The invention relates to 4, 4apos; -(propane-2, 2-diyl) bis (2-((4-aminopyridine-2-yl) amino) phenol) and synthetic method and application thereof

Abstract

The invention discloses 4, 4 '-(propane-2, 2-diyl) bis (2-((4-aminopyridine-2-yl) amino) phenol) as well as a synthesis method and application of the 4, 4'-(propane-2, 2-diyl) bis (2-((4-aminopyridine-2-yl) amino) phenol). The preparation method comprises the following steps: by taking 4, 4 '-(propane-2, 2-diyl) bis (2-bromophenol) as a raw material, carrying out step-by-step substitution reaction to obtain an intermediate 4, 4'-(propane-2, 2-diyl) bis (2-((4-nitropyridine-2-yl) amino) phenol), and reducing the intermediate under the action of a catalyst and hydrazine hydrate to obtain the 4, 4 '-(propane-2, 2-diyl) bis (2-((4-aminopyridine-2-yl) amino) phenol). The method is high in production efficiency, short in production period, environment-friendly, simple and convenient to operate, high in product purity and high in yield, the solvent is convenient to recycle, the dispersity and the antistatic property of the insoluble sulfur can be improved, and the method is suitable for industrial mass production.

Description

Technical Field

[0001] This invention relates to a diamine compound, and more particularly to a 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol) and its synthesis method, belonging to the field of organic synthesis technology. Background Technology

[0002] Insoluble sulfur, also known as elastic sulfur or polymeric sulfur, is a highly polymerized allotrope and polymer-modified variety of ordinary sulfur. As an important vulcanizing agent in the rubber industry, insoluble sulfur possesses excellent vulcanizing properties, improving the bonding strength between rubber compounds and reinforcing materials. Therefore, it is widely used in tire components and rubber products, such as tire carcasses, buffer layers, sidewalls, hoses, and belts, where high bonding strength with reinforcing materials is required. It can also be used in rubber compounds for cables, rubber rollers, rubber shoes, oil seals, and other light-colored rubber products with high sulfur content. With the improvement of road traffic and the development of the automotive industry, the ever-increasing vehicle speeds place higher demands on tires. Radial tires will replace ordinary bias-ply tires, becoming an inevitable trend in the tire industry. As the preferred rubber vulcanizing agent for radial tires, the demand for insoluble sulfur is increasing year by year.

[0003] Insoluble sulfur is prone to particle agglomeration during production, affecting its uniform distribution in the rubber matrix. Furthermore, static charges generated by friction accumulate during production, transportation, and weighing, further contributing to the agglomeration and difficulty in dispersing of insoluble sulfur. The poor dispersibility and static electricity generation of insoluble sulfur severely restrict its application in rubber products. Therefore, it is essential to research additives that can address these issues. Summary of the Invention

[0004] The purpose of this invention is to provide a 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol) compound with a novel structure that can improve the dispersibility and antistatic properties of insoluble sulfur, thereby enhancing the application performance of insoluble sulfur in rubber products.

[0005] The 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol provided by this invention has the following chemical structural formula as shown in Formula 1: Formula 1 The above-mentioned method for synthesizing 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol includes the following steps: (1) Mix 4,4'-(propane-2,2-diyl)bis(2-bromophenol), a catalyst and a strongly polar aprotic organic solvent, and then add 4-nitropyridine-2-amine solution dropwise to the mixture to react and obtain 2-bromo-4-(2-(4-hydroxy-3-(4-nitropyridine-2-yl)amino)phenyl)prop-2-yl)phenol; (2) Continue to add 4-nitropyridine-2-amine solution dropwise to the reaction solution of step (1) to obtain 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridine-2-yl)amino)phenol); (3) 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol) was reduced in the presence of hydrazine hydrate and a catalyst to give 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol); .

[0006] Further, in step (1), the catalyst is a mixture of zirconium oxide and a copper-containing compound, wherein the copper-containing compound is copper oxide and / or copper proline. The zirconium oxide accounts for 55-70% of the total mass of the catalyst, for example, 55%, 60%, 65%, 70%, and the copper-containing compound accounts for 30-45% of the total mass of the catalyst, for example, 30%, 35%, 40%, 45%.

[0007] Preferably, the catalyst is a mixture of zirconium oxide, copper oxide and copper proline, wherein zirconium oxide accounts for 55-70% of the total mass of the catalyst, copper oxide accounts for 20-30% of the total mass of the catalyst, and copper proline accounts for 5-15% of the total mass of the catalyst.

[0008] Furthermore, in step (1), the amount of catalyst used is 5%-10% of the mass of 4,4'-(propane-2,2-diyl)bis(2-bromophenol), for example 5%, 6%, 7%, 8%, 9%, 10%.

[0009] Further, in step (1), the strongly polar aprotic organic solvent is at least one of NMP (N-methyl-2-pyrrolidone), DMF (N,N-dimethylformamide), sulfolane, DMI (1,3-dimethyl-2-imidazolinone), acetone, and DMAC (N,N-dimethylacetamide). The acidity / basicity and coordination selectivity of the solvent will affect the product synthesis, especially the inhibition of byproducts (solvent stability), which will directly affect the purity and yield of the product. Experimental verification shows that the strongly polar aprotic organic solvent is preferably a mixture of sulfolane and DMI. In the mixture of sulfolane and DMI, the mass ratio of sulfolane to DMI is 1-5:1, for example, 1:1, 2:1, 3:1, 4:1, 5:1.

[0010] Furthermore, in step (1), the mass ratio of 4,4'-(propane-2,2-diyl)bis(2-bromophenol) to a strongly polar aprotic organic solvent is 1:1.0-3.0, for example 1:1.0, 1:1.5, 1:2.0, 1:2.5, 1:3.0.

[0011] Furthermore, the molar ratio of 4,4'-(propane-2,2-diyl)bis(2-bromophenol) to 4-nitropyridine-2-amine in step (1) is 1:1.0-1.5, for example 1:1.0, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5.

[0012] Furthermore, the molar ratio of 4,4'-(propane-2,2-diyl)bis(2-bromophenol) to 4-nitropyridine-2-amine in step (2) is 1:1.4-1.8, for example 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8.

[0013] Further, in steps (1) and (2), the 4-nitropyridine-2-amine solution is a mixture of 4-nitropyridine-2-amine and an organic solvent, wherein the organic solvent is at least one selected from NMP (N-methyl-2-pyrrolidone), DMF (N,N-dimethylformamide), sulfolane, DMI (1,3-dimethyl-2-imidazolinone), acetone, and DMAC (N,N-dimethylacetamide), preferably a mixture of sulfolane and DMI. In the mixture of sulfolane and DMI, the mass ratio of sulfolane to DMI is 1-5:1, for example, 1:1, 2:1, 3:1, 4:1, or 5:1.

[0014] Furthermore, in the 4-nitropyridine-2-amine solutions of steps (1) and (2), the mass ratio of 4-nitropyridine-2-amine to organic solvent is 1:1.0-2.0, for example 1:1.0, 1:1.5, or 1:2.0.

[0015] Furthermore, in step (1), a 4-nitropyridine-2-amine solution is added dropwise at a low temperature of 20-30℃ for 0.5-1h. After the addition is complete, the reaction is continued at this temperature for 3-3.5h.

[0016] Furthermore, in step (2), a 4-nitropyridine-2-amine solution is added dropwise at 70-80℃ for 40-60 min, and then kept warm for 4-4.5 h after the addition is complete.

[0017] Further, in step (2), after the reaction is complete, the catalyst is filtered out, the reaction solution is cooled to room temperature, and added dropwise to a precipitate 2-3 times its mass, causing precipitation. The precipitate is then filtered, washed, and vacuum dried at 60-100℃ to obtain the intermediate 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol). The precipitate is a 50-70 wt% aqueous ethanol solution.

[0018] Furthermore, in step (3), the molar ratio of 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol) to hydrazine hydrate is 1:1.5-2.5, for example, 1:1.5, 1:2.0, or 1:2.5. Hydrazine hydrate is generally present in the form of an aqueous solution with a concentration of 80-85 wt%.

[0019] Furthermore, in step (3), the catalyst is a palladium on carbon catalyst, preferably, the amount of catalyst used is 1%-6% of the mass of 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol), for example 1%, 2%, 3%, 4%, 5%, 6%.

[0020] Furthermore, in step (3), the reaction is carried out in a strongly polar aprotic organic solvent, which is at least one of NMP (N-methyl-2-pyrrolidone), DMF (N,N-dimethylformamide), DMI (1,3-dimethyl-2-imidazolinone), acetone, and DMAC (N,N-dimethylacetamide), preferably DMF.

[0021] Furthermore, in step (3), the mass ratio of 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol) to a strongly polar aprotic organic solvent is 1:5.0-8.0, for example 1:5.0, 1:6.0, 1:7.0, 1:8.0.

[0022] Furthermore, in step (3), the reaction temperature is 40℃-90℃, for example 40℃, 50℃, 60℃, 70℃, 80℃, 90℃.

[0023] Further, in step (3), preferably, a mixture of 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol) and a strongly polar aprotic organic solvent is added dropwise to a mixture of hydrazine hydrate, a strongly polar aprotic organic solvent, and a catalyst. The reaction is stopped when the pressure remains constant after the reaction temperature is raised to the desired temperature. After the pressure remains constant, the temperature is lowered to room temperature, and excess hydrogen is directly discharged or quenched with acetic acid before being discharged. The catalyst is filtered out, and the remaining reaction liquid is added dropwise to a precipitate with a mass of 2-3 times its weight to precipitate. The precipitate is collected by filtration, washed with water, and dried under vacuum at 60-100°C to obtain the final product. The precipitate is a mixture of water, ethanol, and acetic acid, with a mass ratio of ethanol, acetic acid, and water of 28-32: 6-10: 60-65.

[0024] The present invention also provides the application of the above-mentioned 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol) in improving the properties of insoluble sulfur, which can improve the dispersibility and / or antistatic properties of insoluble sulfur.

[0025] The present invention has the following beneficial effects: 1. The 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol) of the present invention contains propane and amino groups, which can inhibit the aggregation of insoluble sulfur, reduce charge accumulation, and improve the dispersibility and antistatic properties of insoluble sulfur.

[0026] The reaction of 2,4'-(propane-2,2-diyl)bis(2-bromophenol) and 4-nitropyridine-2-amine is carried out in two steps. A highly soluble, polar, aprotic organic solvent is selected. The yield and purity of the intermediate are maximized by the synergistic combination of catalyst, organic solvent and reaction temperature, the occurrence of side reactions is suppressed and the reaction is well controlled.

[0027] 3. The catalytic system used achieves high-efficiency catalysis through the synergistic effect of multiple components; the solvent used is preferably a combined solvent, taking into account solubility, catalytic activity and reaction selectivity.

[0028] 4. Using hydrazine hydrate instead of hydrogen for the reduction of 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol) improves the safety of the reaction and avoids dangerous operations.

[0029] 5. This invention is simple to operate, environmentally friendly, the solvent is easy to recycle, the production cycle is short, the production efficiency is high, the product yield and purity are high, it is suitable for large-scale industrial production, and has a wide range of applications. Attached Figure Description

[0030] Figure 1 The NMR C-spectrum of the product in Example 1 is shown.

[0031] Figure 2 The NMR spectrum of the product in Example 1 is shown below. Detailed Implementation

[0032] The technical solution of the present invention will be described in detail below through specific embodiments. It should be understood that these embodiments are only for illustrating the present invention and are not intended to limit the scope of the present invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0033] Unless otherwise specified, all raw materials used in the following examples are commercially available products.

[0034] In the following examples and comparative examples, the formulas for calculating the yield of intermediates and products are: actual mass of intermediates or products / theoretical mass of intermediates or products.

[0035] In the following examples and comparative examples, the proline copper used was prepared according to the method described in CN118479994A.

[0036] Example 1 1. Add 52.03 g (0.374 mol) of 4-nitropyridine-2-amine to a beaker containing 54.11 g of sulfolane and 13.53 g of DMI, stir well to obtain a 4-nitropyridine-2-amine solution for later use (mono-substitution titration solution). 2. Add 80.41g (0.578mol) of 4-nitropyridine-2-amine to a beaker containing 52.27g of sulfolane and 52.27g of DMI, stir well to obtain a 4-nitropyridine-2-amine solution for later use (disubstituted titration solution). 3. Add 130g (0.34mol) of 4,4'-(propane-2,2-diyl)bis(2-bromophenol), 8.19g of zirconium oxide, 2.34g of copper oxide, and 1.17g of copper proline to a flask containing 162.5g of sulfolane and 162.5g of DMI. Stir until completely dissolved. After complete dissolution, keep warm at 25℃ to obtain a 4,4'-(propane-2,2-diyl)bis(2-bromophenol) solution. 4. The 4-nitropyridine-2-amine solution from step 1 was added dropwise to the flask from step 3 using a peristaltic pump through a latex tube for mono-substitution. The addition time was 0.5 h. After the addition was complete, the reaction was continued at 25 °C for 3 h. Then, the temperature was raised to 75 °C, and the 4-nitropyridine-2-amine solution from step 2 was added dropwise to the flask for di-substitution. The addition time was 40 min. After the addition was complete, the reaction was continued at this temperature for 4 h. After the di-substitution reaction was complete, the catalyst was filtered out, and the reaction solution was added dropwise to twice its mass of the precipitate (60 wt% ethanol aqueous solution). After the addition was complete, the mixture was stirred for 0.5 h, filtered, and the filter cake was washed with pure water until neutral. It was then vacuum dried at 85 °C and a vacuum degree of 0.095 MPa to obtain 167.09 g of the intermediate 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridine-2-yl)amino)phenol. The yield, calculated as (4,4'-(propane-2,2-diyl)bis(2-bromophenol)), was 97.8%, and the product purity (HPLC) was 98.85%.

[0037] 5. Add 167.09g of 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol) to a beaker containing 1086.09g of DMF, mix thoroughly until the solid is completely dissolved, and set aside. Dissolve 41.62g (80% by mass) of hydrazine hydrate in 54.11g of DMF. Weigh 4.18g of palladium on carbon catalyst, and use the hydrazine hydrate mixture to flush all the palladium on carbon into the reactor. Transfer the remaining hydrazine hydrate mixture into the reactor. Raise the temperature to 70℃, and then use a plunger pump to dropwise add the 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol) solution. Control the temperature at 70-75℃, and react until the pressure inside the reactor no longer changes within 1 hour. Then cool to room temperature. The reaction was quenched by adding 10g of acetic acid, and then the hydrogen gas in the reactor was vented. The reaction solution was then discharged, filtered, and the catalyst was recovered. The reaction solution was then added dropwise to 2.5 times its mass of the precipitate (ethanol:acetic acid:pure water mass ratio 30:8:62) using a peristaltic pump. After the precipitate was formed, the mixture was stirred for 1 hour, filtered, and the filter cake was washed with pure water and then dried under vacuum at 85℃ and 0.095 MPa to obtain 144.65g of 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol). The yield was 98.3% based on (4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol), and the purity (HPLC) was 99.64%.

[0038] Example 2 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol was prepared according to the method of Example 1, except that in step 2, "52.27 g sulfolane and 52.27 g DMI" were replaced with "83.6 g sulfolane and 20.94 g DMI"; and in step 3, "162.5 g sulfolane and 162.5 g DMI" were replaced with "260 g sulfolane and 65 g DMI". The results showed that the yield of the intermediate 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol obtained in step 4 was 97.3% based on (4,4'-(propane-2,2-diyl)bis(2-bromophenol)), and the purity (HPLC) was 98.77%.

[0039] Example 3 4,4'-(prop-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol) was prepared according to the method of Example 1, except that: in step 1, "54.11g sulfolane and 13.53g DMI" were replaced with "67.64g sulfolane"; in step 2, "52.27g sulfolane and 52.27g DMI" were replaced with "104.54g sulfolane"; and in step 3, "162.5g sulfolane and 162.5g DMI" were replaced with "325g sulfolane". The results showed that the yield of the intermediate 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol obtained in step 4 was 94.2% based on (4,4'-(propane-2,2-diyl)bis(2-bromophenol)), and the purity (HPLC) was 98.56%.

[0040] Example 4 4,4'-(prop-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol) was prepared according to the method of Example 1, except that: in step 1, "54.11g sulfolane and 13.53g DMI" was replaced with "67.64g DMI"; in step 2, "52.27g sulfolane and 52.27g DMI" was replaced with "104.54g DMI"; and in step 3, "162.5g sulfolane and 162.5g DMI" was replaced with "325g DMI". The results showed that the yield of the intermediate 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol obtained in step 4 was 94.0% based on (4,4'-(propane-2,2-diyl)bis(2-bromophenol)), and the purity (HPLC) was 98.50%.

[0041] Example 5 4,4'-(propyl-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol) was prepared according to the method of Example 1, except that: in step 1, "54.11g sulfolane and 13.53g DMI" were replaced with "67.64g acetone"; in step 2, "52.27g sulfolane and 52.27g DMI" were replaced with "104.54g acetone"; and in step 3, "162.5g sulfolane and 162.5g DMI" were replaced with "325g acetone". The results showed that the yield of the intermediate 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol obtained in step 4 was 92.8% based on (4,4'-(propane-2,2-diyl)bis(2-bromophenol)), and the purity (HPLC) was 98.25%.

[0042] Example 6 4,4'-(prop-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol was prepared according to the method of Example 1, except that: in step 1, "54.11g sulfolane and 13.53g DMI" was replaced with "54.11g sulfolane and 13.53g DMF"; in step 2, "52.27g sulfolane and 52.27g DMI" was replaced with "52.27g DMF and 52.27g sulfolane"; and in step 3, "162.5g sulfolane and 162.5g DMI" was replaced with "162.5g DMF and 162.5g sulfolane". The results showed that the yield of the intermediate 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol obtained in step 4 was 93.4% based on (4,4'-(propane-2,2-diyl)bis(2-bromophenol)), and the purity (HPLC) was 98.51%.

[0043] Example 7 4,4'-(prop-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol was prepared according to the method of Example 1, except that: in step 1, "54.11g sulfolane and 13.53g DMI" was replaced with "54.11g DMI and 13.53g DMAC"; in step 2, "52.27g sulfolane and 52.27g DMI" was replaced with "52.27g DMI and 52.27g DMAC"; and in step 3, "162.5g sulfolane and 162.5g DMI" was replaced with "162.5g DMI and 162.5g DMAC". The results showed that the yield of the intermediate 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol obtained in step 4 was 92.5% based on (4,4'-(propane-2,2-diyl)bis(2-bromophenol)), and the purity (HPLC) was 98.22%.

[0044] Example 8 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol was prepared according to the method of Example 1, except that in step 3, "8.19 g zirconium oxide, 2.34 g copper oxide, 1.17 g copper proline" was replaced with "8.19 g zirconium oxide, 3.51 g copper oxide". The results showed that the yield of the intermediate 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol obtained in step 4 was 92.1% based on (4,4'-(propane-2,2-diyl)bis(2-bromophenol)), and the purity (HPLC) was 98.15%.

[0045] Example 9 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol was prepared according to the method of Example 1, except that in step 3, "8.19 g zirconium oxide, 2.34 g copper oxide, 1.17 g copper proline" was replaced with "8.19 g zirconium oxide, 3.51 g copper proline". The results showed that the yield of the intermediate 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol obtained in step 4 was 91.0% based on (4,4'-(propane-2,2-diyl)bis(2-bromophenol)), and the purity (HPLC) was 98.11%.

[0046] Example 10 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol was prepared according to the method of Example 1, except that in step 3, "8.19 g zirconium oxide, 2.34 g copper oxide, 1.17 g copper proline" was replaced with "7.02 g zirconium oxide, 2.93 g copper oxide, 1.76 g copper proline". The results showed that the yield of the intermediate 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol obtained in step 4 was 96.3% based on (4,4'-(propane-2,2-diyl)bis(2-bromophenol)), and the purity (HPLC) was 98.63%.

[0047] Comparative Example 1 The intermediate 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol was prepared by the following steps: 1. Add 132.43 g (0.952 mol) of 4-nitropyridine-2-amine to a beaker containing 106.38 g of sulfolane and 65.8 g of DMI, stir well to obtain a 4-nitropyridine-2-amine solution for later use.

[0048] 2. Add 130g (0.34mol) of 4,4'-(propane-2,2-diyl)bis(2-bromophenol), 8.19g of zirconium oxide, 2.34g of copper oxide, and 1.17g of copper proline to a flask containing 162.5g of sulfolane and 162.5g of DMI. Stir until completely dissolved. After complete dissolution, keep warm at 25℃ to obtain a 4,4'-(propane-2,2-diyl)bis(2-bromophenol) solution. 3. The 4-nitropyridine-2-amine solution from step 1 was added dropwise to the flask from step 2 using a peristaltic pump through a latex tube over a period of 1 hour. After the addition was complete, the reaction was maintained at 25°C for 3 hours, then the temperature was increased to 75°C and the reaction was maintained for another 4 hours. After the reaction was complete, the catalyst was filtered out, and the reaction solution was added dropwise to twice its mass of the precipitate (60 wt% ethanol aqueous solution). After the addition was complete, the mixture was stirred for 0.5 hours, filtered, and the filter cake was washed with pure water until neutral. The cake was then dried under vacuum at 85°C and 0.095 MPa to obtain the intermediate 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridine-2-yl)amino)phenol). The yield (based on 4,4'-(propane-2,2-diyl)bis(2-bromophenol)) was 90.5%, and the product purity (HPLC) was 95.21%.

[0049] Comparative Example 2 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol was prepared according to the method of Example 1, except that in step 3, "8.19 g zirconium oxide, 2.34 g copper oxide, and 1.17 g copper proline" were replaced with "11.7 g zirconium oxide". The results showed that the yield of the intermediate 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol obtained in step 4 was 88.2% based on (4,4'-(propane-2,2-diyl)bis(2-bromophenol)), and the purity (HPLC) was 94.95%.

[0050] Comparative Example 3 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol was prepared according to the method of Example 1, except that in step 3, "8.19 g zirconium oxide, 2.34 g copper oxide, and 1.17 g copper proline" were replaced with "6.4 g copper oxide and 5.3 g copper proline". The results showed that the yield of the intermediate 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol obtained in step 4 was 83.5% based on (4,4'-(propane-2,2-diyl)bis(2-bromophenol)), and the purity (HPLC) was 94.08%.

[0051] Comparative Example 4 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol was prepared according to the method of Example 1, except that in step 4, the dropping temperature and holding temperature were both 35°C for the monosubstituted reaction, and 60°C for the disubstituted reaction. The results showed that the yield of the intermediate 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol obtained in step 4, calculated as (4,4'-(propane-2,2-diyl)bis(2-bromophenol)), was 91.4%, and the purity (HPLC) was 94.53%.

[0052] Comparative Example 5 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol was prepared according to the method of Example 1, except that in step 3, "8.19 g zirconium oxide, 2.34 g copper oxide, 1.17 g copper proline" were replaced with "9.36 g copper proline, 1.06 g zirconium oxide, 1.28 g manganese oxide". The results showed that the yield of the intermediate 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol obtained in step 4 was 84.5% based on (4,4'-(propane-2,2-diyl)bis(2-bromophenol)) and the purity (HPLC) was 94.07%.

[0053] Performance verification 1. Preparation of oil-extended insoluble sulfur: 1.1 Weigh the following raw materials: 800 kg of insoluble sulfur powder, 4 g of additive, and 196 kg of naphthenic oil. The additive is 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol).

[0054] 1.2 Mix the additives and the mixed solvent at a mass ratio of 3:7 and stir until completely dissolved to obtain an additive solution; the mixed solvent is NMP, DMF and THF in a volume ratio of 3:6:1. 1.3. Atomize 196 kg of naphthenic oil into the mixer using a high-pressure nozzle, control the spraying time to be 30 min, and continue stirring for 30 min after spraying. 1.4. The additive solution is atomized and sprayed into the mixer using a high-pressure nozzle. The spraying time is controlled to be 10 minutes. After spraying, continue stirring for 45 minutes. 1.5. Transfer the material from the mixer to a double-cone rotary vacuum dryer. Remove the mixed solvent by staged vacuum distillation. First, distill off THF at a vacuum of -0.093 MPa and a removal temperature of 50°C. Then, distill off DMF at a vacuum of -0.087 MPa and a removal temperature of 80°C. Finally, distill off NMP at a vacuum of -0.09 MPa and a removal temperature of 90°C. Then, cool to room temperature to obtain oil-extended insoluble sulfur.

[0055] 2. Dispersion test 2.1. Compound formulation: 100 phr of SCR5# plasticized rubber, 5 phr of oil-extended insoluble sulfur; 2.2. Mixing equipment: Kechuang 1L internal mixer, initial temperature 40℃, rotation speed 40r / min; 2.3. Mixing Process: Add rubber for 25-30 seconds, press for 50-60 seconds, lift for 7-10 seconds, add the prepared oil-extended insoluble sulfur, press for 25-30 seconds, lift for 7-10 seconds, press for 25-30 seconds, lift for 7-10 seconds, press for 25-30 seconds, lift for 7-10 seconds, press for 25-30 seconds, lift for 190-210 seconds, discharge the rubber at a discharge temperature of 100℃ ± 3℃; open mill roll gap 2.8mm, roll wrap for 25-30 seconds, make one cut on each side. Set aside for observation after sheeting. After complete cooling, randomly cut 150g of rubber compound, reduce the open mill gap to 1mm, and observe the number of sulfur beads on the surface of the sheet to test the dispersibility of the prepared oil-extended insoluble sulfur product. Simultaneously, use oil-extended insoluble sulfur without additives as a control.

[0056] The results are shown in Table 1 below: Table 1 3. Antistatic ability test Experimental Method: 50g of oil-extended insoluble sulfur sample was poured into a 100ml beaker, tilted 10cm directly above the beaker opening, using the same pouring method. Immediately after pouring, the electrostatic voltage of the sample in the beaker was measured using a portable electrostatic meter. Oil-extended insoluble sulfur without additives was used as a control. Results showed that the electrostatic voltage of oil-extended insoluble sulfur with additives was 17% lower than that of oil-extended insoluble sulfur without additives.

Claims

1. A 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol), characterized in that... It has the chemical structural formula shown in Formula 1 below: 。 2. A method for synthesizing 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol) as described in claim 1, characterized in that... Includes the following steps: (1) Mix 4,4'-(propane-2,2-diyl)bis(2-bromophenol), a catalyst and a strongly polar aprotic organic solvent, and then add 4-nitropyridine-2-amine solution dropwise to the mixture to react and obtain 2-bromo-4-(2-(4-hydroxy-3-(4-nitropyridine-2-yl)amino)phenyl)prop-2-yl)phenol; (2) Continue to add 4-nitropyridine-2-amine solution dropwise to the reaction solution of step (1) to obtain 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridine-2-yl)amino)phenol); (3) 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol) was reduced in the presence of hydrazine hydrate and a catalyst to give 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol).

3. The synthesis method according to claim 2, characterized in that: In step (1), the catalyst is a mixture of zirconium oxide and a copper-containing compound, wherein the copper-containing compound is copper oxide and / or copper proline, and the zirconium oxide accounts for 55-70% of the total mass of the catalyst, and the copper-containing compound accounts for 30-45% of the total mass of the catalyst; preferably, the catalyst is a mixture of zirconium oxide, copper oxide and copper proline, wherein the zirconium oxide accounts for 55-70% of the total mass of the catalyst, the copper oxide accounts for 20-30% of the total mass of the catalyst, and the copper proline accounts for 5-15% of the total mass of the catalyst; Preferably, the amount of catalyst used is 5%-10% of the mass of 4,4'-(propane-2,2-diyl)bis(2-bromophenol).

4. The synthesis method according to claim 2, characterized in that: In step (1), the strongly polar aprotic organic solvent is at least one of NMP, DMF, sulfolane, DMI, acetone, and DMAC, preferably a mixture of sulfolane and DMI; Preferably, the mass ratio of sulfolane to DMI is 1-5:1; Preferably, in step (1), the mass ratio of 4,4'-(propane-2,2-diyl)bis(2-bromophenol) to a strongly polar aprotic organic solvent is 1:1.0-3.

0.

5. The synthesis method according to claim 2, characterized in that: In steps (1) and (2), the 4-nitropyridine-2-amine solution is a mixture of 4-nitropyridine-2-amine and an organic solvent, wherein the organic solvent is at least one of NMP, DMF, sulfolane, DMI, acetone, and DMAC, preferably a mixture of sulfolane and DMI; Preferably, the mass ratio of sulfolane to DMI is 1-5:1; Preferably, in the 4-nitropyridine-2-amine solution, the mass ratio of 4-nitropyridine-2-amine to the organic solvent is 1:1.0-2.

0.

6. The synthesis method according to claim 2, characterized in that: In step (1), the molar ratio of 4,4'-(propane-2,2-diyl)bis(2-bromophenol) to 4-nitropyridine-2-amine is 1:1.0-1.5; in step (2), the molar ratio of 4,4'-(propane-2,2-diyl)bis(2-bromophenol) to 4-nitropyridine-2-amine is 1:1.4-1.

8.

7. The synthesis method according to claim 2, characterized in that: In step (1), 4-nitropyridine-2-amine solution is added dropwise at 20-30℃ for 0.5-1h, and the reaction is kept warm for 3-3.5h after the addition is complete; in step (2), 4-nitropyridine-2-amine solution is added dropwise at 70-80℃ for 40-60min, and the reaction is kept warm for 4-4.5h after the addition is complete.

8. The synthesis method according to claim 2, characterized in that: In step (3), the molar ratio of 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol) to hydrazine hydrate is 1:1.5-2.5; preferably, in step (3), the concentration of hydrazine hydrate is 80-85 wt%. Preferably, in step (3), the catalyst is a palladium-on-carbon catalyst; Preferably, the catalyst dosage is 1%-6% of the mass of 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol); Preferably, in step (3), the reaction temperature is 40℃-90℃.

9. The synthesis method according to claim 2, characterized in that: In step (3), the reaction is carried out in a strongly polar aprotic organic solvent, wherein the strongly polar aprotic organic solvent is NMP (N-methyl-2-pyrrolidone), DMF (N,N-dimethylformamide), DMI (1,3-dimethyl-2-imidazolinone), acetone, or DMAC (N,N-dimethylformamide). dimethylacetamide At least one of the following: 4,4'-(propane-2,2-diyl)bis(2-((4-nitropyridin-2-yl)amino)phenol) to a strongly polar aprotic organic solvent in a mass ratio of 1:5.0-8.

0.

10. The application of 4,4'-(propane-2,2-diyl)bis(2-((4-aminopyridin-2-yl)amino)phenol) as described in claim 1 in improving the properties of insoluble sulfur, characterized in that: Improves the dispersibility and / or antistatic properties of insoluble sulfur.

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