A preparation method of an antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine
By using hexamethyldisilazane as a catalyst and dehydrating agent, combined with a hydrogenation reaction, the problems of low conversion rate and purity in the synthesis of antioxidant SPPD were solved, and high-purity antioxidant SPPD was prepared efficiently.
Patent Information
- Application Number
- CN202311488504.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-09
- Publication Date
- 2026-01-02
- Estimated Expiration
- 2043-11-09
AI Technical Summary
Existing methods for synthesizing the antioxidant SPPD suffer from low conversion rates, low purity, and numerous byproducts. In particular, the limited solubility in toluene solvent leads to decreased reaction conversion rates and product precipitation. Furthermore, the poor water separation effect affects the quality of the final product.
Using hexamethyldisilazane as a catalyst and dehydrating agent, the intermediate N-phenyl-N'-(1-methyl-2phenyl)ethylenediamine was prepared by heating and reflux reaction. Then, a catalytic hydrogenation reduction reaction was carried out under hydrogenation conditions. Nickel-based, palladium-based, or platinum-based metal catalysts were used for the hydrogenation reaction to avoid the addition of additional solid catalysts and to ensure that the reaction system was in an anhydrous state.
The conversion rate and purity of the antioxidant N-phenyl-N'-(1-methyl-2-phenyl)ethyl-p-phenylenediamine were improved to over 99.6%, reducing costs and improving product quality.
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Abstract
Description
TECHNICAL FIELD
[0001] The application relates to a preparation method of an antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine, and belongs to the technical field of organic synthesis. BACKGROUND
[0002] At present, the main anti-ozone antioxidant used in rubber tire products is p-phenylenediamine antioxidant. The p-phenylenediamine antioxidant mainly includes three types, one is a diaryl antioxidant, such as antioxidant 3100; one is an arylalkyl antioxidant, such as antioxidant 4020, antioxidant 4010NA and the like; and the other is a dialkyl p-phenylenediamine, such as antioxidant 4030 and the like.
[0003] The antioxidant 3100 as the diaryl antioxidant has high solubility in rubber products, can slow down the migration rate of the antioxidant in the rubber products, and provides long-acting protection effect. However, due to the benzene ring conjugation effect, the electron cloud density of the amino group in the antioxidant is reduced, and the ozone capturing capacity of the amino group is reduced, so that the ozone protection effect is poor.
[0004] The antioxidant SPPD has a chemical name of N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine, and a specific structural formula as shown in the following formula. The antioxidant SPPD as a substitute product of the antioxidant 3100 can not only slow down the migration rate in the vulcanized rubber product, but also improve the electron cloud density of the secondary amine group due to the electron-donating effect of the side methyl group, and has more excellent protection effect than the antioxidant 3100.
[0005]
[0006] The antioxidant SPPD is mostly selected to use a solid acid as a catalyst. For example, the patent document WO2005051886A1 discloses that activated bentonite of sulfuric acid is selected, benzaldehyde and 4-amino diphenylamine are used as raw materials, toluene reflux is used for water separation, N-phenyl-N'-(1-methyl-2-phenyl) ethylene diamine is synthesized, and then catalytic hydrogenation is used to produce and synthesize the antioxidant SPPD.
[0007] However, the synthesis method of the antioxidant SPPD provided in the patent has three obvious defects:
[0008] Firstly, the solubility of N-phenyl-N'-(1-methyl-2-phenyl) ethylene diamine in the toluene solvent is limited, and the product is easily precipitated when the catalyst is separated, thereby causing the reaction conversion rate to be reduced.
[0009] Secondly, due to the steric hindrance effect of the phenyl group, the reaction conversion rate of benzaldehyde and 4-amino diphenylamine is only about 80%, thereby causing the conversion rate of the final product antioxidant SPPD to be low.
[0010] Third, the water separation effect of toluene is limited, resulting in partial hydrolysis of N-phenyl-N'-(1-methyl-2-phenyl) ethylene diamine during the crystallization process, and the produced acetophenone is reacted to produce phenethyl alcohol in the hydrogenation process, resulting in increased by-products and decreased product purity.
[0011] Therefore, there is an urgent need to provide a preparation method of antioxidant SPPD with high conversion rate and high purity. SUMMARY
[0012] In view of the deficiencies of the prior art, the present application provides a preparation method of antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine.
[0013] The technical scheme of the present application is as follows:
[0014] A preparation method of antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine, comprising the following steps:
[0015] (1) uniformly mix hexamethyldisilazane, acetophenone and N-phenyl p-phenylenediamine, heat to 115-125℃ under a nitrogen protective atmosphere, and keep the temperature for 3-4h of reflux reaction, then cool the reaction material to 5-15℃, and after filtration, washing and drying, obtain the intermediate product N-phenyl-N'-(1-methyl-2-phenyl) ethylene diamine;
[0016] (2) add an organic solvent and a hydrogenation catalyst to the N-phenyl-N'-(1-methyl-2-phenyl) ethylene diamine, replace with nitrogen, heat to 80-90℃, and perform hydrogenation reduction reaction under the conditions of hydrogen being introduced and the pressure being 2-2.5MPa, and the reaction is determined to be completed when hydrogen is no longer consumed, and after filtration and distillation, obtain the antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine.
[0017] According to the present application, preferably in step (1), the molar ratio of hexamethyldisilazane, acetophenone and N-phenyl p-phenylenediamine is (3-4):(1-1.2):1.
[0018] According to the present application, preferably in step (1), the washing is 2-4 times of washing with xylene.
[0019] According to the present application, preferably in step (2), the organic solvent is any one or more of 1,4-dioxane, toluene or xylene.
[0020] Further preferably, the organic solvent is xylene.
[0021] According to the application, preferably, in step (2), the molar ratio of the organic solvent to N-phenyl-N'-(1-methyl-2-phenyl) ethylene diamine is (5-6):1.
[0022] According to the application, preferably, in step (2), the hydrogenation catalyst is any one or more of nickel-based, palladium-based and platinum-based metal catalysts.
[0023] Further preferably, the hydrogenation catalyst is Pd / C.
[0024] According to the application, preferably, in step (2), the amount of the hydrogenation catalyst is 1-2% of the mass of N-phenyl-N'-(1-methyl-2-phenyl) ethylene diamine.
[0025] The reaction route for preparing the antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine (SPPD) according to the application is as follows:
[0026]
[0027] The details of the application can be implemented by using the prior art.
[0028] The application has the following advantages:
[0029] 1. The application uses acetophenone and N-phenyl p-phenylenediamine as raw materials, and hexamethyldisilazane as a catalyst and water removal agent for preparing the intermediate product N-phenyl-N'-(1-methyl-2-phenyl) ethylene diamine, and then the antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine (SPPD) is prepared by catalytic hydrogenation. The hexamethyldisilazane used in the application has weak alkalinity, can catalyze the condensation reaction of acetophenone and N-phenyl p-phenylenediamine, and hexamethyldisilazane reacts with water to continuously consume the water generated in the condensation reaction of acetophenone and N-phenyl p-phenylenediamine, so as to move the reaction equilibrium in a beneficial direction, effectively shorten the reaction time, improve the conversion rate of acetophenone and 4-aminodiphenylamine, improve the conversion rate of the intermediate product N-phenyl-N'-(1-methyl-2-phenyl) ethylene diamine, and further improve the conversion rate of the antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine, so that the conversion rate of the antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine reaches more than 99.6%.
[0030] 2、The hexamethyldisilazane used as a catalyst for the reaction in the application does not need to add other solid catalysts, effectively improves the purity of the antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine, so that the purity of the antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine reaches more than 99.6%. And hexamethyldisilazane can not only play a catalytic role, but also can remove the water generated in the system as a dehydrating agent, ensure that the reaction system is in a water-free state at all times, and make the reaction equilibrium move in a beneficial direction. At the same time, hexamethyldisilazane is easy to recover, and its hydrolysis product can be recycled or sold as a byproduct, further reducing the cost. BRIEF DESCRIPTION OF DRAWINGS
[0031] Figure 1 Liquid chromatogram of the intermediate product N-phenyl-N'-(1-methyl-2-phenyl) ethylenediamine prepared for Example 1.
[0032] Figure 2 Liquid chromatogram of the antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine prepared for Example 1.
[0033] Figure 3 Liquid chromatogram of the intermediate product N-phenyl-N'-(1-methyl-2-phenyl) ethylenediamine prepared for Comparative Example 1.
[0034] Figure 4 Liquid chromatogram of the antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine prepared for Comparative Example 1. DETAILED DESCRIPTION
[0035] The application will be further described in detail below in conjunction with specific examples, but should not be understood as limiting the application. The experimental methods not specified in the examples and the reagents not specified in the formula are all according to the conventional conditions in the art.
[0036] Example 1
[0037] A preparation method of an antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine, comprising the following steps:
[0038] (1) In a 500ml three-necked flask equipped with a condenser and a mechanical stirrer, 245g of hexamethyldisilazane, 60.07g of phenylacetone and 76.77g of N-phenyl-p-phenylenediamine were added and stirred to mix well. After heating to 115°C under nitrogen atmosphere to form a stable reflux, the reaction was kept at reflux for 3.5h. Then the reaction was cooled to 10°C and filtered. The precipitate was washed with xylene for 3 times and filtered again. After drying, 118.45g of intermediate product N-phenyl-N'-(1-methyl-2-phenyl) ethylenediamine was obtained. The purity was 99.8% and the conversion rate was 99.3% by liquid chromatography. The specific liquid chromatogram is shown in Figure 1 ;
[0039] The filtrate obtained by twice filtration can recover phenylacetone and hexamethyldisilazane by fractional distillation, and the catalyst hexamethyldisiloxane can be recycled to save cost.
[0040] (2) 118.45g of N-phenyl-N'-(1-methyl-2-phenyl) ethylenediamine was added into a 500ml high-pressure reactor, then 220g of xylene and 1.2g of Pd / C were added. After replacing the air in the high-pressure reactor with nitrogen to make it in a nitrogen protective atmosphere, it was heated to 80°C. Hydrogen was introduced under the condition of 2.5MPa pressure to carry out hydrogenation reduction reaction. When hydrogen was no longer consumed, the reaction was determined to be completed. After the reaction, Pd / C was recovered by filtration, and xylene was removed by distillation to obtain 119.04g of antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl-p-phenylenediamine.
[0041] The purity of the antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl-p-phenylenediamine prepared in this example was 99.6% and the conversion rate was 99.8% by liquid chromatography. The specific liquid chromatogram is shown in Figure 2 .
[0042] Example 2
[0043] A preparation method of an antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl-p-phenylenediamine, comprising the following steps:
[0044] (1) In a 500ml three-necked flask equipped with a condenser and a mechanical stirrer, 245g hexamethyldisilazane, 60.07g acetophenone and 76.77g N-phenyl-p-phenylenediamine were added and stirred to mix. After heated to 125℃ under nitrogen atmosphere to form stable reflux, the reaction was kept for 3h. Then the reaction mixture was cooled to 10℃ and filtered. The precipitate was washed with xylene for 3 times and filtered again. After drying, 118.73g of intermediate product N-phenyl-N'-(1-methyl-2-phenyl)ethylidene diamine was obtained. The purity was 99.8% and the conversion rate was 99.5% by liquid chromatography.
[0045] The filtrate obtained by twice filtration can be recycled by fractional distillation to recover acetophenone and hexamethyldisilazane, and the catalyst hexamethyldisiloxane can be recycled to save cost.
[0046] (2) 118.73g of N-phenyl-N'-(1-methyl-2-phenyl)ethylidene diamine was added into a 500ml high-pressure reactor, then 220g of xylene and 2.4g of Pd / C were added. After the air in the high-pressure reactor was replaced by nitrogen to form a nitrogen protective atmosphere, it was heated to 90℃. Hydrogen was introduced under the condition of 2MPa pressure to carry out hydrogenation reduction reaction. When hydrogen was no longer consumed, the reaction was determined to be completed. After the reaction was completed, Pd / C was recovered by filtration, and xylene was removed by distillation to obtain 119.08g of antioxidant N-phenyl-N'-(1-methyl-2-phenyl)ethyl-p-phenylenediamine.
[0047] The purity of the antioxidant N-phenyl-N'-(1-methyl-2-phenyl)ethyl-p-phenylenediamine prepared in this example was 99.8% and the conversion rate was 99.6% by liquid chromatography.
[0048] Example 3
[0049] A preparation method of an antioxidant N-phenyl-N'-(1-methyl-2-phenyl)ethyl-p-phenylenediamine, comprising the following steps:
[0050] (1) In a 500ml three-necked flask equipped with a condenser and a mechanical stirrer, 245g hexamethyldisilazane, 60.07g acetophenone and 76.77g N-phenyl-p-phenylenediamine were added and stirred to mix. After heated to 125℃ under nitrogen atmosphere to form stable reflux, the reaction was kept for 3h. Then the reaction mixture was cooled to 10℃ and filtered. The precipitate was washed with xylene for 3 times and filtered again. After drying, 118.73g of intermediate product N-phenyl-N'-(1-methyl-2-phenyl)ethylidene diamine was obtained. The purity was 99.8% and the conversion rate was 99.5% by liquid chromatography.
[0051] The filtrate obtained by twice filtration can recover acetophenone and hexamethyldisilazane through fractional distillation, and the catalyst hexamethyldisiloxane can be recycled, thereby saving cost.
[0052] (2) 129.39 g of N-phenyl-N'-(1-methyl-2-phenyl) ethylene diamine was added into a 500 ml high-pressure reactor, then 240 g of dimethylbenzene and 2.6 g of Pd / C were continuously added, nitrogen was introduced to replace the air in the high-pressure reactor to make it in a nitrogen protective atmosphere, heated to 90°C, hydrogen was introduced under the condition of 2.5 MPa pressure, and hydrogenation reduction reaction was carried out, the reaction was judged to be completed when hydrogen was no longer consumed, after the reaction, Pd / C was recovered by filtration, and then dimethylbenzene was removed by distillation, 129.89 g of antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine was obtained.
[0053] The purity of the antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine prepared in this embodiment was 99.6% and the conversion rate was 99.7% by liquid chromatography.
[0054] Example 4
[0055] A preparation method of an antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine, comprising the following steps:
[0056] (1) 300 g of hexamethyldisilazane, 60.07 g of acetophenone and 83.75 g of N-phenyl p-phenylenediamine were added into a 500 ml three-necked flask equipped with a condensation reflux device and a mechanical stirring device, and stirred and mixed uniformly, heated to 125°C under nitrogen atmosphere to form stable reflux, and kept refluxing for 3.5 h, then the reaction material was cooled to 10°C and filtered, the precipitate was washed with dimethylbenzene for 3 times and then filtered again, and after drying, 129.65 g of intermediate product N-phenyl-N'-(1-methyl-2-phenyl) ethylene diamine was obtained, the purity of which was 99.5% and the conversion rate was 99.6% by liquid chromatography;
[0057] The filtrate obtained by twice filtration can recover acetophenone and hexamethyldisilazane through fractional distillation, and the catalyst hexamethyldisiloxane can be recycled, thereby saving cost.
[0058] (2) Put 114.21 g of N-phenyl-N'-(1-methyl-2-phenyl) ethylene diamine into a 500 ml high-pressure reactor, then continue to add 240 g of xylene and 2.4 g of Pd / C, replace the air in the high-pressure reactor with nitrogen to make it in a nitrogen protective atmosphere, heat to 85°C, and carry out hydrogenation reduction under the condition of hydrogen being introduced and the pressure being 2.5 MPa. When hydrogen is no longer consumed, it is determined that the reaction is completed. After the reaction is completed, filter and recover Pd / C, and then remove xylene by distillation to obtain 114.80 g of antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine.
[0059] The purity of the antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine prepared in this embodiment is 99.7% and the conversion rate is 99.8% as detected by liquid chromatography.
[0060] Comparative Example 1
[0061] A preparation method of an antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine, comprising the following steps:
[0062] (1) Put 300 g of toluene, 60.07 g of phenylacetone, and 83.75 g of N-phenyl p-phenylenediamine into a 500 ml three-necked flask equipped with a condensation reflux device and a mechanical stirring device, stir and mix uniformly, heat to 125°C under a nitrogen atmosphere to form a stable reflux, and keep refluxing for 8 h. Then, separate 5.37 g of water phase, cool the reaction material to 10°C, filter, wash the precipitate with xylene for 3 times, filter again, and dry to obtain 114.21 g of intermediate product N-phenyl-N'-(1-methyl-2-phenyl) ethylene diamine. The purity is 67.3% and the conversion rate is 65.6% as detected by liquid chromatography. The specific liquid chromatogram is shown in Figure 3 .
[0063] (2) Put 114.21 g of N-phenyl-N'-(1-methyl-2-phenyl) ethylene diamine into a 500 ml high-pressure reactor, then continue to add 240 g of xylene and 2.4 g of Pd / C, replace the air in the high-pressure reactor with nitrogen to make it in a nitrogen protective atmosphere, heat to 85°C, and carry out hydrogenation reduction under the condition of hydrogen being introduced and the pressure being 2.5 MPa. When hydrogen is no longer consumed, it is determined that the reaction is completed. After the reaction is completed, filter and recover Pd / C, and then remove xylene by distillation to obtain 114.80 g of antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl p-phenylenediamine.
[0064] The purity of the antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl-p-phenylenediamine prepared in the present comparative example was 74.9% and the conversion rate was 99.8% as detected by liquid chromatography, and the specific liquid chromatogram is shown in Figure 4
[0065] Comparative Example 2
[0066] A preparation method of an antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl-p-phenylenediamine, comprising the following steps:
[0067] (1) 300 g of toluene, 60.07 g of phenylacetone, 83.75 g of N-phenyl-p-phenylenediamine and 1.6 g of p-methylbenzenesulfonic acid were added into a 500 ml three-necked flask equipped with a condensing reflux device and a mechanical stirring device, and stirred and mixed uniformly. After being heated to 125°C under a nitrogen atmosphere to form a stable reflux, the reflux reaction was kept for 8 h, and 6.98 g of water phase was separated. After the material was filtered while hot to remove the p-methylbenzenesulfonic acid, the filtrate was cooled to 10°C to crystallize, and then filtered again. After the precipitate was washed with xylene for three times and filtered again, it was dried to obtain 123.35 g of intermediate product N-phenyl-N'-(1-methyl-2-phenyl) ethylenediamine. The purity was 90.02% and the conversion rate was 85.3% as detected by liquid chromatography;
[0068] (2) 123.35 g of N-phenyl-N'-(1-methyl-2-phenyl) ethylenediamine was added into a 500 ml high-pressure reaction kettle, and then 240 g of xylene and 2.4 g of Pd / C were continuously added. After the air in the high-pressure reaction kettle was replaced by nitrogen to make it in a nitrogen protective atmosphere, it was heated to 85°C. The hydrogen reduction reaction was carried out under the condition of hydrogen being introduced and the pressure being 2.5 MPa. When the hydrogen was no longer consumed, it was determined that the reaction was completed. After the reaction was completed, the Pd / C was recovered by filtration, and then the xylene was removed by distillation to obtain 123.68 g of antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl-p-phenylenediamine.
[0069] The purity of the antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl-p-phenylenediamine prepared in the present comparative example was 74.9% and the conversion rate was 99.8% as detected by liquid chromatography, and the specific liquid chromatogram is shown in
[0070] Comparative Example 3
[0071] A preparation method of an antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl-p-phenylenediamine, comprising the following steps:
[0072] (1) In a 500ml three-necked flask equipped with a condenser and a mechanical stirrer, 300g of toluene, 60.07g of phenylacetone, 83.75g of N-phenyl-p-phenylenediamine and 3g of p-acid bentonite were added and stirred until uniform. After heating to 115°C under nitrogen atmosphere to form a stable reflux, the reaction was kept at reflux for 8h. After separating 6.98g of water phase, the mixture was filtered while hot to remove p-toluenesulfonic acid. The filtrate was cooled to 10°C to crystallize, filtered again, washed with xylene for 3 times, and dried to obtain 126.64g of intermediate product N-phenyl-N'-(1-methyl-2-phenyl) ethylenediamine. The purity was 95.0% and the conversion rate was 92.4% by liquid chromatography.
[0073] (2) 126.64g of N-phenyl-N'-(1-methyl-2-phenyl) ethylenediamine was added into a 500ml high-pressure reactor, then 240g of xylene and 2.4g of Pd / C were added. After replacing the air in the high-pressure reactor with nitrogen to form a nitrogen protective atmosphere, the mixture was heated to 85°C. Hydrogen was introduced under the condition of 2.5MPa to perform hydrogenation reduction reaction. The reaction was determined to be completed when hydrogen was no longer consumed. After filtering to recover Pd / C, xylene was removed by distillation to obtain 127.48g of antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl-p-phenylenediamine.
[0074] The purity of the antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl-p-phenylenediamine prepared in the comparative example was 94.9% and the conversion rate was 99.8% by liquid chromatography.
[0075] As can be seen from the data comparison of examples 1-4 and comparative examples 1-3, the hexamethyldisilazane used in the present application is weakly basic and can catalyze the condensation reaction of phenylacetone and N-phenyl-p-phenylenediamine. At the same time, hexamethyldisilazane reacts with water, which continuously consumes the water generated in the condensation reaction of phenylacetone and N-phenyl-p-phenylenediamine, so as to move the reaction equilibrium in a beneficial direction, effectively shorten the reaction time, improve the conversion rate of phenylacetone and 4-amino diphenylamine, improve the conversion rate of intermediate product N-phenyl-N'-(1-methyl-2-phenyl) ethylenediamine, and further improve the conversion rate of antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl-p-phenylenediamine, so that the conversion rate of antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl-p-phenylenediamine reaches more than 99.6%. Moreover, the hexamethyldisilazane used in the present application is used as a catalyst for the reaction, without the need to add other solid catalysts, which effectively improves the purity of antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl-p-phenylenediamine, so that the purity of antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethyl-p-phenylenediamine reaches more than 99.6%.
Claims
1. A process for the preparation of an antioxidant N-phenyl-N'-(l-methyl-2- phenyl) ethyl-p-phenylenediamine, characterized in that, The steps comprise: (1) uniformly mixing hexamethyldisilazane, phenylethanone and N-phenyl-p-phenylenediamine, heating to 115-125 DEG C under nitrogen atmosphere, keeping refluxing for 3-4 hours, then cooling the reaction material to 5-15 DEG C, filtering, washing and drying to obtain intermediate product N-phenyl-N'-(1-methyl-2-phenyl) ethylenediamine; The molar ratio of hexamethyldisilazane, phenylethanone and N-phenyl-p-phenylenediamine is (3-4):(1-1.2):1; (2) adding organic solvent and hydrogenation catalyst to N-phenyl-N'-(1-methyl-2-phenyl) ethylenediamine, replacing with nitrogen, heating to 80-90 DEG C, hydrogenation reduction under the conditions of hydrogen input and pressure of 2-2.5 MPa, determining the reaction end when hydrogen is not consumed, filtering and distilling to obtain antioxidant N-phenyl-N'-(1-methyl-2-phenyl) ethylenediamine; The organic solvent is any one or more of 1,4-dioxane, toluene or xylene; the hydrogenation catalyst is any one or more of nickel-based, palladium-based and platinum-based metal catalysts; the amount of hydrogenation catalyst is 1-2% of the mass of N-phenyl-N'-(1-methyl-2-phenyl) ethylenediamine.
2. The production method according to claim 1, wherein In step (1), the washing is 2-4 times with xylene.
3. The production method according to claim 1, wherein The organic solvent is xylene.
4. The production method according to claim 1, wherein In step (2), the molar ratio of organic solvent and N-phenyl-N'-(1-methyl-2-phenyl) ethylenediamine is (5-6):
1.
5. The production method according to claim 1, wherein The hydrogenation catalyst is Pd / C.
Citation Information
Patent Citations
Ketimine composition and epoxy resin composition
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Method of preparation of n-(1-phenylethyl)-n'-phenyl-1,4-phenylenediamine and use thereof
WO2005051886A1