Process for preparing an antioxidant 4010na

Abstract

The application provides a preparation method of antioxidant 4010NA, which comprises the following steps: mixing acetone and 4-amino diphenylamine, performing condensation hydrogenation reaction after heating and stirring under certain acidic conditions to obtain a reaction solution, recovering reaction byproducts in the reaction solution, and performing rectification separation to obtain the antioxidant 4010NA. Through simple raw material pretreatment, the conversion rate of 4-amino diphenylamine and the selectivity of 4010NA can be improved, the antioxidant 4010NA with high yield can be obtained, the occurrence of side reactions and byproducts in the separation reaction can be effectively reduced, and the reaction condition is more moderate and energy consumption is reduced compared with direct hydrogenation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic synthesis, in particular to a preparation method of antioxidant 4010NA. BACKGROUND

[0002] When rubber products are affected by external environment and other factors, the chemical structure in the rubber products is destroyed, and with the passage of time, the mechanical properties, electrical properties and other properties gradually deteriorate, eventually leading to the rubber being unable to use. Taking appropriate measures can delay or inhibit the speed of rubber aging, thereby prolonging the service life of the rubber. Consuming or inhibiting the generation of free radicals and hydrogen peroxide during the aging process is the key to protection, and the antioxidant is an antioxidant that can capture free radicals, which not only has high anti-aging efficiency, but also has simple process and does not affect the rubber processing. Among many antioxidants, amine antioxidants have the widest application range, and common antioxidants include antioxidant 4020 (6PPD), antioxidant 4010NA, antioxidant RD, etc. Among them, 4010NA (N-isopropyl-N'-phenyl-p-phenylenediamine) is a general-purpose excellent antioxidant for natural rubber, synthetic rubber and latex, and has excellent protection performance against ozone, flex cracking, and is also an excellent antioxidant against heat, oxygen, light and general aging. It is commonly used to manufacture products that bear dynamic and static stress, and has comprehensive protection performance.

[0003] The traditional production method of antioxidant 4010NA is that p-aminodiphenylamine (i.e. 4-aminodiphenylamine) is reacted with acetone in the presence of a copper-chromium catalyst at 160-165 DEG C and under a hydrogen pressure of 5-6 MPa. The reaction is filtered while hot to remove the catalyst, and then the product is obtained by freezing crystallization, filtration and drying. In the traditional production method, the catalyst has low activity, so high reaction conditions such as high temperature and high pressure are required. However, under high temperature and high pressure conditions, a large amount of isopropyl alcohol is inevitably generated by hydrogenation of acetone due to the excess of the reaction system, so that the content of isopropyl alcohol in the side reaction is difficult to reduce, and the separation is difficult. SUMMARY

[0004] To solve the technical problems of high side reaction, low raw material utilization rate and difficult reduction of isopropyl alcohol content in the side reaction in the preparation of antioxidant 4010NA in the prior art, the present application provides a preparation method of antioxidant 4010NA, which has a simple process, can effectively reduce the occurrence of side reactions and by-products in the separation reaction, improve the utilization rate of raw materials, and obtain high-yield antioxidant 4010NA.

[0005] The technical problem of the present application is solved by the following technical scheme.

[0006] The embodiment of the present application provides a preparation method of antioxidant 4010NA, which comprises the following steps: mixing acetone and 4-aminodiphenylamine, performing condensation hydrogenation reaction under the condition of a certain acidity after heating and stirring, obtaining a reaction solution, recovering reaction by-products in the reaction solution, and then performing rectification separation to obtain the antioxidant 4010NA.

[0007] Compared with the prior art, the embodiment of the present application has at least the following advantages or beneficial effects:

[0008] 1. The preparation method of the antioxidant 4010NA provided by the present application adopts a noble metal catalyst to synthesize the antioxidant 4010NA on a fixed bed, and the raw material is simply pretreated, and the pretreatment step is performed under a certain acidic condition, which is helpful to the generation of Schiff base of the imine structure of the intermediate of the reaction of acetone and RT, and the Schiff base is an important intermediate of the reaction. In addition, the pretreatment process divides the one-step synthesis process into two steps, which improves the formation of the important intermediate Schiff base, a large amount of the Schiff base not only improves the selectivity of the 4010NA in the subsequent hydrogenation reaction, but also further reduces the reaction pressure and the reaction temperature, so that the acetone is difficult to be hydrogenated under the condition, thereby significantly reducing the content of isopropyl alcohol in the side reaction.

[0009] 2. The preparation method of the antioxidant 4010NA provided by the present application has the advantages of continuous operation, simple operation, more moderate reaction conditions, avoidance of catalyst loss caused by filtration when a powder catalyst is used, reduction of production cost and the like. DETAILED DESCRIPTION

[0010] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be clearly and completely described below. If the specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are adopted. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased in the market.

[0011] It should be noted that, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other, and the present application will be described in detail below with reference to specific embodiments.

[0012] A preparation method of an antioxidant 4010NA comprises the following steps: mixing acetone and 4-aminodiphenylamine, performing condensation hydrogenation reaction under the condition of a certain acidity after heating and stirring, obtaining a reaction solution, recovering reaction by-products in the reaction solution, and then performing rectification separation to obtain the antioxidant 4010NA.

[0013] In some embodiments of the present application, the temperature of the above-mentioned heating and stirring is preferably 20-60℃; the time of the above-mentioned heating and stirring is 1-8h. During the pretreatment process, the generation of the intermediate is an equilibrium reaction, and too high or too low heating temperature will affect the reaction, and too short stirring time will result in insufficient intermediate content; too long heating and stirring time will result in equilibrium of the intermediate content, and the above-mentioned range is the best range through preliminary experiments.

[0014] It should be noted here that the temperature of the heating and stirring can be, but is not limited to, 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃ and 100℃; the time of the heating and stirring can be 1h, 2h, 3h, 4h, 5h, 6h, 7h and 8h.

[0015] In some embodiments of the present application, the temperature of the above-mentioned heating and stirring is 20-60℃; the time of the above-mentioned heating and stirring is 2-5h. Within this range, the reaction is more favorable.

[0016] In some embodiments of the present application, the above-mentioned heating and stirring is carried out in an air or nitrogen atmosphere. In a nitrogen atmosphere, the influence of oxygen in the air on the intermediate during the pretreatment (heating and stirring under certain acidic conditions) process can be reduced, which is the most economical.

[0017] In some embodiments of the present application, the above-mentioned acidic conditions specifically refer to adding a solid acid to adjust the pH to 5-6.

[0018] In some embodiments of the present application, the above-mentioned acidic conditions specifically refer to adding a solid acid to adjust the pH to 6.

[0019] In some embodiments of the present application, the above-mentioned solid acid is any one of phosphoric acid, Hβ molecular sieve and HZSM-5 molecular sieve.

[0020] In some embodiments of the present application, the above-mentioned solid acid is Hβ molecular sieve.

[0021] The raw material is converted into a Schiff base intermediate in the pretreatment stage, and the subsequent hydrogenation conditions are mild and the hydrogen consumption is low; the Schiff base is easy to generate under acidic conditions and is stable and not easy to decompose, and the molecular sieve also has water absorption, which can remove the water generated during the pretreatment process, thereby greatly promoting the reaction to proceed in the positive direction. Hβ molecular sieve has a larger pore size, which is beneficial to the adsorption of reactants and the reaction, so Hβ molecular sieve is preferred.

[0022] In some embodiments of the present application, the mass fraction of the above-mentioned solid acid is 0.1-1%.

[0023] In some embodiments of the present application, the mass fraction of the above-mentioned solid acid is 0.5%.

[0024] The low content of solid acid is more conducive to the reaction, especially when the mass fraction of the solid acid is 0.5%.

[0025] It should be noted that the mass fraction of the solid acid can be, but is not limited to, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% and 1%.

[0026] In some embodiments of the present application, the mass ratio of the above acetone and the above 4-amino diphenylamine is (1-5):(1-3).

[0027] In some embodiments of the present application, the mass ratio of the above acetone and the above 4-amino diphenylamine is (1-3):1.

[0028] The acetone is both a reactant and a solvent in the system. Through preliminary experiments, the mixture with the mass ratio of acetone and 4-amino diphenylamine being (1-5):(1-3) has good fluidity, which is more conducive to the reaction, especially when the mass ratio of acetone and 4-amino diphenylamine is (1-3):1.

[0029] It should be noted that the mass ratio of the acetone and the above 4-amino diphenylamine can be, but is not limited to, 1:1, 1:2, 1:3, 5:1, 5:2 and 5:3.

[0030] In some embodiments of the present application, the conditions of the above condensation hydrogenation reaction include that the reaction temperature is 60-120℃, and the reaction pressure is 0.3-1.5MPa. In this temperature and pressure range, the hydrogenation of acetone can be effectively inhibited, and the smooth progress of the main reaction can be ensured.

[0031] It should be noted that the reaction temperature can be, but is not limited to, 60℃, 70℃, 80℃, 90℃, 100℃, 110℃ and 120℃; and the reaction pressure can be 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa, 1.0MPa, 1.1MPa, 1.2MPa, 1.3MPa, 1.4MPa and 1.5MPa.

[0032] In some embodiments of the present application, the conditions of the above condensation hydrogenation reaction include that the reaction temperature is 80-110℃, and the reaction pressure is 0.5-1.2MPa.

[0033] In some embodiments of the present application, the hydrogen oil ratio of the above condensation hydrogenation reaction, i.e. the ratio of the hydrogen gas volume flow rate to the raw material volume flow rate, is (100-700):1.

[0034] In some embodiments of the present application, the hydrogen oil ratio is (200-500):1.

[0035] The proportion of hydrogen cannot be too high, otherwise the proportion of side reactions will increase, and the hydrogen to oil ratio is (100-700): 1, which is beneficial to the rapid progress of the reaction and the reduction of the generation of by-products, especially the hydrogen to oil ratio of (200-500): 1 is more beneficial to the rapid progress of the reaction and the reduction of the generation of by-products.

[0036] It should be noted here that the hydrogen to oil ratio can be but is not limited to 100:1, 200:1, 300:1, 400:1, 500:1, 600:1 and 700:1.

[0037] In some embodiments of the present application, the above-mentioned condensation hydrogenation reaction uses a noble metal catalyst, and the above-mentioned noble metal is Pt or Pd.

[0038] In some embodiments of the present application, the above-mentioned noble metal is Pt.

[0039] In some embodiments of the present application, the mass percentage of the above-mentioned noble metal is 0.1-5%.

[0040] In some embodiments of the present application, the mass percentage of the above-mentioned noble metal is 0.5%.

[0041] Excessive content of noble metal can easily cause hydrogenation of acetone, thereby affecting the yield of the main reaction, and the content of noble metal within this range has good catalytic effect; it has been verified by experiments that the content of noble metal with a mass percentage of 0.5% is the best.

[0042] It should be noted here that the mass percentage of the noble metal can be but is not limited to 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% and 5%.

[0043] In some embodiments of the present application, the carrier of the above-mentioned catalyst is coconut shell charcoal.

[0044] In some embodiments of the present application, the specific surface area of the above-mentioned coconut shell charcoal is ≥1000m 2 / g, the pore volume is 0.3-2.5g / ml, the pore size is 0.5-2.5nm, the ash content is ≤5%, and the water absorption rate is 40-85%.

[0045] In some embodiments of the present application, the water absorption rate is 60%.

[0046] It should be noted here that the coconut shell charcoal is made of natural coconut shell powder, and the ranges of the specific surface area, pore volume, pore size, ash content and water absorption rate of the coconut shell charcoal listed above are all reasonable ranges, and the performance of the coconut shell charcoal within the ranges is not affected.

[0047] Example 1

[0048] A preparation method of an antioxidant 4010NA, comprising the following steps:

[0049] The acetone and p-aminodiphenylamine were mixed in a mass ratio of 1:2, 0.5% Hβ molecular sieve was added, the solution pH was adjusted to 6, and after stirring at 50°C for 3h under a nitrogen atmosphere, the solution was cooled and filtered; 2% Pt / C catalyst was loaded into a fixed bed reaction device, the aforementioned cooled reaction raw material was added to perform condensation hydrogenation reaction (reaction temperature was 100°C, pressure was 1.0 MPa, hydrogen / oil ratio was 400:1), to obtain a reaction liquid; the reaction liquid was then subjected to gas-liquid separation, and the acetone and methyl isobutyl ketone were recovered by a recovery column, and finally the 4010NA was obtained by distillation separation.

[0050] It should be noted that the distillation of the reaction liquid after gas-liquid separation can use distillation operation well known in the art. That is, after the raw material is subjected to condensation dehydration and hydrogenation reaction, the hydrogen gas and the reaction liquid are separated by a gas-liquid separator, and the hydrogen gas can be recycled. The reaction liquid is passed through a light component column, and water, acetone, methyl isobutyl ketone are sequentially separated, and finally the 4010NA product is obtained.

[0051] Example 2

[0052] This example is basically the same as Example 1, except that the mass ratio of acetone to p-aminodiphenylamine is 1:1.5.

[0053] Example 3

[0054] This example is basically the same as Example 1, except that the mass ratio of acetone to p-aminodiphenylamine is 1:1.

[0055] Example 4

[0056] This example is basically the same as Example 3, except that the condensation hydrogenation reaction temperature is 90°C.

[0057] Example 5

[0058] This example is basically the same as Example 4, except that the condensation hydrogenation reaction temperature is 80°C.

[0059] Example 6

[0060] This example is basically the same as Example 4, except that 1, stirring at 50°C for 5h under a nitrogen atmosphere, and then cooling; 2, the condensation hydrogenation reaction pressure is 0.8 MPa.

[0061] Example 7

[0062] This example is basically the same as Example 6, except that stirring at 30°C for 3h under a nitrogen atmosphere, and then cooling.

[0063] Comparative Example 1

[0064] The comparative example is basically the same as example 6, except that the raw material is not pretreated (i.e. the acetone and p-aminodiphenylamine are mixed in a mass ratio of 1:2, 0.5% Hβ molecular sieve is added, and after stirring at 50°C under a nitrogen atmosphere for 3h, it is cooled and filtered), and after mixing, it is directly introduced into the fixed bed reaction.

[0065] Comparative Example 2

[0066] The comparative example is basically the same as example 6, except that solid acid is not added during the raw material pretreatment process.

[0067] Comparative Example 3

[0068] The comparative example is basically the same as example 6, except that 0.5% phosphoric acid is added as the solid acid during the raw material pretreatment process, and the solution pH is adjusted to 6.

[0069] Test Example

[0070] The antioxidant 4010NA prepared in examples 1-7 and comparative examples 1-3 is analyzed by gas chromatography (gas chromatograph model Agilent GC-7890), and the quantitative method is the area normalization method, which is determined according to the provisions of GB / T 20646-2006 “Rubber additives p-phenylenediamine (PPD) antioxidant test method”. The analysis results are shown in Table 1.

[0071] Table 1: Gas chromatography analysis results

[0072] Group p-aminodiphenylamine conversion 4010 NA selectivity Ketol ratio Example 1 86.96％ 90.24％ 95 / 5 Example 2 93.23％ 92.58％ 92 / 8 Example 3 99.60％ 95.27％ 90 / 10 Example 4 97.49％ 97.33％ 93 / 7 Example 5 92.11％ 98.87％ 96 / 4 Example 6 99.32％ 98.25％ 98 / 2 Example 7 97.17％ 94.28％ 96 / 4 Comparative Example 1 82.45％ 92.85％ 93 / 7 Comparative Example 2 87.99％ 93.41％ 90 / 10 Comparative Example 3 97.25％ 95.11％ 96 / 4

[0073] As can be seen from Table 1, the performance effect of the antioxidant 4010NA prepared in example 6 is the best, and when the reaction pressure is reduced to 0.8Mpa and the temperature is reduced to 90°C, there is still a high selectivity (98.25%) and a p-aminodiphenylamine conversion rate (99.32%), which is more energy-saving, and the ketone / alcohol ratio is 98 / 2, and the content of alcohol byproduct is lower.

[0074] In comparative example 1, the raw material is not pretreated, and after mixing, it is directly introduced into the fixed bed reaction. The p-aminodiphenylamine conversion rate is 82.45%, the 4010NA selectivity is 92.85%, and the ketone / alcohol ratio is 93 / 7. It can be seen that after the raw material is pretreated, the p-aminodiphenylamine conversion rate, the 4010NA selectivity and the content of alcohol byproduct can be effectively improved.

[0075] In comparative example 2, solid acid is not added during the raw material pretreatment process, and the p-aminodiphenylamine conversion rate is only 87.99%, the 4010NA selectivity is 93.41%, and the ketone / alcohol ratio is 90 / 10. The above experimental results show that adding solid acid during the raw material pretreatment process is more conducive to the reaction and reduces the generation of byproducts.

[0076] In the comparative example 3, the solid acid is 0.5% phosphoric acid added in the pretreatment process of raw materials, and the conversion rate of p-aminodiphenylamine is 97.25% and the selectivity of 4010NA is 95.11% and the ketone / alcohol ratio is 96 / 4 by chromatographic analysis. It can be seen that after the adjustment of acidity by phosphoric acid, the conversion rate of p-aminodiphenylamine, the selectivity of 4010NA and the ketone / alcohol ratio are all significantly improved compared with no acid adjustment. Since phosphoric acid does not have the water absorption property of molecular sieve, the content of Schiff base in the pretreatment process is not as high as that after the treatment of molecular sieve, which indicates that the adjustment of acidity by molecular sieve can make the main reaction proceed more smoothly and the performance of the antioxidant 4010NA obtained is better.

[0077] In summary, the preparation method of the antioxidant 4010NA provided by the embodiment of the present application is more moderate in conditions after the pretreatment of raw materials, and realizes the efficient conversion of 4-aminodiphenylamine and the high-quality production of the product 4010NA.

[0078] It should be noted that the above-described embodiments are only used to explain the present application and do not constitute any limitation on the present application. The present application is described by referring to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than limiting words. The present application can be modified as specified within the scope of the claims of the present application, and the present application can be revised without departing from the scope and spirit of the present application. Although the present application described therein relates to specific methods, materials and embodiments, it does not mean that the present application is limited to the specific examples disclosed therein, on the contrary, the present application can be extended to all other methods and applications with the same function.

Claims

1. A method for producing an age resistor 4010NA, characterized by, The preparation method comprises the following steps: mixing acetone and 4-amino diphenylamine, and performing condensation hydrogenation reaction after heating and stirring under acidic conditions to obtain a reaction solution, wherein the heating and stirring temperature is 20-60 ℃, the acidic conditions are specifically adding solid acid to adjust the pH to 5-6, the solid acid is any one of phosphoric acid, Hβ molecular sieve and HZSM-5 molecular sieve, and the condensation hydrogenation reaction temperature is 80-110 ℃; recovering reaction by-products in the reaction solution, and then performing rectification separation to obtain the antioxidant 4010NA.

2. The production method according to claim 1, characterized by, The heating and stirring time is 1-8 h.

3. The production method according to claim 2, characterized by, The heating and stirring time is 2-5 h.

4. The production method according to any one of claims 1 to 3, characterized by, The heating and stirring is performed in an air or nitrogen atmosphere.

5. The production method according to any one of claims 1 to 3, characterized by, The pH is adjusted to 6 by adding the solid acid. The solid acid is Hβ molecular sieve.

6. The production method according to any one of claims 1 to 3, characterized by, The mass percentage of the solid acid is 0.1-1%.

7. The production method according to claim 6, wherein The mass percentage of the solid acid is 0.5%.

8. The production method according to any one of claims 1 to 3, characterized by, The mass ratio of the acetone to the 4-amino diphenylamine is (1-5):(1-3).

9. The preparation method according to claim 8, characterized in that, The mass ratio of the acetone to the 4-amino diphenylamine is (1-3):

1.

10. The production method according to any one of claims 1 to 3, characterized by, The condensation hydrogenation reaction pressure is 0.3-1.5 MPa.

11. The production method according to claim 10, characterized by, The reaction pressure is 0.5-1.2 MPa.

12. The method of any one of claims 1-3, wherein, The condensation hydrogenation reaction hydrogen oil ratio, i.e. the ratio of hydrogen volume flow rate to raw material volume flow rate, is (100-700):

1.

13. The method of claim 12, wherein, The hydrogen oil ratio is (200-500):

1.

14. The production method according to any one of claims 1 to 3, characterized by, The condensation hydrogenation reaction is performed in the presence of a catalyst.

15. The preparation method according to claim 14, characterized in that, The catalyst is a noble metal supported catalyst.

16. The method of claim 15, wherein, The noble metal is Pt or Pd. The mass percentage of the noble metal is 0.1-5%.

17. The preparation method according to claim 16, characterized in that, The mass percentage of the noble metal is 0.5%.

18. The method of any one of claims 15-17, wherein, The carrier of the catalyst is coconut shell charcoal.

19. The method of claim 18, wherein, The specific surface area of the coconut shell charcoal is ≥1000 m 2 / g, a pore volume of 0.3-2.5 g / ml, a pore diameter of 0.5-2.5 nm, an ash content of ≤5%, and a water absorption of 40-85%.

20. The method of claim 19, wherein, The water absorption rate is 60%.