Asymmetric hindered phenol antioxidant 245 and preparation method thereof

Abstract

The invention provides an asymmetric hindered phenol antioxidant 245 and a preparation method thereof. A supported catalyst using zinc acetate and aluminum trifluoromethanesulfonate as active components is adopted. During the reaction, the zinc acetate and the aluminum trifluoromethanesulfonate interact with each other to form a complex. Combined with a vacuum environment, the asymmetric hindered phenol antioxidant 245 can be more effectively catalyzed to carry out an ester exchange reaction between 3-tert-butyl-4-hydroxy-5-methylphenylpropionate and triethylene glycol under the premise of ensuring environmental safety, thereby improving the catalytic efficiency, reducing the energy consumption, and obtaining the antioxidant 245 with a higher yield and purity.

Description

Technical Field

[0001] The present invention relates to the technical field of phenolic antioxidants, and in particular to an asymmetric hindered phenolic antioxidant 245 and a preparation method thereof. Background Art

[0002] Triethylene glycol bis-β-(3-tert-butyl-4-hydroxy-5-methylphenyl)-propionate (Antioxidant 245) is an excellent asymmetric hindered phenol antioxidant. Its single antioxidant effect is far greater than the currently widely used antioxidant BHT, and its synergistic effect with phosphites and thioesters is also significantly better than that of antioxidants 1010 and 1076. It also has good compatibility with polymer resins, high antioxidant efficiency, good anti-extraction properties, no coloring, low volatility, no pollution, and washing resistance. It is widely used in polymer resins such as high-impact polystyrene, ABS, polyacetal, polyamide, and some food packaging materials. Its research and development is of great significance.

[0003] At present, in the preparation method of triethylene glycol bis-β-(3-tert-butyl-4-hydroxy-5-methylphenyl)-propionate, it is more common to use organic tin as a catalyst, 3-tert-butyl-4-hydroxy-5-methylphenyl propionate and triethylene glycol for ester exchange reaction, the reaction is easy to carry out, but tin catalysts are not environmentally friendly and have adverse effects on the environment; and this method has a long reaction time, requiring more than 6 hours, and the reaction temperature is high, exceeding 180°C, the energy consumption loss is huge, and there are certain safety hazards.

[0004] Another common method is to use potassium hydroxide and lithium hydroxide as catalysts to carry out ester exchange reaction between 3-tert-butyl-4-hydroxy-5-methylphenylpropionate and triethylene glycol. The reaction is also easy to carry out, but the post-treatment using this alkaline catalyst requires a large amount of water treatment, which still has the problem of environmental pollution. The reaction time also requires more than 6 hours, the reaction is relatively long, and the reaction temperature is relatively high, exceeding 180°C, which is also not conducive to production and poses a safety hazard.

[0005] Therefore, it is necessary to improve a production process of antioxidant 245 with a short reaction time, low temperature and easy handling of the catalyst after the reaction. Summary of the invention

[0006] The purpose of the present invention is to provide an asymmetric hindered phenol antioxidant 245 and a preparation method thereof in view of the deficiencies in the prior art. The catalytic system has good effect, simple process and environmental protection, short reaction time and low temperature, and the catalyst in the product is easy to recover and can be directly recycled, which is green and environmentally friendly.

[0007] The first aspect of the present invention relates to a method for preparing an asymmetric hindered phenol antioxidant 245, comprising the following steps:

[0008] S1, adding 3-tert-butyl-4-hydroxy-5-methylphenyl propionate and triethylene glycol into a reactor to obtain a first mixture, evacuating the reactor, and controlling the temperature in the reactor to be in a first temperature range;

[0009] S2, after adding the catalyst to the first mixture, maintaining the vacuum degree in step S1, and raising the temperature so that the temperature in the reactor is controlled in the second temperature range to carry out the reaction;

[0010] Wherein, the catalyst is a supported catalyst with zinc acetate and aluminum trifluoromethanesulfonate as active components;

[0011] S3. After the reaction is completed, add methanol aqueous solution to the solution after the reaction, cool and stir to crystallize, filter and dry to obtain an asymmetric hindered phenol antioxidant 245.

[0012] In an optional embodiment, the preparation process of the catalyst is as follows:

[0013] placing the carrier in a zinc acetate aqueous solution, and sequentially allowing the solution to stand at room temperature and drying the solution at a constant temperature to obtain a first intermediate;

[0014] The first intermediate is placed in an aqueous solution of aluminum trifluoromethanesulfonate, and is allowed to stand at room temperature and dried at a constant temperature to obtain a second intermediate;

[0015] The second intermediate is placed in a muffle furnace for calcination, and the temperature is naturally lowered after the calcination is completed to obtain the supported catalyst.

[0016] In an optional embodiment, the concentration of the aqueous zinc acetate solution is 5 to 10 mg / mL, and the concentration of the aqueous aluminum trifluoromethanesulfonate solution is 1 to 5 mg / mL.

[0017] In an optional embodiment, the carrier is placed in an aqueous solution of zinc acetate, and the mixture is allowed to stand at room temperature for 4 to 6 hours and then dried at a constant temperature of 85 to 95° C. for 7 to 9 hours to obtain a first intermediate.

[0018] In an optional embodiment, the first intermediate is placed in an aqueous solution of aluminum trifluoromethanesulfonate, and is allowed to stand at room temperature for 2 to 4 hours and then dried at a constant temperature of 85 to 95° C. for 7 to 9 hours to obtain a second intermediate.

[0019] In an optional embodiment, the second intermediate is placed in a muffle furnace for calcination at a temperature of 500 to 700° C. for a calcination time of 4 to 5 hours.

[0020] In an optional embodiment, the carrier is silicon oxide and is pre-treated, and the pre-treatment process is as follows:

[0021] The carrier is placed in a muffle furnace at 400°C and calcined for 3 to 4 hours.

[0022] In an optional embodiment, in step S1, the reaction conditions are as follows:

[0023] The vacuum degree is -0.08 to -0.1 MPa, the first temperature range is [85°C, 95°C], and the reaction time is 20 to 30 minutes.

[0024] In an optional embodiment, in step S1, the molar ratio of methyl 3-tert-butyl-4-hydroxy-5-methylphenylpropionate to triethylene glycol is (2-3):1.

[0025] In an optional embodiment, in step S2, the reaction conditions are as follows:

[0026] The second temperature range is [125°C, 135°C], and the reaction time is 3 to 4 hours.

[0027] In an optional embodiment, in step S2, the amount of the catalyst used is 0.3-0.5% of the mass of 3-tert-butyl-4-hydroxy-5-methylphenylpropionate.

[0028] The second aspect of the present invention relates to an asymmetric hindered phenol antioxidant 245 prepared by the above method.

[0029] Compared with the prior art, the present invention has the following significant beneficial effects:

[0030] The preparation method of the asymmetric hindered phenol antioxidant 245 of the present invention adopts a supported catalyst with zinc acetate and aluminum trifluoromethanesulfonate as active components. During the reaction process, zinc acetate and aluminum trifluoromethanesulfonate interact with each other to form a complex, thereby significantly improving the catalytic activity, shortening the reaction time, and achieving high catalytic efficiency, which is improved by more than 30%.

[0031] At the same time, zinc acetate and aluminum trifluoromethanesulfonate interact to form a complex, and combined with vacuum conditions, the ester exchange reaction process is affected, so that the target product with higher yield and purity can be obtained within a temperature range not exceeding 140° C., which greatly reduces the hidden dangers brought by high process temperatures and ensures production safety.

[0032] The method of the present invention can obtain antioxidant 245 with higher yield and purity, and the entire reaction system has high efficiency, high safety, green environmental protection, low energy consumption, and reduced production cost.

[0033] The present invention adopts a supported catalyst using silicon oxide as a carrier, the catalyst has good stability, is easy to recover, and still has high catalytic activity after being used many times, further reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a process flow chart of the preparation of the asymmetric hindered phenol antioxidant 245 of the present invention. DETAILED DESCRIPTION

[0035] In order to better understand the technical content of the present invention, specific embodiments are given and described as follows in conjunction with the accompanying drawings.

[0036] Various aspects of the present invention are described in this disclosure with reference to the accompanying drawings, in which many illustrative embodiments are shown. The embodiments of the present disclosure are not necessarily intended to include all aspects of the present invention. It should be understood that the various concepts and embodiments introduced above, as well as those described in more detail below, can be implemented in any of many ways.

[0037] The present invention aims to provide a green and environmentally friendly catalytic system, which can more effectively catalyze the ester exchange reaction between 3-tert-butyl-4-hydroxy-5-methylphenylpropionate and triethylene glycol under the premise of ensuring environmental safety, improve the catalytic efficiency, reduce energy consumption, and obtain antioxidant 245 with higher yield and purity.

[0038] Combination Figure 1 As shown, in an exemplary embodiment of the present invention, a method for preparing an asymmetric hindered phenol antioxidant 245 is provided, comprising the following steps:

[0039] S1, adding 3-tert-butyl-4-hydroxy-5-methylphenyl propionate and triethylene glycol into a reactor to obtain a first mixture, evacuating the reactor, and controlling the temperature in the reactor to be in a first temperature range;

[0040] S2, after adding the catalyst to the first mixture, maintaining the vacuum degree in step S1, and raising the temperature so that the temperature in the reactor is controlled in the second temperature range, reacting, and extracting the methanol generated during the reaction;

[0041] Wherein, the catalyst is a supported catalyst with zinc acetate and aluminum trifluoromethanesulfonate as active components;

[0042] S3. After the reaction is completed, the catalyst is filtered out and separated, and then methanol aqueous solution is added to the filtered solution, cooled and stirred for crystallization, filtered, and dried to obtain an asymmetric hindered phenol antioxidant 245. The filtered catalyst can be recycled.

[0043] In an optional embodiment, the preparation process of the catalyst is as follows:

[0044] placing the carrier in a zinc acetate aqueous solution, and sequentially allowing the solution to stand at room temperature and drying the solution at a constant temperature to obtain a first intermediate;

[0045] The first intermediate is placed in an aqueous solution of aluminum trifluoromethanesulfonate, and is allowed to stand at room temperature and dried at a constant temperature to obtain a second intermediate;

[0046] The second intermediate is placed in a muffle furnace for calcination, and the temperature is naturally lowered after the calcination is completed to obtain the supported catalyst.

[0047] In an optional embodiment, the concentration of the aqueous zinc acetate solution is 5 to 10 mg / mL, and the concentration of the aqueous aluminum trifluoromethanesulfonate solution is 1 to 5 mg / mL.

[0048] In an optional embodiment, the concentration ratio of the aqueous zinc acetate solution to the aqueous aluminum trifluoromethanesulfonate solution is (2-3):1.

[0049] In an optional embodiment, the carrier is placed in an aqueous solution of zinc acetate, and the mixture is allowed to stand at room temperature for 4 to 6 hours and then dried at a constant temperature of 85 to 95° C. for 7 to 9 hours to obtain a first intermediate.

[0050] In an optional embodiment, the first intermediate is placed in an aqueous solution of aluminum trifluoromethanesulfonate, and is allowed to stand at room temperature for 2 to 4 hours and then dried at a constant temperature of 85 to 95° C. for 7 to 9 hours to obtain a second intermediate.

[0051] In an optional embodiment, the second intermediate is placed in a muffle furnace for calcination at a temperature of 400 to 600° C. for a calcination time of 4 to 5 hours.

[0052] In an optional embodiment, the carrier is silicon oxide and is pre-treated, and the pre-treatment process is as follows:

[0053] The carrier is placed in a muffle furnace at 400°C and calcined for 3 to 4 hours.

[0054] It should be understood that the carrier includes but is not limited to silicon oxide, and may also be a catalyst carrier commonly used in the art, and those skilled in the art may select one according to actual conditions.

[0055] In an optional embodiment, in step S1, the reaction conditions are as follows:

[0056] The vacuum degree is -0.08 to -0.1 MPa, the first temperature range is [85°C, 95°C], and the reaction time is 20 to 30 minutes.

[0057] In an optional embodiment, in step S1, the molar ratio of methyl 3-tert-butyl-4-hydroxy-5-methylphenylpropionate to triethylene glycol is (2-3):1.

[0058] In an optional embodiment, in step S2, the reaction conditions are as follows:

[0059] The second temperature range is [125°C, 135°C], and the reaction time is 3 to 4 hours.

[0060] In an optional embodiment, in step S2, the amount of the catalyst used is 0.3-0.5% of the mass of 3-tert-butyl-4-hydroxy-5-methylphenylpropionate.

[0061] In a typical embodiment, a method for preparing an asymmetric hindered phenol antioxidant 245 is provided, comprising the following steps:

[0062] [Preparation of supported catalyst]

[0063] (1) Calcination activation of the supported catalyst carrier: Take the prepared silica carrier, place it in a muffle furnace at 400°C and calcine it for 3 to 4 hours, and then cool it down to obtain the treated carrier.

[0064] (2) Loading the active component 1 onto the pretreated carrier: impregnating the carrier in step (1) with an aqueous solution of zinc acetate having a concentration of 5 to 10 mg / mL, and then standing at room temperature for 4 to 6 hours and drying at a constant temperature of 85 to 95° C. for 7 to 9 hours.

[0065] (3) Continue to load the active component 2 onto the carrier: impregnate the carrier in step (2) with an aqueous solution of aluminum trifluoromethanesulfonate having a concentration of 1 to 5 mg / mL, and then let it stand at room temperature for 2 to 4 hours and dry it at a constant temperature of 85 to 95° C. for 7 to 9 hours.

[0066] Among them, the concentration ratio of the zinc acetate aqueous solution to the aluminum trifluoromethanesulfonate aqueous solution is preferably (2-3):1.

[0067] (4) The carrier in step (3) is placed in a muffle furnace at 600° C. and calcined for 4-5 h to finally obtain the supported catalyst used.

[0068] [Preparation of Antioxidant 245]

[0069] (i) 3-tert-butyl-4-hydroxy-5-methylphenylpropionic acid methyl ester and triethylene glycol in a molar ratio of 2.1:1 are added into a reactor, the temperature is controlled at 85 to 95° C., the vacuum degree is -0.08 to -0.1 MPa, and the reaction time is 0.5 h.

[0070] (ii) adding the supported catalyst prepared above in an amount of 0.4% of the mass of 3-tert-butyl-4-hydroxy-5-methylphenylpropionic acid methyl ester, raising the temperature to 125-135° C., maintaining the vacuum degree at -0.08 to -0.1 MPa, reacting for 4 hours, extracting the methanol generated during the reaction, and filtering and recovering the supported catalyst for recycling.

[0071] (iii) adding methanol aqueous solution, slowly cooling and stirring to crystallize, filtering, and drying to obtain the target product as a white powder.

[0072] It should be understood that the addition of methanol aqueous solution is for purification. The target product and impurities exist in the reaction liquid after the esterification reaction, and purification is carried out by solvent crystallization, that is, methanol aqueous solution is added to make the reaction liquid completely dissolved in the solvent. Different solubilities are utilized at different temperatures. When cooling, the final product is precipitated first, and the impurities are still in the solvent, thereby purifying the target product. Therefore, the amount of methanol aqueous solution is only needed to completely dissolve the substances in the reaction liquid, and can be added according to actual conditions.

[0073] Furthermore, the stirring speed, filtering process, and drying process are all commonly used processes in the art and can be selected according to actual production conditions, and will not be described in detail here.

[0074] In another exemplary embodiment of the present invention, an asymmetric hindered phenol antioxidant 245 prepared by the above method is provided, and the obtained antioxidant 245 has a high yield and purity.

[0075] For better understanding, the present invention is further described below in conjunction with several specific examples, but the preparation process is not limited thereto, and the content of the present invention is not limited thereto.

[0076] Unless otherwise specified, the materials in the examples were prepared according to existing methods or directly purchased from the market.

[0077] Example 1

[0078] [Preparation of Catalyst]

[0079] (1) Calcination activation of the supported catalyst carrier: Take the prepared silica carrier, place it in a muffle furnace at 400°C and calcine it for 4 hours, and then cool it down to obtain the treated carrier.

[0080] (2) Loading the active component 1 onto the pretreated carrier: 6 g of the active component 1 zinc acetate was dissolved in 100 mL of deionized water and impregnated with the carrier in step (1), and then allowed to stand at room temperature for 5 h and dried at a constant temperature of 90° C. for 8 h.

[0081] (3) Continue to load the active component 2 onto the carrier: 3 g of the active component 2 aluminum trifluoromethanesulfonate was dissolved in 100 mL of deionized water and impregnated with the carrier in step (2), and then allowed to stand at room temperature for 3 h and dried at a constant temperature of 90° C. for 8 h.

[0082] (4) The carrier in step (3) was placed in a muffle furnace at 600° C. and calcined for 5 h to obtain the supported catalyst.

[0083] Example 2

[0084] In a 500mL four-necked flask equipped with a mechanical stirrer, a thermometer, a distillation condenser, and a nitrogen inlet, 157.69g (0.63mol) of methyl 3-tert-butyl-4-hydroxy-5-methylphenylpropionate and 45.05g (0.3mol) of triethylene glycol were added. The vacuum degree was -0.08MPa, and the temperature was gradually raised to 95°C and maintained for 0.5h.

[0085] Then, 0.63 g of the supported catalyst obtained in Example 1 was added, the temperature was raised to 125° C., the vacuum degree was adjusted to −0.1 MPa, and the reaction was carried out for 4 hours.

[0086] After the reaction is completed, the catalyst is filtered out while hot, and then methanol aqueous solution is added to the reaction solution. The temperature is slowly lowered and stirred for crystallization. After filtering and drying, 167.73 g of white powder is obtained, which is the product.

[0087] Example 3

[0088] In a 500mL four-necked flask equipped with a mechanical stirrer, a thermometer, a distillation condenser, and a nitrogen inlet, 157.69g (0.63mol) of methyl 3-tert-butyl-4-hydroxy-5-methylphenylpropionate and 45.05g (0.3mol) of triethylene glycol were added. The vacuum degree was -0.09MPa, and the temperature was gradually raised to 90°C and maintained for 0.5h.

[0089] Then, 0.63 g of the supported catalyst obtained in Example 1 was added, the temperature was raised to 130° C., the vacuum degree was adjusted to -0.09 MPa, and the reaction was carried out for 4 hours.

[0090] After the reaction is completed, the catalyst is filtered out while hot, and then methanol aqueous solution is added to the reaction solution. The temperature is slowly lowered and stirred for crystallization. After filtering and drying, 168.82 g of white powder is obtained, which is the product.

[0091] Example 4

[0092] In a 500mL four-necked flask equipped with a mechanical stirrer, a thermometer, a distillation condenser, and a nitrogen inlet, 157.69g (0.63mol) of methyl 3-tert-butyl-4-hydroxy-5-methylphenylpropionate and 45.05g (0.3mol) of triethylene glycol were added. The vacuum degree was -0.1MPa, and the temperature was gradually raised to 85°C and maintained for 0.5h.

[0093] Then, 0.63 g of the supported catalyst obtained in Example 1 was added, the temperature was raised to 135° C., the vacuum degree was adjusted to -0.08 MPa, and the reaction was carried out for 4 hours.

[0094] After the reaction is completed, the catalyst is filtered out while hot, and then methanol aqueous solution is added to the reaction solution. The temperature is slowly lowered and stirred to crystallize. After filtering and drying, 166.99 g of white powder is obtained, which is the product.

[0095] Example 5

[0096] In a 500mL four-necked flask equipped with a mechanical stirrer, a thermometer, a distillation condenser, and a nitrogen inlet, 157.69g (0.63mol) of methyl 3-tert-butyl-4-hydroxy-5-methylphenylpropionate and 45.05g (0.3mol) of triethylene glycol were added. The vacuum degree was -0.09MPa, and the temperature was gradually raised to 90°C and maintained for 0.5h.

[0097] Then, 0.63 g of the supported catalyst obtained in Example 1 was added, the temperature was raised to 130° C., the vacuum degree was adjusted to -0.09 MPa, and the reaction was carried out for 4 hours.

[0098] After the reaction is completed, the catalyst is filtered out while hot, and then methanol aqueous solution is added to the reaction solution. The temperature is slowly lowered and stirred for crystallization. After filtering and drying, 168.58 g of white powder is obtained, which is the product.

[0099] Example 6

[0100] In a 500mL four-necked flask equipped with a mechanical stirrer, a thermometer, a distillation condenser, and a nitrogen inlet, 157.69g (0.63mol) of methyl 3-tert-butyl-4-hydroxy-5-methylphenylpropionate and 45.05g (0.3mol) of triethylene glycol were added. The vacuum degree was -0.09MPa, and the temperature was gradually raised to 90°C and maintained for 0.5h.

[0101] Then, 0.63 g of the supported catalyst obtained in Example 1 (which had been recycled 25 times) was added, the temperature was raised to 130° C., the vacuum degree was adjusted to −0.09 MPa, and the reaction was carried out for 4 hours.

[0102] After the reaction is completed, the catalyst is filtered out while hot, and then methanol aqueous solution is added to the reaction solution. The temperature is slowly lowered and stirred for crystallization. After filtering and drying, 168.58 g of white powder is obtained, which is the product.

[0103] Example 7

[0104] In a 500mL four-necked flask equipped with a mechanical stirrer, a thermometer, a distillation condenser, and a nitrogen inlet, 157.69g (0.63mol) of methyl 3-tert-butyl-4-hydroxy-5-methylphenylpropionate and 45.05g (0.3mol) of triethylene glycol were added. The vacuum degree was -0.09MPa, and the temperature was gradually raised to 90°C and maintained for 0.5h.

[0105] Then, 0.63 g of the supported catalyst obtained in Example 1 (which had been recycled 50 times) was added, the temperature was raised to 130° C., the vacuum degree was adjusted to −0.09 MPa, and the reaction was carried out for 4 hours.

[0106] After the reaction is completed, the catalyst is filtered out while hot, and then methanol aqueous solution is added to the reaction solution. The temperature is slowly lowered and stirred for crystallization. After filtering and drying, 168.58 g of white powder is obtained, which is the product.

[0107] Comparative Example 1

[0108] [Preparation of a single active component catalyst using zinc acetate]

[0109] (1) Calcination activation of the supported catalyst carrier: Take the prepared silica carrier, place it in a muffle furnace at 400°C and calcine it for 4 hours, and then cool it down to obtain the treated carrier.

[0110] (2) Loading zinc acetate onto the pretreated carrier: 6 g of active component 1 zinc acetate was dissolved in 100 mL of deionized water and impregnated with the carrier in step (1), and then allowed to stand at room temperature for 5 h and dried at a constant temperature of 90° C. for 8 h.

[0111] (3) The product obtained in step (2) was immersed in 100 mL of deionized water, and then allowed to stand at room temperature for 3 h and dried at a constant temperature of 90° C. for 8 h.

[0112] (4) The product obtained in step (3) was placed in a muffle furnace at 600° C. and calcined for 5 h to finally obtain the supported catalyst using zinc acetate as the single active component.

[0113] [Synthetic antioxidant 245]

[0114] In a 500mL four-necked flask equipped with a mechanical stirrer, a thermometer, a distillation condenser, and a nitrogen inlet, 157.69g (0.63mol) of methyl 3-tert-butyl-4-hydroxy-5-methylphenylpropionate and 45.05g (0.3mol) of triethylene glycol were added. The vacuum degree was -0.09MPa, and the temperature was gradually raised to 90°C and maintained for 0.5h.

[0115] Then, 0.63 g of a supported catalyst having zinc acetate as a single active component was added, the temperature was raised to 180° C., the vacuum degree was adjusted to -0.09 MPa, and the reaction was carried out for 7 hours.

[0116] After the reaction is completed, the catalyst is filtered out while hot, and then methanol aqueous solution is added to the reaction solution, the temperature is slowly lowered and stirred for crystallization, and the white powder obtained after filtering and drying is the product.

[0117] Comparative Example 2

[0118] [Preparation of a single active component catalyst using aluminum trifluoromethanesulfonate]

[0119] (1) Calcination activation of the supported catalyst carrier: Take the prepared silica carrier, place it in a muffle furnace at 400°C and calcine it for 4 hours, and then cool it down to obtain the treated carrier.

[0120] (2) The carrier prepared in step (1) was immersed in 100 mL of deionized water, and then allowed to stand at room temperature for 5 h and then dried at 90° C. for 8 h.

[0121] (3) 3 g of aluminum trifluoromethanesulfonate was dissolved in 100 mL of deionized water and impregnated with the product obtained in step (2), and then allowed to stand at room temperature for 3 h and dried at a constant temperature of 90° C. for 8 h.

[0122] (4) The product obtained in step (3) is calcined in a muffle furnace at 600° C. for 5 hours to finally obtain the supported catalyst using aluminum trifluoromethanesulfonate as the single active component.

[0123] [Synthetic antioxidant 245]

[0124] In a 500mL four-necked flask equipped with a mechanical stirrer, a thermometer, a distillation condenser, and a nitrogen inlet, 157.69g (0.63mol) of methyl 3-tert-butyl-4-hydroxy-5-methylphenylpropionate and 45.05g (0.3mol) of triethylene glycol were added. The vacuum degree was -0.09MPa, and the temperature was gradually raised to 90°C and maintained for 0.5h.

[0125] Then, 0.63 g of a supported catalyst having a single active component of aluminum trifluoromethanesulfonate was added, the temperature was raised to 180° C., the vacuum degree was adjusted to -0.09 MPa, and the reaction was carried out for 7 hours.

[0126] After the reaction is completed, the catalyst is filtered out while hot, and then methanol aqueous solution is added to the reaction solution, the temperature is slowly lowered and stirred for crystallization, and the white powder obtained after filtering and drying is the product.

[0127] Comparative Example 3

[0128] In a 500mL four-necked flask equipped with a mechanical stirrer, a thermometer, a distillation condenser, and a nitrogen inlet, 157.69g (0.63mol) of methyl 3-tert-butyl-4-hydroxy-5-methylphenylpropionate and 45.05g (0.3mol) of triethylene glycol were added. Maintaining an air atmosphere, the temperature was gradually raised to 90°C and maintained for 0.5h.

[0129] Then, 0.63 g of the supported catalyst obtained in Example 1 (which had been recycled 50 times) was added, the temperature was raised to 180° C., and the reaction was carried out for 5 hours.

[0130] After the reaction is completed, the catalyst is filtered out while hot, and then methanol aqueous solution is added to the reaction solution. The temperature is slowly lowered and stirred for crystallization. After filtering and drying, 168.58 g of white powder is obtained, which is the product.

[0131] Comparative analysis of results

[0132] The changes in reaction conditions of Examples 2-7 and Comparative Examples 1-3, as well as the final product yield and purity results are shown in Table 1.

[0133] Table 1

[0134]

[0135] It can be seen from the results of Examples 2-5 that the antioxidant 245 prepared by the method of the present invention has a high yield and purity, with the yield being as high as 95.92% and the purity being as high as 99.40%.

[0136] It can be seen from the results of Examples 6 and 7 that, under other conditions that are the same as those of Example 5, the catalyst recycled for multiple times still has a stable catalytic effect, and can still make the yield and purity of the target product antioxidant 245 reach 90.4% and 97.6%, respectively; this shows that the supported catalyst prepared by the method of the present invention has good stability and can still maintain good catalytic activity after multiple uses.

[0137] It can be seen from the results of Comparative Examples 1 and 2 that when other conditions are the same as those of Example 5, only one of zinc acetate and aluminum trifluoromethanesulfonate is used as the active component for catalysis, and when the reaction conditions are the same, the yield of the target product antioxidant 245 is only about 80%, and the purity is only about 85%.

[0138] From the results of Comparative Example 3, it can be seen that, under other conditions that are the same as those of Example 5, if the reaction is not vacuumed, under the same reaction conditions, the yield of the target product antioxidant 245 is only about 40% and the purity is only about 50%.

[0139] As can be seen from the above, the present invention forms a complex through the interaction of zinc acetate and aluminum trifluoromethanesulfonate, thereby significantly improving the catalytic activity and shortening the reaction time; and because zinc acetate and aluminum trifluoromethanesulfonate interact to form a complex, combined with vacuum conditions, the ester exchange reaction process is affected, so that the present invention can obtain a target product with a high yield and purity within a temperature range not exceeding 140° C., and the reaction temperature is reduced; at the same time, the prepared catalyst has good stability, is easy to recover, and still has a high catalytic activity after multiple uses.

[0140] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. A method for preparing an asymmetric hindered phenol antioxidant 245, characterized in that: The following steps are involved: S1. Put methyl 3-tert-butyl-4-hydroxy-5-methylphenylpropionate and triethylene glycol into a reactor to obtain a first mixture, evacuate the reactor to a vacuum degree of -0.08 to -0.1 MPa, and control the temperature in the reactor at [85°C, 95°C]; S2, after adding the catalyst to the first mixture, maintaining the vacuum degree in step S1, and raising the temperature so that the temperature in the reactor is controlled at [125° C., 135° C.] to carry out the reaction; Wherein, the catalyst is a supported catalyst with zinc acetate and aluminum trifluoromethanesulfonate as active components; S3. After the reaction is completed, add methanol aqueous solution to the solution after the reaction, cool and stir to crystallize, filter and dry to obtain an asymmetric hindered phenol antioxidant 245.

2. The method for preparing the asymmetric hindered phenol antioxidant 245 according to claim 1, characterized in that: The preparation process of the catalyst is as follows: placing the carrier in a zinc acetate aqueous solution, and sequentially allowing the solution to stand at room temperature and drying the solution at a constant temperature to obtain a first intermediate; The first intermediate is placed in an aqueous solution of aluminum trifluoromethanesulfonate, and is allowed to stand at room temperature and dried at a constant temperature to obtain a second intermediate; The second intermediate is placed in a muffle furnace for calcination, and the temperature is naturally lowered after the calcination is completed to obtain the supported catalyst.

3. The method for preparing the asymmetric hindered phenol antioxidant 245 according to claim 2, characterized in that: The concentration of the zinc acetate aqueous solution is 5-10 mg / mL, and the concentration of the aluminum trifluoromethanesulfonate aqueous solution is 1-5 mg / mL.

4. The method for preparing the asymmetric hindered phenol antioxidant 245 according to claim 2, characterized in that: The carrier is placed in a zinc acetate aqueous solution, and the solution is allowed to stand at room temperature for 4 to 6 hours and then dried at a constant temperature of 85 to 95° C. for 7 to 9 hours to obtain a first intermediate.

5. The method for preparing the asymmetric hindered phenol antioxidant 245 according to claim 2, characterized in that: The first intermediate is placed in an aqueous solution of aluminum trifluoromethanesulfonate, and is allowed to stand at room temperature for 2 to 4 hours, and then dried at a constant temperature of 85 to 95° C. for 7 to 9 hours to obtain a second intermediate.

6. The method for preparing the asymmetric hindered phenol antioxidant 245 according to claim 2, characterized in that: The second intermediate is placed in a muffle furnace and calcined at a temperature of 500-700°C for 4-5 hours.

7. The method for preparing the asymmetric hindered phenol antioxidant 245 according to any one of claims 2 to 6, characterized in that: The carrier is silicon oxide and is pre-treated. The pre-treatment process is as follows: The carrier is placed in a muffle furnace at 400°C and calcined for 3 to 4 hours.

8. The method for preparing the asymmetric hindered phenol antioxidant 245 according to claim 1, characterized in that: In step S1, the reaction time is 20 to 30 minutes.

9. The method for preparing the asymmetric hindered phenol antioxidant 245 according to claim 1, characterized in that: In the step S1, the molar ratio of methyl 3-tert-butyl-4-hydroxy-5-methylphenylpropionate to triethylene glycol is (2-3):

1.

10. The method for preparing the asymmetric hindered phenol antioxidant 245 according to claim 1, characterized in that: In step S2, the reaction time is 3 to 4 hours.

11. The method for preparing the asymmetric hindered phenol antioxidant 245 according to claim 1, characterized in that: In the step S2, the amount of the catalyst used is 0.3-0.5% of the mass of 3-tert-butyl-4-hydroxy-5-methylphenylpropionate.

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