Purification method of 2, 2 '-di (substituted or unsubstituted alkoxy)-4, 4'-biphenyl diamine crude product, obtained purified product and application

Abstract

The invention discloses a purification method of a 2, 2 '-di (substituted or unsubstituted alkoxy)-4, 4'-biphenyl diamine crude product, an obtained purified product and application, and the purification method comprises the following steps: (1) mixing the 2, 2 '-di (substituted or unsubstituted alkoxy)-4, 4'-biphenyl diamine crude product with an ether solvent, washing with water, splitting phases, and taking an oil phase; (2) concentrating the oil phase to remove the ether solvent in the oil phase to obtain a concentrated phase; (3) carrying out reduced pressure distillation on the concentrated phase to obtain a fraction at 120-140 DEG C; and (4) crystallizing the fraction at 120-140 DEG C to obtain a purified product of 2, 2 '-di (substituted or unsubstituted alkoxy)-4, 4'-biphenyl diamine, The product obtained by the purification method has the advantages of high purity, low ion residual rate, high whiteness and the like, and provides favorable guarantee for preparation of high-performance polymer materials.

Description

Technical Field

[0001] The present invention belongs to the field of organic synthesis, and particularly relates to the purification of products. Specifically, it relates to a method for purifying crude 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine, the purified product obtained thereby, and applications thereof. Background Art

[0002] Polyimide (PI) is a high-performance polymer engineering material with excellent properties, which is polymerized from dianhydride and diamine. Among them, biphenyl diamine compounds are important monomers for preparing high-performance PI. For example, PI materials prepared from 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB) have achieved important application values in the field of flexible transparency (CN101337895A, CN105541637A, CN109535005A). And 2,2'-bis(alkoxy)-4,4'-biphenyldiamine is an important diamine monomer for PI. Especially for some high-end application scenarios, there are relatively high requirements for the purity, ionic impurity content, and product color of the monomer. Therefore, it is of great significance to develop the preparation and purification methods of such monomers.

[0003] Currently, the methods for preparing such 2,2'-bis(alkoxy)-4,4'-biphenyldiamine are as follows: Using 3-alkoxynitrobenzene as the raw material, reducing and coupling it with sodium borohydride to obtain a 3,3'-bis(alkoxy)diphenylhydrazine compound, and then carrying out a rearrangement reaction through Lewis acid catalysis in a strong acid medium to obtain the corresponding target product. This method has a relatively short route, and the raw materials are more readily available than the previous route, with high practical value. However, there are two problems in the current preparation method. One is that a large amount of sodium borohydride equivalent is used, and a large amount of hydrogen gas will be generated when quenching with a large amount of strong acid in the subsequent step, which is not conducive to large-scale preparation. The other is that Lewis acid is added in the subsequent rearrangement reaction, introducing transition metal ions will increase the ionic impurity content, increasing the difficulty of subsequent product purification. Summary of the Invention

[0004] In order to overcome the problems existing in the prior art, the present invention provides a method for purifying crude 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine, the purified product obtained thereby, and applications thereof. The product obtained through the purification method has the advantages of high purity, low ion residue rate, high whiteness, etc., providing a favorable guarantee for the preparation of high-performance polymer materials.

[0005] One of the objectives of the present invention is to provide a purification method for the crude product of 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine, including: (1) mixing the crude product of 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine with an ether solvent, washing with water, separating phases, and taking the oil phase; (2) concentrating the oil phase to remove the ether solvent therein to obtain a concentrated phase; (3) subjecting the concentrated phase to vacuum distillation and taking the fraction at 120-140°C; (4) crystallizing the fraction at 120-140°C to obtain the purified product of 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine.

[0006] In a preferred embodiment, the substituted or unsubstituted alkoxy in the 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine is selected from at least one of alkoxy groups with 1-8 carbon atoms and substituted alkoxy groups with 1-8 carbon atoms, preferably at least one of alkoxy groups with 1-8 carbon atoms and halogen-substituted alkoxy groups with 1-8 carbon atoms, such as at least one of methoxy, ethoxy, propoxy, and trifluoromethoxy.

[0007] In a preferred embodiment, the ether solvent in step (1) is selected from at least one of diethyl ether, methyl tert-butyl ether, methyl tetrahydrofuran, diisopropyl ether, ethyl butyl ether, dimethoxymethane, diethoxymethane, and 1,4-dioxane.

[0008] In a further preferred embodiment, in step (1), the weight ratio of the crude product of 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine to the ether solvent is 1:(1-10), preferably 1:(2-5), such as 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10.

[0009] In a preferred embodiment, the water washing in step (1) is carried out 2-8 times, preferably 3-6 times, such as 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, or 8 times.

[0010] In a preferred embodiment, in step (2), the concentration is carried out by rotary evaporation to remove the ether solvent therein.

[0011] In a further preferred embodiment, the temperature of the concentration is 30-100°C, preferably 50-70°C, such as 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C.

[0012] In a preferred embodiment, in step (3), the fraction at 125 - 135 °C is taken by vacuum distillation, for example, the fraction at 125 °C, 126 °C, 128 °C, 130 °C, 132 °C, 134 °C or 135 °C.

[0013] In a preferred embodiment, in step (4), the fraction at 120 - 140 °C is mixed with a mixed solvent and then subjected to crystallization. The mixed solvent includes solvent one and solvent two. Solvent one is selected from at least one of ether solvents and ester solvents, and solvent two is selected from at least one of hydrocarbon solvents.

[0014] In a further preferred embodiment, solvent one is selected from at least one of ethyl ether, methyl tert-butyl ether, ethyl acetate, tetrahydrofuran, diisopropyl ether, ethyl butyl ether, dimethoxymethane, diethoxymethane, 1,4-dioxane (preferably methyl tert-butyl ether), and / or solvent two is selected from at least one of n-pentane, n-hexane, petroleum ether, n-heptane, n-octane, cyclopentane, cyclohexane.

[0015] Among them, the inventors found through a large number of experiments that crystallization needs to be carried out in the above solvents, and the effects of other solvents are not good. For example, if toluene is used for crystallization, it is easy to form clusters.

[0016] In a preferred embodiment, the weight ratio of solvent one to solvent two is 1:(2 - 10), preferably 1:(3 - 5), for example, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0017] In a further preferred embodiment, the ratio of the total weight of solvent one and solvent two to the weight of the crude product is (2 - 12):1, preferably (2.5 - 5):1, for example, 2:1, 4:1, 6:1, 8:1, 10:1 or 12:1.

[0018] In a preferred embodiment, in step (4), the crystallization is rotary evaporation crystallization, that is, the crystallization is carried out during the rotary evaporation process.

[0019] In a further preferred embodiment, solvent one in the mixed solvent is slowly removed by rotary evaporation. The conditions for the rotary evaporation crystallization include: temperature is 0 - 30 °C, vacuum degree is 0.01 - 0.1 Kpa, and rotation speed is 20 - 50 rmp.

[0020] For example, the conditions for rotary evaporation and crystallization include: temperature being 0°C, 5°C, 10°C, 15°C, 20°C, 25°C or 30°C, vacuum degree being 0.01 Kpa, 0.02 Kpa, 0.04 Kpa, 0.06 Kpa, 0.08 Kpa or 0.1 Kpa, and rotation speed being 20, 25, 30, 35, 40, 45 or 50 rmp.

[0021] In a further preferred embodiment, the conditions for rotary evaporation include: temperature being 5 - 15°C, vacuum degree being 0.05 - 0.08 Kpa, and rotation speed being 20 - 30 rmp.

[0022] The second object of the present invention is to provide a 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine product obtained by using the purification method described in the first object of the present invention.

[0023] In a preferred embodiment, the purity of the 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine product is greater than 98%, and the whiteness of the substance is greater than 70.

[0024] Among them, the whiteness of the product has an important influence on the transparency of the subsequent polymer.

[0025] In a further preferred embodiment, the purity of the 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine product is greater than 99%.

[0026] In a preferred embodiment, the total content of cations in the 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine product is less than 150 ppm, preferably less than 100 ppm, and more preferably less than 50 ppm.

[0027] In a preferred embodiment, the total content of anions in the 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine product is less than 150 ppm, preferably less than 100 ppm, and more preferably less than 50 ppm.

[0028] In a preferred embodiment, the content of alkali metal ions in the 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine product is less than or equal to 20 ppm, the content of alkaline earth metal ions is less than or equal to 20 ppm, and the content of transition metal ions is less than or equal to 5 ppm.

[0029] Among them, the alkali metal ions are selected from sodium ions and / or potassium ions, the alkaline earth metal ions are selected from calcium ions and / or magnesium ions, and the transition metal ions are selected from at least one of copper ions, iron ions, manganese ions, nickel ions, cobalt ions, lead ions, and zinc ions.

[0030] In a preferred embodiment, the content of each anion in the 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine product is independently less than or equal to 30 ppm, wherein the anion is selected from at least one of chloride ion, sulfate ion, phosphate ion, and silicate ion.

[0031] Among them, the purity of the product and the content of ionic impurities have an important impact on the mechanical properties of the subsequent polymer.

[0032] The third object of the present invention is to provide the application of the purification method described in the first object of the present invention in the preparation of 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine.

[0033] The fourth object of the present invention is to provide a preparation method of 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine, comprising: (1) preparing a 3,3'-bis(substituted or unsubstituted alkoxy)diphenylhydrazine intermediate using 3-(substituted or unsubstituted alkoxy)nitrobenzene as a raw material; (2) subjecting the 3,3'-bis(substituted or unsubstituted alkoxy)diphenylhydrazine intermediate to transposition rearrangement to obtain a crude product of 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine; (3) purifying the crude product of 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine using the purification method described in the first object of the present invention to obtain a 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine product.

[0034] The substituted or unsubstituted alkoxy is selected from at least one of C1-C8 alkoxy and C1-C8 substituted alkoxy, preferably from at least one of C1-C8 alkoxy and C1-C8 halogen-substituted alkoxy, such as at least one of methoxy, ethoxy, propoxy, and trifluoromethoxy.

[0035] In a preferred embodiment, step (1) includes: using 3-(substituted or unsubstituted alkoxy)nitrobenzene as a raw material, and obtaining a 3,3'-bis(substituted or unsubstituted alkoxy)diphenylhydrazine intermediate through catalysis and reduction under alkaline conditions.

[0036] In a further preferred embodiment, step (1) includes: dissolving 3-(substituted or unsubstituted alkoxy)nitrobenzene and an alkaline substance in an organic solvent, then adding a catalyst and a reducing agent, and reacting to obtain a 3,3'-bis(substituted or unsubstituted alkoxy)diphenylhydrazine intermediate.

[0037] In a preferred embodiment, in step (1), the alkaline substance is selected from at least one of metal hydroxides and metal alcoholates.

[0038] In a further preferred embodiment, in step (1), the basic substance is selected from at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, sodium alkoxide, and potassium alkoxide.

[0039] Among them, the sodium alkoxide and potassium alkoxide are selected from at least one of sodium methoxide, sodium ethoxide, potassium ethoxide, sodium tert-butoxide, and potassium tert-butoxide.

[0040] In a preferred embodiment, in step (1), the organic solvent is selected from at least one of ether solvents and alcohol solvents, preferably at least one of alcohol solvents.

[0041] In a further preferred embodiment, in step (1), the organic solvent is selected from methyl tert-butyl ether, tetrahydrofuran, dioxane, ethylene glycol, diethylene glycol, dimethoxyethane, and C1-C8 alcohols. Preferably, the C1-C8 alcohols are selected from at least one of methanol, ethanol, and propanol.

[0042] In a preferred embodiment, in step (1), the catalyst is selected from commonly used catalysts in the art, preferably metal carbon catalysts, and more preferably at least one of palladium carbon catalyst, nickel carbon catalyst, and platinum carbon catalyst; and / or, the reducing agent is selected from commonly used reducing agents in the art, preferably from at least one of hydrogen, hydrazine hydrate, formic acid, ammonium formate, and sodium formate, and more preferably hydrazine hydrate.

[0043] Among them, the by-product of hydrazine hydrate as a reducing agent is nitrogen, and the reaction system is relatively pure. And under the action of the catalyst, hydrazine hydrate will also gradually decompose, avoiding a series of problems caused by using concentrated acid to quench the sodium borohydride reducing agent in the prior art.

[0044] In a preferred embodiment, in step (1), the weight ratio of 3-(substituted or unsubstituted alkoxy) nitrobenzene to the basic substance is 1:(0.01-3.0); and / or, the weight ratio of 3-(substituted or unsubstituted alkoxy) nitrobenzene to the catalyst is 1:(0.001-0.5); and / or, the mass ratio of 3-(substituted or unsubstituted alkoxy) nitrobenzene to the organic solvent is 1:(1-20); and / or, the molar ratio of 3-(substituted or unsubstituted alkoxy) nitrobenzene to the reducing agent is 1:(1.5-10.0).

[0045] In a further preferred embodiment, in step (1), the weight ratio of 3-(substituted or unsubstituted alkoxy) nitrobenzene to the basic substance is 1:(0.1 - 1.0); and / or, the weight ratio of 3-(substituted or unsubstituted alkoxy) nitrobenzene to the catalyst is 1:(0.001 - 0.1); and / or, the mass ratio of 3-(substituted or unsubstituted alkoxy) nitrobenzene to the organic solvent is 1:(2 - 10); and / or, the molar ratio of 3-(substituted or unsubstituted alkoxy) nitrobenzene to the reducing agent is 1:(2.5 - 5.0).

[0046] For example, in step (1), the weight ratio of 3-(substituted or unsubstituted alkoxy) nitrobenzene to the basic substance is 1:0.1, 1:0.2, 1:0.4, 1:0.6, 1:0.8 or 1:1.0; and / or, the weight ratio of 3-(substituted or unsubstituted alkoxy) nitrobenzene to the catalyst is 1:0.001, 1:0.005, 1:0.01, 1:0.02, 1:0.04, 1:0.06, 1:0.08 or 1:0.1; and / or, the mass ratio of 3-(substituted or unsubstituted alkoxy) nitrobenzene to the organic solvent is 1:2, 1:4, 1:6, 1:8 or 1:10; and / or, the molar ratio of 3-(substituted or unsubstituted alkoxy) nitrobenzene to the reducing agent is 1:2.5, 1:3.0, 1:3.5, 1:4.0, 1:4.5 or 1:5.0.

[0047] In a preferred embodiment, step (1) is carried out at 20 - 100 °C, such as 20 °C, 30 °C, 40 °C, 50 °C, 60 °C, 70 °C, 80 °C, 90 °C or 100 °C.

[0048] In a further preferred embodiment, after the reaction in step (1), the following post-treatment is carried out: the catalyst is removed by filtration, and the filtrate is concentrated and washed with water to obtain the 3,3'-bis(substituted or unsubstituted alkoxy)diphenylhydrazine intermediate.

[0049] In a preferred embodiment, step (2) includes: the 3,3'-bis(alkoxy)diphenylhydrazine intermediate undergoes a rearrangement in the presence of a polar aprotic solvent and an inorganic acid to obtain 2,2'-di(alkoxy)-4,4'-biphenyldiamine.

[0050] In a further preferred embodiment, the polar aprotic solvent is selected from at least one of dimethyl sulfoxide, sulfolane, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, preferably from at least one of dimethyl sulfoxide, N,N-dimethylformamide, N-methylpyrrolidone; and / or, the inorganic acid is selected from hydrochloric acid and / or sulfuric acid.

[0051] In a further preferred embodiment, the weight ratio of the 3,3'-bis(substituted or unsubstituted alkoxy)diphenylhydrazine intermediate to the polar aprotic solvent is 1:(0.5 - 4.0), preferably 1:(1.0 - 2.0); the mass ratio of the 3,3'-bis(substituted or unsubstituted alkoxy)diphenylhydrazine intermediate to the inorganic acid is 1:(3.0 - 8.0), preferably 1:(4.0 - 6.0).

[0052] For example, the weight ratio of the 3,3'-bis(substituted or unsubstituted alkoxy)diphenylhydrazine intermediate to the polar aprotic solvent is 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5 or 1:4.0; the weight ratio of the 3,3'-bis(substituted or unsubstituted alkoxy)diphenylhydrazine intermediate to the inorganic acid is 1:3.0, 1:4.0, 1:5.0, 1:6.0, 1:7.0 or 1:8.0.

[0053] In a preferred embodiment, step (2) is carried out below 0 °C, preferably at -20 °C to 0 °C, such as -20 °C, -15 °C, -10 °C, -5 °C, -2 °C or 0 °C.

[0054] In a further preferred embodiment, after the rearrangement in step (2), the following post-treatment is carried out: raising the temperature to room temperature, filtering and washing to obtain 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-diaminobiphenyl hydrochloride, adding ammonia water to adjust the pH of the hydrochloride to between 7 and 9, and obtaining the crude product of 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-diaminobiphenyl after extraction and concentration.

[0055] In a preferred embodiment, the preparation method includes: adding 3-(substituted or unsubstituted alkoxy)nitrobenzene, a basic substance and an organic solvent into a reactor equipped with a stirring and reflux device, stirring evenly, adding a catalyst and a reducing agent, reacting at 20 - 100 °C until the raw materials are completely converted, filtering to remove the catalyst, and concentrating and washing the filtrate to obtain the 3,3'-bis(substituted or unsubstituted alkoxy)diphenylhydrazine intermediate; dissolving the intermediate in a polar aprotic solvent, dropping it into a hydrochloric acid system at -20 - 0 °C and keeping stirring evenly, raising the temperature to room temperature after dropping, and filtering and washing to obtain 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-diaminobiphenyl hydrochloride. The hydrochloride is neutralized with ammonia water to a pH between 7 and 9, and the crude product of 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-diaminobiphenyl can be obtained after extraction and concentration. Finally, the crude product is purified by the purification method described in one of the objects of the present invention to obtain the 2,2'-di(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine product.

[0056] Preferably, the mass fraction of the hydrochloric acid used is 20-38%, such as 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36% or 38%.

[0057] The chemical reaction process of the method of the present invention is as follows:

[0058]

[0059] In the ranges disclosed in the present invention, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein. In the following, in principle, the various technical solutions can be combined with each other to obtain new technical solutions, which should also be regarded as specifically disclosed herein.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] (1) The purification method is simple, and the prepared product has high purity, low ion residue rate and high whiteness, which can meet the purity requirements of the electronic grade diamine monomer required for polyimide;

[0062] (2) In the present invention, 3,3'-bis(substituted or unsubstituted alkoxy)diphenylhydrazine is prepared under alkaline conditions, avoiding a series of problems caused by using concentrated acid to quench sodium borohydride;

[0063] (3) The transposition rearrangement of 3,3'-bis(substituted or unsubstituted alkoxy)diphenylhydrazine is catalyzed by an inorganic acid in a polar aprotic solvent, avoiding the introduction of transition metal ions and facilitating product purification. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 The nuclear magnetic resonance hydrogen spectrum of 2,2'-bis(trifluoromethoxy)-4,4'-biphenyldiamine prepared in Example 1 of the present invention is shown;

[0065] Figure 2 The liquid chromatogram of 2,2'-bis(trifluoromethoxy)-4,4'-biphenyldiamine prepared in Example 1 of the present invention is shown. DETAILED DESCRIPTION OF THE INVENTION

[0066] The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and cannot be understood as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art according to the content of the present invention still fall within the protection scope of the present invention.

[0067] In addition, it should be noted that the various specific technical features described in the following specific embodiments can be combined in any appropriate manner without conflict. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0068] In addition, any combination can be made among various different embodiments of the present invention as long as it does not violate the idea of the present invention. The technical solutions thus formed belong to a part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0069] If there is no special limitation on the raw materials used in the examples and comparative examples, they are all disclosed in the prior art. For example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0070]

Example 1

[0071] Preparation of 2,2’-bis(trifluoromethoxy)-4,4’-biphenyldiamine:

[0072] 2000 g of 3-trifluoromethoxynitrobenzene, 200 g of sodium hydroxide and 4000 g of propanol were added to a reactor equipped with a stirring and reflux device. After stirring evenly, 2 g of platinum-carbon catalyst (where the platinum content was 5 wt%) was added. Subsequently, 1511 g of 80% hydrazine hydrate was added. The reaction was carried out at 100 °C until the raw materials were completely converted. The catalyst was removed by filtration. The filtrate was concentrated and washed with water to obtain 1580 g of the intermediate 3,3'-bis(trifluoromethoxy)diphenylhydrazine, with a yield of 92.9%. 1580 g of this intermediate was dissolved in 1640 g of N-methylpyrrolidone. It was dropped into 4740 g of 38% hydrochloric acid at -20 °C while keeping stirring evenly. After the dropping was completed, the temperature was raised to room temperature. After filtration and washing, 2,2'-bis(trifluoromethoxy)-4,4'-biphenyldiamine hydrochloride could be obtained. The hydrochloride was neutralized with ammonia water to pH 7. After extraction and concentration, 1360 g of the crude product of 2,2'-bis(trifluoromethoxy)-4,4'-biphenyldiamine was obtained. The yield based on the 3,3'-bis(trifluoromethoxy)diphenylhydrazine intermediate was 86.1%, and the total reaction yield was 80.0%. The purity of the crude product was 94.3%, and the sodium ion content was 87 ppm.

[0073] Purification of 2,2’-bis(trifluoromethoxy)-4,4’-biphenyldiamine:

[0074] 1360 g of the crude product of 2,2'-bis(trifluoromethoxy)-4,4'-diaminobiphenyl (purity: 94.3%, sodium ion: 87 ppm) was dissolved in 2720 g of methyl tert-butyl ether. The oil phase was extracted and washed with deionized water, and washed with deionized water three times. The oil phase was concentrated at 50 °C and then subjected to vacuum distillation (collecting the fraction at 130 °C) to obtain a light yellow liquid. The light yellow liquid was mixed with 680 g of methyl tert-butyl ether and 2720 g of n-hexane for rotary evaporation and crystallization. The temperature was controlled at 5 °C, the vacuum degree was maintained at 0.08 Kpa, and the rotation speed was maintained at 20 rmp. Methyl tert-butyl ether was slowly removed by rotary evaporation. After crystallization, 1205 g of the pure solid of 2,2'-bis(trifluoromethoxy)-4,4'-biphenyldiamine was obtained as the final product, and the purification yield was 88.6%. The purity was about 99.9%, and the whiteness was 74.2. Among them, the sodium ion was 7.1 ppm, and potassium ions, calcium ions, magnesium ions and other transition metal ions were not detected, and anions such as chloride ions and sulfate ions were not detected.

[0075]

Example 2

[0076] Preparation of 2,2’-bis(methoxy)-4,4’-biphenyldiamine:

[0077] 1530 g of 3-methoxynitrobenzene, 153 g of sodium hydroxide and 3060 g of propanol were added to a reactor equipped with a stirring and reflux device. After stirring evenly, 1.53 g of platinum-carbon catalyst (platinum content: 5 wt%) was added, and then 1564 g of 80% hydrazine hydrate was added. The reaction was carried out at 100 °C until the raw materials were completely converted. The catalyst was removed by filtration, and the filtrate was concentrated and washed with water to obtain 1140 g of the intermediate 3,3'-bis(methoxy)diphenylhydrazine, and the yield was 93.31%. 1140 g of this intermediate was dissolved in 1140 g of N-methylpyrrolidone, and dropped into 5070 g of 36% hydrochloric acid at -15 °C while keeping stirring evenly. After the dropping was completed, the temperature was raised to room temperature. After filtration and washing, 2,2'-bis(methoxy)-4,4'-diaminobiphenyl hydrochloride was obtained. The hydrochloride was neutralized with ammonia water to pH 7, and after extraction and concentration, 1026 g of the crude product of 2,2'-bis(methoxy)-4,4'-diaminobiphenyl was obtained. The yield based on the 3,3'-bis(methoxy)diphenylhydrazine intermediate was 90.0%, and the total reaction yield was 84.0%. The purity of the crude product was 95.4%, and the sodium ion was 85 ppm.

[0078] Purification of 2,2’-bis(methoxy)-4,4’-biphenyldiamine:

[0079] 1026 g of crude 2,2'-bis(methoxy)-4,4'-biphenyldiamine (purity: 95.4%, sodium ion: 85 ppm) was dissolved in 2060 g of methyl tert-butyl ether. The oil phase was extracted and washed with deionized water, and washed 4 times with deionized water. The oil phase was concentrated at 55 °C and then subjected to vacuum distillation (taking the fraction at 130 °C) to obtain a light yellow liquid. The light yellow liquid was mixed with 520 g of methyl tert-butyl ether and 2060 g of n-hexane for rotary evaporation and crystallization. The temperature was controlled at 15 °C, the vacuum was maintained at 0.05 Kpa, and the rotation speed was maintained at 30 rmp. Methyl tert-butyl ether was slowly removed by rotary evaporation. After crystallization, 910 g of pure solid of 2,2'-bis(methoxy)-4,4'-biphenyldiamine was obtained, and the purification yield was 88.7%. The purity was about 99.9%, and the whiteness was 75.6. Among them, the sodium ion was 7.6 ppm, and potassium ions, calcium ions, magnesium ions and other transition metal ions were not detected, and anions such as chloride ions and sulfate ions were not detected.

[0080]

Example 3

[0081] Preparation of 2,2’-bis(methoxy)-4,4’-biphenyldiamine:

[0082] 1840 g of 3-methoxynitrobenzene, 1100 g of potassium hydroxide and 9200 g of propanol were added to a reactor equipped with a stirring and reflux device. After stirring evenly, 80 g of nickel-carbon catalyst (nickel content: 5 wt%) was added. Subsequently, 3380 g of 80% hydrazine hydrate (the calculated molar ratio was 1:4.5) was added. The reaction was carried out at 50 °C until the raw materials were completely converted. The catalyst was removed by filtration. The filtrate was concentrated and washed with water to obtain 1360 g of 3,3'-bis(methoxy)diphenylhydrazine intermediate, and the yield was 92.8%. 1360 g of this intermediate was dissolved in 2000 g of N-methylpyrrolidone, and dropped into 7300 g of 30% hydrochloric acid at -15 °C while keeping stirring evenly. After the dropping was completed, the temperature was raised to room temperature. After filtration and washing, 2,2'-bis(methoxy)-4,4'-biphenyldiamine hydrochloride was obtained. The hydrochloride was neutralized with ammonia water to pH 7, and after extraction and concentration, 1200 g of crude 2,2'-bis(methoxy)-4,4'-biphenyldiamine was obtained. The yield based on the 3,3'-bis(methoxy)diphenylhydrazine intermediate was 88.2%, and the total reaction yield was 81.8%. The purity of the crude product was 92.1%, and the sodium ion was 96 ppm.

[0083] Purification of 2,2’-bis(methoxy)-4,4’-biphenyldiamine:

[0084] 1200 g of crude 2,2'-bis(methoxy)-4,4'-biphenyldiamine (purity 92.1%, sodium ion 96 ppm) was dissolved in 3000 g of methyl tert-butyl ether. The oil phase was extracted and washed with deionized water, and washed 3 times with deionized water. The oil phase was concentrated at 60 °C and then subjected to vacuum distillation (taking the fraction at 130 °C) to obtain a light yellow liquid. The light yellow liquid was mixed with 1200 g of methyl tert-butyl ether and 2400 g of n-pentane for rotary evaporation and crystallization. The temperature was controlled at 5 °C, the vacuum was maintained at 0.06 Kpa, and the rotation speed was maintained at 20 rmp. Methyl tert-butyl ether was slowly removed by rotary evaporation. After crystallization, 1020 g of pure solid 2,2'-bis(methoxy)-4,4'-biphenyldiamine was obtained, and the purification yield was 85.0%. The purity was about 99.9%, and the whiteness was 72.1. Among them, the sodium ion was 9.2 ppm, and potassium ions, calcium ions, magnesium ions and other transition metal ions were not detected, and anions such as chloride ions and sulfate ions were not detected.

[0085]

Example 4

[0086] Preparation of 2,2’-bis(methoxy)-4,4’-biphenyldiamine:

[0087] 1240 g of 3-methoxynitrobenzene, 500 g of sodium hydroxide and 3720 g of methanol were added to a reactor equipped with a stirring and reflux device. After stirring evenly, 40 g of palladium-carbon catalyst (palladium content 5 wt%) was added, and then 1500 g of 80% hydrazine hydrate (the calculated molar ratio was 1:3.0) was added. The reaction was carried out at 70 °C until the raw materials were completely converted. The catalyst was removed by filtration, and the filtrate was concentrated and washed with water to obtain 920 g of 3,3'-bis(methoxy)diphenylhydrazine intermediate, and the yield was 94.2%. 920 g of this intermediate was dissolved in 1480 g of N,N-dimethylformamide, and dropped into 4300 g of 34% hydrochloric acid at -20 °C while maintaining stirring evenly. After the dropping was completed, the temperature was raised to room temperature. After filtration and washing, 2,2'-bis(methoxy)-4,4'-biphenyldiamine hydrochloride was obtained. The hydrochloride was neutralized with ammonia water to pH 8, and after extraction and concentration, 840 g of crude 2,2'-bis(methoxy)-4,4'-biphenyldiamine was obtained. The yield based on the 3,3'-bis(methoxy)diphenylhydrazine intermediate was 91.3%, and the total reaction yield was 86.0%. The purity of the crude product was 94.6%, and the sodium ion was 89 ppm.

[0088] Purification of 2,2’-bis(methoxy)-4,4’-biphenyldiamine:

[0089] 840 g of crude 2,2'-bis(methoxy)-4,4'-biphenyldiamine (purity: 94.6%, sodium ion: 89 ppm) was dissolved in 2100 g of methyl tert-butyl ether. The oil phase was extracted and washed with deionized water, and washed 3 times with deionized water. The oil phase was concentrated at 40 °C and then subjected to vacuum distillation (taking the fraction at 130 °C) to obtain a light yellow liquid. The light yellow liquid was mixed with 840 g of methyl tert-butyl ether and 4020 g of petroleum ether for rotary evaporation and crystallization. The temperature was controlled at 10 °C, the vacuum was maintained at 0.06 Kpa, and the rotation speed was maintained at 20 rmp. Methyl tert-butyl ether was slowly removed by rotary evaporation. After crystallization, 688 g of pure solid of 2,2'-bis(methoxy)-4,4'-biphenyldiamine was obtained, and the purification yield was 81.9%. The purity was about 99.9%, and the whiteness was 72.3. Among them, the sodium ion was 8.3 ppm, and potassium ions, calcium ions, magnesium ions and other transition metal ions were not detected, and anions such as chloride ions and sulfate ions were not detected.

[0090]

Example 5

[0091] Preparation of 2,2’-bis(ethoxy)-4,4’-biphenyldiamine:

[0092] 1336 g of 3-ethoxynitrobenzene, 800 g of potassium hydroxide and 6000 g of ethanol were added to a reactor equipped with a stirring and reflux device. After stirring evenly, 28 g of 5% palladium-carbon catalyst was added, and then 1760 g of 80% hydrazine hydrate (the calculated molar ratio was 1:3.5) was added. The reaction was carried out at 80 °C until the raw materials were completely converted. The catalyst was removed by filtration, and the filtrate was concentrated and washed with water to obtain 1040 g of the intermediate 3,3'-bis(ethoxy)diphenylhydrazine, and the yield was 95.5%. 1040 g of this intermediate was dissolved in 1880 g of N-methylpyrrolidone, and dropped into 4300 g of 34% hydrochloric acid at -5 °C while keeping stirring evenly. After the dropping was completed, the temperature was raised to room temperature, and 2,2'-bis(ethoxy)-4,4'-biphenyldiamine hydrochloride could be obtained after filtration and washing. The hydrochloride was neutralized with ammonia water to pH 7, and after extraction and concentration, 960 g of crude 2,2'-bis(ethoxy)-4,4'-biphenyldiamine was obtained. The yield based on the intermediate 3,3'-bis(ethoxy)diphenylhydrazine was 92.3%, and the total reaction yield was 88.1%. The purity of the crude product was 92.6%, and the sodium ion was 94 ppm.

[0093] Purification of 2,2’-bis(ethoxy)-4,4’-biphenyldiamine:

[0094] 960 g of crude 2,2'-bis(ethoxy)-4,4'-biphenyldiamine (purity 92.6%, sodium ions 94 ppm) was dissolved in 3000 g of methyl tert-butyl ether. The oil phase was extracted and washed with deionized water, and washed 5 times with deionized water. The oil phase was concentrated at 70 °C and then subjected to vacuum distillation (taking the fraction at 130 °C) to obtain a pale yellow liquid. The pale yellow liquid was mixed with 1440 g of methyl tert-butyl ether and 2880 g of n-hexane for rotary evaporation and crystallization. The temperature was controlled at 5 °C, the vacuum was maintained at 0.07 Kpa, and the rotation speed was maintained at 20 rmp. Methyl tert-butyl ether was slowly removed by rotary evaporation. After crystallization, 800 g of pure solid 2,2'-bis(ethoxy)-4,4'-biphenyldiamine was obtained, and the purification yield was 83.3%. The purity was about 99.9%, and the whiteness was 77.5. Among them, the sodium ions were 8.6 ppm, and potassium ions, calcium ions, magnesium ions and other transition metal ions were not detected, and anions such as chloride ions and sulfate ions were not detected.

[0095]

Example 6

[0096] Preparation of 2,2’-bis(ethoxy)-4,4’-biphenyldiamine:

[0097] 1670 g of 3-ethoxynitrobenzene, 500 g of sodium hydroxide and 6000 g of propanol were added to a reactor equipped with a stirring and reflux device. After stirring evenly, 30 g of platinum-carbon catalyst (platinum content 5 wt%) was added. Subsequently, 1900 g of 80% hydrazine hydrate was added. The reaction was carried out at 85 °C until the raw materials were completely converted. The catalyst was removed by filtration. The filtrate was concentrated and washed with water to obtain 1250 g of 3,3'-bis(ethoxy)diphenylhydrazine intermediate, and the yield was 91.8%. 1250 g of this intermediate was dissolved in 1900 g of N,N-dimethyl sulfoxide, and dropped into 5000 g of 38% hydrochloric acid at -10 °C while keeping stirring evenly. After the dropping was completed, the temperature was raised to room temperature. After filtration and washing, 2,2'-bis(ethoxy)-4,4'-biphenyldiamine hydrochloride was obtained. The hydrochloride was neutralized with ammonia water to pH 7, and after extraction and concentration, 1100 g of crude 2,2'-bis(ethoxy)-4,4'-biphenyldiamine was obtained. The yield based on the 3,3'-bis(ethoxy)diphenylhydrazine intermediate was 88.0%, and the total reaction yield was 80.8%. The purity of the crude product was 95.3%, and the sodium ions were 85 ppm.

[0098] Purification of 2,2’-bis(ethoxy)-4,4’-biphenyldiamine:

[0099] 1100 g of crude 2,2'-bis(ethoxy)-4,4'-biphenyldiamine (purity: 95.3%, sodium ion: 85 ppm) was dissolved in 4000 g of methyl tert-butyl ether. The oil phase was extracted and washed with deionized water, and washed 6 times with deionized water. The oil phase was concentrated at 50 °C and then subjected to vacuum distillation (taking the fraction at 130 °C) to obtain a light yellow liquid. The light yellow liquid was mixed with 2000 g of methyl tert-butyl ether and 9000 g of petroleum ether for rotary evaporation and crystallization. The temperature was controlled at 5 °C, the vacuum was maintained at 0.06 Kpa, and the rotation speed was maintained at 30 rmp. Methyl tert-butyl ether was slowly removed by rotary evaporation. After crystallization, 900 g of pure solid of 2,2'-bis(ethoxy)-4,4'-biphenyldiamine was obtained, and the purification yield was 81.8%. The purity was about 99.9%, and the whiteness was 72.1. Among them, the sodium ion was 13.1 ppm, and potassium ions, calcium ions, magnesium ions and other transition metal ions were not detected, and anions such as chloride ions and sulfate ions were not detected.

[0100]

Example 7

[0101] Preparation of 2,2’-bis(propoxy)-4,4’-biphenyldiamine:

[0102] 1448 g of 3-propoxynitrobenzene, 1160 g of sodium hydroxide and 12000 g of ethanol were added to a reactor equipped with a stirring and reflux device. After stirring evenly, 80 g of 5% platinum-carbon catalyst was added, and then 2000 g of 80% hydrazine hydrate (the calculated molar ratio was 1:4.0) was added. The reaction was carried out at 60 °C until the raw materials were completely converted. The catalyst was removed by filtration, and the filtrate was concentrated and washed with water to obtain 1104 g of 3,3'-bis(propoxy)diphenylhydrazine intermediate, and the yield was 91.9%. 1104 g of this intermediate was dissolved in 2208 g of N,N-dimethyl sulfoxide, and dropped into 4560 g of 32% hydrochloric acid at -5 °C while keeping stirring evenly. After the dropping was completed, the temperature was raised to room temperature. After filtration and washing, 2,2'-bis(propoxy)-4,4'-biphenyldiamine hydrochloride was obtained. The hydrochloride was neutralized with ammonia water to pH 8, and after extraction and concentration, 1000 g of crude 2,2'-bis(propoxy)-4,4'-biphenyldiamine was obtained. The yield based on 3,3'-bis(propoxy)diphenylhydrazine intermediate was 90.6%, and the total reaction yield was 83.3%. The purity of the crude product was 91.6%, and the sodium ion was 95 ppm.

[0103] Purification of 2,2’-bis(propoxy)-4,4’-biphenyldiamine:

[0104] 1000 g of crude 2,2'-bis(propoxy)-4,4'-biphenyldiamine (purity: 91.6%, sodium ion: 95 ppm) was dissolved in 4000 g of methyl tert-butyl ether. The oil phase was extracted and washed with deionized water, and washed 4 times with deionized water. The oil phase was concentrated at 60 °C and then obtained a light yellow liquid through vacuum distillation. The light yellow liquid was mixed with 720 g of methyl tert-butyl ether and 6720 g of n-hexane for rotary evaporation and crystallization. The temperature was controlled at 10 °C, the vacuum was maintained at 0.06 Kpa, and the rotation speed was maintained at 30 rmp. Methyl tert-butyl ether was slowly removed by rotary evaporation. After crystallization, 874 g of pure solid of 2,2'-bis(propoxy)-4,4'-biphenyldiamine was obtained, and the purification yield was 87.4%. The purity was about 99.9%, and the whiteness was 72.8. Among them, the sodium ion was 12.6 ppm, and potassium ions, calcium ions, magnesium ions and other transition metal ions were not detected, and anions such as chloride ions and sulfate ions were not detected.

[0105]

Example 8

[0106] Preparation of 2,2’-bis(butoxy)-4,4’-biphenyldiamine:

[0107] 1170 g of 3-butoxynitrobenzene, 1170 g of potassium hydroxide and 11700 g of propanol were added to a reactor equipped with a stirring and reflux device. After stirring evenly, 117 g of nickel-carbon catalyst (nickel content: 5 wt%) was added. Subsequently, 1878 g of 80% hydrazine hydrate (the calculated molar ratio was 1:5.0) was added. The reaction was carried out at 20 °C until the raw materials were completely converted. The catalyst was removed by filtration, and the filtrate was concentrated and washed with water to obtain 930 g of 3,3'-bis(butoxy)diphenylhydrazine intermediate, and the yield was 94.4%. 930 g of this intermediate was dissolved in 1860 g of N,N-dimethyl sulfoxide, and 5580 g of 20% hydrochloric acid was added dropwise at 0 °C while maintaining stirring evenly. After the addition was completed, the temperature was raised to room temperature. After filtration and washing, 2,2'-bis(butoxy)-4,4'-biphenyldiamine hydrochloride was obtained. The hydrochloride was neutralized with ammonia water to pH 9, and after extraction and concentration, 840 g of crude 2,2'-bis(butoxy)-4,4'-biphenyldiamine was obtained. The yield based on the 3,3'-bis(butoxy)diphenylhydrazine intermediate was 90.3%, and the total reaction yield was 85.2%. The purity of the crude product was 93.6%, and the sodium ion was 91 ppm.

[0108] Purification of 2,2’-bis(butoxy)-4,4’-biphenyldiamine:

[0109] 840 g of crude 2,2'-bis(butoxy)-4,4'-biphenyldiamine (purity: 93.6%, sodium ion: 91 ppm) was dissolved in 4200 g of methyl tert-butyl ether. The oil phase was extracted and washed with deionized water, and washed with deionized water three times. After concentration at 60 °C, the oil phase was subjected to vacuum distillation (taking the fraction at 130 °C) to obtain a pale yellow liquid. The pale yellow liquid was mixed with 1680 g of methyl tert-butyl ether and 8400 g of n-hexane for rotary evaporation and crystallization. The temperature was controlled at 15 °C, the vacuum was maintained at 0.06 Kpa, and the rotation speed was maintained at 40 rmp. Methyl tert-butyl ether was slowly removed by rotary evaporation for crystallization to obtain 732 g of pure solid of 2,2'-bis(butoxy)-4,4'-biphenyldiamine as the final product. The purification yield was 87.1%. The purity was about 99.9%, and the whiteness was 70.0. Among them, the sodium ion was 15.1 ppm, and potassium ions, calcium ions, magnesium ions and other transition metal ions were not detected, and anions such as chloride ions and sulfate ions were not detected.

[0110]

Comparative Example 1

[0111] The process of Example 1 was repeated, except for purification: placing it in a refrigerator and maintaining crystallization at 0 °C instead of "under the conditions of controlling the temperature at 5 °C, maintaining the vacuum at 0.08 Kpa, and maintaining the rotation speed at 20 rmp, slowly removing methyl tert-butyl ether by rotary evaporation", and other conditions remained unchanged.

[0112] 1027 g of pure solid of 2,2'-bis(trifluoromethoxy)-4,4'-biphenyldiamine as the final product was obtained. The purification yield was 75.4%. The purity was about 98.2%, and the whiteness was 67.5. Among them, the sodium ion was 9.4 ppm.

[0113]

Comparative Example 2

[0114] The process of Example 1 was repeated, except for purification: using 680 g of methyl tert-butyl ether to replace "680 g of methyl tert-butyl ether and 2720 g of n-hexane", and other conditions remained unchanged.

[0115] Crystallization could not occur at room temperature, and it remained in an oily state, and the purity could not be improved.

[0116]

Comparative Example 3

[0117] The process of Example 1 was repeated, except for purification: using 620 g of tetrahydrofuran to replace "680 g of methyl tert-butyl ether and 2720 g of n-hexane", and other conditions remained unchanged.

[0118] The pure product of 2,2'-bis(trifluoromethoxy)-4,4'-biphenyldiamine as the final product was in an oily state, with a purity of about 97.9% and a whiteness of 68.6. Among them, the sodium ion was 7.4 ppm.

[0119]

Comparative Example 4

[0120] Repeat the process of Example 1, with the difference in purification: use 650 g of ethyl acetate to replace "680 g of methyl tert-butyl ether and 2720 g of n-hexane", and keep other conditions unchanged.

[0121] Crystallization cannot occur at room temperature, and it still remains in the state of an oil, and the purity cannot be improved.

[0122] The present invention has been described in detail above in conjunction with specific embodiments and exemplary examples, but these descriptions should not be construed as limiting the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications or improvements can be made to the technical solutions and their implementation manners of the present invention, and these all fall within the scope of the present invention. The protection scope of the present invention is subject to the appended claims.

Claims

1. A purification method for crude 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine, comprising: (1) Mix the crude product of 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine with an ether solvent, wash with water, separate the phases, and take the oil phase; (2) Concentrate the oil phase to remove the ether solvent therein to obtain a concentrated phase; (3) Subject the concentrated phase to vacuum distillation and collect the fraction at 120-140 °C; (4) Crystallize the fraction at 120-140 °C to obtain a purified product of 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine.

2. The purification method according to claim 1, wherein the substituted or unsubstituted alkoxy in the 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine is selected from at least one of C1-C8 alkoxy and C1-C8 substituted alkoxy, preferably selected from at least one of C1-C8 alkoxy and C1-C8 halogen-substituted alkoxy; and / or, the ether solvent is selected from at least one of diethyl ether, methyl tert-butyl ether, methyl tetrahydrofuran, diisopropyl ether, ethyl butyl ether, dimethoxymethane, diethoxymethane, 1,4-dioxane; preferably, the weight ratio of the crude product of 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine to the ether solvent is 1:(1-10), preferably 1:(2-5).

3. The purification method according to claim 1, wherein the water washing in step (1) is carried out 2-8 times, preferably 3-6 times; and / or, in step (2), the concentration is carried out by rotary evaporation to remove the ether solvent therein; and / or, in step (3), the fraction at 125-135 °C is collected by vacuum distillation.

4. The purification method according to claim 1, wherein In step (4), the fraction at 120-140 °C is mixed with a mixed solvent and then crystallized. The mixed solvent includes solvent one and solvent two. Solvent one is selected from at least one of ether solvents and ester solvents, and solvent two is selected from at least one of hydrocarbon solvents; preferably, solvent one is selected from at least one of diethyl ether, methyl tert-butyl ether, ethyl acetate, tetrahydrofuran, diisopropyl ether, ethyl butyl ether, dimethoxymethane, diethoxymethane, 1,4-dioxane, and / or, solvent two is selected from at least one of n-pentane, n-hexane, petroleum ether, n-heptane, n-octane, cyclopentane, cyclohexane; preferably, the weight ratio of solvent one to solvent two is 1:(2-10), preferably 1:(3-5); preferably, the total weight of solvent one and solvent two to the weight of the crude product is (2-12):1, preferably (2.5-5):

1.

5. The purification method according to any one of claims 1 to 4, characterized in that, In step (4), the crystallization is rotary evaporation crystallization; preferably, the conditions of the rotary evaporation crystallization include: temperature 0-30 °C, vacuum degree 0.01-0.1 Kpa, rotation speed 20-50 rmp.

6. A 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine product obtained by using the purification method according to any one of claims 1-5; Preferably, the purity of the 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine product is greater than 98%, and the whiteness of the substance is greater than 70; Preferably, the total content of cations in the 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine product is less than 150 ppm, preferably less than 100 ppm, and more preferably less than 50 ppm; Preferably, the total content of anions in the 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine product is less than 150 ppm, preferably less than 100 ppm, and more preferably less than 50 ppm; Preferably, the content of alkali metal ions in the 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine product is less than or equal to 20 ppm, the content of alkaline earth metal ions is less than or equal to 20 ppm, and the content of transition metal ions is less than or equal to 5 ppm.

7. Use of the purification method according to any one of claims 1 to 5 in the preparation of 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine.

8. A method for preparing 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine, comprising: (1) Using 3-(substituted or unsubstituted alkoxy)nitrobenzene as a raw material to prepare a 3,3'-bis(substituted or unsubstituted alkoxy)diphenylhydrazine intermediate; (2) subjecting the 3,3'-bis(substituted or unsubstituted alkoxy)diphenylhydrazine intermediate to a rearrangement to obtain a crude product of 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine; (3) purifying the crude product of 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine using the purification method according to any one of claims 1 to 5 to obtain a 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-biphenyldiamine product.

9. The preparation method according to claim 8, characterized in that, Step (1) includes: using 3-(substituted or unsubstituted alkoxy)nitrobenzene as a raw material, and obtaining a 3,3'-bis(substituted or unsubstituted alkoxy)diphenylhydrazine intermediate through catalysis and reduction under alkaline conditions; Preferably, dissolving 3-(substituted or unsubstituted alkoxy)nitrobenzene and an alkaline substance in an organic solvent, then adding a catalyst and a reducing agent, and obtaining a 3,3'-bis(substituted or unsubstituted alkoxy)diphenylhydrazine intermediate through reaction; More preferably, the alkaline substance is selected from at least one of metal hydroxides and metal alcoholates, preferably at least one of sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, sodium alkoxide, and potassium alkoxide; and / or, the organic solvent is selected from at least one of ether solvents and alcohol solvents; and / or, the catalyst is selected from metal carbon catalysts, more preferably at least one of palladium carbon catalyst, nickel carbon catalyst, and platinum carbon catalyst; and / or, the reducing agent is selected from at least one of hydrogen, hydrazine hydrate, formic acid, ammonium formate, and sodium formate.

10. The preparation method according to claim 9, characterized in that, In step (1): The weight ratio of 3-(substituted or unsubstituted alkoxy) nitrobenzene to the basic substance is 1:(0.01 - 3.0), and / or, the weight ratio of 3-(substituted or unsubstituted alkoxy) nitrobenzene to the catalyst is 1:(0.001 - 0.5), and / or, the mass ratio of 3-(substituted or unsubstituted alkoxy) nitrobenzene to the organic solvent is 1:(1 - 20), and / or, the molar ratio of 3-(substituted or unsubstituted alkoxy) nitrobenzene to the reducing agent is 1:(1.5 - 10.0); and / or, Step (1) is carried out at 20 - 100 °C; and / or, After the reaction described in step (1), the following post-treatment is carried out: filtering to remove the catalyst, and concentrating and washing the filtrate to obtain a 3,3'-bis(substituted or unsubstituted alkoxy) diphenylhydrazine intermediate.

11. The preparation method according to any one of claims 8 to 10, characterized in that Step (2) includes: the 3,3'-bis(alkoxy) diphenylhydrazine intermediate undergoes a transposition rearrangement in the presence of a polar aprotic solvent and an inorganic acid to obtain 2,2'-di(alkoxy)-4,4'-biphenyldiamine; Preferably, the polar aprotic solvent is selected from at least one of dimethyl sulfoxide, sulfolane, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; Preferably, the inorganic acid is selected from hydrochloric acid and / or sulfuric acid; More preferably, the weight ratio of the 3,3'-bis(substituted or unsubstituted alkoxy) diphenylhydrazine intermediate to the polar aprotic solvent is 1:(0.5 - 4.0), preferably 1:(1.0 - 2.0); and / or, the mass ratio of the 3,3'-bis(substituted or unsubstituted alkoxy) diphenylhydrazine intermediate to the inorganic acid is 1:(3.0 - 8.0), preferably 1:(4.0 - 6.0).

12. The preparation method according to claim 11, wherein Step (2) is carried out below 0 °C, preferably at -20 °C to 0 °C; and / or, After the transposition rearrangement in step (2), the following post-treatment is carried out: raising the temperature to room temperature, filtering and washing to obtain 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-diaminobiphenyl hydrochloride, adding ammonia water to adjust the pH of the hydrochloride to between 7 and 9, and concentrating by extraction to obtain a crude product of 2,2'-bis(substituted or unsubstituted alkoxy)-4,4'-diaminobiphenyl.

Images