the reaction selectivity. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way.

[0052] This invention provides a method for preparing benzotriazole compounds, comprising: reacting a compound of formula (I) with hydrogen gas in a solvent to generate a benzotriazole compound of formula (II), wherein the solvent includes an ionic liquid.

[0053]

[0054] In formulas (I) and (II), R1 and R2 are each independently selected from H and alkyl groups having 1-10 carbon atoms.

[0055] In this invention, "ionic liquid" refers to a salt composed of organic cations and inorganic or organic anions that is liquid at or near room temperature. Ionic liquids have the characteristics of a wide liquid temperature range, no significant vapor pressure, good thermal stability, and good solubility in many inorganic and organic compounds, and have wide applications in extraction and separation, catalytic reactions, electrochemistry, and other fields.

[0056] This invention uses a solvent containing ionic liquids, which can reduce the solubility of the product in the reaction solution and make it easy to separate the solvent from the product after the reaction. This can overcome the disadvantages of difficult solvent separation and recovery in the reaction and environmental pollution.

[0057] As one specific embodiment, the preparation method of the benzotriazole ultraviolet absorber includes the following steps:

[0058] In a high-pressure reactor, a certain amount of a Pt-containing catalyst (containing a Pt bimetallic organic framework material), the azo intermediate shown in formula (I), and a mixed solution of ionic liquid, preferably 1-butyl-3-methylimidazolium chloride and water, are added. The reactor is sealed, and the air inside is repeatedly replaced with hydrogen gas to adjust the hydrogen pressure to 0.5-3 MPa, preferably 1-3 MPa. The reactor is heated to 30-80°C, preferably 50-55°C, and then stirred (stirring rate 800-1000 rpm) for 1-10 hours. After the reaction is completed, the catalyst is filtered, the organic layer is separated (the composition of the hydrogenation product in the filtrate can be analyzed by high performance liquid chromatography), the solvent is filtered out under reduced pressure, and the product benzotriazole compounds are obtained after washing with deionized water and methanol and drying.

[0059] Preferably, the mass ratio of the compound shown in formula (I) to the volume ratio of the mixed solution of ionic liquid and water is 1 g:(2-6) mL, more preferably 1 g:(4-6) mL.

[0060] As one specific embodiment, the preparation method of the Pt-containing catalyst includes the following steps:

[0061] Magnesium salt and ligand 2,5-dihydroxyterephthalic acid were dissolved in DMF, and chloroplatinic acid was added to obtain a mixture. The mixture was transferred to a hydrothermal reactor with a polytetrafluoroethylene liner and allowed to react at 100-140°C for 20-30 hours. After washing, filtration, and drying, an intermediate product was obtained. The intermediate product was dispersed in water, the pH was adjusted, a reducing agent was added for reduction, and the mixture was stirred, washed, filtered, and vacuum dried to obtain the Pt-containing bimetallic organic framework material Pt@Mg-MOF-74.

[0062] In the following examples, the structural formulas of the prepared benzotriazole ultraviolet absorbers UV-P, UV-326, UV-327, UV-328, and UV-329, as well as the azo intermediates used in their preparation, are as follows:

[0063]

[0064]

[0065] In the following examples, 2% Pt@Mg-MOF-74 refers to a Pt content of 2 wt% in the catalyst.

[0066] Example 1

[0067] Step 1. Preparation of Pt@Mg-MOF-74 catalyst:

[0068] 0.7917 g (5.556 mmol) of magnesium acetate and 0.334 g (1.68 mmol) of 2,5-dihydroxyterephthalic acid were added to a mixed solvent of 135 mL N,N-dimethylformamide (DMF), 9 mL ethanol, and 9 mL water. After ultrasonic dissolution, 0.0526 g (0.1 mmol) of H2PtCl6 aqueous solution was added. The mixed solution was transferred to a 200 mL stainless steel reaction vessel lined with polytetrafluoroethylene (PPL). The reaction was allowed to stand at 120 °C for 24 hours. After washing and filtration, the catalyst was dried in a vacuum oven at 80 °C for 12 hours. The resulting unreduced catalyst was dispersed in water, the pH was adjusted, and hydrazine hydrate was added for reduction. The mixture was stirred overnight, washed, filtered, and vacuum dried to obtain a defect-type MOF material-encapsulated metal Pt catalyst 2% Pt@Mg-MOF-74.

[0069] Step 2. Catalytic hydrogenation synthesis of benzotriazole UV absorbers:

[0070] In a 250 mL high-pressure reactor, 0.5 g of the 2% Pt@Mg-MOF-74 prepared in step 1 above, 10 g of UV-P azo intermediate, 40 mL of H2O, and 10 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0071] Example 2

[0072] The difference from Example 1 is that the reaction temperature in step 2 is 30°C.

[0073] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, 40 mL of H2O, and 10 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 30 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0074] Example 3

[0075] The difference from Example 1 is that the reaction temperature in step 2 is 70°C.

[0076] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, 40 mL of H2O, and 10 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 70 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0077] Example 4

[0078] The difference from Example 1 is that the hydrogen pressure inside the reactor in step 2 is 0.5 MPa.

[0079] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, 40 mL of H2O, and 10 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 0.5 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0080] Example 5

[0081] The difference from Example 1 is that the hydrogen pressure inside the reactor in step 2 is 3 MPa.

[0082] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, 40 mL of H2O, and 10 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 3 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0083] Example 6

[0084] The difference from Example 1 is that the amount of catalyst used in step 2 is 2% of the mass of the azo intermediate.

[0085] In a 250 mL high-pressure reactor, 0.2 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, 40 mL of H2O, and 10 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0086] Example 7

[0087] The difference from Example 1 is that the amount of catalyst used in step 2 is 8% of the mass of the azo intermediate.

[0088] In a 250 mL high-pressure reactor, 0.8 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, 40 mL of H2O, and 10 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0089] Example 8

[0090] The difference from Example 1 is that the solvent in step 2 is 24 mL H2O and 6 mL 1-butyl-3-methylimidazolium chloride ionic liquid.

[0091] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, 24 mL of H2O, and 6 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0092] Example 9

[0093] The difference from Example 1 is that the solvent in step 2 is 48 mL H2O and 12 mL 1-butyl-3-methylimidazolium chloride ionic liquid.

[0094] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, 48 mL of H2O, and 12 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0095] Example 10

[0096] The difference from Example 1 is that the reaction time in step 2 is 1 hour.

[0097] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, 40 mL of H2O, and 10 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 1 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0098] Example 11

[0099] The difference from Example 1 is that the reaction time in step 2 is 4 hours.

[0100] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, 40 mL of H2O, and 10 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 4 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0101] Example 12

[0102] Difference from Example 1: The azo intermediate in step 2 is UV-326.

[0103] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-326 azo intermediate, 40 mL of H2O, and 10 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0104] Example 13

[0105] Difference from Example 1: The azo intermediate in step 2 is UV-327.

[0106] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-327 azo intermediate, 40 mL of H2O, and 10 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0107] Example 14

[0108] Difference from Example 1: The azo intermediate in step 2 is UV-328.

[0109] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-328 azo intermediate, 40 mL of H2O, and 10 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0110] Example 15

[0111] Difference from Example 1: The azo intermediate in step 2 is UV-329.

[0112] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-329 azo intermediate, 40 mL of H2O, and 10 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0113] Example 16

[0114] The difference from Example 1 is that the solvent in step 2 is 10 mL H2O and 40 mL 1-butyl-3-methylimidazolium chloride ionic liquid.

[0115] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, 10 mL of H2O, and 40 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0116] Example 17

[0117] The difference from Example 1 is that the solvent in step 2 is 45 mL H2O and 5 mL 1-butyl-3-methylimidazolium chloride ionic liquid.

[0118] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, 45 mL of H2O, and 5 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0119] Example 18

[0120] The difference from Example 1 is that the solvent in step 2 is 47.5 mL H2O and 2.5 mL 1-butyl-3-methylimidazolium chloride ionic liquid.

[0121] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, 47.5 mL of H2O, and 2.5 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0122] Example 19

[0123] The difference from Example 1 is that in step 2, the ionic liquid is replaced with 1-ethyl-3-methylimidazolium chloride.

[0124] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, 40 mL of H2O, and 10 mL of 1-ethyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0125] Example 20

[0126] The difference from Example 1 is that in step 2, the solvent is replaced with 50 mL of 1-butyl-3-methylimidazolium chloride ionic liquid.

[0127] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, and 50 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0128] Example 21

[0129] The difference from Example 1 is that the catalyst in step 2 is replaced with 2% Pt / C.

[0130] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt / C, 10 g of UV-P azo intermediate, 40 mL of H2O, and 10 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (at a stirring rate of approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high-performance liquid chromatography. The solvent was filtered off under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0131] Comparative Example 1

[0132] The difference from Example 1 is that the solvent in step 2 does not contain ionic liquid and is replaced with 50 mL H2O; the catalyst is replaced with 2% Pt / C.

[0133] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt / C, 10 g of UV-P azo intermediate, and 50 mL of H2O were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the reactor was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high-performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0134] Comparative Example 2

[0135] The difference from Example 1 is that the solvent in step 2 is replaced with 50 mL of toluene.

[0136] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, and 50 mL of toluene were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0137] Comparative Example 3

[0138] The difference from Example 1 is that the solvent in step 2 is replaced with 50 mL of water.

[0139] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, and 50 mL of water were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0140] Comparative Example 4

[0141] The difference from Example 1 is that the solvent in step 2 is replaced with 50 mL of ethyl acetate.

[0142] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, and 50 mL of ethyl acetate were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0143] Comparative Example 5

[0144] The difference from Example 1 is that the solvent in step 2 is replaced with 50 mL of chlorobenzene.

[0145] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, and 50 mL of chlorobenzene were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0146] Comparative Example 6

[0147] The difference from Example 1 is that the solvent in step 2 is replaced with 50 mL of tetrahydrofuran.

[0148] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 from step 1 of Example 1, 10 g of UV-P azo intermediate, and 50 mL of tetrahydrofuran were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0149] Comparative Example 7

[0150] The difference from Example 1 is that in step 2, the solvent is replaced with 50 mL (0.02 g / mL) of NaOH solution; and the catalyst is replaced with 2% Pt / C.

[0151] In a 250 mL high-pressure reactor, 0.5 g of the 2% Pt / C prepared in step 1 above, 10 g of UV-P azo intermediate, 50 mL of H2O, and 1 g of NaOH were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0152] Comparative Example 8

[0153] The difference from Example 1 is that in step 2, the solvent is replaced with 50 mL of methyl butyl imidazole trifluoromethanesulfonate ionic liquid.

[0154] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, and 50 mL of methyl butylimidazolium trifluoromethanesulfonate ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0155] Comparative Example 9

[0156] The difference from Example 1 is that in step 2, the solvent is replaced with a mixture of 40 mL H2O and 10 mL methyl butyl imidazole trifluoromethanesulfonate ionic liquid.

[0157] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Mg-MOF-74 prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, 40 mL of H2O, and 10 mL of methyl butylimidazolium trifluoromethanesulfonate ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0158] Comparative Example 10

[0159] The difference from Example 1 is that the catalyst in step 2 is replaced with 2% Pt@MIL-101(Cr)-NH2.

[0160] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@MIL-101(Cr)-NH2, 10 g of UV-P azo intermediate, 40 mL of H2O, and 10 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (at a stirring rate of approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high-performance liquid chromatography. The solvent was filtered off under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0161] Comparative Example 11

[0162] The difference from Example 1 is that the catalyst in step 2 is replaced with 2% Pt@UiO-66-(OH)2.

[0163] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@UiO-66-(OH)2, 10 g of UV-P azo intermediate, 40 mL of H2O, and 10 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (at a stirring rate of approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high-performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0164] Comparative Example 12

[0165] The difference from Example 1 is that the catalyst in step 2 is replaced with 2% Pt@Fe-MIL-101-NH2.

[0166] In a 250 mL high-pressure reactor, 0.5 g of 2% Pt@Fe-MIL-101-NH2, 10 g of UV-P azo intermediate, 40 mL of H2O, and 10 mL of 1-butyl-3-methylimidazolium chloride ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (at a stirring rate of approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, the organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high-performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0167] The process conditions, products, raw material conversion rates, and product selectivity results for the catalytic hydrogenation synthesis of benzotriazole UV absorbers in the above embodiments and comparative examples are shown in Table 1.

[0168] Table 1

[0169]

[0170]

[0171]

[0172] As shown in Table 1, the method of the present invention, by adding an ionic liquid to the solvent to synthesize benzotriazole UV absorbers, exhibits high product selectivity, reaching 90% or even over 95%. Compared with the use of other solvents such as n-hexane, toluene, water, ethyl acetate, chlorobenzene, and tetrahydrofuran in Comparative Examples 1-7, the selectivity of the reaction is significantly improved. Furthermore, compared with other catalysts in Comparative Examples 1 and 7-12, the catalyst 2% Pt@Mg-MOF-74 of the present invention not only increases the reaction rate but also significantly improves product selectivity.

[0173] Using the catalyst from Example 1

[0174] In a 250 mL high-pressure reactor, 0.5 g of the 2% Pt@Mg-MOF-74 catalyst prepared in step 1 of Example 1, 10 g of UV-P azo intermediate, 40 mL of H2O, and 10 mL of ionic liquid were added sequentially. The reactor was sealed, and the air inside was repeatedly replaced with hydrogen five times. The hydrogen pressure inside the reactor was then adjusted to 1 MPa, and the mixture was heated to 50 °C and stirred (stirring rate approximately 900 rpm) for 2 h. After the reaction was completed, the catalyst was filtered, and the catalyst cake was washed with deionized water and methanol before being reused in the next experiment. The organic layer was separated, and the composition of the hydrogenation product in the filtrate was analyzed by high performance liquid chromatography. The solvent was filtered out under reduced pressure, washed with deionized water and methanol, and dried to obtain the target product.

[0175] The experimental results are shown in Table 2:

[0176] Table 2 shows the catalyst performance results applied to Example 1. a)

[0177]

[0178]

[0179] a) The catalyst used in the experiment was: the 2% Pt@Mg-MOF-74 catalyst in Example 1.

[0180] As can be seen from Table 2, the method of the present invention, using Pt@Mg-MOF-74 as a catalyst, not only has high catalytic activity, but can also be reused at least 10 times, and the raw material conversion rate after multiple reuses is 100%, and the product selectivity is not much different from that of the first use, still reaching more than 95%.

[0181] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing a benzotriazole compound, comprising: The compound shown in formula (I) is reacted with hydrogen in a solvent to produce the benzotriazole compound shown in formula (II). Equation (I) Equation (II) in, In formulas (I) and (II), R1 and R2 are each independently selected from H, methyl, tert-butyl, 1,1-dimethylpropyl and tert-octyl; The solvent is an ionic liquid or composed of water and an ionic liquid, wherein the ionic liquid is 1-ethyl-3-methylimidazolium chloride or 1-butyl-3-methylimidazolium chloride; the volume fraction of the ionic liquid in the solvent is 10% to 100%. A catalyst, Pt@Mg-MOF-74, is also added to the reaction. The Pt loading in the catalyst is 1wt%-5wt%. The catalyst is prepared by the following method: a magnesium salt, ligand 2,5-dihydroxyterephthalic acid, and N,N-dimethylformamide are mixed and then reacted with a Pt-containing compound. The reaction product is then reduced to obtain Pt@Mg-MOF-74. The Pt-containing compound is selected from chloroplatinic acid. The reducing agent used for the reduction is selected from at least one of hydrazine hydrate, hydrogen, and sodium borohydride. The reaction temperature is 40-70℃.

2. The preparation method according to claim 1, characterized in that, The ionic liquid is 1-butyl-3-methylimidazolium chloride.

3. The preparation method according to claim 1, characterized in that, The volume fraction of water in the solvent is no more than 80%.

4. The preparation method according to claim 1, characterized in that, The mass ratio of the compound shown in formula (I) to the volume ratio of the solvent is 1 g: (2-6) mL.

5. The preparation method according to claim 1, characterized in that, The mass ratio of the compound shown in formula (I) to the volume ratio of the solvent is 1 g: (4-6) mL.

6. The preparation method according to claim 1, characterized in that, The reaction is carried out in a closed container at a hydrogen pressure of 0.5-3 MPa.

7. The preparation method according to claim 1, characterized in that, The reaction is carried out in a closed container at a hydrogen pressure of 1-3 MPa.

8. The preparation method according to claim 1, characterized in that, The amount of catalyst used is 1-10% of the mass of the compound shown in formula (I).

9. The preparation method according to claim 1, characterized in that, The amount of catalyst used is 2-8% of the mass of the compound shown in formula (I).

10. The preparation method according to claim 1, characterized in that, The molar ratio of the magnesium salt to the Pt-containing compound is (55-275):1, and the molar ratio of the ligand 2,5-dihydroxyterephthalic acid to the Pt-containing compound is (16-85):

1.

11. The preparation method according to claim 1, characterized in that, The magnesium salt is selected from magnesium acetate, magnesium chloride, magnesium sulfate, or magnesium nitrate.

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