Preparation method of tetrakis [beta-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester

Abstract

The invention provides a preparation method of tetrakis [beta-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester. The method comprises the following steps: S1, feeding pentaerythritol and a first part of 3, 5-methyl ester, vacuumizing, feeding a first part of a liquid lithium catalyst, and reacting at the temperature of 130-150 DEG C and the pressure of 200-400 mbar; s2, adding a second part of a liquid lithium catalyst, and reacting at the temperature of 135-165 DEG C and the pressure of 100-300 mbar; and S3, mixing the third part of the liquid lithium catalyst and the second part of 3, 5-methyl ester, vacuumizing, adding, and reacting at the temperature of 160-195 DEG C and the pressure of 10-150mbar to form a target product. According to the invention, the problems of low product yield and low purity during large-scale synthesis of the tetrakis [beta-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester are solved.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a method for preparing pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate. Background Art

[0002] Pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (Antioxidant 1010), with the structural formula shown below, is a high molecular weight hindered phenol antioxidant, widely used in the processing of polyethylene, polypropylene, polyoxymethylene, ABS resin and synthetic rubber to prevent discoloration or oxidative degradation caused by light and heat. It has good compatibility and can be used with a variety of auxiliary antioxidants and stabilizers to achieve significant synergistic and synergistic effects. It also has the characteristics of low toxicity, odorlessness and tastelessness.

[0003]

[0004] At present, there are many methods for synthesizing tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] pentaerythritol ester, among which the most widely used method is as follows: 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid methyl ester (referred to as 35 methyl ester) and pentaerythritol are subjected to ester exchange reaction, and the route is as follows:

[0005]

[0006] However, in the actual synthesis process, especially in the enlarged production process, due to the large steric hindrance effect after the reaction of pentaerythritol and three 3,5 methyl esters, a large number of three substitution bodies will be generated during the transesterification reaction (i.e., only three hydroxyls in pentaerythritol undergo transesterification), which not only reduces the transesterification reaction yield, but also is difficult to completely separate and remove during refining, resulting in a low product purity. Therefore, how to reduce the generation of by-products during the synthesis of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] ester and improve the product yield and purity is a problem that needs to be solved in this field. Summary of the invention

[0007] The main purpose of the present invention is to provide a method for preparing pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, so as to solve the problem that a large number of by-products are produced during the large-scale synthesis of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate in the prior art, resulting in a decrease in product yield and purity.

[0008] In order to achieve the above-mentioned object, according to one aspect of the present invention, there is provided a method for preparing pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, which comprises the following steps: step S1, adding pentaerythritol and a first part of methyl 3,5-di-tert-butyl-4-hydroxyphenylpropionate, evacuating, adding a first part of liquid lithium catalyst thereto, reacting at a temperature of 130 to 150° C. and a pressure of 200 to 400 mbar to form a pre-reaction system; step S2, adding a first part of liquid lithium catalyst to the pre-reaction system; The second part of the liquid lithium catalyst is added into the system, and the reaction is carried out at a temperature of 135-165° C. and a pressure of 100-300 mbar to form an intermediate reaction system; step S3, the third part of the liquid lithium catalyst and the second part of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid methyl ester are mixed and evacuated, and then added into the intermediate reaction system, and the reaction is carried out at a temperature of 160-195° C. and a pressure of 10-150 mbar to form pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid].

[0009] Furthermore, the reaction temperature in step S1 is 130-135° C., and the reaction pressure is 250-380 mbar; the reaction temperature in step S2 is 145-150° C., and the reaction pressure is 220-280 mbar; and the reaction temperature in step S3 is 180-185° C., and the reaction pressure is 30-40 mbar.

[0010] Further, the first part of the liquid lithium catalyst, the second part of the liquid lithium catalyst and the third part of the liquid lithium catalyst are independently selected from one or more of liquid lithium methanol, liquid lithium ethoxide and liquid lithium isopropoxide; preferably, the first part of the liquid lithium catalyst, the second part of the liquid lithium catalyst and the third part of the liquid lithium catalyst are all liquid lithium methanol.

[0011] Further, step S1 comprises: adding pentaerythritol into a reactor, preheating the first part of 3,5-di-tert-butyl-4-hydroxybenzenepropionic acid methyl ester and then adding it into the reactor; heating the reactor and evacuating it, and then adding the first part of liquid lithium catalyst to react to form a pre-reaction system; preferably, the molar ratio of the first part of 3,5-di-tert-butyl-4-hydroxybenzenepropionic acid methyl ester to pentaerythritol is (3.8-4.5):1, and the amount of the first part of liquid lithium catalyst added is 1-5% of the weight of pentaerythritol.

[0012] Furthermore, in step S2, the amount of the second portion of liquid lithium catalyst added is 1-3% by weight of pentaerythritol, preferably 2-3%; preferably, in step S2, before adding the second portion of liquid lithium catalyst into the pre-reaction system, the pre-reaction system is first vacuumed.

[0013] Furthermore, in step S3, before adding the third portion of liquid lithium catalyst and the second portion of methyl 3,5-di-tert-butyl-4-hydroxyphenylpropionate into the intermediate reaction system, the intermediate reaction system is first subjected to vacuum treatment.

[0014] Furthermore, the addition amount of the third part of liquid lithium catalyst is 1-3% by weight of pentaerythritol, preferably 1-2%, and the molar ratio of the second part of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid methyl ester to pentaerythritol is (0.1-1.0):1.

[0015] Furthermore, the reaction time in step S1 is 1 to 4 hours; the reaction time in step S2 is 2 to 3 hours; and the reaction time in step S3 is 1 to 4 hours.

[0016] Furthermore, after the reaction in step S3, a crude product containing pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate is obtained, and step S3 also includes: removing light from the crude product to obtain pentaerythritol tetrakis[β-(3,5)-di-tert-butyl-4-hydroxyphenyl)propionate.

[0017] Furthermore, in the light removal step, a recovered material of 3,5-di-tert-butyl-4-hydroxybenzenepropionate is obtained, and the preparation method further comprises: returning the recovered material of 3,5-di-tert-butyl-4-hydroxybenzenepropionate to step S1.

[0018] In the preparation method provided by the present invention, a liquid lithium catalyst is used to catalyze the reaction of methyl 3,5-di-tert-butyl-4-hydroxyphenylpropionate and pentaerythritol, and the feeding method and reaction temperature, pressure and other conditions at different stages are optimized, so that the present invention effectively solves the problem of the generation of triple substitution body by-products, especially effectively improves the yield and purity of pentaerythritol tetrakis[β-(3,5)-di-tert-butyl-4-hydroxyphenyl)propionate in the process of large-scale production. DETAILED DESCRIPTION

[0019] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0020] As described in the background technology section, in the prior art, when tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester is synthesized on a large scale, there are many three-substitution body by-products, which leads to the problem of decreased product yield and purity. In the traditional preparation process, it is often necessary to add 3,5-di-tert-butyl-4-hydroxyphenyl propionic acid methyl ester in large quantities. On the one hand, the improvement effect is not obvious, and on the other hand, it also leads to the waste of raw materials, which is not conducive to large-scale industrial application. In order to solve the above problems, the present invention provides a preparation method of tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester, which has significant improvements on the above problems. The preparation method of the present invention can also ensure a higher yield and purity when tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester is produced on a large scale, and it is not necessary to add 3,5-di-tert-butyl-4-hydroxyphenyl propionic acid methyl ester in large quantities.

[0021] In a typical embodiment of the present invention, a method for preparing pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] is provided, which comprises the following steps: step S1, adding pentaerythritol and a first portion of 3,5-di-tert-butyl-4-hydroxyphenylpropionate, evacuating, adding a first portion of liquid lithium catalyst thereto, reacting at a temperature of 130 to 150° C. and a pressure of 200 to 400 mbar to form a pre-reaction system; step S2, adding The second part of the liquid lithium catalyst is added, and the reaction is carried out at a temperature of 135-165° C. and a pressure of 100-300 mbar to form an intermediate reaction system; step S3, the third part of the liquid lithium catalyst and the second part of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid methyl ester are mixed and evacuated, and then added to the intermediate reaction system, and the reaction is carried out at a temperature of 160-195° C. and a pressure of 10-150 mbar to form pentaerythritol tetrakis[β-(3,5)-di-tert-butyl-4-hydroxyphenyl)propionic acid].

[0022] In the preparation method provided by the present invention, a liquid lithium catalyst is used to catalyze the reaction of methyl 3,5-di-tert-butyl-4-hydroxyphenylpropionate and pentaerythritol, and the feeding method and reaction temperature, pressure and other conditions at different stages are optimized, so that the present invention effectively solves the problem of the generation of triple substitution body by-products, especially effectively improves the yield and purity of pentaerythritol tetrakis[β-(3,5)-di-tert-butyl-4-hydroxyphenyl)propionate in the process of large-scale production.

[0023] Specifically, the present invention adopts a liquid lithium catalyst. Considering the changes in the catalyst activity at different stages of the reaction and the reaction activity of the substrate and / or the ester exchange intermediate in the reaction system, the present invention has conducted a lot of research on the timing of adding the liquid lithium catalyst and the reaction conditions at different stages. In the above preparation method, since small molecules such as water and methanol are inevitably present in the raw materials, in order to avoid affecting the catalyst activity and substrate reaction efficiency, the present invention first feeds pentaerythritol and the first part of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid methyl ester, vacuumizes, and removes these small molecules. Secondly, the present invention adds the first part of the liquid lithium catalyst into the reaction system. Since the catalytic activity of the liquid lithium catalyst is relatively high at this time, and the substrate is easy to undergo a preliminary ester exchange reaction at the initial stage of the reaction, the reaction temperature of this stage is controlled at 130-150°C and the pressure is controlled at 200-400mbar. As the first stage of the transesterification reaction proceeds, the catalytic activity of the liquid lithium catalyst changes, and the pre-reaction system already contains a large amount of target transesterification products and intermediate transesterification products, so the present invention further adds a second portion of liquid lithium catalyst to the pre-reaction system, and adjusts the reaction conditions to a temperature of 135-165°C and a pressure of 100-300 mbar. After the second stage of the reaction, most of the target product tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester is generated, but there are still some three-substitution body by-products. In order to allow this part of the three-substitution body to continue to transesterify and ensure the depth of the reaction, the present invention further adds a third portion of liquid lithium catalyst to the intermediate reaction system, and mixes it with the second portion of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid methyl ester in advance and evacuates it before feeding, and controls the reaction temperature at 160-195°C and the pressure at 10-150 mbar. The third part of liquid lithium catalyst and the second part of methyl 3,5-di-tert-butyl-4-hydroxyphenylpropionate are mixed in advance and vacuumized before adding, which can remove small molecular components. In this stage, a new catalyst and a new methyl 3,5-di-tert-butyl-4-hydroxyphenylpropionate substrate are further introduced. Under the above temperature and pressure conditions, the obstacle of further ester exchange of the triple displacement by-product can be better overcome and it can be converted into the target product.

[0024] Based on the fact that the present invention fully considers the catalyst activity, the existence state of substances in the system and the ester exchange reaction conditions at different reaction stages, the batch addition method of the raw materials and the catalyst and the process conditions such as temperature and pressure are fully matched, so that high-yield and high-purity preparation can be achieved without significantly excessive addition of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid methyl ester raw materials, especially in the large-scale production process. It shows a huge advantage.

[0025] In a preferred embodiment, the reaction temperature in step S1 is 130-135°C, and the reaction pressure is 250-380 mbar; the reaction temperature in step S2 is 145-150°C, and the reaction pressure is 220-280 mbar; the reaction temperature in step S3 is 180-185°C, and the reaction pressure is 30-40 mbar. Controlling the reaction temperature and pressure conditions of each stage within the above range can form a better match with the reaction activity and catalytic activity of different stages, which is more beneficial to improving the yield and purity of the target product.

[0026] In order to more fully exert the catalytic effect at different stages, further reduce the occurrence of by-products while improving the reaction efficiency, or further enhance the generation of target products, in a preferred embodiment, the first part of the liquid lithium catalyst, the second part of the liquid lithium catalyst and the third part of the liquid lithium catalyst are independently selected from one or more of liquid lithium methanol, liquid lithium ethanol and liquid lithium isopropoxide, such as those available from Sigma-Aldrich; preferably, the first part of the liquid lithium catalyst, the second part of the liquid lithium catalyst and the third part of the liquid lithium catalyst are all liquid lithium methanol.

[0027] The reaction substrate used in the present invention, especially 3,5-di-tert-butyl-4-hydroxybenzene propionic acid methyl ester, often carries some small molecules such as water and methanol. Therefore, the present invention removes this part of impurity small molecules by vacuuming after feeding, so as not to affect the activity of the catalyst. In a preferred embodiment, the above step S1 includes: adding pentaerythritol to the reactor, preheating the first part of 3,5-di-tert-butyl-4-hydroxybenzene propionic acid methyl ester and then putting it into the reactor; heating the reactor and vacuuming it, and then adding the first part of liquid lithium catalyst to react to form a pre-reaction system. Preheating the first part of 3,5-di-tert-butyl-4-hydroxybenzene propionic acid methyl ester is conducive to faster removal of small molecule impurities in the subsequent vacuuming process, and better dispersion with pentaerythritol, so as to prepare for subsequent reactions. Preferably, the first part of 3,5-di-tert-butyl-4-hydroxybenzene propionic acid methyl ester can be preheated to 80-90°C before feeding.

[0028] As mentioned above, the present invention can effectively improve the product yield and purity without adding a large amount of 3,5-di-tert-butyl-4-hydroxybenzene propionic acid methyl ester raw material. Preferably, the molar ratio of the first part of 3,5-di-tert-butyl-4-hydroxybenzene propionic acid methyl ester to pentaerythritol is (3.8-4.5):1, and the amount of the first part of the liquid lithium catalyst added is 1-5% of the weight of pentaerythritol. Controlling the amount of the reaction raw materials added in the first stage within the above range is conducive to promoting a more efficient reaction, and also helps the first part of the liquid lithium catalyst to give full play to the catalytic effect of this stage, so that the substrate forms a more sufficient preliminary ester exchange reaction, and even makes most of the substrate react to form the target product. More preferably, the molar ratio of the first part of 3,5-di-tert-butyl-4-hydroxybenzene propionic acid methyl ester to pentaerythritol is 4.2-4.5:1, and the amount of the first part of the liquid lithium catalyst added is 3-5% of the weight of pentaerythritol.

[0029] Preferably, in step S2, the amount of the second part of the liquid lithium catalyst added is 1-3% of the weight of pentaerythritol, preferably 2-3%. Controlling the amount of the second part of the liquid lithium catalyst added within the above range is also conducive to the further efficient esterification reaction. More preferably, in step S2, before adding the second part of the liquid lithium catalyst to the pre-reaction system, the pre-reaction system is first vacuumed. As the esterification reaction proceeds. Small molecule methanol will continue to accumulate in the system, and in order to further move the reaction forward, it can be removed by vacuuming.

[0030] Similarly, in step S3, the intermediate reaction system is preferably vacuumed before the third portion of the liquid lithium catalyst and the second portion of methyl 3,5-di-tert-butyl-4-hydroxyphenylpropionate are added to the intermediate reaction system.

[0031] In order to more fully convert the triple substitution product in the intermediate product system into the target product, in a preferred embodiment, the addition amount of the third part of the liquid lithium catalyst is 1 to 3% by weight of pentaerythritol, preferably 1 to 2%, and the molar ratio of the second part of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid methyl ester to pentaerythritol is (0.1 to 1.0):1, preferably (0.4 to 0.6):1.

[0032] In a preferred embodiment, the reaction time in step S1 is 1 to 4 hours; the reaction time in step S2 is 1 to 4 hours; and the reaction time in step S3 is 1 to 2 hours. Controlling the reaction time of each stage within the above range fully balances the reaction efficiency and the degree of different stages of the esterification reaction, and achieves a higher yield and purity result in a relatively short time.

[0033] In the actual preparation process, after the reaction in step S3, a crude product containing pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate is obtained, and preferably step S3 further comprises: removing light from the crude product to obtain pentaerythritol tetrakis[β-(3,5)-di-tert-butyl-4-hydroxyphenyl)propionate. Since the three-substitution body by-product in the system is greatly reduced, the target product in the crude product is easier to separate.

[0034] In a preferred embodiment, the light removal step also obtains 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid methyl ester recovery material, and the preparation method further comprises: returning the 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid methyl ester recovery material to step S1. Such operation is also conducive to the recycling of reaction raw materials, thereby reducing production costs.

[0035] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0036] Example 1

[0037] The present embodiment provides a method for preparing pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and the steps are as follows:

[0038] Step S1, 500 kg of pentaerythritol is metered by gas phase transport and then put into the reactor, and the first part of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid methyl ester is preheated to 85° C. and then added into the reactor (at a molar ratio of 4.2:1 with pentaerythritol). The reactor is heated and vacuumed, and then the first part of liquid lithium methoxide is added thereto (at a molar ratio of 3% of the weight of pentaerythritol), and then the system temperature is controlled to be 135° C. and the pressure is 300 mbar for reaction for 2 hours to form a pre-reaction system.

[0039] Step S2, after the pre-reaction system is vacuumed to remove small molecules, a second portion of liquid lithium methoxide (2% by weight of pentaerythritol) is added to the pre-reaction system, and then the system temperature is controlled to be 145° C. and the pressure is 240 mbar, and the reaction is continued for 1 hour to form an intermediate reaction system;

[0040] Step S3, after the intermediate reaction system is vacuumed to remove small molecules, the third part of liquid lithium methoxide (added at 2% of the weight of pentaerythritol) and the second part of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid methyl ester (added at a molar ratio of 0.4:1 to pentaerythritol) are added to the intermediate reaction system, and the third part of liquid lithium methoxide and the second part of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid methyl ester are pre-mixed, preheated and vacuumed. After adding the materials, the system temperature is controlled to be 185° C. and the pressure is 20 mbar, and the reaction is continued for 3 hours to obtain a crude product.

[0041] Step S4, sequentially performing light removal treatment and crystallization treatment on the crude product to obtain pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; after testing, the pentaerythritol conversion rate is 99.3%, the yield of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] is 94.7%, and the product purity is 96.7%.

[0042] Examples 2 to 5, Comparative Example 1

[0043] In Examples 2 to 5 and Comparative Example 1, the reaction conditions in Step S1 to Step S3 were changed on the basis of Example 1. The specific changed process conditions and product indicators are shown in the following table:

[0044]

[0045]

[0046] Examples 6 to 9, Comparative Example 2

[0047] Examples 6 to 9 and Comparative Example 2 respectively change the feeding ratio on the basis of Example 1. The specific changed feeding methods and product indicators are shown in the following table:

[0048]

[0049] Example 10

[0050] The only difference between Example 10 and Example 1 is that the third part of liquid lithium methanol and the second part of methyl 3,5-di-tert-butyl-4-hydroxyphenylpropionate are pre-mixed without preheating or vacuuming.

[0051] After testing, the conversion rate of pentaerythritol was 98.5%, the yield of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate was 92.1%, and the product purity was 85.4%.

[0052] Embodiment 11

[0053] The only difference between Example 11 and Example 1 is that the catalyst used is liquid lithium ethanol.

[0054] The test showed that the conversion rate of pentaerythritol was 97.2%, the yield of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate was 93.5%, and the product purity was 93.1%.

[0055] Example 12

[0056] The only difference between Example 12 and Example 1 is that the catalyst used is liquid lithium isopropoxide.

[0057] The test showed that the conversion rate of pentaerythritol was 97.3%, the yield of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate was 93.1%, and the product purity was 92.4%.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, characterized in that: The following steps are involved: Step S1, adding pentaerythritol and the first part of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid methyl ester, evacuating, adding the first part of liquid lithium catalyst thereto, reacting at a temperature of 130-150° C. and a pressure of 200-400 mbar to form a pre-reaction system; Step S2, adding a second portion of liquid lithium catalyst into the pre-reaction system, reacting at a temperature of 135-165° C. and a pressure of 100-300 mbar to form an intermediate reaction system; Step S3, mixing the third part of the liquid lithium catalyst and the second part of methyl 3,5-di-tert-butyl-4-hydroxyphenylpropionate, evacuating the mixture, and then adding the mixture into the intermediate reaction system to react at a temperature of 160 to 195° C. and a pressure of 10 to 150 mbar to form pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

2. The preparation method according to claim 1, characterized in that: The reaction temperature in step S1 is 130-135° C., and the reaction pressure is 250-380 mbar; the reaction temperature in step S2 is 145-150° C., and the reaction pressure is 220-280 mbar; the reaction temperature in step S3 is 180-185° C., and the reaction pressure is 30-40 mbar.

3. The preparation method according to claim 1 or 2, characterized in that: The first portion of liquid lithium catalyst, the second portion of liquid lithium catalyst and the third portion of liquid lithium catalyst are independently selected from one or more of liquid lithium methanol, liquid lithium ethoxide and liquid lithium isopropoxide; preferably, the first portion of liquid lithium catalyst, the second portion of liquid lithium catalyst and the third portion of liquid lithium catalyst are all liquid lithium methanol.

4. The preparation method according to any one of claims 1 to 3, characterized in that The step S1 comprises: Putting the pentaerythritol into the reaction kettle, and preheating the first part of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid methyl ester and then putting it into the reaction kettle; Heating and evacuating the reactor, and then adding the first portion of liquid lithium catalyst to react to form the pre-reaction system; Preferably, the molar ratio of the first part of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid methyl ester to the pentaerythritol is (3.8-4.5):1, and the amount of the first part of liquid lithium catalyst added is 1-5% of the weight of the pentaerythritol.

5. The preparation method according to any one of claims 1 to 4, characterized in that: In the step S2, the amount of the second portion of liquid lithium catalyst added is 1 to 3% by weight of the pentaerythritol, preferably 2 to 3%; Preferably, in the step S2, before adding the second portion of liquid lithium catalyst into the pre-reaction system, the pre-reaction system is first subjected to vacuum treatment.

6. The preparation method according to any one of claims 1 to 5, characterized in that In the step S3, before adding the third portion of the liquid lithium catalyst and the second portion of methyl 3,5-di-tert-butyl-4-hydroxyphenylpropionate into the intermediate reaction system, the intermediate reaction system is first subjected to vacuum treatment.

7. The preparation method according to any one of claims 1 to 6, characterized in that The addition amount of the third part of liquid lithium catalyst is 1-3% of the weight of the pentaerythritol, preferably 1-2%, and the molar ratio of the second part of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid methyl ester to the pentaerythritol is (0.1-1.0):

1.

8. The preparation method according to any one of claims 1 to 6, characterized in that The reaction time in step S1 is 1 to 4 hours; the reaction time in step S2 is 2 to 3 hours; and the reaction time in step S3 is 1 to 4 hours.

9. The preparation method according to any one of claims 1 to 6, characterized in that: After the reaction in step S3, a crude product containing the tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol ester is obtained, and step S3 also includes: removing light from the crude product to obtain the tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol ester.

10. The preparation method according to claim 9, characterized in that: The light removal step also obtains 3,5-di-tert-butyl-4-hydroxybenzenepropionate methyl ester recovery material, and the preparation method further comprises: returning the 3,5-di-tert-butyl-4-hydroxybenzenepropionate methyl ester recovery material to the step S1.

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