Production method for 4,4'-diaminodiphenyl ether

Abstract

A production method for 4,4'-diaminodiphenyl ether. The production method comprises the following steps: (A) carrying out a hydrogenation reaction on 4,4'-dinitrodiphenyl ether to obtain a first material liquid containing 4,4'-diaminodiphenyl ether; and (B) adding polymethylhydrosiloxane to the first material liquid obtained in step A, fully dispersing same to obtain a second material liquid, and cooling and crystallizing same to obtain solid 4,4'-diaminodiphenyl ether. The production method involves mild reaction conditions and simple operation and thus facilitates industrial production.

Description

A production method of 4,4'-diaminodiphenyl ether Technical Field

[0001] The present invention relates to the field of organic synthesis, and in particular to a method for producing 4,4'-diaminodiphenyl ether. Background Art

[0002] 4,4'-Diaminodiphenyl ether (ODA) can be used to manufacture heat-resistant plastics such as polyimide resin, polymaleimide resin, polyamide-imide resin, polyester-imide resin, epoxy resin, polyurethane and other polymer materials. It is a chemical raw material with a wide range of uses.

[0003] 4,4'-Diaminodiphenyl ether can be prepared by reducing 4,4'-dinitrodiphenyl ether. Common reducing agents include iron powder, stannous chloride, hydrazine hydrate, sulfide, and hydrogen. Because the use of these reducing agents can produce significant wastewater or be highly toxic, hydrogen reduction is currently the most common method for preparing 4,4'-diaminodiphenyl ether.

[0004] However, in the process of preparing 4,4'-diaminodiphenyl ether using hydrogen reduction, a series of oxidation products are generated due to differences in the degree of reduction, resulting in a darker color of the final product. Since the chromaticity of the ODA monomer will ultimately affect the quality of the polymer, it is necessary to solve the problem of excessive chromaticity in the production process of the ODA monomer. CN 114671770 A reports a method for reducing oxidation products in the product to prevent the product color from darkening. However, this method requires the use of a crystallization solvent that has been deoxygenated during the recrystallization process and needs to be carried out under a nitrogen atmosphere. The operation is difficult and the production cost is high. In addition, the above-mentioned operating conditions are very harsh for industrial production and are not suitable for industrial production.

[0005] Therefore, there is an urgent need for a preparation method for 4,4'-diaminodiphenyl ether that is simple in process, convenient in purification, green and safe, and easy to industrialize.

[0006] Summary of the Invention

[0007] In order to solve the above problems, the present invention provides a method for producing 4,4'-diaminodiphenyl ether with mild reaction conditions, simple operation and easy industrial production.

[0008] In a first aspect of the present invention, a method for producing 4,4'-diaminodiphenyl ether is provided, characterized in that it comprises the following steps:

[0009] (A) performing a hydrogenation reaction on 4,4'-dinitrodiphenyl ether to obtain a first feed solution containing 4,4'-diaminodiphenyl ether;

[0010] (B) adding polymethyl hydrogen siloxane to the first liquid obtained in step A, fully dispersing the polymethyl hydrogen siloxane to obtain a second liquid, cooling the liquid for crystallization, and thereby obtaining solid 4,4'-diaminodiphenyl ether.

[0011] In a preferred embodiment, in the step (B), before, during or after the dispersion, the temperature of the first liquid and the second liquid is maintained at 70-80°C.

[0012] In a preferred embodiment, the amount of polymethylhydrogensiloxane added is 0.1-1.0 wt %, preferably 0.2-0.8 wt %, more preferably 0.4-0.6 wt % of 4,4'-dinitrodiphenyl ether, based on the amount of material added in step (A).

[0013] In a preferred embodiment, the step (B) further comprises: stirring the second liquid during the cooling and crystallization process.

[0014] In another preferred embodiment, the stirring speed is 100-300 rpm, preferably 100-280 rpm, more preferably 100-245 rpm.

[0015] In another preferred embodiment, the stirring time in step (B) is 0.5-3 h, preferably 0.5-2 h, more preferably 1-2 h.

[0016] In another preferred embodiment, the stirring temperature is 45-80°C, preferably 55-80°C, more preferably 65-80°C.

[0017] In a preferred embodiment, the step (B) further comprises: controlling the cooling rate during the crystallization to be 5-20°C / h.

[0018] In another preferred embodiment, the step (B) further comprises: controlling the cooling rate during the cooling and crystallization to be 5-15°C / h, more preferably 10-15°C / h.

[0019] In a preferred embodiment, the cooling crystallization is gradient cooling crystallization, which includes the following steps: starting from the stirring temperature, cooling at least twice, and each cooling amplitude is 5-20°C (preferably 10-15°C), and stirring for 30-60 minutes after each cooling.

[0020] In a preferred embodiment, the step (B) further comprises: after the cooling and crystallization, mixing the obtained solid with water and slurrying, and then separating to obtain a purified solid product.

[0021] In another preferred embodiment, the volume / mass ratio of the amount of water added to the obtained solid is (3-8):1 (L / g), preferably (4-7):1 (L / g).

[0022] (Step (A) Inert Solvent: Starting Materials = (3-5): 1. Here, the starting materials yield the product in a substantially quantitative manner. The molar mass of the product / starting material is 200.23 / 260.2 ≈ 0.77, so the conversion is as above.)

[0023] In a preferred embodiment, the step (A) further comprises:

[0024] (i) providing a reaction solution, wherein the reaction solution comprises: an inert solvent, and 4,4'-dinitrodiphenyl ether and a hydrogenation catalyst dispersed in the inert solvent;

[0025] (ii) hydrogen gas is introduced into the reaction system to carry out a hydrogenation reaction.

[0026] In another preferred embodiment, the catalyst is selected from the group consisting of Raney nickel, Pd / C, Pt / C, or a combination thereof.

[0027] In another preferred embodiment, the catalyst is Raney nickel.

[0028] In a preferred embodiment, in the step (ii), the pressure of the hydrogen gas introduced is 0.1-1.0 MPa, preferably 0.2-0.8 MPa, and more preferably 0.4-0.6 MPa.

[0029] In a preferred embodiment, the inert solvent is selected from the group consisting of DMF, toluene, water, or a combination thereof.

[0030] In another preferred embodiment, the volume / mass ratio of the inert solvent to the 4,4'-dinitrodiphenyl ether is (3-5):1 (L / g).

[0031] In another preferred embodiment, the reaction temperature is 70-120°C.

[0032] In another preferred embodiment, the reaction time is 8-12 hours.

[0033] It should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features described in detail below (such as in the embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be listed here one by one. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is a diagram of a product solution when the reducing agent is polymethylhydrogensiloxane in Example 2 of the present invention.

[0035] FIG2 is a liquid phase spectrum of the product obtained in Example 5 of the present invention.

[0036] FIG3 is a diagram of the product obtained in Example 5 of the present invention.

[0037] FIG4 is a diagram of a product solution when no reducing agent is added in Example 2 of the present invention.

[0038] FIG5 is a diagram of a product solution when the reducing agent is sodium sulfite in Example 2 of the present invention.

[0039] FIG6 is a diagram of a product solution when the reducing agent is vitamin C in Example 2 of the present invention.

[0040] FIG7 is a diagram of a product solution when the reducing agent is sodium borohydride in Example 2 of the present invention.

[0041] FIG8 is a diagram of a product solution when the reducing agent is sodium thiosulfate in Example 2 of the present invention.

[0042] FIG9 is a diagram showing the appearance of the product when the stirring rate is 25 rpm in Example 3 of the present invention.

[0043] FIG10 is a diagram showing the appearance of the product when the stirring rate is 50 rpm in Example 3 of the present invention.

[0044] FIG11 is a diagram showing the appearance of the product when the stirring rate is 100 rpm in Example 3 of the present invention.

[0045] FIG12 is a product appearance diagram when the stirring rate is 245 rpm in Example 3 of the present invention and a product appearance diagram when the cooling rate is 10° C. / h in Example 4.

[0046] FIG13 is a diagram showing the appearance of the product when the stirring rate is 400 rpm in Example 3 of the present invention.

[0047] FIG14 is a diagram showing the appearance of the product when the stirring rate is 500 rpm in Example 3 of the present invention.

[0048] FIG15 is a product appearance diagram when the cooling rate is 20° C. / h in Example 4 of the present invention.

[0049] FIG16 is a product appearance diagram when the cooling rate is 15° C. / h in Example 4 of the present invention.

[0050] Figure 17 is a picture of the product obtained in Comparative Example 1.

[0051] FIG18 is an appearance diagram of the product obtained by the gradient cooling process under the production scale in Example 6. DETAILED DESCRIPTION

[0052] After long and in-depth research and a large number of experiments, the inventors have developed for the first time a production method for 4,4'-diaminodiphenyl ether with mild reaction conditions, simple operation, and easy industrial production.

[0053] The main advantages of the present invention are:

[0054] In the production method of 4,4'-diaminodiphenyl ether of the present invention, polymethylhydrogensiloxane is used as a reducing agent during the purification process. Therefore, even under conventional conditions, the crude product obtained by the reaction can be recrystallized to obtain colorless and extremely pure 4,4'-diaminodiphenyl ether.

[0055] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present invention and are not intended to limit the scope of the invention. The experimental methods in the following examples, for which no specific conditions are specified, are generally carried out under conventional conditions or according to the conditions recommended by the manufacturer. Unless otherwise stated, percentages and parts are percentages by weight and parts by weight.

[0056] In the following examples, unless otherwise specified, all raw materials are commercially available products.

[0057] In the following examples, polymethylhydrogensiloxane is polymethylhydrogensiloxane purchased from Sigma-Aldrich, with a number average molecular weight of 1700-3200 and CAS No. 63148-57-2.

[0058] High performance liquid chromatography (HPLC)

[0059] Example 1. General Method - Production of 4,4'-diaminodiphenyl ether

[0060] This embodiment provides a method for producing 4,4'-diaminodiphenyl ether, comprising the following steps:

[0061] 100 g of 4,4'-dinitrodiphenyl ether was dissolved in 420 mL of DMF, 2 g of Raney nickel was added, the hydrogen was replaced, and hydrogen was introduced to pressurize the mixture to 0.5 MPa. The temperature was raised to 90°C and the reaction was maintained at this temperature and pressure for 10 h. The mixture was filtered, and 0.5 g of a reducing agent was added or not. The mixture was stirred at 75°C for 1 h to obtain a product solution. The solution was then cooled to 45°C at a cooling rate of 10°C / h for crystallization. A large amount of solid precipitated, and the solution was centrifuged. The solid was collected and slurried with 420 g of water. The mixture was centrifuged and dried to obtain 4,4'-diaminodiphenyl ether. The results are detailed in the following examples.

[0062] Example 2. Screening of reducing agents

[0063] This example uses the basic method of Example 1 to screen the reducing agent used in the production process, and the steps are as follows:

[0064] Dissolve 100 g of 4,4'-dinitrodiphenyl ether in 420 mL of DMF, add 2 g of Raney nickel, displace the hydrogen, and introduce hydrogen to the pressure of 0.5 MPa. Raise the temperature to 90°C, maintain the temperature and pressure for 10 hours, filter, add or not add 0.5 g of a reducing agent, and stir at 75°C for 1 hour to obtain the product solution. Subsequently, cool the temperature to 45°C at a rate of 10°C / h for crystallization. A large amount of solid precipitates, which is centrifuged. The solid is collected and slurried with 420 g of water. Centrifuge and dry the solid to obtain 4,4'-diaminodiphenyl ether.

[0065] The screening results are shown in Figures 4-8 and Table 1.

[0066] Table 1 Screening of reducing agents

[0067] As shown in FIG4 , when no reducing agent is used in the post-treatment process, the product is severely oxidized. Not only does the solution turn black, but the purity is also significantly lower, at only 97.5%.

[0068] When other reducing agents such as sodium sulfite, vitamin C, sodium borohydride, and sodium thiosulfate are used, the product decolorization is poor and the product purity is low, only about 98%, which indirectly indicates that some oxidation products that cause coloration still exist in the product. Therefore, polymethylhydrogensiloxane is selected as the reducing agent in the process of the present invention.

[0069] Example 3. Screening of stirring rate

[0070] This example aims to screen the stirring rate during the dispersion and crystallization process. The specific steps are as follows:

[0071] 100g of 4,4'-dinitrodiphenyl ether was dissolved in 420mL of DMF, 2g of Raney nickel was added, hydrogen was replaced, and hydrogen was introduced to pressurize to 0.5MPa. The temperature was raised to 90°C, and the reaction was maintained at this temperature and pressure for 10h. After filtration, 0.5g of polymethylhydrogensiloxane was added and stirred at 75°C for 1h to obtain a product solution. The temperature was then lowered for crystallization. During the crystallization process, stirring was maintained at the designed rate (X revolutions / min). The cooling rate was 10°C / h. When the temperature was lowered to 45°C, a large amount of solid was precipitated. The solid was centrifuged, 420g of water was added for slurrying, centrifuged, and the solid was dried.

[0072] Table 2 Screening of stirring rate

[0073] The results showed that when the stirring speed was too low, the decolorization effect of the final product was poor, resulting in a yellow crystal. At the same time, the crystals obtained at a lower stirring speed were large, hollow, and fragile, making them unsuitable for transportation and storage. When the stirring speed was too fast, although it could achieve better decolorization effect, it would lead to overly fine crystals, causing sticking to the wall during subsequent production. Taking all these factors into consideration, the stirring speed in the final process was determined to be 100-300 rpm.

[0074] Example 4. Screening of cooling rate

[0075] Based on Example 1, this example screened the cooling rate during the cooling and crystallization process, and the steps were as follows:

[0076] 100g of 4,4'-dinitrodiphenyl ether was dissolved in 420mL of DMF, 2g of Raney nickel was added, hydrogen was replaced, and hydrogen was introduced to pressurize to 0.5MPa. The temperature was raised to 90°C, and the reaction was maintained at this temperature and pressure for 10h. After filtration, 0.5g of polymethylhydrogensiloxane was added, and the mixture was stirred at 75°C for 1h to obtain a product solution. The temperature was then lowered for crystallization. During the crystallization process, stirring was maintained at 245 rpm, and the cooling rate was Y°C / h. The temperature was lowered to 45°C, and a large amount of solid precipitated. The solution was centrifuged, and the solid was taken. 420g of water was added for slurrying, centrifuged, and the solid was dried.

[0077] Table 2 Screening of cooling rate

[0078] As can be seen from the above table, better crystals can be obtained when the cooling rate is in the range of 5-20℃ / h. Among them, the crystal form obtained when the cooling rate is controlled at 10-15℃ / h is better, so this cooling rate is used in the scale-up experiment.

[0079] Comparative Example 1. Production Method of 4,4'-Diaminodiphenyl Ether

[0080] This comparative example provides a method for producing 4,4'-diaminodiphenyl ether, the steps of which are as follows:

[0081] 100 g of 4,4'-dinitrodiphenyl ether was dissolved in 420 mL of DMF, 2 g of Raney nickel was added, hydrogen was replaced, and hydrogen was introduced to pressurize to 0.5 MPa. The temperature was raised to 90°C, and the reaction was maintained at this temperature and pressure for 10 hours. The mixture was filtered and stirred at 75°C for 1 hour to obtain the product solution. The solution was then cooled and crystallized. During the cooling and crystallization process, stirring was maintained at 245 rpm and the cooling rate was 5°C / h. The solution was cooled to 45°C, and a large amount of solid precipitated. The solution was centrifuged, the solid was taken, 420 g of water was added for slurrying, centrifuged, and the solid was dried.

[0082] The product image of 4,4'-diaminodiphenyl ether prepared in this example is shown in FIG17 .

[0083] As shown in Figure 17, not adding a reducing agent during the post-processing process will result in a darker product color.

[0084] Experimental Conclusion

[0085] According to the production method of 4,4'-diaminodiphenyl ether involved in the above embodiment, since polymethylhydrogensiloxane is used as a reducing agent during the purification process, the production method of 4,4'-diaminodiphenyl ether provided by the present invention can obtain colorless and extremely high-purity 4,4'-diaminodiphenyl ether by recrystallization under conventional conditions.

[0086] Furthermore, during the decolorization and crystallization process, controlling the stirring speed at 100-245 rpm can not only achieve better decolorization but also obtain crystals of appropriate size. Therefore, this speed range is also used in the scale-up experiment.

[0087] During the crystallization process, the crystal quality obtained was better when the cooling rate was controlled in the range of 10-20℃ / h, so this cooling rate was used in the scale-up experiment.

[0088] In addition, when a water slurrying step is adopted after the crystallization step, the DMF solvent remaining in the product can be further removed to further improve the purity of the product. Therefore, the preferred post-treatment method also includes the steps of dispersing the product in water and then slurrying.

[0089] Example 5. Production method of 4,4'-diaminodiphenyl ether on an industrial scale

[0090] This embodiment provides a large-scale production method of 4,4'-diaminodiphenyl ether, the steps are as follows:

[0091] 1200 kg of 4,4'-dinitrodiphenyl ether was dissolved in 5000 kg of N,N-dimethylformamide (DMF), 24 kg of Raney nickel was added, hydrogen was replaced, and hydrogen was introduced to pressurize to 0.5 MPa. The temperature was raised to 90 ° C. and the reaction was maintained at this temperature and pressure for 10 hours. The mixture was filtered, and 6 kg of polymethylhydrogensiloxane was added to the filtrate. The mixture was stirred at 75 ° C. for 1 hour at a stirring rate of 245 rpm. The resulting solution is shown in Figure 1. The mixture was then cooled and crystallized. During the cooling and crystallization process, stirring was maintained at a stirring rate of 245 rpm. The cooling rate was 10 ° C. / h. The mixture was cooled to 45 ° C. A large amount of solid precipitated. The mixture was centrifuged, the solid was taken, 5000 kg of water was added for slurrying, centrifuged, and the solid was dried to obtain 908.7 kg of 4,4'-diaminodiphenyl ether with a yield of 98.4% and an HPLC purity of 99.9%.

[0092] The HPLC spectrum of 4,4'-diaminodiphenyl ether prepared in this example is shown in FIG2 .

[0093] The product image of 4,4'-diaminodiphenyl ether prepared in this example is shown in FIG3 .

[0094] Example 6. Study on industrial-scale cooling method

[0095] Since controlling the linear cooling rate in industrial-scale production places too high demands on the equipment, we further studied whether the step cooling method would affect the crystallization quality. The experimental process is as follows:

[0096] This embodiment provides a large-scale production method of 4,4'-diaminodiphenyl ether, the steps are as follows:

[0097] 1200 kg of 4,4'-dinitrodiphenyl ether was dissolved in 5000 kg of N,N-dimethylformamide (DMF). 24 kg of Raney nickel was added to displace the hydrogen and pressurized to 0.5 MPa. The temperature was raised to 90°C and the reaction was maintained at this temperature and pressure for 10 hours. The mixture was filtered, and 6 kg of polymethylsiloxane was added to the filtrate. The stirrer was adjusted to 245 rpm and stirred at 75°C for 1 hour, 65°C for 1 hour, 55°C for 1 hour, and 45°C for 1 hour. A large amount of solid precipitated during the stirring process. After stirring, the resulting liquid was centrifuged, the solid was collected, slurried in 5000 kg of water, centrifuged, and dried. The yield was 98.6% and the purity was 99.9%.

[0098] The results showed that the gradient cooling method can also be used to prepare high-quality crystals, and the yield and product purity are not significantly affected. Therefore, the gradient cooling process is adopted in the final industrial production.

[0099] The above embodiments are preferred examples of the present invention and are not intended to limit the scope of protection of the present invention.

[0100] All documents mentioned in this application are incorporated herein by reference, just as if each document were incorporated herein by reference individually. It should also be understood that after reading the above teachings of the present invention, those skilled in the art may make various changes or modifications to the present invention, and that such equivalents also fall within the scope of the claims appended hereto.

Claims

1. A method for producing 4,4'-diaminodiphenyl ether, characterized in that: The steps include: (A) performing a hydrogenation reaction on 4,4'-dinitrodiphenyl ether to obtain a first feed solution containing 4,4'-diaminodiphenyl ether; (B) adding polymethyl hydrogen siloxane to the first liquid obtained in step A, fully dispersing the polymethyl hydrogen siloxane to obtain a second liquid, cooling the liquid for crystallization, and thereby obtaining solid 4,4'-diaminodiphenyl ether.

2. The production method according to claim 1, characterized in that In the step (B), before, during or after the dispersion, the temperature of the first liquid and the second liquid is maintained at 70-80°C.

3. The production method according to claim 1, characterized in that The amount of the polymethylhydrogensiloxane added is 0.1-1.0 wt %, preferably 0.2-0.8 wt %, more preferably 0.4-0.6 wt % of 4,4'-dinitrodiphenyl ether, based on the amount of material added in step (A).

4. The production method according to claim 1, characterized in that The step (B) further comprises: stirring the second liquid during the cooling and crystallization process.

5. The production method according to claim 4, characterized in that The stirring speed is 100-300 rpm, preferably 100-280 rpm, more preferably 100-245 rpm.

6. The production method according to claim 4, characterized in that The stirring temperature is 45-80°C, preferably 55-80°C, more preferably 65-80°C.

7. The production method according to claim 1, characterized in that The step (B) further comprises: controlling the cooling rate during the crystallization to be 5-20°C / h.

8. The production method according to claim 1, characterized in that The cooling crystallization is a gradient cooling crystallization, which includes the following steps: starting from the stirring temperature, cooling at least twice, and each cooling range is 5-20°C (preferably 10-15°C), and stirring for 30-60 minutes after each cooling.

9. The production method according to claim 1, characterized in that The step (B) further comprises: after the cooling and crystallization, mixing the obtained solid with water and slurrying, and then separating to obtain a purified solid product.

10. The production method according to claim 9, characterized in that The volume / mass ratio of the amount of water added to the obtained solid is (3-8):1 (L / g), preferably (4-7):1 (L / g).

11. The production method according to claim 1, characterized in that The step (A) further comprises: (i) providing a reaction solution, wherein the reaction solution comprises: an inert solvent, and 4,4'-dinitrodiphenyl ether and a hydrogenation catalyst dispersed in the inert solvent; (ii) hydrogen gas is introduced into the reaction system to carry out a hydrogenation reaction.

12. The production method according to claim 11, characterized in that The catalyst is selected from the group consisting of Raney nickel, Pd / C, Pt / C, or a combination thereof.

13. The production method according to claim 11, characterized in that In the step (ii), the pressure of the hydrogen introduced is 0.1-1.0 MPa, preferably 0.2-0.8 MPa, more preferably 0.4-0.6 MPa.

14. The production method according to claim 11, characterized in that The inert solvent is selected from the group consisting of DMF, toluene, water, or a combination thereof.

15. The production method according to claim 11, characterized in that The volume / mass ratio of the inert solvent to the 4,4'-dinitrodiphenyl ether is (3-5):1 (L / g).

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