A clean process for the preparation of antioxidant 1790

Abstract

The application discloses a clean preparation method of antioxidant 1790, and comprises the following steps: step one: 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl alcohol, long-chain amine hydrogen chloride salt [R3NH][Cl] and aluminum trichloride are added into a 500ml pressure-resistant reaction kettle, and then reacted at a specific temperature, and then residual moisture is evaporated; step two: in the above reaction kettle containing the reaction liquid obtained in the first step, cyanuric acid is added, and then reacted at a specific temperature, and then the product is extracted with ethyl acetate, and then the solvent is evaporated to obtain crude antioxidant 1790, and the 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl chloride and the cyanuric acid are converted into the antioxidant 1790 under the action of the long-chain amine and aluminum hydroxide, meanwhile, the long-chain amine and the aluminum hydroxide and the hydrogen chloride released in the process are converted back into the long-chain amine hydrogen chloride salt and the aluminum trichloride, compared with the prior method, the method realizes the circulation of the chlorinating reagent in the system, avoids the generation of salt-containing waste, and is a clean preparation method of the antioxidant 1790.

Description

Technical Field

[0001] This invention relates to a method for preparing antioxidant 1790, specifically a clean preparation method for antioxidant 1790, belonging to the field of fine chemicals. Background Technology

[0002] Antioxidant 1790 (CAS No.: 40601-76-1; Chemical Name: 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione) is a highly efficient sterically hindered phenolic antioxidant and a primary antioxidant for organic polymers. It is widely used in the synthesis of polyethylene, polypropylene, polystyrene, ABS resin, polyester, cellulose resin, etc.

[0003] The current mainstream synthesis process for antioxidant 1790 is shown in [link to original text]. Figure 1 Related patent CN106699678A discloses the use of thionyl chloride, phosphorus trichloride, etc. to chlorinate 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl alcohol to produce 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl chloride, and then dehydrochlorinates 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl chloride and cyanuric acid under the action of tributylphosphine to obtain antioxidant 1790; patent CN104557752A discloses the use of phosphorus trichloride as a chlorinating agent to chlorinate 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl alcohol to produce 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl chloride, and then dehydrochlorinates 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl chloride and cyanuric acid under the action of triethylamine to obtain antioxidant 1790.

[0004] The aforementioned patents require a large amount of chlorination reagent to prepare antioxidant 1790, while also generating salt-containing waste liquid. The cost of chlorination reagent and the cost of waste treatment are relatively high. In order to improve the reaction activity, the relevant patent CN112661710 discloses a method for preparing antioxidant 1790 using 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl bromide as raw material and dehydrobromide removal from bis(trimethylsilyl)amino potassium. This method uses a bromine-containing substrate and expensive bis(trimethylsilyl)amino potassium as a base, but this method has no industrial value. In addition, the relevant patent CN103420932A discloses a method for preparing antioxidant 1790 by reacting NaOH and cyanuric acid to obtain sodium cyanate, and then dechlorinating sodium cyanate with 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl chloride. Although this method has relatively low raw material costs, it still generates a large amount of waste salt.

[0005] Based on this, a clean preparation method for antioxidant 1790 is proposed to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a clean preparation method for antioxidant 1790 to solve the above-mentioned problems. This method uses a mixed system of long-chain amine hydrogen chloride and aluminum trichloride as solvent, catalyst and chlorinating agent, to chlorinate 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl alcohol to generate 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl chloride. At the same time, the long-chain amine hydrogen chloride and aluminum trichloride are converted into long-chain amine and aluminum hydroxide. Then, 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl chloride and cyanuric acid generate antioxidant 1790 under the action of long-chain amine and aluminum hydroxide. Meanwhile, the long-chain amine and aluminum hydroxide react with the hydrogen chloride released in the process to be converted back into long-chain amine hydrogen chloride and aluminum trichloride. Compared with the existing methods, this method realizes the recycling of chlorinating agent in the system and avoids the generation of salt-containing waste, which is a clean preparation method for antioxidant 1790.

[0007] This invention achieves the above objective through the following technical solution: a clean preparation method for antioxidant 1790, comprising the following steps:

[0008] Step 1: Add 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl alcohol, long-chain amine hydrogen chloride [R3NH][Cl], and aluminum trichloride to a 500ml pressure-resistant reactor, react at a specific temperature, and then evaporate the residual moisture.

[0009] Step 2: In the above reaction vessel containing the reaction solution obtained in Step 1, add cyanuric acid and react at a specific temperature. After the reaction is completed, extract the product with ethyl acetate, evaporate the solvent to obtain crude antioxidant 1790.

[0010] As a further feasible option, the long-chain amine hydrochloride [R3NH][Cl] used is tripentylamine hydrochloride, trihexylamine hydrochloride, triheptylamine hydrochloride, or trioctylamine hydrochloride.

[0011] As a further feasible option, the molar ratio of 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl alcohol to long-chain amine hydrogen chloride [R3NH][Cl] in the first step reaction is 1:1 to 1:3.

[0012] As a further feasible option, the molar ratio of 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl alcohol to aluminum trichloride in the first step reaction is 1:1 to 1:3.

[0013] As a further feasible option, the first step reaction temperature is between 130-160℃.

[0014] As a further feasible option, the molar ratio of cyanuric acid used in the second step reaction to 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl alcohol used in the first step is 1:3-1.5:3.

[0015] As a further feasible option, the second step reaction temperature is between 90-120℃.

[0016] As a further feasible option, after the second step reaction is completed, the long-chain amine hydrogen chloride [R3NH][Cl] and aluminum trichloride obtained after extraction and separation of the product can be directly applied to the first step reaction after distillation to remove the extract.

[0017] The beneficial effects of this invention are as follows: 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl chloride and cyanuric acid are reacted with long-chain amines and aluminum hydroxide to generate antioxidant 1790. At the same time, the long-chain amines, aluminum hydroxide, and hydrogen chloride released during the process react to transform back into long-chain amine hydrogen chloride salt and aluminum trichloride. Compared with existing methods, this method realizes the recycling of chlorination reagents within the system, avoids the generation of salt-containing waste, and is a clean method for preparing antioxidant 1790. Attached Figure Description

[0018] Figure 1 This is the existing synthesis process for antioxidant 1790.

[0019] Figure 2 This invention relates to the synthesis process of antioxidant 1790. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1

[0022] Step 1 reaction: 62.4 g (0.3 mol) of 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl alcohol, 183.0 g (0.6 mol) of trihexylamine hydrochloride and 80.1 g (0.6 mol) of aluminum trichloride were added to a 500 ml pressure-resistant reactor. The mixture was heated to 150 °C with stirring and reacted at this temperature for 12 hours. Then, it was distilled under reduced pressure at 90 °C for 1 hour.

[0023] Second step reaction: In the above reaction vessel containing the reaction solution obtained in the first step, 12.9 g (0.1 mol) of cyanuric acid was added, and the mixture was heated to 100°C with stirring and reacted at this temperature for 8 hours. After the reaction was completed, the reaction solution was cooled to 40°C, and the product was extracted with ethyl acetate. After evaporating the solvent, 65.2 g of crude antioxidant 1790 was obtained. Liquid chromatography analysis showed that the content of antioxidant 1790 was 91.6%, and the yield was 85.4%.

[0024] Examples 2-4

[0025] Similar to Example 1, different long-chain amine hydrogen chloride salts were used for the reaction.

[0026] Step 1: 62.4 g (0.3 mol) of 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl alcohol and 183.0 g (0.6 mol) of other compounds were added sequentially to three 500 ml pressure-resistant reactors. Then, tripentylamine hydrochloride / triheptylamine hydrochloride / trioctylamine hydrochloride were added to the three reactors respectively. Next, 80.1 g (0.6 mol) of aluminum trichloride was added to each of the three reactors. The mixture was stirred and heated to 150 °C and reacted at this temperature for 12 hours. Then, the mixture was distilled under reduced pressure at 90 °C for 1 hour.

[0027] Second step reaction: In the above reaction vessel containing the reaction solution obtained in the first step, 12.9 g (0.1 mol) of cyanuric acid was added, and the mixture was heated to 100 °C with stirring and reacted at this temperature for 8 hours. After the reaction was completed, the reaction solution was cooled to 40 °C, and the product was extracted with ethyl acetate. After evaporating the solvent, crude antioxidant 1790 was obtained. The results are shown in Table 1.

[0028] Table 1. Results of reactions using different long-chain amine hydrogen chloride salts

[0029] Long-chain amine hydrogen chloride Yield (%) content(%) Example 2 Tripentylamine hydrochloride 81.1 89.6 Example 3 Triheptanyl Hydrochloride 86.3 91.9 Example 4 Trioctylamine hydrochloride 88.5 92.7

[0030] Examples 5-8

[0031] Similar to Example 1, different amounts of long-chain amine hydrogen chloride and aluminum trichloride were used in the reaction, and the results are shown in Table 2:

[0032] Table 2. Results of the reaction using different amounts of trihexylamine hydrochloride and aluminum trichloride

[0033]

[0034] Examples 9-12

[0035] Similar to Example 1, the reaction was carried out at different temperatures, and the results are shown in Table 3:

[0036] Table 3. Reaction results at different temperatures

[0037]

[0038] Example 13

[0039] Trihexylamine hydrochloride and aluminum trichloride recovery: Similar to Example 1, after the product was extracted with ethyl acetate in the second step of the reaction, the residue was subjected to vacuum distillation at 70°C for 2 hours. The resulting trihexylamine hydrochloride-aluminum trichloride mixture was directly used in the next batch reaction.

[0040] Trihexylamine hydrochloride and aluminum trichloride are used interchangeably:

[0041] Step 1 reaction: 62.4 g (0.3 mol) of 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl alcohol and the recovered trihexylamine hydrochloride-aluminum trichloride mixture were added to a 500 ml pressure-resistant reactor. The mixture was heated to 150 °C with stirring and reacted at this temperature for 12 hours. Then, it was distilled under reduced pressure at 90 °C for 1 hour.

[0042] Second step reaction: In the above reaction vessel containing the reaction solution obtained in the first step, 12.9 g (0.1 mol) of cyanuric acid was added, and the mixture was heated to 100°C with stirring and reacted at this temperature for 8 hours. After the reaction was completed, the reaction solution was cooled to 40°C, and the product was extracted with ethyl acetate. After evaporating the solvent, 65.2 g of crude antioxidant 1790 was obtained. Liquid chromatography analysis showed that the content of antioxidant 1790 was 91.0%, and the yield was 84.9%.

[0043] In this invention, 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl alcohol, long-chain amine hydrogen chloride [R3NH][Cl], and aluminum trichloride are added to a 500ml pressure-resistant reactor and reacted at a specific temperature. Then, residual water is evaporated. In the reactor containing the reaction solution obtained in the first step, cyanuric acid is added and reacted at a specific temperature. After the reaction is completed, the product is extracted with ethyl acetate, and the solvent is evaporated to obtain crude antioxidant 1790. This realizes the circulation of chlorination reagents within the system and avoids the generation of salt-containing waste.

[0044] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0045] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A clean preparation method for antioxidant 1790, characterized in that, It includes the following two steps: Step 1: Add 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl alcohol, long-chain amine hydrogen chloride [R3NH][Cl], and aluminum trichloride to a 500ml pressure-resistant reactor, react at a specific temperature, and then evaporate the residual water. The long-chain amine hydrogen chloride [R3NH][Cl] is tripentylamine hydrochloride, trihexylamine hydrochloride, triheptylamine hydrochloride, or trioctylamine hydrochloride. Step 2: Add cyanuric acid to the reaction vessel containing the reaction solution obtained in Step 1, react at a specific temperature, extract the product with ethyl acetate after the reaction is completed, and obtain crude antioxidant 1790 by evaporating the solvent.

2. The clean preparation method of antioxidant 1790 according to claim 1, characterized in that: In the first step of the reaction, the molar ratio of 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl alcohol to long-chain amine hydrogen chloride [R3NH][Cl] is 1:1 to 1:

3.

3. The clean preparation method of antioxidant 1790 according to claim 1, characterized in that: In the first step of the reaction, the molar ratio of 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl alcohol to aluminum trichloride is 1:1 to 1:

3.

4. The clean preparation method of antioxidant 1790 according to claim 1, characterized in that: The first step reaction temperature is 130-160°C. o Between C.

5. The clean preparation method of antioxidant 1790 according to claim 1, characterized in that: The molar ratio of cyanuric acid used in the second step reaction to 4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl alcohol used in the first step is 1:3-1.5:

3.

6. The clean preparation method of antioxidant 1790 according to claim 1, characterized in that: The second step reaction temperature is 90-120°C. o Between C.

7. The clean preparation method of antioxidant 1790 according to claim 1, characterized in that: After the second step reaction is completed, the long-chain amine hydrogen chloride [R3NH][Cl] and aluminum trichloride obtained after extraction and separation of the product can be directly used in the first step reaction after distillation to remove the extract.

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