Diphenylamine compound as well as preparation method and application thereof

Abstract

The invention discloses a diphenylamine compound and a preparation method and application thereof.The preparation method comprises the steps that a 2, 4-diaminobenzene compound and a 3-haloaniline compound react to obtain an intermediate A, and the intermediate A and ketone are subjected to a hydrogenation condensation reaction under the action of a catalyst and hydrogen to obtain a final product. The raw materials are convenient to purchase and transport, the reaction process is simple, the product yield is high, the cost is low, the environmental pollution is small, the anti-aging effect is good, and compared with existing mainstream anti-aging agents 4020 and the like which are not easy to migrate out of PPDQ, the anti-aging agent has the advantages of low toxicity and migration resistance, and has industrial development prospects.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of aniline compound, further relate to the preparation method of the compound and its application as rubber antioxidant, belong to organic chemistry technical field. BACKGROUND

[0002] At present, the main anti ozone type antioxidant used in rubber tire products at home and abroad is p-phenylenediamine antioxidant, and p-phenylenediamine antioxidant mainly includes antioxidant 3100, antioxidant 4020, antioxidant 4030 and the like.

[0003] Antioxidant 4020 and 4030 are mainly used as anti ozone agents for natural rubber and general synthetic rubber, and have protective effect on thermal aging and flex cracking, and have excellent chemical corrosion resistance, but its shortcomings are also very obvious, such as toxicity, color pollution, poor migration resistance and the like. Among them, the most serious problem is that p-phenylenediamine antioxidant reacts with ozone to form highly toxic PPDQ (p-phenylenediamine derivative quinone). Studies have shown that these pollutants exist widely in rainwater, soil and air, and even are detected in human urine. These compounds can enter the human body through inhalation, food intake and contact with contaminated water bodies.

[0004] Therefore, it is urgent to develop a new diamine antioxidant with antioxidant aging resistance and environmental friendliness. SUMMARY

[0005] In view of the problems existing in the mainstream antioxidant, the present application provides a diphenylamine compound, which has good anti-aging effect and is environmentally friendly, and is a new type of rubber antioxidant.

[0006] The diphenylamine compound provided by the present application has the structural formula shown in the following formula (1): In the above formula (1), the positions of R1 and R2 on the benzene ring are arbitrary, R1 and R2 each independently represent hydrogen or C1-C3 alkyl, and C1-C3 alkyl can be methyl, ethyl, propyl and the like. R1 and R2 can be the same or different, but R1 and R2 cannot be hydrogen at the same time.

[0007] In the above formula (1), R3 and R4 each independently represent cycloalkyl, 1,3-dimethylbutyl, isopropyl or 1,2-dimethylpropyl, and the cycloalkyl can be cyclohexyl. R3 and R4 can be the same or different.

[0008] Among them, the structural formula of 1,3-dimethylbutyl is: , and the structural formula of 1,2-dimethylpropyl is , represents a connection site.

[0009] Furthermore, the diphenylamine compound is one of the compounds shown in the following structural formulas: The present invention also provides a method for preparing the above-mentioned diphenylamine compounds, wherein the diphenylamine compounds are prepared by reacting 2,4-diaminobenzene compounds and 3-haloaniline compounds to obtain intermediate A, and then intermediate A is reacted with a ketone by hydrogenation to obtain the final product.

[0010] Furthermore, the preparation method includes the following steps: (1) The diaminobenzene compound shown in formula (2) is reacted with the 3-haloaniline compound shown in formula (3) to obtain intermediate A; (2) Intermediate A is reacted with ketone under the action of catalyst and hydrogen to obtain the diphenylamine compound.

[0011] Furthermore, in step (1), the definitions of R1 and R2 in formulas (2) and (3) are consistent with those described above, and X is a halogen, such as chlorine or bromine. Diaminobenzene compounds can be 2,4-diaminotoluene, etc., and 3-haloaniline compounds can be 3-bromo-2-methylaniline, m-bromoaniline, 3-chloro-2-methylaniline, m-chloroaniline, etc.

[0012] Furthermore, in step (1), when the reactants are 2,4-diaminotoluene and 3-bromo-2-methylaniline or 3-chloro-2-methylaniline, the structural formula of intermediate A is: .

[0013] Furthermore, in step (1), when the reactants are 2,4-diaminotoluene and m-bromoaniline or m-chloroaniline, the structural formula of intermediate A is: .

[0014] Furthermore, in step (1), the reaction is carried out in an organic solvent, which can be at least one of toluene, DMSO, etc. The organic solvent serves as the reaction medium to ensure that the reaction is carried out in a uniform liquid phase environment, and its amount can be adjusted and selected according to the actual situation.

[0015] Furthermore, in step (1), the reaction is carried out in the presence of an acid-binding agent, which can be sodium tert-butoxide, tetramethylammonium hydroxide, etc. Commercially available tetramethylammonium hydroxide is generally a 25% aqueous solution by mass, which needs to be removed by vacuum distillation before being added to the reaction system.

[0016] Furthermore, in step (1), the molar ratio of the acid-binding agent to the 2,4-diaminobenzene compound is 2 to 4:1, for example, 2:1, 3:1, or 4:1.

[0017] Furthermore, in step (1), the molar ratio of 2,4-diaminobenzene compounds to 3-haloaniline compounds is 1-1.1:1.

[0018] Furthermore, in step (1), the 2,4-diaminobenzene compound reacts with the 3-haloaniline compound at 100~120℃, for example 100℃, 105℃, 110℃, 115℃, 120℃. At this reaction temperature, the reaction time is generally 5~10h, for example 5h, 6h, 7h, 8h, 9h, 10h.

[0019] Furthermore, in step (1), after the reaction is complete, intermediate A is obtained by removing the solvent by distillation or by adding water to the reaction solution to precipitate the intermediate A.

[0020] Furthermore, in the above formula (1), the substituents R3 and R4 are derived from residues of the ketone, and the ketone is selected based on the substituents R3 and R4. In step (2), the ketone can be at least one of cyclohexanone, MIBK (methyl isobutyl ketone), methyl isopropyl ketone, etc.

[0021] Furthermore, in step (2), the molar ratio of intermediate A to all ketones is 1:5 to 10, for example, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10. The ketones serve as both reactants and solvents during the reaction.

[0022] Furthermore, when the substituents R3 and R4 in formula (1) are different, the ketones added in step (2) are of two kinds, and the molar ratio of the two different ketones is 1:1.

[0023] Furthermore, in step (2), the catalyst is at least one of copper-based catalyst, palladium-carbon catalyst, platinum-carbon catalyst, and Raney nickel catalyst. The copper-based catalyst can be Cu-Mn catalyst, Cu-Zr catalyst, etc.

[0024] Furthermore, in step (2), the amount of catalyst used is 1%-8% of the mass of intermediate A, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%.

[0025] Furthermore, in step (2), the reaction temperature is 100-170℃, for example 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃.

[0026] Furthermore, in step (2), the hydrogen pressure is maintained at 1-4 MPa throughout the reaction process, and the reaction is stopped when the hydrogen pressure no longer changes.

[0027] Furthermore, in step (2), after the reaction is completed, the catalyst is recovered by filtration, the reaction solution is distilled under reduced pressure to remove ketones, water and a small amount of by-product alcohol, and then dried to obtain the final product.

[0028] The diphenylamine compounds of this invention have excellent ozone resistance and can be used as rubber antioxidants in the rubber industry. When used in rubber products or tire products, these compounds not only have excellent anti-aging properties but also good migration resistance. Moreover, they do not produce toxic substances during use and are low in toxicity and more environmentally friendly.

[0029] This invention also provides the application of the above-described diphenylamine compounds, or diphenylamine compounds prepared according to the above method, in the field of rubber. These diphenylamine compounds serve as rubber antioxidants.

[0030] The present invention has the following beneficial effects: 1. This invention designs a special compound molecular skeleton that avoids the structural characteristics of traditional p-phenylenediamines (N,N'-disubstituted p-phenylenediamines). This novel structural design eliminates or significantly inhibits the possibility of its reaction with ozone to generate highly toxic PPDQ (p-phenylenediamine-derived quinone), thereby greatly reducing environmental residues and biological exposure risks, resulting in higher environmental friendliness and safety.

[0031] 2. The diphenylamine derivatives designed in this invention have a large molecular weight, and the compound polarity is optimized through molecular design. They exhibit superior extraction and migration resistance compared to traditional antioxidants 4020 / 4030, reducing the amount that leaches from rubber products or migrates into the environment during use, extending the protective lifespan and reducing pollution. Furthermore, this molecular structure may facilitate microbial degradation, reducing its accumulation in the environment.

[0032] 3. This invention uses 2,4-diaminobenzene compounds and 3-haloaniline compounds as raw materials. The purchase and transportation of raw materials are very convenient, and there are many raw material options, which improves the flexibility of raw material selection and the space for cost optimization.

[0033] 4. The hydrogenation condensation reaction of this invention is carried out under a catalyst, which has high reaction efficiency. The catalyst can be filtered and recycled, which is in line with the principles of green chemistry.

[0034] 5. The preparation steps of this invention are simple, the reaction process is straightforward, and the product yield is high. By optimizing the reaction conditions, the reproducibility of the reaction and the quality stability of the target product are ensured, which facilitates industrial production. Attached Figure Description

[0035] Figure 1 NMR spectrum of sample in Example 1.

[0036] Figure 2 NMR spectrum of sample in Example 2. Detailed Implementation

[0037] The following description illustrates exemplary embodiments of the present invention, including various details to aid understanding, and should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the invention. Similarly, for clarity and brevity, descriptions of well-known functions, operations, and structures are omitted in the following description.

[0038] Unless otherwise defined, the technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art. While similar or identical methods and materials may be applied in experimental or practical applications, the present invention describes materials and methods hereinafter. In case of conflict, the definitions included herein shall prevail.

[0039] In the following examples, the purity of the intermediate was determined by high performance liquid chromatography, and the content of different components in the product was determined by gas chromatography.

[0040] In this example, the molecular weight of the product of Example 3 is calculated based on component 1.

[0041] Example 1 A method for preparing a diphenylamine compound, comprising the following steps: Step (1): Add 50g of 2,4-diaminotoluene and 76.14g of 3-bromo-2-methylaniline to a flask, add 256g of DMSO to dissolve the raw materials, then add 78.66g of sodium tert-butoxide and mix thoroughly. Stir and react at 120℃ for 5 hours. After the reaction, distill off the DMSO solvent under reduced pressure. After distillation until no obvious solvent remains, wash with water to obtain 90.69g of the intermediate. The intermediate was found to have a purity of 98.53%, with a yield of 97.5% based on 2,4-diaminotoluene.

[0042] Step (II): The obtained intermediate and 210g of cyclohexanone were added to a high-pressure reactor, along with 10g of platinum-carbon catalyst. The platinum-carbon catalyst was washed with methanol and activated by soaking in cyclohexanone before being added to the high-pressure reactor. Hydrogen gas was introduced into the reactor at 100℃ to 3MPa to hydrogenate the intermediate. The hydrogen pressure was maintained at 2-4MPa; if the pressure was insufficient, hydrogen gas was continued until the pressure inside the reactor no longer changed, at which point the reaction was stopped. The hydrogenation condensation reaction took approximately 10 hours. After the reaction, the temperature was lowered, the hydrogen gas was discharged, the catalyst was recovered by filtration, and cyclohexanone, alcohol, and water were removed under reduced pressure. The cyclohexanone was reused. The final product, product 1, was obtained, with the following structural formula and carbon NMR spectrum. Figure 1 As shown.

[0043] Product 1 has a purity of 97.21% and a yield of 87.5% based on 2,4-diaminotoluene.

[0044] Example 2 The diphenylamine compounds were prepared according to the steps of Example 1, except that in step (i), 3-bromo-2-methylaniline in the raw materials was replaced with m-bromoaniline; and in step (ii), cyclohexanone was completely replaced with MIBK. The specific steps are as follows: Step (1): Add 50g of 2,4-diaminotoluene and 70g of m-bromoaniline to a flask, add 256g of DMSO to dissolve the raw materials, then add 78.66g of sodium tert-butoxide and mix thoroughly. Stir and react at 120℃ for 5 hours. After the reaction, distill off the DMSO solvent under reduced pressure. After distillation until no obvious solvent remains, wash with water to obtain 84.59g of the intermediate. The intermediate was found to have a purity of 98.30%, with a yield of 97% based on 2,4-diaminotoluene.

[0045] Step (II): Add the obtained intermediate and 223g of MIBK2 to a high-pressure reactor, along with 10g of platinum-carbon catalyst. Before use, the platinum-carbon catalyst is washed with methanol, activated by soaking in cyclohexanone, and then added to the high-pressure reactor. At 100°C, hydrogen gas is introduced into the reactor to 3MPa to hydrogenate the intermediate. The hydrogen pressure is maintained at 2-4MPa; if the pressure is insufficient, hydrogen gas is continued to be introduced until the pressure inside the reactor no longer changes, at which point the reaction is stopped. The hydrogenation condensation reaction takes approximately 10 hours. After the reaction, the temperature is lowered, the hydrogen gas is released, the catalyst is recovered by filtration, and MIBK, alcohol, and water are removed under reduced pressure. The MIBK is reused. The final product 2 is obtained, with the following structural formula and carbon NMR spectrum. Figure 2 As shown.

[0046] Product 2 had a purity of 96.42% and a yield of 86.7% based on 2,4-diaminotoluene.

[0047] Example 3 The intermediate was prepared according to the method in step (a) of Example 1.

[0048] Step (II): 90g of the obtained intermediate, 108g of cyclohexanone, and 110g of MIBK were added to a high-pressure reactor, along with 10g of platinum-carbon catalyst. The platinum-carbon catalyst was washed with methanol and activated by soaking in cyclohexanone before being added to the high-pressure reactor. Hydrogen gas was introduced into the reactor at 100℃ to 3MPa to perform hydrogenation condensation of the intermediate. The hydrogen pressure was maintained at 2-4MPa; if the pressure was insufficient, hydrogen gas was continued to be introduced until the pressure inside the reactor no longer changed, at which point the reaction was stopped. The hydrogenation condensation reaction took approximately 10 hours. After the reaction, the temperature was lowered, the hydrogen gas was discharged, the catalyst was recovered by filtration, and the ketone, water generated during the hydrogenation condensation reaction, and alcohol generated by the side reaction were removed under reduced pressure. The ketone was reused. Finally, 140.70g of product was obtained. Product 3 was a mixture. After gas chromatography-mass spectrometry (GC-MS) analysis, the specific components and their contents in product 3 are as follows. The yield of product 3 was 87.4%.

[0049] Comparative Example 1 The migration-resistant antioxidant was synthesized according to the method in Example 2 of CN119661376A.

[0050] Performance verification 1. Rubber compound formulation and preparation Rubber compound formulation (parts by weight): SSBR 96.25 parts, BR 30 parts, silica 80 parts, carbon black N220 5 parts, ZnO-80 3 parts, SA (stearic acid) 1 part, S175 (thermoplastic polyurethane elastomer) 8 parts, protective wax 1.5 parts, antioxidant RD 1 part, accelerator DPG-80 2.5 parts, tread resin 30 parts, sulfur S-80 2 parts, accelerator CBS-80 2 parts, antioxidant of Example 1, Example 2, Example 3, or Comparative Example 1 2 parts. Meanwhile, the antioxidant prepared in the embodiments of the present invention was replaced with antioxidant 4020 as a comparison, and a blank control was used without the antioxidant of the present invention. These were respectively designated as 1# blank, 2# 4020, 3# Example 1, 4# Example 2, 5# Example 3, and 6# Comparative Example 1.

[0051] 2. Test methods for various performance parameters of the rubber compound Vulcanization characteristics: The P3555 B2 disc vulcanizer manufactured by Beijing Huanfeng Rubber & Plastics Machinery Manufacturing Plant was used for testing in accordance with GB / T9869-2014.

[0052] Mechanical properties: The tensile properties of the vulcanizate were determined using a CMT 4104 electronic tensile testing machine manufactured by Shenzhen Xin Sansi Materials Testing Co., Ltd., in accordance with GB / T 528-2009.

[0053] Dynamic ozone aging: According to GB / T 13642-2015, dynamic tensile test of ozone crack resistance for vulcanized rubber or thermoplastic rubber; static ozone aging: According to GB / T 7762-2014, static tensile test of ozone crack resistance for vulcanized rubber or thermoplastic rubber. Ozone volume concentration: 100 pphm; temperature: (40±2)℃; humidity: (50±5)%. During static testing, pre-stretch by 20% and observe the cracking of the samples periodically. During dynamic testing, pre-stretch by 10% and dynamic stretch by 10%, frequency: 0.5Hz, observe the cracking of the samples periodically.

[0054] Crack grade evaluation: according to GB / T 11206-2009 Rubber aging test surface cracking method.

[0055] 3. Experimental Results Table 1 As shown in Table 1, the scorch time of the rubber compound with added antioxidant is shorter, the vulcanization rate of the rubber compound with added antioxidant is significantly faster than that of the 4020 rubber compound, and the mechanical properties of the new antioxidant after aging are better than those of the control rubber compound, demonstrating excellent aging resistance. The ozone aging cracking level is superior to that of antioxidant 4020.

[0056] After aging, the above-mentioned vulcanized rubber compounds #1, #2, #3, #4, and #5 were extracted using acetone solvent, and the extracts were analyzed using ultra-high performance liquid chromatography-high resolution tandem mass spectrometry (UPLC-HRMS / MS). No quinone compounds were detected in compounds #1, #3, #4, and #5; however, quinone compounds were detected in the extract of compound #2 after aging. This indicates that the diphenylamine antioxidant provided by this invention does not produce highly toxic PPDQ (p-phenylenediamine-derived quinone) in rubber residues, making it an environmentally friendly rubber additive.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been shown above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A diphenylamine compound, characterized in that... It has the following structural formula (1): In formula (1), R1 and R2 each independently represent hydrogen or C1-C3 alkyl groups, and R1 and R2 are not both hydrogen; R3 and R4 each independently represent cycloalkyl, 1,3-dimethylbutyl, isopropyl, and 1,2-dimethylpropyl.

2. The diphenylamine compound according to claim 1, characterized in that: R1 and R2 each independently represent hydrogen, methyl, ethyl or propyl; preferably, R3 and R4 each independently represent cyclohexyl or 1,3-dimethylbutyl.

3. A method for preparing the diphenylamine compound according to claim 1, characterized in that: Includes the following steps: (1) Reacting the 2,4-diaminobenzene compound shown in formula (2) with the 3-haloaniline compound shown in formula (3) yields intermediate A; (2) Intermediate A is reacted with a ketone under the action of a catalyst and hydrogen to obtain the diphenylamine compound of claim 1.

4. The preparation method according to claim 3, characterized in that: In step (1), the 2,4-diaminobenzene compound is 2,4-diaminotoluene, and the 3-haloaniline compound is 3-bromo-2-methylaniline, m-bromoaniline, 3-chloro-2-methylaniline, or m-chloroaniline; Preferably, in step (1), the molar ratio of 2,4-diaminobenzene compounds to 3-haloaniline compounds is 1-1.1:

1.

5. The preparation method according to claim 3 or 4, characterized in that: In step (1), the reaction is carried out in the presence of an acid-binding agent, preferably sodium tert-butoxide or tetramethylammonium hydroxide; Preferably, in step (1), the molar ratio of the acid-binding agent to the 2,4-diaminobenzene compound is 2~4:

1.

6. The preparation method according to claim 3, characterized in that: In step (1), the reaction temperature is 100~120℃, and the reaction time is preferably 5~10h; Preferably, in step (1), the reaction is carried out in an organic solvent, which is preferably at least one of toluene and DMSO.

7. The preparation method according to claim 3, characterized in that: In step (2), the ketone is at least one of cyclohexanone, methyl isobutyl ketone, and methyl isopropyl ketone; Preferably, in step (2), the molar ratio of intermediate A to ketone is 1:5~10.

8. The preparation method according to claim 3 or 7, characterized in that: In step (2), the catalyst is at least one of copper-based catalyst, palladium on carbon catalyst, platinum on carbon catalyst, and Raney nickel catalyst; preferably, the amount of catalyst used is 1%-8% of the mass of intermediate A.

9. The preparation method according to claim 3, characterized in that: In step (2), the reaction temperature is 100-170℃ and the hydrogen pressure is 1-4MPa.

10. The application of the diphenylamine compound according to claim 1 or 2 or the diphenylamine compound prepared according to any one of claims 3-9 in the field of rubber, preferably as a rubber antioxidant.

Images