Preparation method of 3, 4 '-diaminodiphenyl ether

Abstract

The invention relates to a preparation method of 3, 4 '-diaminodiphenyl ether (3, 4'-ODA). A first aspect of the present application relates to a method for preparing 3-amino-4 '-nitrodiphenyl ether, comprising: (1) synthesizing 3-amino-4'-nitrodiphenyl ether from p-nitrochlorobenzene, m-aminophenol in a first solvent in the presence of a condensing agent wherein the first solvent is selected from sulfones, sulfoxides, amides, phosphamides, and step (1) is carried out under reduced pressure, and step (2) is carried out under reduced pressure; and removing the generated water during the proceeding of the step (1). The invention relates to a method for preparing 3, 4 '-ODA in the second aspect, and the method comprises the steps of (a) preparing 3-amino-4'-nitrodiphenyl ether through the method in the first aspect, and (b) reducing the 3-amino-4 '-nitrodiphenyl ether obtained in the step (a) in the presence of a reducing agent to obtain the 3, 4'-ODA. The invention further relates to the 3, 4 '-ODA obtained through the method in the second aspect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of organic chemical synthesis, in particular, the present application relates to a method for preparing 3,4'-diaminodiphenyl ether. BACKGROUND

[0002] 3,4'-diaminodiphenyl ether (3,4'-ODA for short) is an important intermediate, which can be used to prepare soluble polyimide. If a third monomer 3,4'-ODA is added in the para-aramid polymerization process, the obtained copolyaramid has better high tensile strength, and has high impact resistance, fatigue resistance, chemical corrosion resistance and wet heat aging resistance, etc. performance, so as to meet the market demand of global industry, automobile, oil and gas field transmission belt, hose and many other fields.

[0003] With the continuous expansion of the downstream application field of 3,4'-ODA, the demand for 3,4'-ODA continues to rise, and its development and research have also attracted high attention from the industry.

[0004] The structure of 3,4'-ODA is as follows:

[0005]

[0006] At present, the main synthesis method of 3,4'-ODA is to use m-dinitrobenzene, m-nitrophenol or m-aminophenol and p-chloronitrobenzene or p-aminophenol as raw materials, and to obtain it by ether condensation and reduction.

[0007] Japanese Teijin Company discloses patent application JPH07118211A, which uses m-dinitrobenzene, p-nitrochlorobenzene or p-aminophenol as raw materials, uses aprotic polar solvent as diluent, and uses carbonate or hydroxide as condensing agent. In this application, 3,4'-dinitrodiphenyl ether or 3-amino-4'-nitrodiphenyl ether is first synthesized, and then reduced by catalytic hydrogenation to obtain 3,4'-ODA. As one of the raw materials of this route, m-dinitrobenzene has the characteristics of high reactivity, many side reactions and easy explosion. In addition, the application uses 1,3-dimethyl-2-imidazolinone DMI as a solvent, which has a high price, resulting in high production cost.

[0008] Patent application CN1583713A reports a method as follows: in toluene solution, m-nitrophenol or m-aminophenol is reacted with sodium hydroxide to prepare sodium phenolate; then DMF is added, and toluene is removed by distillation; then condensation reaction is carried out at 140-150℃ to synthesize 3,4'-dinitrodiphenyl ether or 3-amino-4'-nitrodiphenyl ether; then reduction by catalytic hydrogenation or iron powder to obtain 3,4'-ODA. This route is complex in process, and has many separation steps. In addition, sodium phenolate needs to be prepared first in this route, and then ether condensation reaction is carried out. M-nitrophenol belongs to an explosive chemical, which has high risk coefficient, unstable source, and high price. Using iron powder as a reducing agent will produce a large amount of "three wastes", making the reaction post-treatment difficult, so that this process is difficult to apply to industrial production.

[0009] Patent application CN119528747A discloses a method as follows: m-dinitrobenzene is used as raw material to synthesize m-nitroaniline by selective hydrogenation; then m-nitroaniline is reacted with sodium hydroxide to obtain m-nitrophenolate; then ether condensation reaction of m-nitrophenolate with p-nitroiodobenzene is carried out, and then 3,4'-ODA is obtained by catalytic hydrogenation. In this method, the process of synthesizing m-nitroaniline by selective hydrogenation is difficult, the whole reaction steps are long, and the operation is complex; and the process uses expensive p-nitroiodobenzene, resulting in high cost.

[0010] Patent CN111072503 discloses a method as follows: m-aminophenol and p-nitrochlorobenzene are used as raw materials, and DMF is used as solvent for ether condensation reaction; then the salt is removed by filtration, and the filtrate is directly subjected to catalytic hydrogenation to prepare 3,4'-ODA. In this method, the intermediate is not separated, but is directly subjected to catalytic hydrogenation in the presence of impurities from the condensation reaction, which easily leads to catalyst poisoning and cannot be recycled, and the product has high impurity content.

[0011] In summary, the synthesis technology of 3,4'-ODA still has technical bottlenecks such as complex process, high cost, high safety risk, and large amount of "three wastes". Therefore, it is urgent to develop a high-efficiency and low-cost, green and safe preparation method. SUMMARY

[0012] The present application provides a preparation method of 3-amino-4'-nitrodiphenyl ether and then 3,4'-ODA, to overcome the deficiencies in the prior art.

[0013] Surprisingly, the applicants have found that 3-amino-4'-nitro-diphenyl ether can be obtained in high yield by removing the water generated during the condensation process in the preparation of 3-amino-4'-nitro-diphenyl ether by vacuum. In addition, the solvents used in the preparation, purification, and washing of 3-amino-4'-nitro-diphenyl ether can be reused without purification, and still achieve high yield of 3-amino-4'-nitro-diphenyl ether and high conversion of raw materials. In addition, the applicants have also found that 3-amino-4'-nitro-diphenyl ether does not need to be further purified before the subsequent step of reducing to prepare 3,4'-ODA, and surprisingly has no adverse effect on the activity of the catalyst, and the catalyst can be reused without treatment. Therefore, the method provided by the present application has less "three wastes" throughout the whole process, and is suitable for industrial application.

[0014] In the first aspect of the present application, a method for preparing 3-amino-4'-nitro-diphenyl ether is provided, which comprises the following steps:

[0015] (1) synthesizing 3-amino-4'-nitro-diphenyl ether from p-nitrochlorobenzene and m-aminophenol in a first solvent in the presence of a condensing agent,

[0016] wherein the first solvent is selected from sulfones, sulfoxides, amides, and phosphoramides, and step (1) is carried out under reduced pressure, and during the performance of step (1), the generated water is removed.

[0017] In the second aspect of the present application, a method for preparing 3,4'-diamino-diphenyl ether 3,4'-ODA is provided, which comprises:

[0018] (a) preparing 3-amino-4'-nitro-diphenyl ether by the method of the first aspect of the present application;

[0019] (b) reducing the 3-amino-4'-nitro-diphenyl ether obtained in step (a) in the presence of a reducing agent to obtain 3,4'-diamino-diphenyl ether 3,4'-ODA.

[0020] In the third aspect of the present application, 3,4'-diamino-diphenyl ether (3,4'-ODA) obtained by the method of the second aspect of the present application is provided. DETAILED DESCRIPTION

[0021] The application will now be described in more detail with reference to the following specific embodiments. A person skilled in the art will realize that the exemplary embodiments described and illustrated herein can be modified in various ways without departing from the principles and scope of the application. Furthermore, the discussion above focuses on specific embodiments, but other configurations are also contemplated. In particular, although expressions such as "in an embodiment", "in another embodiment", and the like are used herein, these expressions are intended to generally refer to the possibility that an embodiment can be combined with one or more of the other embodiments, and are not intended to limit the application to the specific embodiment configuration. As used herein, these terms can denote the same or different embodiments that can be combined into other embodiments. As a rule, any embodiment cited herein can be freely combined with any one or more other embodiments cited herein, and any number of features of different embodiments can be combined with each other, unless otherwise indicated.

[0022] "ranges" disclosed herein are defined by a lower limit and an upper limit, the selected lower limit and upper limit define the boundaries of a particular range. Ranges defined in this manner can be inclusive or exclusive of the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise indicated, a numerical range "a to b" means a shorthand way of describing each and every intervening real number, a and b being real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 to 5" have been listed herein, "0 to 5" is just a shorthand way of describing these numerical combinations. Also, when it is stated that a parameter is an integer > 2, it is equivalent to disclose that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0023] In this application, unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined with each other to form new technical solutions.

[0024] In this application, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form new technical solutions.

[0025] In the present application, unless otherwise specified, all steps mentioned herein can be carried out in sequence or randomly, but preferably in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method mentioned herein can further comprise step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0026] In the present application, unless otherwise specified, "comprise" and "include" mentioned herein means open-ended, and can also be closed-ended. For example, "comprise" and "include" can mean that other components not listed can also be included, or only the listed components can be included.

[0027] In the description herein, it is to be noted that, unless otherwise specified, "above", "below" include the number itself, and "several" means two or more.

[0028] In the description herein, unless otherwise specified, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any one of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0029] In the present application, unless otherwise specified, the percentage (%) or the part refers to the percentage by weight or the parts by weight of the composition.

[0030] In the present application, unless otherwise specified, the sum of the contents of the components in the composition is 100%.

[0031] In the present application, unless otherwise specified, the sum of the parts of the components in the composition can be 100 parts by weight.

[0032] In the present application, unless otherwise specified, "combination thereof" means a multi-component mixture of the elements, for example, two, three, four, and up to the maximum possible multi-component mixture.

[0033] Unless otherwise specified, the term "one" used in the present specification means "at least one".

[0034] In the present application, unless otherwise specified, each reaction is carried out at room temperature and pressure.

[0035] In the context of the present application, the expression "reuse" means that the solvent, catalyst, etc. in the operating step is used again without purification.

[0036] A first aspect of the present application relates to a process for the preparation of 3-amino-4'-nitrodiphenyl ether, said process comprising the steps of:

[0037] (1) synthesizing 3-amino-4'-nitrodiphenyl ether from p-nitrochlorobenzene, m- aminophenol in a first solvent in the presence of a condensing agent,

[0038] wherein

[0039] said first solvent is selected from the group consisting of sulfones, sulfoxides, amides, phosphoramides, and

[0040] Step (1) is carried out under reduced pressure, and during the performance of step (1), the generated water is removed.

[0041] In the context of the present application, the expression "removing the generated water" or similar expressions is intended to mean that the water is vaporized under reduced pressure, and the vaporized water is removed from the reaction system using a device (for example, but not limited to, a vacuum machine, a ventilation device), and the water removed from the reaction system is liquefied using a condensing means (for example, heat exchange with a condensing medium).

[0042] The applicant of the present application has found that by using a specific first solvent, and removing the generated water under vacuum during the performance of step (1), 3-amino-4'-nitrodiphenyl ether can be obtained in high yield, while achieving high conversion of the raw materials p-nitrochlorobenzene, m- aminophenol. In addition, by using a specific first solvent, and removing the generated water under vacuum during the performance of step (1), the first solvent can be reused without purification, and even if the first solvent is reused, the yield of 3-amino-4'-nitrodiphenyl ether and the conversion of p-nitrochlorobenzene, m- aminophenol will not be significantly reduced.

[0043] According to a preferred embodiment, the sulfones used as said first solvent are selected from the group consisting of sulfolane, dimethyl sulfone, 3-methylsulfolane, diethyl sulfone, diphenyl sulfone, phenyl methyl sulfone, p-tolyl methyl sulfone.

[0044] According to a preferred embodiment, the sulfoxides used as said first solvent are selected from the group consisting of dimethyl sulfoxide, diethyl sulfoxide, dipropyl sulfoxide, dibutyl sulfoxide, methyl ethyl sulfoxide, diphenyl sulfoxide, phenyl methyl sulfoxide, p-tolyl sulfoxide.

[0045] According to a preferred embodiment, the amide used as the first solvent is selected from the group consisting of N,N-dimethylformamide DMF, N,N-dimethylacetamide DMAc, N,N-diethylformamide DEF, N,N-dimethylpropionamide DMPA, N-methylpyrrolidone NMP, 1,3-dimethyl-2-imidazolidinone DMI, N-formylpiperidine, N-acetylmorpholine.

[0046] According to a preferred embodiment, the phosphoramide used as the first solvent is selected from the group consisting of hexamethylphosphorotriamide, hexaethylphosphorotriamide, trimethylphosphoramide, tris(dimethylamino)phosphoramide.

[0047] The skilled person is aware that the mass ratio of the first solvent to the raw material can be adjusted depending on the reaction conditions. According to an embodiment, the mass ratio of the first solvent to meta-aminophenol is from 2 to 10, or from 2 to 9, or from 3 to 8, or from 3 to 7.

[0048] As non-limiting examples, the mass ratio of the first solvent to meta-aminophenol can be 2.0, or 2.1, or 2.2, or 2.3, or 2.4, or 2.5, or 2.6, or 2.7, or 2.8, or 2.9, or 3.0, or 3.1, or 3.2, or 3.3, or 3.4, or 3.5, or 3.6, or 3.7, or 3.8, or 3.9, or 4.0, or 4.1, or 4.2, or 4.3, or 4.4, or 4.5, or 4.6, or 4.7, or 4.8, or 4.9, or 5.0, or 5.1, or 5.2, or 5.3, or 5.4, or 5.5, or 5.6, or 5.7, or 5.8, or 5.9, or 6.0, or 6.1, or 6.2, or 6.3, or 6.4, or 6.5, or 6.6, or 6.7, or 6.8, or 6.9, or 7.0, or 7.1, or 7.2, or 7.3, or 7.4, or 7.5, or 7.6, or 7.7, or 7.8, or 7.9, or 8.0, or 8.1, or 8.2, or 8.3, or 8.4, or 8.5, or 8.6, or 8.7, or 8.8, or 8.9, or 9.0, or 9.1, or 9.2, or 9.3, or 9.4, or 9.5, or 9.6, or 9.7, or 9.8, or 9.9, or 10.0.

[0049] In the process of the first aspect of the present application, the condensing agent used in step (1) is not particularly limited. The skilled person can select a suitable condensing agent depending on the actual situation of the reaction and the desired reaction process.

[0050] As non-limiting examples, the condensing agent used in step (1) is selected from the group consisting of oxides, hydroxides, carbonates, acetates, fluorides of alkali metals or alkaline earth metals.

[0051] According to a preferred embodiment, the condensing agent is selected from lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium carbonate, potassium carbonate, sodium carbonate or cesium carbonate, calcium oxide.

[0052] In the process according to the first aspect of the present application, the relative amounts of the starting materials p-nitrochlorobenzene and m-aminophenol can be adjusted according to the actual requirements.

[0053] According to a preferred embodiment, in the process according to the first aspect of the present application, in step (1), the molar ratio of p-nitrochlorobenzene to m-aminophenol as starting materials is in the range of 1.00 to 1.20, preferably 1.00 to 1.05.

[0054] As a non-limiting embodiment, the molar ratio of p-nitrochlorobenzene to m-aminophenol can be 1.00, or 1.01, or 1.02, or 1.03, or 1.04, or 1.05, or 1.06, or 1.07, or 1.08, or 1.09, or 1.10, or 1.11, or 1.12, or 1.13, or 1.14, or 1.15, or 1.16, or 1.17, or 1.18, or 1.19, or 1.20.

[0055] In step (1), the molar ratio of condensing agent to starting materials can be adjusted and selected according to the selected condensing agent and the desired reaction process.

[0056] In a non-limiting embodiment, in step (1) of the process according to the first aspect of the present application, the molar ratio of condensing agent to m-aminophenol is in the range of 0.50 to 1.20, or 0.55 to 1.20, or 0.60 to 1.10.

[0057] According to non-limiting embodiments, in step (1) of the process of the first aspect of the application, the molar ratio of condensing agent to meta-aminophenol can be 0.50, or 0.51, or 0.52, or 0.53, or 0.54, or 0.55, or 0.56, or 0.57, or 0.58, or 0.59, or 0.60, or 0.61, or 0.62, or 0.63, or 0.64, or 0.65, or 0.66, or 0.67, or 0.68, or 0.69, or 0.70, or 0.71, or 0.72, or 0.73, or 0.74, or 0.75, or 0.76, or 0.77, or 0.78, or 0.79, or 0.80, or 0.81, or 0.82, or 0.83, or 0.84, or 0.85, or 0.86, or 0.87, or 0.88, or 0.89, or 0.90, or 0.91, or 0.92, or 0.93, or 0.94, or 0.95, or 0.96, or 0.97, or 0.98, or 0.99, or 1.00, or 1.01, or 1.02, or 1.03, or 1.04, or 1.05, or 1.06, or 1.07, or 1.08, or 1.09, or 1.10, or 1.11, or 1.12, or 1.13, or 1.14, or 1.15, or 1.16, or 1.17, or 1.18, or 1.19, or 1.20.

[0058] According to preferred embodiments, step (1) of the process of the first aspect of the application is performed in the presence of an antioxidant.

[0059] According to preferred embodiments, the antioxidant is selected from the group consisting of chlorides, sulfates, nitrates, or oxalates of a sub-valent metal, or a combination thereof, wherein the sub-valent metal is selected from the group consisting of Fe(II), Cu(I), Sn(II), Cr(II), or a combination thereof.

[0060] According to preferred embodiments, in step (1) as described above, the antioxidant is selected from the group consisting of ferrous sulfate, ferrous chloride, stannous chloride, chromous sulfate, cuprous chloride, ferrous nitrate.

[0061] According to yet another embodiment, in step (1) as described above, the antioxidant is selected from the group consisting of sulfites, bisulfites, thiosulfates, nitrites, phosphites, hypophosphites, dithionites, iodides, oxalates, sulfides of an alkali metal.

[0062] According to yet another embodiment, in step (1) described above, the antioxidant is selected from the group consisting of sodium hypophosphite, potassium hypophosphite, sodium bisulfite, potassium bisulfite, sodium sulfite, potassium sulfite, sodium metabisulfite, potassium metabisulfite, sodium thiosulfate, potassium thiosulfate, sodium dithionite, potassium dithionite, sodium iodide, potassium iodide, sodium sulfide, potassium sulfide, sodium oxalate, potassium oxalate.

[0063] In step (1) described above, the amount of antioxidant to be added can be adjusted according to the specific type of antioxidant and the actual reaction.

[0064] According to non-limiting embodiments, in step (1) described above, the molar ratio of the antioxidant to m-aminophenol is 0.0005 to 0.005, or 0.001 to 0.005.

[0065] According to non-limiting embodiments, in step (1) described above, the molar ratio of the antioxidant to m-aminophenol can be 0.0005, or 0.0006, or 0.0007, or 0.0008, or 0.0009, or 0.0010, or 0.0011, or 0.0012, or 0.0013, or 0.0014, or 0.0015, or 0.0016, or 0.0017, or 0.0018, or 0.0019, or 0.0020, or 0.0021, or 0.0022, or 0.0023, or 0.0024, or 0.0025, or 0.0026, or 0.0027, or 0.0028, or 0.0029, or 0.0030, or 0.0031, or 0.0032, or 0.0033, or 0.0034, or 0.0035, or 0.0036, or 0.0037, or 0.0038, or 0.0039, or 0.0040, or 0.0041, or 0.0042, or 0.0043, or 0.0044, or 0.0045, or 0.0046, or 0.0047, or 0.0048, or 0.0049, or 0.0050.

[0066] As described above, in the method of the first aspect of the present application, step (1) is carried out under reduced pressure. The vacuum degree is such that the water generated in step (1) can be removed, and can be selected and / or adjusted according to the specific reaction process.

[0067] According to an embodiment, the vacuum degree of step (1) is -15 kPa to -65 kPa, preferably -20 kPa to -50 kPa.

[0068] According to non-limiting embodiments, the vacuum degree of step (1) is -15 kPa, or -16 kPa, or -17 kPa, or -18 kPa, or -19 kPa, or -20 kPa, or -21 kPa, or -22 kPa, or -23 kPa, or -24 kPa, or -25 kPa, or -26 kPa, or -27 kPa, or -28 kPa, or -29 kPa, or -30 kPa, or -31 kPa, or -32 kPa, or -33 kPa, or -34 kPa, or -35 kPa, or -36 kPa, or -37 kPa, or -38 kPa, or -39 kPa, or -40 kPa, or -41 kPa, or -42 kPa, or -43 kPa, or -44 kPa, or -45 kPa, or -46 kPa, or -47 kPa, or -48 kPa, or -49 kPa, or -50 kPa, or -51 kPa, or -52 kPa, or -53 kPa, or -54 kPa, or -55 kPa, or -56 kPa, or -57 kPa, or -58 kPa, or -59 kPa, or -60 kPa, or -61 kPa, or -62 kPa, or -63 kPa, or -64 kPa, or -65 kPa.

[0069] The temperature of step (1) is not particularly limited. Those skilled in the art can select a suitable temperature for the above-mentioned step (1) according to the specific reaction.

[0070] The reaction is carried out at a reaction temperature of 110 to 150°C, preferably 130 to 140°C.

[0071] As non-limiting examples, the following temperatures can be used for step (1): 110°C, or 111°C, or 112°C, or 113°C, or 114°C, or 115°C, or 116°C, or 117°C, or 118°C, or 119°C, or 120°C, or 121°C, or 122°C, or 123°C, or 124°C, or 125°C, or 126°C, or 127°C, or 128°C, or 129°C, or 130°C, or 131°C, or 132°C, or 133°C, or 134°C, or 135°C, or 136°C, or 137°C, or 138°C, or 139°C, or 140°C, or 141°C, or 142°C, or 143°C, or 144°C, or 145°C, or 146°C, or 147°C, or 148°C, or 149°C, or 150°C.

[0072] According to a preferred embodiment, the method of the first aspect of the application further comprises step (2): recovering the first solvent to obtain a recycled first solvent.

[0073] According to a preferred embodiment, the method of the first aspect of the present application can use the recycled first solvent to replace the first solvent partially or totally in step (1).

[0074] The applicant unexpectedly found that the conversion of raw materials p-nitrochlorobenzene and m-aminophenol and the yield of 3-amino-4'-nitrodiphenyl ether almost did not change when the recycled first solvent was used to replace the first solvent partially or totally for the synthesis of 3-amino-4'-nitrodiphenyl ether from p-nitrochlorobenzene and m-aminophenol.

[0075] According to a preferred embodiment, the recovery in step (2) described above is carried out by distillation. Those skilled in the art know that other ways can also be used to recover the first solvent.

[0076] According to a preferred embodiment, the method of the first aspect of the present application further comprises step (3): purifying the obtained 3-amino-4'-nitrodiphenyl ether using a second solvent.

[0077] The selection of the second solvent is not particularly limited, and those skilled in the art can select a suitable second solvent according to the desired purification effect.

[0078] According to an embodiment, the second solvent is selected from water, a water-organic solvent mixture.

[0079] If a water-organic solvent mixture is used as the second solvent, those skilled in the art know that the mass fraction of the organic solvent can be selected according to the desired purification effect.

[0080] According to an embodiment, the mass fraction of the organic solvent in the water-organic solvent mixture is 1 to 10 wt%.

[0081] According to an exemplary embodiment, the organic solvent in the water-organic solvent mixture can be selected from the group consisting of: nitriles, alcohols, carboxylic acid derivatives, ethers, sulfoxides.

[0082] The person skilled in the art knows that, if a water-organic solvent mixture is used as the second solvent, a suitable organic solvent can be selected depending on the desired purification effect.

[0083] According to an exemplary embodiment, the organic solvent in the water-organic solvent mixture can be selected from the group consisting of: nitriles, alcohols, carboxylic acid derivatives, ethers, sulfoxides.

[0084] According to an embodiment, the nitriles that can be used in the water-organic solvent mixture can be selected from the group consisting of: acetonitrile, propionitrile, or a combination thereof.

[0085] According to an embodiment, the alcohols that can be used in the water-organic solvent mixture can be selected from the group consisting of: methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol, propylene glycol, glycerol, pentaerythritol, or a combination thereof.

[0086] According to an embodiment, the carboxylic acid derivatives that can be used in the water-organic solvent mixture can be selected from the group consisting of: ethyl lactate, N,N-dimethylformamide DMF, N,N-dimethylacetamide DMAc, N,N-diethylformamide DEF, N,N-dimethylpropionamide DMPA, 2-pyrrolidone, N-methylpyrrolidone NMP, or a combination thereof.

[0087] According to an embodiment, the ethers that can be used in the water-organic solvent mixture can be selected from the group consisting of: tetrahydrofuran, 1,4-dioxane, dioxolane, diglyme, triglyme, 18-crown-6, 15-crown-5, or a combination thereof.

[0088] According to an embodiment, the sulfoxides that can be used in the water-organic solvent mixture are selected from the group consisting of dimethyl sulfoxide, diethyl sulfoxide, methyl ethyl sulfoxide, cyclobutyl sulfoxide, 3-methylcyclobutyl sulfoxide, or a combination thereof.

[0089] It should be understood that the organic solvents that can be used in the water-organic solvent mixture are not limited to those listed above.

[0090] According to a preferred embodiment, step (3) comprises crystallizing 3-amino-4'- nitrodiphenyl ether using a second solvent to obtain purified 3-amino-4'-nitrodiphenyl ether and used second solvent.

[0091] It is known to the person skilled in the art that, in addition to crystallization, other suitable methods can be used to purify 3-amino-4'-nitrodiphenyl ether.

[0092] According to a preferred embodiment, step (3) of the method according to the first aspect of the present application further comprises distilling the used second solvent to obtain a recycled second solvent.

[0093] According to a preferred embodiment, in step (3), the second solvent is partially or totally replaced by the recycled second solvent.

[0094] The present inventors have unexpectedly found that, if step (1) is performed as described above, even if in step (3) the fresh second solvent is partially or totally replaced by the recycled second solvent, there is no adverse effect on step (3).

[0095] In embodiments in which step (3) is performed by crystallization, the temperature at which the crystallization is performed can be adjusted according to the practical situation.

[0096] According to an embodiment, the crystallization is performed at a temperature of between 50 and 100 °C, preferably between 70 and 80 °C.

[0097] According to a non-limiting embodiment, in step (3) of the method according to the first aspect of the present application, the crystallization is performed at a temperature of 50 °C, or 52 °C, or 54 °C, or 56 °C, or 58 °C, or 60 °C, or 62 °C, or 64 °C, or 66 °C, or 68 °C, or 70 °C, or 72 °C, or 74 °C, or 76 °C, or 78 °C, or 80 °C, or 82 °C, or 84 °C, or 86 °C, or 88 °C, or 90 °C, or 92 °C, or 94 °C, or 96 °C, or 98 °C, or 100 °C.

[0098] According to a preferred embodiment, the method of the first aspect of the present application further comprises a step (4) of washing the purified 3-amino-4'-nitro diphenyl ether using a washing solvent to obtain purified and washed 3-amino-4'-nitro diphenyl ether and used washing solvent; wherein the washing solvent is a second solvent, which is optionally partially or totally replaced by the recycled second solvent.

[0099] The person skilled in the art can select or adjust the number of times the 3-amino-4'-nitro diphenyl ether is washed depending on the desired washing effect. According to a preferred embodiment, the washing is performed two or more times, for example 2, 3, 4, 5, 6 or more times.

[0100] The solvent used for washing the 3-amino-4'-nitro diphenyl ether can be fresh solvent, or partially or totally replaced by used washing solvent.

[0101] The present inventors surprisingly found that even if the used washing solvent is partially or totally replaced by fresh washing solvent in step (4) of the method of the first aspect of the present application, no adverse effect on the washing is observed.

[0102] The second aspect of the present application relates to a method for preparing 3,4'- diaminodiphenyl ether 3,4'-ODA, said method comprising:

[0103] (a) preparing 3-amino-4'-nitro diphenyl ether by the method of the first aspect of the present application;

[0104] (b) reducing the 3-amino-4'-nitro diphenyl ether obtained in step (a) in the presence of a reducing agent to obtain 3,4'-diaminodiphenyl ether 3,4'-ODA.

[0105] According to a further embodiment, the above step (b) is performed in a third solvent selected from the group consisting of: aliphatic alcohol, aromatic hydrocarbon, amide.

[0106] According to a preferred embodiment, the aliphatic alcohol that can be used in step (b) of the method of the second aspect of the present application is selected from the group consisting of: methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, or a combination thereof.

[0107] According to a preferred embodiment, the aromatic hydrocarbon that can be used in step (b) of the method of the second aspect of the present application is selected from the group consisting of: benzene, toluene, ethylbenzene, xylene, cumene, naphthalene, biphenyl, diphenylmethane, and a combination thereof.

[0108] According to a preferred embodiment, the amide which can be used in step (b) of the process according to the second aspect of the present application is selected from the group consisting of N,N-dimethylformamide DMF, N,N-dimethylacetamide DMAc, N,N-diethylformamide DEF, N,N-dimethylpropionamide DMPA, N-methylpyrrolidone NMP, 1,3-dimethyl-2-imidazolidinone DMI, N-formylpiperidine, N-acetylmorpholine.

[0109] According to a preferred embodiment, the concentration of 3-amino-4'-nitrophenyl ether in the third solvent in step (b) of the process according to the second aspect of the present application is comprised between 10 and 40 wt%.

[0110] According to a non-limiting embodiment, the concentration of 3-amino-4'-nitrophenyl ether in the third solvent in step (b) of the process according to the second aspect of the present application can be 10 wt%, or 11 wt%, or 12 wt%, or 13 wt%, or 14 wt%, or 15 wt%, or 16 wt%, or 17 wt%, or 18 wt%, or 19 wt%, or 20 wt%, or 21 wt%, or 22 wt%, or 23 wt%, or 24 wt%, or 25 wt%, or 26 wt%, or 27 wt%, or 28 wt%, or 29 wt%, or 30 wt%, or 31 wt%, or 32 wt%, or 34 wt%, or 35 wt%, or 36 wt%, or 37 wt%, or 38 wt%, or 39 wt%, or 40 wt%.

[0111] According to an embodiment, step (b) of the process according to the second aspect of the present application is carried out in the presence of a catalyst.

[0112] The skilled person knows that the appropriate catalyst can be selected depending on the desired reaction process.

[0113] According to a preferred embodiment, the catalyst used in step (b) of the process according to the second aspect of the present application comprises a metal M and a support for loading the metal M, wherein the metal M is selected from the group consisting of transition metals.

[0114] According to a preferred embodiment, the metal M is selected from the group consisting of iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, silver, gold, titanium, vanadium, chromium, manganese.

[0115] According to a preferred embodiment, the support is selected from the group consisting of alumina, silica, titania, zirconia, magnesia, zinc oxide, activated carbon, zeolite, diatomite, silicon carbide, hydroxyapatite, clay, and combinations thereof.

[0116] The amount of catalyst used in step (b) of the process according to the second aspect of the present application can be expressed in terms of a mass fraction relative to the mass fraction of 3-amino-4'-nitrophenyl ether, and this mass fraction can be selected and / or adjusted depending on the specific catalyst species and the desired reaction conditions, as known to the person skilled in the art.

[0117] According to a preferred embodiment, the mass ratio of catalyst to 3-amino-4'-nitrophenyl ether used in step (b) of the process according to the second aspect of the present application is in the range of 0.5% to 5%.

[0118] According to a non-limiting embodiment, the mass ratio of catalyst to 3-amino-4'-nitrophenyl ether used in step (b) of the process according to the second aspect of the present application is 0.5%, or 0.6%, or 0.7%, or 0.8%, or 0.9%, or 1.0%, or 1.1%, or 1.2%, or 1.3%, or 1.4%, or 1.5%, or 1.6%, or 1.7%, or 1.8%, or 1.9%, or 2.0%, or 2.1%, or 2.2.%, or 2.3%, or 2.4%, or 2.5%, or 2.6%, or 2.7%, or 2.8%, or 2.9%, or 3.0%, or 3.1%, or 3.2%, or 3.3%, or 3.4%, or 3.5%, or 3.6%, or 3.7%, or 3.8%, or 3.9%, or 4.0%, or 4.1%, or 4.2%, or 4.3%, or 4.4%, or 4.5%, or 4.6%, or 4.7%, or 4.8%, or 4.9%, or 5.0%.

[0119] The reducing agent used in step (b) of the process according to the second aspect of the present application is not particularly limited. According to a preferred embodiment, the reducing agent used in step (b) of the process according to the second aspect of the present application is hydrogen.

[0120] In the embodiment of step (b) described above, in which hydrogen gas is used as the reducing agent, the hydrogen gas pressure can be 0.1 to 0.5 MPa. According to a non-limiting embodiment, the hydrogen gas pressure can be 0.1 MPa, or 0.11 MPa, or 0.12 MPa, or 0.13 MPa, or 0.14 MPa, or 0.15 MPa, or 0.16 MPa, or 0.17 MPa, or 0.18 MPa, or 0.19 MPa, or 0.20 MPa, or 0.21 MPa, or 0.22 MPa, or 0.23 MPa, or 0.24 MPa, or 0.25 MPa, or 0.26 MPa, or 0.27 MPa, or 0.28 MPa, or 0.29 MPa, or 0.30 MPa, or 0.31 MPa, or 0.32 MPa, or 0.33 MPa, or 0.34 MPa, or 0.35 MPa, or 0.36 MPa, or 0.37 MPa, or 0.38 MPa, or 0.39 MPa, or 0.40 MPa, or 0.41 MPa, or 0.42 MPa, or 0.43 MPa, or 0.44 MPa, or 0.45 MPa, or 0.46 MPa, or 0.47 MPa, or 0.48 MPa, or 0.49 MPa, or 0.50 MPa.

[0121] In the embodiment of step (b) described above, in which hydrogen gas is used as the reducing agent, the reaction temperature can be adjusted or selected according to the desired reaction speed, time, and other factors.

[0122] According to an embodiment, in the embodiment of step (b) described above, in which hydrogen gas is used as the reducing agent, the reaction temperature is 70 to 120°C. For example, the reaction temperature can be 70°C, or 72°C, or 74°C, or 76°C, or 78°C, or 80°C, or 82°C, or 84°C, or 86°C, or 88°C, or 90°C, or 92°C, or 94°C, or 96°C, or 98°C, or 100°C, or 102°C, or 104°C, or 106°C, or 108°C, or 110°C, or 112°C, or 114°C, or 116°C, or 118°C, or 120°C.

[0123] According to a specific embodiment, the method of the second aspect of the present application can comprise the following steps:

[0124] (1) mixing p-nitrochlorobenzene, m-aminophenol, a condensing agent, a first solvent, and an antioxidant; under nitrogen protection, the reaction system is subjected to vacuum and heating to cause the reaction to occur, and the water generated by the reaction is removed.

[0125] (2) after the reaction is completed, the reaction solution is cooled to room temperature.

[0126] (3) The reaction solution is filtered to remove inorganic salts, the filtrate is distilled to recover the first solvent, the inorganic salt filter cake is washed with the recovered first solvent, and the recovered first solvent is directly used in subsequent batches of step (1) without purification, and the 3-amino-4'-nitro diphenyl ether product remains in the distillation kettle.

[0127] (4) The 3-amino-4'-nitro diphenyl ether product obtained in step (3) is added with a second solvent, crystallization is performed, filtration is performed, and the second solvent is washed to obtain purified 3-amino-4'-nitro diphenyl ether; optionally, the filtrate is distilled to obtain recovered second solvent.

[0128] (5) The purified 3-amino-4'-nitro diphenyl ether obtained in step (4), a third solvent, and a catalyst are put into an autoclave, the gas in the autoclave is replaced with nitrogen; then hydrogen is introduced, and the reaction is performed by heating.

[0129] (6) After the reaction is completed, the reaction system is filtered to recover the catalyst; the filtrate is distilled to obtain 3,4'-ODA product, and the third solvent is optionally recovered.

[0130] The present application relates to 3,4'-diamino diphenyl ether obtained by the method of the second aspect of the present application.

[0131] Examples

[0132] The present application will now be described in more detail with reference to the following examples. It should be understood that these examples are provided for illustrative purposes only and in no way limit the present application.

[0133] The reagents used in the examples of the present application are as follows:

[0134]

[0135]

[0136] Preparation of 3-amino-4'-nitro diphenyl ether

[0137] Example 1:

[0138] Into a 250 mL four-necked flask, 44.19 g (0.40 mol) of meta-aminophenol, 64.28 g of p-nitrochlorobenzene, 34.83 g of potassium carbonate, 0.14 g of sodium bisulfite, and 226.73 g of fresh DMAc were added. Among them, the molar ratio of meta-aminophenol, p-nitrochlorobenzene, potassium carbonate and sodium bisulfite was 1:1.02:0.63:0.003; the mass ratio of meta-aminophenol to DMAc was 12:88.

[0139] The vacuum of the four-necked flask was set to -45 kPa under nitrogen protection. The reaction system was heated to 130°C under stirring to carry out the reaction. The water generated in the reaction was removed under vacuum. The four-necked flask was kept at the reaction temperature for 14 h.

[0140] After the reaction, the reaction system was cooled and filtered to obtain a first filter cake and a first filtrate. The filtrate was distilled in a distillation column to obtain recovered DMAc and a residue containing 3-amino-4'-nitro diphenyl ether. The residue was cooled to 70°C and 180 g of 5 wt% methanol aqueous solution was added to the residue for crystallization. The residue was further cooled to room temperature and filtered to obtain a second filter cake and a second filtrate. The second filtrate was distilled to recover the methanol aqueous solution. The second filter cake was washed twice with 360 g of 5 wt% methanol aqueous solution to obtain a first washing liquid and a second washing liquid, and a third filter cake after washing.

[0141] The third filter cake after washing was dried to obtain 90.67 g of bright yellow 3-amino-4'-nitro diphenyl ether product, the content of 3-amino-4'-nitro diphenyl ether in the product was 99.28%, the conversion rate of m-aminophenol was 99.88%, and the yield of 3-amino-4'-nitro diphenyl ether was 97.81%. The first filter cake was washed once with the recovered DMAc to obtain a salt washing liquid, which was used for the ether condensation reaction of the next batch.

[0142] Subsequently, the recovered DMAc and the salt washing liquid were used to carry out the reaction of the subsequent batches under the same other conditions, and the recovered methanol aqueous solution was used for the post-treatment. Such a cycle was repeated for multiple times to obtain the results shown in Table 1.

[0143] Table 1: Results of the ether condensation reaction solvent DMAc and washing liquid reuse

[0144]

[0145] Unless otherwise specified, the content w1 of the 3-amino-4'-nitro diphenyl ether product in this application is calculated by gas chromatography. A 3-amino-4'-nitro diphenyl ether product with a mass of m1 is dissolved in a solution to obtain a solution with a volume of v1. Then the molar concentration c1 of 3-amino-4'-nitro diphenyl ether in the solution is calculated by gas chromatography (Agilent 7890). Then the content of the 3-amino-4'-nitro diphenyl ether product is

[0146]

[0147] wherein M1 is the molar mass of 3-amino-4'-nitro diphenyl ether.

[0148] The conversion rate of m-aminophenol in the present application is determined by the content of m-aminophenol before and after the reaction, unless otherwise specified. The content of m-aminophenol in the feed is denoted as m2, the volume of the filtrate after the reaction is denoted as v2, and the molar concentration of m-aminophenol in the filtrate is denoted as c2. The conversion rate S1 of m-aminophenol is

[0149]

[0150] wherein M2 is the molar mass of m-aminophenol.

[0151] The yield Y1 of 3-amino-4'-nitro diphenyl ether in the present application is calculated by the theoretical yield y1 and the actual yield y2 of 3-amino-4'-nitro diphenyl ether, unless otherwise specified.

[0152]

[0153] The theoretical yield y1 is calculated by the raw materials in the feed, as well known to those skilled in the art.

[0154] Example 2:

[0155] Into a 250 mL four-necked flask, 44.19 g (0.40 mol) of m-aminophenol, 63.02 g of p-nitrochlorobenzene, 29.68 g of sodium carbonate, 0.076 g of sodium pyrosulfite, and 294.60 g of fresh DMF were added. The molar ratio of m-aminophenol, p-nitrochlorobenzene, sodium carbonate, and sodium pyrosulfite was 1:1:0.70:0.001, and the mass ratio of m-aminophenol to DMF was 15:85.

[0156] Under nitrogen protection, the vacuum degree in the four-necked flask was brought to -40 kPa. The reaction was carried out at 135°C for 14 h. During the reaction, the water generated in the reaction was removed.

[0157] After the reaction was completed, the reaction system was cooled and filtered to obtain a first filter cake and a first filtrate. The filtrate was distilled in a distillation column to obtain recovered DMF and a residue containing 3-amino-4'-nitro diphenyl ether. The residue was cooled to 75°C, 180 g of 8 wt% ethanol aqueous solution was added to the residue for crystallization. The temperature was continuously cooled to room temperature and filtered to obtain a second filter cake and a second filtrate. The second filtrate was distilled to recover the ethanol aqueous solution.

[0158] The second filter cake was washed with 540 g of 8 wt% ethanol aqueous solution in three times to obtain a first washing liquid, a second washing liquid, and a third washing liquid. The second filter cake was dried to obtain 91.15 g of bright yellow 3-amino-4'-nitro diphenyl ether product.

[0159] The content of 3-amino-4'-nitro diphenyl ether in the product was 99.35%, the conversion rate of m-aminophenol was 99.85%, and the yield of 3-amino-4'-nitro diphenyl ether was 98.40%.

[0160] Subsequently, under the same conditions, the recovered DMF and salt washing liquid were used for ether condensation reaction, and the recovered washing liquid was used for post-treatment, to obtain 91.86 g of bright yellow 3-amino-4'-nitro diphenyl ether, with a content of 99.68%, a conversion rate of m-aminophenol of 99.90%, and a yield of 3-amino-4'-nitro diphenyl ether of 99.50%.

[0161] Example 3:

[0162] In a 250 mL four-necked flask, 44.19 g (0.40 mol) of m-aminophenol, 66.17 g of p-nitrochlorobenzene, 17.60 g of sodium hydroxide, 0.14 g of sodium hypophosphite, and 220.95 g of dimethyl sulfoxide were added. The molar ratio of m-aminophenol, p-nitrochlorobenzene, sodium hydroxide, and sodium hypophosphite was 1:1.05:1.1:0.004, and the mass ratio of m-aminophenol to dimethyl sulfoxide was 20:80.

[0163] Under nitrogen protection, the vacuum degree in the four-necked flask was-35 kPa. The reaction system was heated to 140°C under stirring, and the reaction was carried out. The water generated in the reaction was removed. The four-necked flask was kept at the reaction temperature for 9 h.

[0164] After the reaction was completed, the reaction system was cooled and filtered to obtain a first filter cake and a first filtrate. The filtrate was distilled in a distillation column to obtain recovered dimethyl sulfoxide and a residue containing 3-amino-4'-nitro diphenyl ether. The residue was cooled to 80°C, and 180 g of 10 wt% acetonitrile aqueous solution was added to the residue for crystallization.

[0165] The cooling was continued to room temperature, and the second filter cake and the second filtrate were obtained by filtration. The second filtrate was distilled to recover the acetonitrile aqueous solution. The second filter cake was washed three times with 540 g of 10 wt% acetonitrile aqueous solution to obtain a first washing liquid, a second washing liquid, and a third washing liquid, and a third filter cake after washing.

[0166] The third filter cake was dried to obtain 92.16 g of bright yellow 3-amino-4'-nitro diphenyl ether, with a content of 3-amino-4'-nitro diphenyl ether in the product of 99.42%, a conversion rate of m-aminophenol of 99.97%, and a yield of 3-amino-4'-nitro diphenyl ether of 99.56%. The first filter cake was washed once with the recovered DMAc to obtain a salt washing liquid, which was used for the ether condensation reaction of the next batch.

[0167] The raw material feeding amount, reaction conditions and post-treatment process are the same as above, the recovered dimethyl sulfoxide and salt washing liquid are used for ether condensation reaction, the recovered washing liquid is used for post-treatment, and 92.23 g of bright yellow 3-amino-4'-nitrodiphenyl ether is obtained, with a content of 99.67%, an m-aminophenol conversion rate of 99.96%, and a 3-amino-4'-nitrodiphenyl ether yield of 99.89%.

[0168] Example 4:

[0169] 250 mL four-port bottle is added 44.19 g (0.40 mol) of m-aminophenol, 66.17 g of p-nitrochlorobenzene, 24.69 g of potassium hydroxide, 0.06 g of sodium thiosulfate, and 176.76 g of sulfolane. The molar ratio of m-aminophenol, p-nitrochlorobenzene, potassium hydroxide and sodium thiosulfate is 1:1.05:1.1:0.001; the mass ratio of m-aminophenol to sulfolane is 25:75.

[0170] Under nitrogen protection, the vacuum degree in the four-port bottle is-45 kPa. The reaction system is heated to 130°C under stirring to carry out the reaction. The water generated in the reaction is removed. The four-port bottle is kept at the reaction temperature for 13 h.

[0171] After the reaction is completed, the reaction system is cooled and filtered to obtain a first filter cake and a first filtrate. The filtrate is distilled in a distillation column to obtain recovered and still containing 3-amino-4'-nitrodiphenyl ether. The still is cooled to 80°C, and 180 g of 6 wt% tetrahydrofuran aqueous solution is added to the still for crystallization. The temperature is continuously cooled to room temperature and filtered to obtain a second filter cake and a second filtrate. The second filtrate is distilled to recover the tetrahydrofuran aqueous solution; the second filter cake is washed twice with 360 g of 6 wt% tetrahydrofuran aqueous solution to obtain a first washing liquid and a second washing liquid, and a third filter cake after washing.

[0172] The third filter cake is dried to obtain 91.22 g of bright yellow 3-amino-4'-nitrodiphenyl ether, with a content of 3-amino-4'-nitrodiphenyl ether in the product of 99.37%, an m-aminophenol conversion rate of 99.95%, and a 3-amino-4'-nitrodiphenyl ether yield of 98.50%.

[0173] Subsequently, under the same other conditions, the recovered sulfolane and salt washing liquid are used for ether condensation reaction, and the recovered washing liquid is used for post-treatment to obtain 92.34 g of bright yellow 3-amino-4'-nitrodiphenyl ether, with a content of 99.40%, an m-aminophenol conversion rate of 99.97%, and a 3-amino-4'-nitrodiphenyl ether yield of 99.74%.

[0174] Comparative Example 1

[0175] Example 1 was repeated, except that the reaction for synthesizing 3-amino-4'- nitrodiphenyl ether was carried out at normal pressure, and the generated water was not removed during the reaction; the reaction time was 18 h.

[0176] After the reaction was completed, 89.07 g of bright yellow 3-amino-4'-nitrodiphenyl ether crude product was obtained, the 3-amino-4'-nitrodiphenyl ether content in the crude product was 98.73%, the conversion rate of m-aminophenol was 98.73%, and the yield of 3-amino-4'-nitrodiphenyl ether was 95.56%.

[0177] The above reaction was repeated, and the recovered DMAc was used for the ether condensation reaction, the reaction was carried out at normal pressure at 130°C, the reaction time was 20 h, and the reaction liquid was treated to obtain 90.32 g of brownish yellow 3-amino-4'-nitrodiphenyl ether product, the 3-amino-4'-nitrodiphenyl ether content was 95.21%, the conversion rate of m-aminophenol was 96.73%, and the yield of 3-amino-4'-nitrodiphenyl ether was 93.44%.

[0178] Preparation of 3,4'-diaminodiphenyl ether

[0179] Example 5:

[0180] In a 1 L autoclave, 85.73 g of 3-amino-4'-nitrodiphenyl ether prepared according to the method of Example 1 (content 99.28%), 255.0 g of DMAc, and 2.66 g of 2% Pt catalyst (solid content 32%) were added. The mass ratio of the catalyst to the substrate was 1%.

[0181] Nitrogen was introduced into the reaction kettle to replace the gas therein. After the pressure test was qualified, hydrogen was introduced into the reaction kettle, the pressure was charged to 0.2 MPa, and the temperature was raised to 110°C, and the reaction was carried out for 2 h.

[0182] After the reaction was completed, the reaction kettle was cooled and opened. The reaction kettle was rinsed with DMAc, and the catalyst was recovered by filtration to obtain the recovered catalyst and the filtrate. The filtrate was analyzed by gas chromatography, and the conversion rate of 3-amino-4'-nitrodiphenyl ether was 99.98%. The filtrate was distilled to obtain the recovered DMAc. Subsequently, under a vacuum degree of -100 kPa high vacuum, the fraction of 208 to 212°C was collected to obtain 71.58 g of white 3,4'-ODA product, and the high-performance liquid chromatography normalized content of 3,4'-ODA in the product was 99.98% (using Agilent 1260 Infinity II). The product yield was 96.7%.

[0183] Unless otherwise stated, the 3,4'-ODA yield Y2 in this application is calculated by the theoretical yield y3 of 3,4'-ODA and the actual yield y4 after purification:

[0184]

[0185] The theoretical yield y3 is calculated based on the raw materials used, as is well known to those skilled in the art.

[0186] Example 6:

[0187] The following were added to a 1L autoclave: 85.56g of 3-amino-4'-nitrodiphenyl ether (99.48% purity) prepared according to the method of Example 1, 255.0g of DMF, and 5.28g of 2% Pt catalyst (32% solids content). The mass ratio of catalyst to substrate was 2%.

[0188] Nitrogen gas was introduced into the reactor to replace the existing gas. After the pressure test was passed, hydrogen gas was introduced into the reactor, pressurized to 0.3 MPa, and heated to 90°C for 1.5 hours.

[0189] After the reaction was completed, the temperature was lowered and the reactor was opened. The reactor was rinsed with DMF, filtered, and the catalyst was recovered, yielding the recovered catalyst and filtrate. Gas chromatography analysis of the filtrate showed a 99.99% conversion of 3-amino-4'-nitrodiphenyl ether. The filtrate was distilled to obtain the recovered DMF. Subsequently, it was distilled under a high vacuum of -100 kPa, and the fraction from 208 to 212 °C was collected to obtain 72.39 g of white 3,4'-ODA product, of which the 3,4'-ODA content was 99.97% as normalized by high performance liquid chromatography, and the product yield was 97.78%.

[0190] Under otherwise identical conditions, using the recovered DMF and catalyst, the reaction results are shown in the table below:

[0191] Table 2. Catalyst reuse and separation results for the hydrogenation of 3-amino-4'-nitrodiphenyl ether after separation.

[0192]

[0193]

[0194] Example 7:

[0195] The following were added to a 1L autoclave: 85.62g of 3-amino-4'-nitrodiphenyl ether (99.44% purity) prepared according to the method of Example 1, 255.0g of methanol, and 7.97g of 2% Pt catalyst (32% solids content). The mass ratio of catalyst to substrate was 3%.

[0196] Nitrogen gas was introduced into the reactor to replace the existing gas. After the pressure test was passed, hydrogen gas was introduced into the reactor, pressurized to 0.5 MPa, and heated to 70°C for 4 hours.

[0197] After the reaction was completed, the temperature was lowered and the reactor was opened. The reactor was rinsed with methanol, filtered, and the catalyst was recovered, yielding the recovered catalyst and filtrate. Gas chromatography analysis of the filtrate showed a 99.99% conversion of 3-amino-4'-nitrodiphenyl ether. The filtrate was distilled to obtain recovered methanol. Subsequently, the filtrate was distilled under a high vacuum of -100 kPa, and the fraction from 208 to 212 °C was collected to obtain 71.93 g of white 3,4'-ODA product, with a 99.99% purity of 3,4'-ODA as determined by high-performance liquid chromatography (HPLC), resulting in a product yield of 97.15%.

[0198] Comparative Example 2

[0199] Example 6 was repeated, except that the hydrogenation reaction was carried out using the reaction solution of Comparative Example 1 (which was filtered to remove solids) and a catalyst was used. Subsequently, the catalyst was used under the same conditions, and the results are shown in Table 3.

[0200] Table 3 Results of catalyst reuse for hydrogenation of unseparated 3-amino-4'-nitrodiphenyl ether

[0201]

[0202] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing 3-amino-4'-nitrodiphenyl ether, the method comprising the following steps: (1) In the presence of a condensing agent, 3-amino-4'-nitrodiphenyl ether is synthesized from p-nitrochlorobenzene and m-aminophenol in a first solvent. in The first solvent is selected from sulfones, sulfoxides, amides, and phosphoramides, and Step (1) is performed under reduced pressure, and during step (1), the generated water is removed.

2. The method of claim 1, wherein the method satisfies at least one of the following features: (i) The sulfones used as the first solvent are selected from sulfolane, dimethyl sulfone, 3-methylsulfolane, diethyl sulfone, diphenyl sulfone, phenyl methyl sulfone, and p-tolyl methyl sulfone; (ii) The sulfoxides used as the first solvent are selected from dimethyl sulfoxide, diethyl sulfoxide, dipropyl sulfoxide, dibutyl sulfoxide, methyl ethyl sulfoxide, diphenyl sulfoxide, phenyl methyl sulfoxide, and p-tolyl sulfoxide; (iii) The amide used as the first solvent is selected from N,N-dimethylformamide DMF, N,N-dimethylacetamide DMAc, N,N-diethylformamide DEF, N,N-dimethylpropionamide DMPA, N-methylpyrrolidone NMP, 1,3-dimethyl-2-imidazolinone DMI, N-formylpiperidine, and N-acetylmorpholine; (iv) The phosphoramide used as the first solvent is selected from: hexamethylphosphoric acid triamine, hexaethylphosphoric acid triamine, trimethylphosphoramide, and tris(dimethylamino)phosphate; (v) The mass ratio of the first solvent to m-aminophenol is 2 to 10; (vi) In step (1), the condensing agent is selected from oxides, hydroxides, carbonates, acetates, and fluorides of alkali metals or alkaline earth metals; more preferably, the condensing agent is selected from lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium carbonate, potassium carbonate, sodium carbonate, or cesium carbonate and calcium oxide. (vii) In step (1), the molar ratio of p-nitrochlorobenzene to m-aminophenol is 1.00 to 1.20; (viii) In step (1), the molar ratio of the condensing agent to m-aminophenol is 0.50 to 1.20; (ix) The vacuum degree in step (1) is -15 to -65 kPa, preferably -20 to -50 kPa; and / or (x) Step (1) is carried out at a reaction temperature of 110 to 150°C, preferably 130 to 140°C.

3. The method of claim 1, wherein step (1) is performed in the presence of an antioxidant; Preferably, the method has at least one of the following features: (1) The antioxidant is selected from the following low-valent metal chlorides, sulfates, nitrates, or oxalates, or combinations thereof, wherein the low-valent metal is selected from Fe(II), Cu(I), Sn(II), Cr(II), or combinations thereof; more preferably, the antioxidant is selected from ferrous sulfate, ferrous chloride, stannous chloride, chromium sulfate, cuprous chloride, and ferrous nitrate; (2) The antioxidant is selected from alkali metal sulfites, bisulfites, thiosulfates, nitrites, phosphites, hypophosphites, dithionites, iodides, oxalates, and sulfides; more preferably, the antioxidant is selected from sodium hypophosphite, potassium hypophosphite, sodium bisulfite, potassium bisulfite, sodium sulfite, potassium sulfite, sodium metabisulfite, potassium metabisulfite, sodium thiosulfate, potassium thiosulfate, sodium dithionite, potassium dithionite, sodium iodide, potassium iodide, sodium sulfide, potassium sulfide, sodium oxalate, and potassium oxalate; and / or (3) The molar ratio of the antioxidant to m-aminophenol is 0.0005 to 0.

005.

4. The method of claim 1, wherein the method further comprises the step of: (2) Recover the first solvent to obtain the recycled first solvent. Preferably: In step (1), the first solvent is partially or completely replaced by the recycled first solvent; and / or In step (2), recovery is carried out by distillation.

5. The method of claim 1, wherein the method further comprises the following steps: (3) Purification of the obtained 3-amino-4'-nitrodiphenyl ether using a second solvent Preferably, the second solvent is selected from: water, water-organic solvent mixtures. Preferably, the method has one or more of the following features: (a) In the water-organic solvent mixture, the mass fraction of the organic solvent is 1 to 10 wt%; and / or (b) The organic solvent is selected from: nitriles, alcohols, carboxylic acid derivatives, ethers, and sulfoxides; More preferably, the method has one or more of the following features: (i) The nitrile is selected from: acetonitrile, propionitrile, or combinations thereof; and / or (ii) The alcohols are selected from: methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol, propylene glycol, glycerol, pentaerythritol, or combinations thereof; and / or (iii) The carboxylic acid derivative is selected from ethyl lactate, N,N-dimethylformamide DMF, N,N-dimethylacetamide DMAc, N,N-diethylformamide DEF, N,N-dimethylpropionamide DMPA, 2-pyrrolidone, N-methylpyrrolidone NMP, or combinations thereof; and / or (iv) The ethers mentioned are selected from: tetrahydrofuran, 1,4-dioxane, dioxolane, diethylene glycol dimethyl ether, Triethylene glycol dimethyl ether, 18-crown-6, 15-crown-5, or combinations thereof; and / or (v) Sulfoxides are selected from: dimethyl sulfoxide, diethyl sulfoxide, methyl ethyl sulfoxide, cyclobutane sulfoxide, 3-Methylcyclobutane sulfoxide, or combinations thereof.

6. The method of claim 5, wherein step (3) comprises: crystallizing 3-amino-4'-nitrodiphenyl ether using a second solvent to obtain purified 3-amino-4'-nitrodiphenyl ether and the second solvent used; Preferably, the method satisfies at least one of the following: (a) Step (3) further comprises distilling the used second solvent to obtain a recycled second solvent; more preferably, in step (3), the second solvent is partially or entirely replaced by the recycled second solvent; (b) The crystallization temperature is 50 to 100°C, preferably 70 to 80°C; (c) The method further includes the following steps: Step (4) Wash the purified 3-amino-4'-nitrodiphenyl ether with a washing solvent to obtain purified and washed 3-amino-4'-nitrodiphenyl ether and the washing solvent used; wherein the washing solvent is a second solvent, which is optionally partially or wholly replaced by the recycled second solvent; More preferably, The washing is performed two or more times; and / or The washing solvent is partially or entirely replaced by the used washing solvent.

7. A method for preparing 3,4'-diaminodiphenyl ether 3,4'-ODA, the method comprising: (a) 3-amino-4'-nitrodiphenyl ether is prepared by the method of any one of claims 1 to 6; (b) In the presence of a reducing agent, the 3-amino-4'-nitrodiphenyl ether obtained in step (a) is reduced to give 3,4'-diaminodiphenyl ether 3,4'-ODA. Preferably, the reducing agent in step (b) is hydrogen gas; More preferably, In step (b), the hydrogen pressure is 0.1 to 0.5 MPa, and / or In step (b), the reaction temperature is 70 to 120°C.

8. The method of claim 7, wherein step (b) is carried out in a third solvent selected from: aliphatic alcohols, aromatic hydrocarbons, and amides; Preferably, the method satisfies at least one of the following: (i) The aliphatic alcohol is selected from: methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, or combinations thereof; (ii) The aromatic hydrocarbons are selected from: benzene, toluene, ethylbenzene, xylene, cumene, naphthalene, biphenyl, diphenylmethane, and combinations thereof; (iii) The amide is selected from N,N-dimethylformamide DMF, N,N-dimethylacetamide DMAc, N,N-diethylformamide DEF, N,N-dimethylpropionamide DMPA, N-methylpyrrolidone NMP, 1,3-dimethyl-2-imidazolinone DMI, N-formylpiperidine, and N-acetylmorpholine; (iv) In step (b), the concentration of 3-amino-4'-nitrodiphenyl ether in the third solvent is from 10 wt% to 40 wt%.

9. The method of claim 7, wherein step (b) is performed in the presence of a catalyst; Preferably, the catalyst comprises a metal M and a support for supporting the metal M, wherein the metal M is selected from transition metals, and / or The mass ratio of the catalyst to 3-amino-4'-nitrodiphenyl ether is 0.5% to 5%; More preferably, the method has at least one of the following features: (i) The metal M is selected from iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, copper, silver, gold, titanium, vanadium, chromium, and manganese; (ii) The carrier is selected from: alumina, silicon dioxide, titanium dioxide, zirconium oxide, magnesium oxide, zinc oxide, activated carbon, zeolite, diatomite, silicon carbide, hydroxyapatite, clay, and combinations thereof.

10. 3,4'-diaminodiphenyl ether obtained by the method according to any one of claims 7 to 9.

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