A process for the synthesis of antioxidant 44PD
By adding an inert solvent and optimizing the reaction conditions during the synthesis of antioxidant 44PD, the problem of excessive 2-butanol production was solved, enabling the production of high-purity products and cost reduction, while allowing the solvent to be recycled multiple times.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-12-18
- Publication Date
- 2026-06-19
AI Technical Summary
During the synthesis of antioxidant 44PD, a large amount of 2-butanol is generated by the side reaction, which leads to a decrease in reaction conversion rate and selectivity, increases production costs, and makes it difficult to control the high boiling temperature.
By using inert solvents such as benzene, toluene, and dimethylformamide to mix with methyl ethyl ketone, controlling the reaction temperature and pressure, optimizing the reaction conditions, reducing the formation of 2-butanol, and improving the formation rate and selectivity of the target product.
The purity of antioxidant 44PD has been increased to over 98.1%, the generation of byproducts has been reduced, production costs have been reduced, and the solvent can be recycled multiple times, meeting environmental protection requirements.
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Figure CN122233918A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of antioxidant preparation, and specifically to a method for synthesizing antioxidant 44PD. Background Technology
[0002] Antioxidant 44PD, chemically known as N,N'-di-sec-butyl-p-phenylenediamine, is a high-performance amine antioxidant, particularly suitable as an additive for pyrolysis or thermal cracking gasoline (high olefin content gasoline). It can effectively prevent olefin oxidation and gel formation, thereby avoiding carbon deposits during oil use. Compared with other amine antioxidants, antioxidant 44PD requires less dosage and has better antioxidant effects. It can also be used as a polyurethane extender.
[0003] The synthesis of antioxidant 44PD generally uses p-nitroaniline and butanone as raw materials, reacting in the presence of a catalyst. However, this synthesis process involves some side reactions. For example, butanone undergoes hydrogenation to 2-butanol under the action of a catalyst, with the alcohol-ketone ratio in the reaction solution reaching as high as 15%-18%, meaning that 15-18% of butanone is converted to 2-butanol. On the one hand, this leads to a decrease in the conversion rate or selectivity of the reaction, increased raw material consumption, and increased production costs. On the other hand, since the boiling point of butanone is 76.9℃ and that of 2-butanol is 99.5℃, the azeotropic temperature of the reaction is higher, making it difficult to control the temperature of the entire synthesis reaction. Summary of the Invention
[0004] Based on the above analysis, the present invention aims to provide a method for synthesizing antioxidant 44PD to solve at least one of the following existing technical problems: reducing the alcohol-ketone ratio during the synthesis reaction of antioxidant 44PD, reducing the generation of high-boiling impurities, and increasing the content of antioxidant 44PD in the product.
[0005] The objective of this invention is mainly achieved through the following technical solutions:
[0006] This invention provides a method for synthesizing antioxidant 44PD, comprising the following steps: obtaining a mixture comprising butanone, p-nitroaniline and an inert solvent, and performing a condensation hydrogenation reaction using the mixture, wherein the inert solvent comprises at least one selected from benzene, toluene, dimethylformamide, xylene, cyclohexane, dimethyl sulfoxide, diethyl ether, methanol, ethanol, acetone, acetonitrile, and dichloromethane.
[0007] Preferably, the mass ratio of the inert solvent to methyl ethyl ketone is (1:3) to (3:1).
[0008] Preferably, the inert solvent includes a first inert solvent and a second inert solvent, wherein the first inert solvent and the second inert solvent are different, and each of the first inert solvent and the second inert solvent independently includes at least one of benzene, toluene, dimethylformamide, xylene, cyclohexane, dimethyl sulfoxide, diethyl ether, methanol, ethanol, acetone, acetonitrile, and dichloromethane.
[0009] Preferably, the mass ratio of the first inert solvent to the second inert solvent is (1:2) to (2:1).
[0010] Preferably, the reaction temperature of the condensation hydrogenation reaction is 100-140℃, and more preferably 120-130℃.
[0011] Preferably, the reaction pressure of the condensation hydrogenation reaction is 2.0-4 MPa, more preferably 2.0-3.0 MPa.
[0012] Preferably, the reaction time for the condensation hydrogenation reaction is 1-5 hours.
[0013] Preferably, the synthesis method includes the following steps:
[0014] Step 1: Obtain a mixture comprising butanone, p-nitroaniline, and an inert solvent.
[0015] Step 2: Perform a condensation hydrogenation reaction using the mixture.
[0016] Step 3: Separate and distill the products of the condensation and hydrogenation reaction sequentially to obtain antioxidant 44PD.
[0017] Preferably, the condensation hydrogenation reaction is carried out in the presence of a catalyst.
[0018] Preferably, the catalyst comprises at least one of nickel-based, copper-based, platinum-based, or palladium-based catalysts; more preferably, the catalyst support is activated carbon.
[0019] Preferably, the mass ratio of p-nitroaniline to butanone is (1:1) to (1:10).
[0020] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:
[0021] A) The synthesis method of antioxidant 44PD provided by this invention improves product quality: by reducing the formation of 2-butanol, the purity of antioxidant 44PD product can be increased to over 98.1%, which is higher than the 96% requirement for superior grade products, making it more in line with application requirements.
[0022] B) The synthesis method of antioxidant 44PD provided by this invention optimizes the synthesis reaction conditions, reduces the alcohol-ketone ratio to 0.1%-5%, reduces the generation of by-products, and thus lowers production costs. Furthermore, the selected inert solvent is more economical.
[0023] C) The method for synthesizing antioxidant 44PD provided by this invention uses a solvent with good chemical stability, which will not cause pollution to the environment and meets environmental protection requirements.
[0024] D) The synthesis method of antioxidant 44PD provided by this invention improves the synthesis process, enhances product quality and production efficiency, reduces production costs, and reduces the content of 2-butanol in the solvent after use. It does not require additional dehydrogenation treatment and can be repeatedly recycled, making the synthesis process more competitive. Attached Figure Description
[0025] Figure 1 A schematic flowchart of the synthesis method of antioxidant 44PD provided by the present invention;
[0026] Wherein: 1-p-nitroaniline; 2-butanone; 3-inert solvent; 4-filtrate; 5-catalyst; 6-filter residue. Detailed Implementation
[0027] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of the present invention and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention.
[0028] Generally, the production process of antioxidant 44PD is as follows: p-nitroaniline is dissolved and purified using methyl ethyl ketone (MEK). The clarified liquid is then subjected to condensation of p-nitroaniline and MEK in the presence of a catalyst at 2.0-6.0 MPa and 110-160℃ to produce a Schiff base and water. The Schiff base is then hydrogenated and reduced for 2-6 hours to generate the 44PD reaction solution. After the reaction is complete, the catalyst is filtered and recycled. The reaction water is separated, and excess MEK is distilled off and recycled directly. The residue is the finished product, 44PD. The reaction formula is shown in Chemical Formula I.
[0029]
[0030] However, some side reactions occur during the production of antioxidant 44PD. One significant side reaction is the hydrogenation of butanone (MEK) to 2-butanol under the action of a catalyst. The alcohol-ketone ratio in the reaction solution can reach as high as 15%-18%, meaning that 15-18% of MEK is converted to 2-butanol. This ratio can even increase with the repeated use of solvents and catalysts. On the one hand, this leads to a decrease in reaction conversion or selectivity, increased raw material consumption, and higher production costs. On the other hand, because MEK has a boiling point of 76.9℃ while 2-butanol has a boiling point of 99.5℃, the azeotropic temperature of the reaction is higher, making it difficult to control the overall temperature of the synthesis reaction. Therefore, controlling the amount of 2-butanol generated and reducing the alcohol-ketone ratio during the synthesis of antioxidant 44PD is a crucial issue.
[0031] Generally, the alcohol-ketone ratio can be reduced in the following ways: (1) Precisely control the reaction conditions to reduce the amount of 2-butanol produced. (2) Improve the catalyst to reduce its selectivity for butanone. (3) Convert the generated 2-butanol back into butanone through dehydrogenation. However, all of the above measures have shortcomings: (1) If the reaction conditions are precisely controlled, that is, the reaction temperature and pressure are appropriately reduced to reduce the rate of 2-butanol production as much as possible, although it is theoretically feasible, in actual operation, the temperature and pressure are not conducive to the production of the target product antioxidant 44PD. At the same time, since the hydrogenation reaction is an exothermic reaction, its heating rate is relatively fast, so the reaction temperature is not easy to precisely control. (2) Improving the catalyst, that is, researching and developing a more selective catalyst to promote the production of the target product while inhibiting the production of 2-butanol, may require structural improvement of the catalyst or finding a new catalyst formulation, which is also not easy to do. (3) Alternatively, the generated 2-butanol can be converted back into butanone through a dehydrogenation reaction. This requires specialized equipment and catalysts, and the material and energy consumption increases significantly during this process, which is time-consuming and labor-intensive.
[0032] To overcome the numerous difficulties in reducing the alcohol-ketone ratio during the synthesis of antioxidant 44PD, continuous improvement of the synthesis process is necessary. This invention reduces the total amount of butanone (MEK) hydrogenated to 2-butanol under a catalyst during the 44PD synthesis reaction, allowing MEK to participate more in the main reaction of 44PD synthesis via hydrogenation of p-nitroaniline. This reduces side reactions of 44PD, lowers the alcohol-ketone ratio in the reaction solution, and thus reduces production costs, material consumption, and energy consumption.
[0033] The present invention will now be described in detail. As can be seen from the production process, in the synthesis reaction of antioxidant 44PD, butanone (MEK) serves not only as a reactant but also as a solvent in the entire system. Therefore, the present invention employs a method of adding a new solvent to adjust the reaction system and reduce the formation of 2-butanol. Selecting a suitable solvent can alter the reaction equilibrium, reduce the occurrence of the MEK hydrogenation side reaction, and ultimately control the alcohol-ketone ratio between 0.1% and 5%.
[0034] In a first aspect, the present invention provides a method for synthesizing antioxidant 44PD, comprising the following steps:
[0035] Step 1: Mix methyl ethyl ketone (MEK), p-nitroaniline, and an inert solvent.
[0036] Step 2: Perform the condensation and hydrogenation reaction.
[0037] Step 3: Separate the reaction water and distill it to obtain antioxidant 44PD.
[0038] As a specific embodiment of the present invention, the inert solvent is selected from at least one of benzene, toluene, dimethylformamide, xylene, cyclohexane, dimethyl sulfoxide, diethyl ether, methanol, ethanol, acetone, acetonitrile, and dichloromethane.
[0039] To reduce the alcohol-ketone ratio during the synthesis of antioxidant 44PD, a new solvent needs to be selected: a solvent with good solubility and compatibility with the reaction system should be chosen. Simultaneously, the solvent should possess good chemical stability and not undergo side reactions or decomposition reactions with the reactants. The solvent selection should be based on its impact on reaction equilibrium and the selectivity of the target product. Key points are as follows: the new solvent must be an inert solvent, i.e., it does not participate in the hydrogenation reaction, or the requirements for the hydrogenation reaction are extremely stringent: for example, it requires very high temperatures, high pressures, or a highly potent catalyst to participate in the hydrogenation reaction; otherwise, there is almost no possibility of addition with hydrogen. Furthermore, the boiling point of the solvent should be close to that of methyl ethyl ketone (MEK), but for safety reasons, a higher boiling point is preferred. Because the 44PD reaction is rapidly exothermic, solvents with excessively low boiling points will make it more difficult to control the reaction temperature, leading to runaway reactions. Therefore, solvents with boiling points significantly lower than MEK can be used in combination with solvents with boiling points higher than MEK, such as dichloromethane and xylene, as inert solvents. All the inert solvents used in this invention meet the above requirements. Considering economic costs, safety, and environmental factors, the preferred inert solvent is at least one of toluene, xylene, cyclohexane, diethyl ether, methanol, and ethanol.
[0040] Reference Figure 1In one specific embodiment of the present invention, in step 1, butanone 2, p-nitroaniline 1, and inert solvent 3 can be mixed, filtered and purified, and the filtrate 4 can be used for subsequent reactions. Alternatively, butanone 2 and p-nitroaniline 1 can be mixed first, filtered and purified, and then inert solvent 3 can be added to the filtrate 4 to continue the subsequent reactions. It should be noted that adding the inert solvent after filtration and purification can further reduce the synthesis time and energy consumption.
[0041] In one specific embodiment of the present invention, in step 1, the mass ratio of the inert solvent to methyl ethyl ketone is between (1:3) and (3:1), for example, 1:2.8, 1:2.6, 1:2.4, 1:2.2, 1:2, 1:1.8, 1:1.6, 1:1.4, 1:1.2, 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1, etc.
[0042] To reduce the alcohol-ketone ratio during the synthesis of antioxidant 44PD, the reaction system needs to be optimized. This involves introducing a selected inert solvent into the system and ensuring its concentration is within an appropriate range. A low mass ratio of inert solvent to butanone will not effectively reduce 2-butanol formation, while a high ratio will negatively impact the reaction. The key is to optimize the proportion of inert solvent in the reaction system, controlling the mass ratio of inert solvent to butanone between (1:3) and (3:1) to ensure the formation rate and selectivity of the target product while simultaneously reducing the alcohol-ketone ratio.
[0043] In one specific embodiment of the present invention, the inert solvent is selected from at least two of benzene, toluene, dimethylformamide, xylene, cyclohexane, dimethyl sulfoxide, diethyl ether, methanol, ethanol, acetone, acetonitrile, and dichloromethane. Preferably, the inert solvent includes a first inert solvent and a second inert solvent, wherein the first inert solvent and the second inert solvent are different, and each of the first inert solvent and the second inert solvent is independently selected from at least one of benzene, toluene, dimethylformamide, xylene, cyclohexane, dimethyl sulfoxide, diethyl ether, methanol, ethanol, acetone, acetonitrile, and dichloromethane. The mass ratio of the first inert solvent to the second inert solvent is (1:2)-(2:1), for example, 1:1.8, 1:1.6, 1:1.4, 1:1.2, 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, etc.
[0044] In this invention, the amounts of nitroaniline and butanone are not particularly limited, as long as the reaction proceeds smoothly. As a specific embodiment of this invention, the mass ratio of nitroaniline to butanone is (1:1)-(1:10), for example, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, etc.
[0045] In a specific embodiment of the present invention, the reaction conditions for the condensation hydrogenation reaction in step 2 include: a reaction temperature of 100-140℃, such as 105, 110, 115, 120, 125, 130, 135℃, etc.; a reaction pressure of 2.0-4MPa, such as 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8MPa, etc.; and a reaction time of 1-5 hours, such as 1.5, 2, 2.5, 3, 3.5, 4, 4.5 hours, etc.
[0046] To reduce the alcohol-ketone ratio during the synthesis of antioxidant 44PD, precise control of reaction conditions is necessary. After adding an inert solvent, further control of temperature and pressure parameters can suppress the formation of 2-butanol, thus contributing to a lower alcohol-ketone ratio. The operating temperature and pressure for 44PD should be slightly reduced after adding the inert solvent, but not too low; the key is to keep them within a reasonable range (100-140℃, 2.0-4MPa). Excessive temperature and pressure can easily generate high-boiling substances, increasing operational risks and increasing 2-butanol formation. Insufficient pressure can affect the rate of the main reaction or prevent the intermediate product, Schiff base, from further converting into the target product 44PD, leading to a lower conversion rate. This invention optimizes the reaction system by precisely controlling the reaction temperature and pressure at 100-140℃ and 2.0-4MPa, thereby improving the formation rate and selectivity of the target product and reducing the formation of high-boiling substances (substances with boiling points higher than 44PD) to below 0.5%. The reaction is most effective when the reaction temperature is 120-130℃ and the reaction pressure is 2-3MPa.
[0047] Reference Figure 1 As a specific embodiment of the present invention, step 2 can be as follows: in the presence of catalyst 5, under conditions of 2.0-4.0 MPa and 100-140°C, p-nitroaniline 1 and butanone 2 are condensed to generate Schiff base and water, and then the Schiff base is hydrogenated to generate 44PD reaction solution. The reaction is completed in 1-5 hours, and the catalyst is filtered and recycled.
[0048] Reference Figure 1 In a specific embodiment of the present invention, in step 3, the reaction water is separated, and the excess butanone 2 and inert solvent 3 are distilled off and recycled, and the reactor liquid is 44PD.
[0049] This invention does not limit the type or amount of catalyst, as long as the catalytic reaction can be carried out. The type of catalyst can be, for example, nickel-based, copper-based, platinum-based, or palladium-based activated carbon powder catalyst or columnar granular catalyst.
[0050] This invention incorporates a specific proportion of inert solvent into the reaction system and precisely controls the reaction conditions, thereby reducing the alcohol-ketone ratio in the 44PD synthesis reaction and decreasing the formation of high-boiling impurities. This ultimately yields a high-content product with a purity exceeding 98.1%. The alcohol-ketone ratio in the solvent after the reaction is controlled at 0.1%-5%, allowing the recovered solvent to be repeatedly recycled without dehydrogenation, achieving significant beneficial results.
[0051] The following detailed description of preferred embodiments of the present invention illustrates the principles of the invention and is not intended to limit the scope of the invention.
[0052] In this invention, the catalyst used in the examples has a composition of 0.2% Pt-0.5% Cu / C, and the catalyst can be prepared using conventional catalyst preparation methods.
[0053] Example 1
[0054] This embodiment provides a method for synthesizing antioxidant 44PD.
[0055] Step 1: Dissolve and purify 200 kg of p-nitroaniline using 400 kg of butanone, then add 250 kg of inert solvent toluene;
[0056] Step 2: In the presence of a catalyst, p-nitroaniline and butanone are condensed to produce Schiff base and water. The Schiff base is then hydrogenated and reduced to produce 44PD reaction solution. The reaction is completed after 3 hours. The catalyst is then filtered and recycled.
[0057] Step 3: Separate the reaction water, distill off the excess butanone and inert solvent and recycle them directly. The ratio of 2-butanol to butanone in the solvent is 0.5%. The residue is the finished product 44PD with a content of 98.62%.
[0058] Example 2
[0059] This embodiment provides a method for synthesizing antioxidant 44PD.
[0060] Step 1: Dissolve and purify 200 kg of p-nitroaniline using 400 kg of butanone, then add 200 kg of inert solvent dichloromethane and 200 kg of xylene.
[0061] Step 2: In the presence of a catalyst, at 2.0-3.0 MPa and 110-120 °C, p-nitroaniline and butanone are condensed to produce Schiff base and water. The Schiff base is then hydrogenated and reduced to produce 44PD reaction solution. The reaction is completed after 3 hours, and the catalyst is filtered and recycled.
[0062] Step 3: Separate the reaction water, distill off the excess butanone and inert solvent and recycle them directly. The ratio of 2-butanol to butanone in the solvent is 0.4%. The residue is the finished product 44PD with a content of 98.15%.
[0063] Example 3
[0064] This embodiment provides a method for synthesizing antioxidant 44PD.
[0065] Step 1: Dissolve and purify 200 kg of p-nitroaniline using 300 kg of butanone, then add 450 kg of xylene as an inert solvent;
[0066] Step 2: In the presence of a catalyst, at 2.5-3.5 MPa and 120-130 °C, p-nitroaniline and butanone are condensed to produce Schiff base and water. The Schiff base is then hydrogenated and reduced to produce 44PD reaction solution. The reaction is completed after 3 hours, and the catalyst is filtered and recycled.
[0067] Step 3: Separate the reaction water, distill off the excess butanone and inert solvent and recycle them directly. The ratio of 2-butanol to butanone in the solvent is 1.0%. The residue is the finished product 44PD with a content of 98.55%.
[0068] Example 4
[0069] This embodiment provides a method for synthesizing antioxidant 44PD.
[0070] Step 1: Dissolve and purify 200 kg of p-nitroaniline using 600 kg of butanone, then add 550 kg of inert solvent benzene.
[0071] Step 2: In the presence of a catalyst, at 2.0-3.0 MPa and 130-140 °C, p-nitroaniline and butanone are condensed to produce Schiff base and water. The Schiff base is then hydrogenated and reduced to produce 44PD reaction solution. The reaction is completed after 2 hours, and the catalyst is filtered and recycled.
[0072] Step 3: Separate the reaction water, distill off the excess butanone and inert solvent and recycle them directly. The ratio of 2-butanol to butanone in the solvent is 1.5%. The residue is the finished product 44PD with a content of 98.28%.
[0073] Example 5
[0074] This embodiment provides a method for synthesizing antioxidant 44PD.
[0075] Step 1: Dissolve and purify 200 kg of p-nitroaniline using 300 kg of butanone, then add 650 kg of inert solvent toluene.
[0076] Step 2: In the presence of a catalyst, at 3.0-4.0 MPa and 120-130 °C, p-nitroaniline and butanone are condensed to produce Schiff base and water. The Schiff base is then hydrogenated and reduced to produce 44PD reaction solution. The reaction is completed after 3 hours, and the catalyst is filtered and recycled.
[0077] Step 3: Separate the reaction water, distill off the excess butanone and inert solvent and recycle them directly. The ratio of 2-butanol to butanone in the solvent is 3.5%. The residue is the finished product 44PD with a content of 98.66%.
[0078] Example 6
[0079] This embodiment provides a method for synthesizing antioxidant 44PD.
[0080] Step 1: Dissolve and purify 200 kg of p-nitroaniline using 300 kg of butanone, then add 350 kg of inert solvent toluene and 300 kg of xylene.
[0081] Step 2: In the presence of a catalyst, at 3.0-4.0 MPa and 120-130 °C, p-nitroaniline and butanone are condensed to produce Schiff base and water. The Schiff base is then hydrogenated and reduced to produce 44PD reaction solution. The reaction is completed after 3 hours, and the catalyst is filtered and recycled.
[0082] Step 3: Separate the reaction water, distill off the excess butanone and inert solvent and recycle them directly. The ratio of 2-butanol to butanone in the solvent is 3.0%. The residue is the finished product 44PD with a purity of 98.69%.
[0083] Example 7
[0084] This embodiment provides a method for synthesizing antioxidant 44PD.
[0085] Step 1: Dissolve and purify 200 kg of p-nitroaniline using 400 kg of butanone, then add 550 kg of xylene as an inert solvent;
[0086] Step 2: In the presence of a catalyst, at 2.0-3.5 MPa and 125-135 °C, p-nitroaniline and butanone are condensed to produce Schiff base and water. The Schiff base is then hydrogenated and reduced to produce 44PD reaction solution. The reaction is completed after 1.5 h. The catalyst is then filtered and recycled.
[0087] Step 3: Separate the reaction water, distill off the excess butanone and inert solvent and recycle them directly. The ratio of 2-butanol to butanone in the solvent is 1.5%. The residue is the finished product 44PD with a content of 98.76%.
[0088] Comparative Example 1
[0089] This comparative example is essentially the same as Example 1, except that the inert solvent toluene is not added. In step 3, the ratio of 2-butanol to butanone in the solvent is 13.5%, and the content of 44PD in the reactor liquid is 98.25%.
[0090] Comparative Example 2
[0091] This comparative example is basically the same as Example 1, except that in step 1, 200 kg of p-nitroaniline was dissolved and purified by filtration using 650 kg of butanone. In step 3, the ratio of 2-butanol to butanone in the solvent was 17.2%, and the content of 44PD in the reaction solution was 97.73%.
[0092] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.
Claims
1. A method for synthesizing antioxidant 44PD, characterized in that, The process includes the following steps: obtaining a mixture comprising butanone, p-nitroaniline, and an inert solvent, and performing a condensation hydrogenation reaction using said mixture. The inert solvent includes at least one of benzene, toluene, dimethylformamide, xylene, cyclohexane, dimethyl sulfoxide, diethyl ether, methanol, ethanol, acetone, acetonitrile, and dichloromethane.
2. The synthesis method according to claim 1, characterized in that, The mass ratio of the inert solvent to methyl ethyl ketone is (1:3) to (3:1).
3. The synthesis method according to any one of claims 1-2, characterized in that, The inert solvent includes a first inert solvent and a second inert solvent. The first inert solvent is different from the second inert solvent. The first inert solvent and the second inert solvent each independently include at least one of benzene, toluene, dimethylformamide, xylene, cyclohexane, dimethyl sulfoxide, diethyl ether, methanol, ethanol, acetone, acetonitrile, and dichloromethane.
4. The synthesis method according to claim 3, characterized in that, The mass ratio of the first inert solvent to the second inert solvent is (1:2) to (2:1).
5. The synthesis method according to any one of claims 1-4, characterized in that, The reaction temperature for the condensation hydrogenation reaction is 100-140℃, preferably 120-130℃.
6. The synthesis method according to any one of claims 1-5, characterized in that, The reaction pressure of the condensation hydrogenation reaction is 2-4 MPa, preferably 2-3 MPa.
7. The synthesis method according to any one of claims 1-6, characterized in that, The reaction time for the condensation hydrogenation reaction is 1-5 hours.
8. The synthesis method according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Obtain a mixture comprising butanone, p-nitroaniline, and an inert solvent. Step 2: Perform a condensation hydrogenation reaction using the mixture. Step 3: Separate and distill the products of the condensation and hydrogenation reaction sequentially to obtain antioxidant 44PD.
9. The synthesis method according to any one of claims 1-8, characterized in that, The condensation hydrogenation reaction is carried out in the presence of a catalyst; Preferably, the catalyst comprises at least one of nickel-based, copper-based, platinum-based, or palladium-based catalysts; preferably, the catalyst support is activated carbon.
10. The synthesis method according to any one of claims 1-9, characterized in that, The mass ratio of p-nitroaniline to butanone is (1:1)-(1:10).