Preparation method of 2, 4, 6-tri (2-hydroxy-4-n-hexyloxyaryl)-1, 3, 5-triazine

Abstract

The invention discloses a preparation method of 2, 4, 6-tris (2-hydroxy-4-n-hexyloxy aryl)-1, 3, 5-triazine, and belongs to the technical field of organic synthesis.The preparation method comprises the steps that benzenediol compounds and chloro-n-hexane are used as raw materials and subjected to an etherification reaction under the action of hexahydropyridine, after-treatment is conducted, an intermediate is obtained, the intermediate is subjected to post-treatment, and the 2, 4, 6-tris (2-hydroxy-4-n-hexyloxy aryl)-1, 3, 5-triazine is obtained. Reacting the intermediate with cyanuric chloride under the action of an AlOsupported ZnO catalyst to generate 2, 4, 6-tri (2-hydroxy-4-n-hexyloxy aryl)-1, 3, 5-triazine; the raw materials in the synthesis route are cheap, easy to obtain and wide in source, and the process route can effectively reduce the generation of industrial wastewater and waste acid, so that the production cost is reduced, the yield is high, byproducts are few, and industrial production is facilitated.

Description

Technical Field

[0001] This application belongs to the field of organic synthesis technology, and in particular relates to a method for preparing 2,4,6-tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine. Background Technology

[0002] 2,4,6-Tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine is a highly efficient triazine UV absorber with broad development prospects and diverse application potential. As consumers become more aware of UV protection, the global sunscreen market continues to expand. Due to its high UVA / UVB absorption capacity (especially in the 290-400 nm band) and photostability, this class of compounds holds promise as a replacement for traditional UV absorbers. Compared to some traditional UV absorbers (such as certain benzophenones which may have endocrine effects), triazine compounds offer greater structural designability. Their biodegradability and low toxicity can be optimized by adjusting the alkoxy chain (such as the n-hexyloxy group), complying with increasingly stringent environmental regulations (such as EU REACH and China's Cosmetic Safety Technical Specifications). Furthermore, by altering the side chains (such as hydroxyl and alkoxy groups), their solubility, compatibility, and absorption spectrum can be further controlled, adapting them to different matrices (such as oily / water-based cosmetics and polar / non-polar polymers). When combined with nanomaterials (such as titanium dioxide) and antioxidants (such as vitamin E), it can enhance UV shielding efficiency and reduce photodegradation byproducts. The preparation method generally involves first synthesizing the intermediate 2,4,6-tris(2,4-dihydroxy-aryl)-1,3,5-triazine via a classic Friedel-Crafts reaction, and then etherifying the intermediate to prepare the aforementioned triazine-based UV absorber. However, when using chlorobenzene or dichlorobenzene solvents in the Friedel-Crafts reaction process, the catalyst anhydrous aluminum trichloride is difficult to dissolve in the solvent, resulting in a heterogeneous catalytic reaction with numerous byproducts. Furthermore, the substrate selectivity of the Friedel-Crafts reaction is high, significantly affecting the reaction's success and yield. Additionally, using aluminum trichloride as a catalyst in the Friedel-Crafts reaction generates substantial wastewater, leading to low yields, high costs, and environmental problems in the synthetic route. Summary of the Invention

[0003] The purpose of this application is to provide a method for preparing 2,4,6-tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine, in order to solve the technical problems of traditional synthesis methods of 2,4,6-tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine, such as generating a lot of wastewater, difficult post-treatment, poor selectivity, and low yield.

[0004] To achieve the above objectives, the technical solution adopted in this application is: to provide a method for preparing 2,4,6-tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine, specifically including the following steps: (i) Add hydroquinone compounds, n-hexane chloride, toluene, and hexahydropyridine catalyst to a reaction vessel, stir and heat to carry out the etherification reaction, and obtain the reaction solution; (ii) The reaction solution was washed once to obtain an organic phase and an aqueous phase. The organic phase was washed a second time, the pH was adjusted to neutral, and the solution was concentrated and crystallized to obtain the intermediate 2,4,6-tris(2,4-dihydroxyaryl)-1,3,5-triazine. (III) Add intermediate, cyanuric chloride, Al2O3 supported ZnO catalyst and toluene to the reaction vessel, heat and carry out Friedel-Crafts reaction. After the reaction is completed, decolorize, crystallize and dry to obtain 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine; The reaction equation is shown below:

[0005]

[0006] In the reaction equation, R is H or a methyl group.

[0007] In one embodiment, Step (1) The hydroquinone compound is resorcinol or 2-methylresorcinol.

[0008] In one embodiment, Step (1) The molar ratio of hydroquinone compound to n-hexane chloride is 1.2-2:1, and the molar ratio of hexahydropyridine catalyst to cyanuric chloride is 0.03-0.06:1; preferably, the molar ratio of hydroquinone compound to n-hexane chloride is 1.3-1.4:1, and the molar ratio of hexahydropyridine catalyst to cyanuric chloride is 0.035-0.045:1.

[0009] In one embodiment, Step (1) involves heating to a temperature of 70-80 ℃ and etherification reaction for 6-8 h.

[0010] In one embodiment, Step (II) The solvent used for the first wash is water, and the solvent used for the second wash is 5% dilute hydrochloric acid.

[0011] In one embodiment, Preparation method of Al2O3 supported ZnO catalyst: Alumina is immersed in zinc solution, dried at 110 °C and then calcined to obtain Al2O3 supported ZnO catalyst; the molar ratio of alumina to zinc ions in zinc solution is 2-5:1; preferably, the molar ratio or mass ratio of alumina to zinc ions in zinc solution is 3-3.5:1.

[0012] In one embodiment, The zinc solution is zinc nitrate or zinc chloride; the calcination temperature is 400-600 ℃, and the calcination time is 2-4 h.

[0013] In one embodiment, After the Al2O3-supported ZnO catalyst reaction is completed, it is filtered and calcined for reuse.

[0014] In one embodiment, The molar ratio of hydroquinone compounds to cyanuric chloride is 2-4:1, the molar ratio of Al2O3-supported ZnO catalyst to cyanuric chloride is 0.1-0.3:1, and the molar ratio of intermediate to cyanuric chloride is 2.5-5:1; preferably, the molar ratio of hydroquinone compounds to cyanuric chloride is 2.5-3:1, the molar ratio of Al2O3-supported ZnO catalyst to cyanuric chloride is 0.15-0.2:1, and the molar ratio of intermediate to cyanuric chloride is 3-3.5:1.

[0015] In one embodiment, Step (3) The heating temperature is 50-60 ℃, and the Friedel-Crafts reaction time is 4-6 h; the drying temperature is 90-100 ℃.

[0016] In one embodiment, The preferred solvent for the etherification reaction is toluene, with a weight ratio of toluene to cyanuric chloride of 8-15:1.

[0017] This application provides a method for preparing 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine. This method uses hexahydropyridine as a catalyst to generate hexahydropyridine hydrochloride during the reaction. The hydrochloride is soluble in the aqueous phase and easily separated after the reaction, making it suitable for a two-phase system. The generated hexahydropyridine hydrochloride can be removed by washing with dilute hydrochloric acid to avoid metal residue. Simultaneously, the weak basicity of hexahydropyridine limits the concentration of phenoxy anions, making it suitable for monoetherification reactions, preventing the formation of byproducts, and effectively improving the reaction yield. During the reaction, an appropriate amount of potassium iodide can be added to enhance the activity of chlorohexane, thereby shortening the reaction time and increasing the reaction yield. The Al₂O₃-supported ZnO catalyst combines the high specific surface area and thermal stability of Al₂O₃ with the acid-base redox properties of ZnO, effectively improving the catalytic efficiency of the Friedel-Crafts reaction, accelerating the reaction process, and increasing the reaction yield. Traditional methods involve a Friedel-Crafts reaction followed by an etherification reaction, which generates a large amount of industrial wastewater, making subsequent wastewater treatment difficult. This application first involves an etherification reaction followed by a solvent-free condensation reaction, using a supported catalyst instead of a traditional catalyst, which greatly shortens the reaction time, provides extremely high selectivity, and is more suitable for industrial production. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 The liquid phase diagram is for 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine. Detailed Implementation

[0020] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, this application will be further described in detail. It should be understood that the specific embodiments described herein are only for explaining this application and are not intended to limit this application.

[0021] Example 1 (a) Add 148.5 g resorcinol (1.35 mol) and 120 g n-hexane to a 2000 ml four-necked flask equipped with a mechanical stirrer, thermometer and condenser. Evacuate the flask, replace with nitrogen three times, add 300 g toluene, stir to dissolve, add 1.5 g hexahydropyridine catalyst, stir evenly, heat to 75 ℃, reflux for 7 h to obtain the reaction solution; (ii) After the reaction is completed, the reaction solution is washed twice with 150 ml of water to obtain an organic phase and an aqueous phase. The aqueous phase is separated from the organic phase. The organic phase is washed twice with 5% dilute hydrochloric acid to remove hexahydropyridine hydrochloride. Then it is washed with water until the pH is neutral. The solution is concentrated and crystallized to obtain the intermediate 2,4,6-tris(2,4-dihydroxyaryl)-1,3,5-triazine. (III) 180 g of the intermediate and 83.02 g of cyanuric chloride were added to a flask, along with 13 g of Al2O3-supported ZnO catalyst. A Friedel-Crafts reaction was carried out using 600 g of toluene as the solvent at 55 ℃ for 5 h. After the reaction, activated carbon was added for decolorization, followed by hot filtration and crystallization. The product was dried at 90-100 ℃ to obtain 2,4,6-tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine. The product purity was 99.5%, melting point was 145.2-146.8 ℃, and yield was 85%. Preparation method of Al2O3-supported ZnO catalyst: Alumina is immersed in zinc nitrate solution, dried at 110 ℃ and then calcined (calcination temperature is 400-600 ℃, calcination time is 2-4 h) to obtain Al2O3-supported ZnO catalyst. After the reaction of Al2O3-supported ZnO catalyst is completed, it is filtered and calcined again, and can be reused.

[0022] Example 2 The difference between this embodiment and Example 1 is that resorcinol is replaced with 2-methylresorcinol, while the rest of the operation is the same, to obtain the product 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine with a purity of 99.4%, a melting point of 144.8-146.2 °C, and a yield of 85%.

[0023] Example 3 The difference between this example and Example 1 is that the molar ratio of resorcinol to chlorohexane is 1.2:1. The rest of the operation is the same, and the product 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine is obtained with a purity of 99.0%, a melting point of 145-146 °C, and a yield of 83%.

[0024] Example 4 The difference between this example and Example 1 is that the molar ratio of resorcinol to chlorohexane is 2:1. The other operations are the same, and the product 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine is obtained with a purity of 98.6%, a melting point of 143.1-144.3 °C, and a yield of 78%.

[0025] Example 5 The difference between this example and Example 1 is that the molar ratio of hexahydropyridine catalyst to cyanuric chloride is 0.03:1. The rest of the operation is the same, and the product 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine is obtained with a purity of 99.5%, a melting point of 145-146 °C, and a yield of 85%.

[0026] Example 6 The difference between this example and Example 1 is that the molar ratio of hexahydropyridine catalyst to cyanuric chloride is 0.06:1. The rest of the operation is the same, and the product 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine is obtained with a purity of 95.4%, a melting point of 141.3-142.5 °C, and a yield of 75%.

[0027] Example 7 The difference between this embodiment and Example 1 is that in step (i), the etherification reaction temperature is 70 °C and the time is 6 h, while the rest of the operation is the same, yielding the product 2,4,6-tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine with a purity of 96.8%, a melting point of 144.4-145 °C, and a yield of 80%.

[0028] Example 8 The difference between this embodiment and Example 1 is that in step (i), the etherification reaction temperature is 80 °C and the time is 8 h, while the rest of the operation is the same, yielding the product 2,4,6-tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine with a purity of 95.7%, a melting point of 142.3-142.1 °C, and a yield of 78%.

[0029] Example 9 The difference between this embodiment and Example 1 is that in the preparation method of Al2O3-supported ZnO catalyst, zinc nitrate solution is replaced with zinc chloride solution, while the other operations are the same, yielding the product 2,4,6-tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine with a purity of 97.8%, a melting point of 143.2-144.3 °C, and a yield of 79%.

[0030] Example 10 The difference between this embodiment and Example 1 is that the molar ratio of alumina to zinc ions in the zinc solution is 2:1. The rest of the operation is the same, and the product 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine is obtained with a purity of 94.6%, a melting point of 137.9-139.1 °C, and a yield of 72%.

[0031] Example 11 The difference between this embodiment and Example 1 is that the molar ratio of alumina to zinc ions in the zinc solution is 5:1. The rest of the operation is the same, and the product 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine is obtained with a purity of 93.2%, a melting point of 136.3-137.4 °C, and a yield of 69%.

[0032] Example 12 The difference between this embodiment and Example 1 is that in step (iii), the molar ratio of the intermediate to cyanuric chloride is 2.5:1, and the rest of the operation is the same, yielding the product 2,4,6-tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine with a purity of 95.4%, a melting point of 139.4-141.5 °C, and a yield of 66%.

[0033] Example 13 The difference between this embodiment and Example 1 is that in step (iii), the molar ratio of the intermediate to cyanuric chloride is 5:1, and the rest of the operation is the same, yielding the product 2,4,6-tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine with a purity of 93.6%, a melting point of 135.2-137.4 °C, and a yield of 64.3%.

[0034] Example 14 The difference between this example and Example 1 is that the molar ratio of the hydroquinone compound to cyanuric chloride is 2:1. The other operations are the same, and the product 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine is obtained with a purity of 97.0%, a melting point of 141.2-142.5 °C, and a yield of 78%.

[0035] Example 15 The difference between this example and Example 1 is that the molar ratio of the hydroquinone compound to cyanuric chloride is 4:1. The other operations are the same, and the product 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine is obtained with a purity of 95.3%, a melting point of 139.4-140.2 °C, and a yield of 78%.

[0036] Example 16 The difference between this embodiment and Example 1 is that in step (iii), the molar ratio of Al2O3-supported ZnO catalyst to cyanuric chloride is 0.1:1. The remaining operations are the same, yielding the product 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine with a purity of 95.3%, a melting point of 139.4-141.2 °C, and a yield of 75%.

[0037] Example 17 The difference between this embodiment and Example 1 is that in step (iii), the molar ratio of Al2O3-supported ZnO catalyst to cyanuric chloride is 0.3:1. The remaining operations are the same, yielding the product 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine with a purity of 94.6%, a melting point of 137.8-139.2 °C, and a yield of 78%.

[0038] Example 18 The difference between this embodiment and Example 1 is that in step (iii), the Friedel-Crafts reaction temperature is 50 °C and the time is 4 h, while the rest of the operation is the same, yielding the product 2,4,6-tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine with a purity of 93.4%, a melting point of 135.6-137.8 °C, and a yield of 71%.

[0039] Example 19 The difference between this embodiment and Example 1 is that in step (iii), the Friedel-Crafts reaction temperature is 60 °C and the time is 6 h, while the rest of the operation is the same, yielding the product 2,4,6-tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine with a purity of 96.1%, a melting point of 137.4-138.6 °C, and a yield of 78%.

[0040] This application provides a method for preparing 2,4,6-tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine, comprising the following steps: adding a quinone compound, n-hexane chloride, toluene, and a hexahydropyridine catalyst to a reaction vessel, stirring and heating to carry out an etherification reaction to obtain a reaction solution; washing the reaction solution once to obtain an organic phase and an aqueous phase, washing the organic phase a second time, adjusting the pH to neutral, concentrating and crystallizing to obtain the intermediate 2,4,6-tris(2,4-dihydroxyaryl)-1,3,5-triazine; adding the intermediate, cyanuric chloride, an Al2O3-supported ZnO catalyst, and toluene to the reaction vessel, and heating. A Friedel-Crafts reaction was carried out, followed by decolorization, crystallization, and drying to obtain 2,4,6-tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine. This application uses hexahydropyridine as the catalyst for the etherification reaction and Al2O3-supported ZnO catalyst as the catalyst for the Friedel-Crafts reaction. The two catalysts synergistically improve the efficiency of the reaction route and reduce the generation of byproducts. Resorcinol or 2-methylresorcinol, cyanuric chloride, and n-hexane chloride are used as reactants. The required reactants are inexpensive, readily available, and widely sourced. The process route effectively reduces the generation of industrial wastewater and waste acid, thereby lowering production costs and facilitating industrial production.

[0041] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0042] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing 2,4,6-tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine, characterized in that, Specifically, the following steps are included: (i) Add hydroquinone compounds, n-hexane chloride, toluene, and hexahydropyridine catalyst to a reaction vessel, stir and heat to carry out the etherification reaction, and obtain the reaction solution; (ii) The reaction solution is washed once to obtain an organic phase and an aqueous phase. The organic phase is washed a second time, the pH is adjusted to neutral, and the solution is concentrated and crystallized to obtain the intermediate 2,4,6-tris(2,4-dihydroxyaryl)-1,3,5-triazine. (III) Add the intermediate, cyanuric chloride, Al2O3-supported ZnO catalyst and toluene to the reaction vessel, heat and carry out Friedel-Crafts reaction. After the reaction is completed, decolorize, crystallize and dry to obtain 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine.

2. The method for preparing 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine according to claim 1, characterized in that, The hydroquinone compound mentioned in step (i) is resorcinol or 2-methylresorcinol.

3. The method for preparing 2,4,6-tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine according to claim 1, characterized in that, In step (i), the molar ratio of the hydroquinone compound to n-hexane chloro is 1.2-2:1, and the molar ratio of the hexahydropyridine catalyst to cyanuric chloride is 0.03-0.06:

1.

4. The method for preparing 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine according to claim 1, characterized in that, The temperature for heating in step (1) is 70-80 ℃, and the etherification reaction time is 6-8 h.

5. The method for preparing 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine according to claim 1, characterized in that, The solvent used for the first wash in step (ii) is water, and the solvent used for the first wash is 5% dilute hydrochloric acid.

6. The method for preparing 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine according to claim 1, characterized in that, The preparation method of the Al2O3-supported ZnO catalyst is as follows: alumina is immersed in zinc solution, dried at 110 °C and then calcined to obtain Al2O3-supported ZnO catalyst; the molar ratio of alumina to zinc ions in zinc solution is 2-5:

1.

7. The method for preparing 2,4,6-tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine according to claim 6, characterized in that, The zinc solution is zinc nitrate or zinc chloride; the calcination temperature is 400-600 ℃, and the calcination time is 2-4 h.

8. The method for preparing 2,4,6-tris(2-hydroxy-4-n-hexyloxyaryl)-1,3,5-triazine according to claim 6, characterized in that, The Al2O3-supported ZnO catalyst is filtered and calcined after the reaction is complete, and can be reused.

9. The method for preparing 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine according to claim 1, characterized in that, The molar ratio of the hydroquinone compound to cyanuric chloride is 2-4:1, the molar ratio of the Al2O3-supported ZnO catalyst to cyanuric chloride is 0.1-0.3:1, and the molar ratio of the intermediate to cyanuric chloride is 2.5-5:

1.

10. The method for preparing 2,4,6-tris(2-hydroxy-4-hexyloxyaryl)-1,3,5-triazine according to claim 1, characterized in that, The heating temperature in step (iii) is 50-60 ℃, and the Friedel-Crafts reaction time is 4-6 h; the drying temperature is 90-100 ℃.

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