A preparation method of 3,3'-diaminophenolphthalein

Abstract

The present invention belongs to the technical field of chemical raw material preparation, and particularly relates to a preparation method of 3,3'-diaminophenolphthalein. The method includes: mixing 3,3'-dinitrophenolphthalein, Pd / C catalyst and tetrahydrofuran, and performing a hydrogenation reaction to obtain a reaction solution containing 3,3'-diaminophenolphthalein. The preparation method has a simple reaction process, low requirements for the reaction device, does not require high temperature, has mild conditions, short reaction time, reduces the risk of the hydrogenation reduction reaction, and is suitable for large-scale production; moreover, there are no reaction by-products, and high-purity products can be directly obtained through sedimentation, filtration and drying, with a high product yield of over 85% and a purity of over 99%.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical raw material preparation, and particularly relates to a preparation method of 3,3'-diaminophenolphthalein. Background Art

[0002] Aromatic polyimide has the advantages of high mechanical properties, high temperature resistance, chemical corrosion resistance and good chemical stability, and is an excellent gas separation membrane material. When its chemical main chain has a bulky group (such as phenolphthalein), it has the advantages of high free volume, high gas permeability and selectivity. In addition, when polyimide is synthesized from 3,3'-diaminophenolphthalein, the hydroxyl functional group adjacent to the imino group can undergo a thermally rearranged reaction with it under high temperature conditions to form a polybenzimidazole structure with more excellent gas separation performance.

[0003] The existing patent CN102391226A discloses a synthesis method of 3,3'-diaminophenolphthalein. The synthesis steps are as follows: dissolve 3,3'-dinitrophenolphthalein in ethanol or methanol, use Pd / C or Raney-Ni as a catalyst, and perform hydrogenation reduction under normal pressure conditions to obtain 3,3'-diaminophenolphthalein. The reaction temperature is 30-70°C, the reaction time requires 4-12h, the single batch product is only 2-3g, and the product needs to be purified by recrystallization, resulting in a low yield. The preparation method in this patent has a long reaction time and low yield, is not suitable for large-scale production, and limits the preparation scale of polyimide with 3,3'-diaminophenolphthalein as a monomer and the research and industrial development of polyimide hollow fiber membranes.

[0004] Therefore, a preparation method of 3,3'-diaminophenolphthalein with a short reaction time and high yield is necessary. Summary of the Invention

[0005] Aiming at the above problems, the purpose of the present invention is to provide a preparation method of 3,3'-diaminophenolphthalein. The yield of this method can reach more than 85%, the reaction conditions are relatively mild, the reaction steps are simple, and it is suitable for large-scale production.

[0006] In order to achieve the above purpose, the following technical solutions can be adopted:

[0007] On the one hand, the present invention provides a preparation method of 3,3'-diaminophenolphthalein, including: mixing 3,3'-dinitrophenolphthalein, Pd / C catalyst and tetrahydrofuran, and performing a hydrogenation reaction to obtain a reaction solution containing 3,3'-diaminophenolphthalein.

[0008] Specifically, the structural formula of 3,3'-diaminophenolphthalein is shown as formula I below:

[0009]

[0010] Further, in some embodiments of the above preparation method, the addition amount of tetrahydrofuran can be 5 mL - 7 mL of tetrahydrofuran per gram of 3,3'-dinitrophenolphthalein.

[0011] Further, in some embodiments of the above preparation method, the reaction time can be 1.5 hours - 8 hours, such as 2 hours, 3 hours or 5 hours, etc.

[0012] Further, in some embodiments of the above preparation method, the pressure of the hydrogenation reaction can be 0.3 MPa - 5 Mpa, such as 2 Mpa - 5 Mpa, such as 3 Mpa, 4 Mpa or 4.5 Mpa, etc.

[0013] Further, in some embodiments of the above preparation method, the Pd / C catalyst is a 5% or 10% Pd / C catalyst.

[0014] Further, in some embodiments of the above preparation method, the dosage of the Pd / C catalyst is 5% - 10% of the mass of 3,3'-dinitrophenolphthalein, such as 6%, 7%, 8% or 9%, etc.

[0015] Further, in some embodiments of the above preparation method, the temperature of the hydrogenation reaction can be 20°C - 30°C, such as 25°C, 26°C or 27°C.

[0016] Further, in some embodiments of the above preparation method, the reaction solution containing 3,3'-diaminophenolphthalein is removed of the Pd / C catalyst, and the filtrate after removing the Pd / C catalyst is mixed with water at 2°C - 5°C and allowed to stand for precipitation, and then filtered and dried to obtain 3,3'-diaminophenolphthalein.

[0017] Further, in some embodiments of the above preparation method, the drying temperature is 50°C - 55°C, such as 52°C or 54°C, etc.

[0018] Further, in some embodiments of the above preparation method, the addition amount of water at 2°C - 5°C can be 1 - 3 times the volume of tetrahydrofuran.

[0019] Further, in some embodiments of the above preparation method, a reaction device that can increase the contact surface between hydrogen and the reaction solution can be selected, such as a self-priming reactor agitator, which can greatly improve the reaction rate, shorten the reaction time, and increase the reaction yield.

[0020] It should be noted that the present invention is based on the preparation method of 3,3'-diaminophenolphthalein disclosed in Patent CN102391226A, and research, analysis and experimental improvement have been carried out on the problems existing in the preparation and scale-up process:

[0021] (1) In this patent, under the conditions of a reaction temperature of 30 - 70 °C and a reaction pressure of normal pressure or increased pressure, by-products will appear. When the crude product is separated and purified by silica gel column chromatography, the eluent is dichloromethane:methanol = 6:1. After separating the by-products, through test analysis, the by-product is 2-(bis(3-amino-4-hydroxyphenyl)methyl)benzoic acid, that is, the lactone ring is opened. By changing the reaction temperature to 20 °C - 30 °C at room temperature, no by-products will appear, and pure 3,3'-diaminophenolphthalein can be obtained.

[0022] (2) When the solvent selected in this patent is ethanol / methanol, the solubility of 3,3'-dinitrophenolphthalein in it is low, the reaction time is long, and there is still unreacted nitrophenolphthalein after the reaction ends. Moreover, due to the low solubility of 3,3'-diaminophenolphthalein in ethanol / methanol, there will be product loss when filtering the catalyst after the reaction ends, resulting in a low yield. After changing the solvent to tetrahydrofuran, the solubility of 3,3'-dinitrophenolphthalein in it is good, which provides its mass concentration in the solvent, increases the contact frequency between 3,3'-dinitrophenolphthalein and hydrogen, and speeds up the reaction rate, enabling the reaction to proceed completely. Generally, a protic solvent such as ethanol or methanol is selected for the hydrogenation reaction, which can provide a hydrogen bond donor. In the experimental exploration of this invention, it is found that using the aprotic solvent tetrahydrofuran has a very good effect.

[0023] (3) In this patent, the reaction is carried out at normal pressure in a three-necked flask, the reaction time is long, and at the same time, it is found in the experiment that the sealing is not good, causing air to enter. Since amine substances are sensitive to oxygen, the reaction terminates. When changing to a reaction kettle for pressurized reaction, the sealing is good, and increasing the pressure can speed up the reaction rate.

[0024] (4) In order to increase the contact amount between hydrogen and the reaction solution, a self-priming reaction kettle stirrer is used. The self-priming stirrer can make the contact between hydrogen and the reactants more complete, enabling hydrogen to enter the interior of the solution, no longer being limited to only the surface of the solution being able to contact hydrogen, increasing the gas-liquid contact area, enhancing the gas-liquid mass transfer process, greatly improving the reaction rate, shortening the reaction time, and increasing the reaction yield.

[0025] The beneficial effects of this invention at least include:

[0026] (1) The preparation method of 3,3'-diaminophenolphthalein provided by this invention has a simple reaction process, low requirements for the reaction device, does not require high temperature, has mild conditions, short reaction time, reduces the danger of the hydrogenation reduction reaction, and is suitable for large-scale production.

[0027] (2) In the preparation method of 3,3'-diaminophenolphthalein provided by this invention, there are no reaction by-products. High-purity products can be directly obtained through sedimentation, filtration, and drying. The product yield is high, reaching more than 85%, and the purity reaches more than 99%. Detailed implementation mode

[0028] The examples given are for better illustration of the present invention, but the content of the present invention is not limited to the examples given. Therefore, those skilled in the art can make non-essential improvements and adjustments to the implementation solutions based on the above-mentioned invention content, and it still falls within the protection scope of the present invention.

[0029] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. Unless there is an obvious different meaning in the context, the singular form of the expression includes the plural form of the expression. As used herein, it should be understood that terms such as "including", "having", "containing" are intended to indicate the existence of features, numbers, operations, components, parts, elements, materials or combinations. The terms of the present invention are disclosed in the specification, and it is not intended to exclude the possibility that one or more other features, numbers, operations, components, parts, elements, materials or their combinations may exist or can be added. As used herein, depending on the situation, " / " can be interpreted as "and" or "or".

[0030] Example 1

[0031] Weigh 6.0 g of 3,3'-dinitrophenolphthalein and place it in a 300 mL high-pressure reactor. Add 36 mL of tetrahydrofuran, stir to dissolve the dinitrophenolphthalein, then add 0.6 g of 10% Pd / C, tighten the reactor lid, and fill it with nitrogen to check the airtightness. After replacing the air with nitrogen three times, introduce hydrogen. After replacing nitrogen three times, fill the hydrogen pressure to 1.0 MPa, turn on the stirrer, with a rotation speed of 650 r / min and a temperature of 25 °C. After reacting for 2 h, the pressure in the reactor remains unchanged. Take a small amount of sample from the discharge pipe for thin-layer chromatography detection and analysis. After passing the analysis, open the reactor, pour out the reaction product, filter to remove the Pd / C catalyst, pour the filtrate into ice deionized water, place it in a refrigerator at 0 °C - 6 °C for cooling crystallization, precipitate solid particles, filter, wash with ice deionized water, and place it in a vacuum oven for drying at 55 °C. Obtain 4.366 g of white-yellow solid 3,3'-diaminophenolphthalein, with a yield of 85.3%.

[0032] Example 2

[0033] Weigh 16.0 g of 3,3′-dinitrophenolphthalein and place it in a 300 mL high-pressure reactor. Add 90 mL of tetrahydrofuran and stir to dissolve the dinitrophenolphthalein. Then add 1.5 g of 10% Pd / C, tighten the reactor lid, and fill it with nitrogen to check the airtightness. After replacing the air with nitrogen three times, introduce hydrogen. After replacing the nitrogen three times, fill the hydrogen pressure to 1.0 MPa, turn on the stirrer with a rotation speed of 750 r / min, and keep the temperature at 25 °C. When the hydrogen pressure drops to 0.5 MPa, continue to fill the hydrogen pressure to 1.0 MPa. After reacting for 6 h, when the pressure in the reactor remains unchanged, take a small amount of sample from the discharge pipe for thin-layer chromatography detection and analysis. After passing the analysis, open the reactor, pour out the reaction product, filter to remove the Pd / C catalyst, pour the filtrate into ice-cold deionized water, place it in a refrigerator at 0 - 6 °C for cooling crystallization to precipitate solid particles, filter, wash with ice-cold deionized water, and place it in a vacuum oven for drying at 55 °C. Obtain 11.90 g of white-yellow solid 3,3’-diaminophenolphthalein with a yield of 87.2%.

[0034] Example 3

[0035] Weigh 30 g of 3,3′-dinitrophenolphthalein and place it in a 300 mL high-pressure reactor with a self-priming stirrer. Add 190 mL of tetrahydrofuran and stir to dissolve the dinitrophenolphthalein. Then add 2.4 g of 10% Pd / C, tighten the reactor lid, and fill it with nitrogen to check the airtightness. After replacing the air with nitrogen three times, introduce hydrogen. After replacing the nitrogen three times, fill the hydrogen pressure to 2.0 MPa, turn on the stirrer with a rotation speed of 750 r / min, and keep the temperature at 25 °C. When the hydrogen pressure drops to 0.5 MPa, continue to fill the hydrogen pressure to 2.0 MPa. After reacting for 4.3 h, when the pressure in the reactor remains unchanged, take a small amount of sample from the discharge pipe for thin-layer chromatography detection and analysis. After passing the analysis, open the reactor, pour out the reaction product, filter to remove the Pd / C catalyst, pour the filtrate into ice-cold deionized water, place it in a refrigerator at 0 °C - 6 °C for cooling crystallization to precipitate solid particles, filter, wash with ice-cold deionized water, and place it in a vacuum oven for drying at 55 °C. Obtain 22.42 g of white-yellow solid 3,3’-diaminophenolphthalein with a yield of 87.6%.

[0036] Example 4

[0037] Weigh 1000 g of 3,3'-dinitrophenolphthalein and place it in a 10 L high-pressure reactor equipped with a self-priming stirrer. Add 650 mL of tetrahydrofuran and stir to dissolve the dinitrophenolphthalein. The solution turns into a clear and transparent red liquid. Then add 7.3 g of 10% Pd / C, tighten the reactor lid, and fill it with nitrogen to check the airtightness. After replacing the air with nitrogen three times, introduce hydrogen. After replacing nitrogen with hydrogen three times, fill the hydrogen pressure to 5.0 MPa, turn on the stirrer with a rotation speed of 750 r / min, and the temperature is 25 °C. When the hydrogen pressure drops to 1 MPa, continue to fill the hydrogen pressure to 5.0 MPa. After reacting for 8 h, the pressure in the reactor remains unchanged. Take a small amount of sample from the discharge pipe for thin-layer chromatography detection and analysis. After passing the analysis, open the reactor, pour out the reaction product, filter to remove the Pd / C catalyst, pour the filtrate into ice-cold deionized water, place it in a refrigerator at 0 °C - 6 °C for cooling crystallization, precipitate solid particles, filter, wash with ice-cold deionized water, and place it in a vacuum oven at 55 °C for drying. Obtain 77.88 g of white-yellow solid 3,3'-diaminophenolphthalein, with a yield of 91.3%.

[0038] Example 5

[0039] The experimental process of this example repeats that of Example 2, except that the reactor used in this example is a self-priming high-pressure reactor, and other reaction conditions and experimental operations are the same as those in Example 2. The final reaction time is 3 hours, and 12.28 g of 3,3'-diaminophenolphthalein is obtained, with a yield of 90%.

[0040] Comparative Example 1

[0041] Weigh 6.0 g of 3,3'-dinitrophenolphthalein and place it in a 250 mL three-necked flask. Add 36 mL of tetrahydrofuran and stir to dissolve the dinitrophenolphthalein. Then add 0.6 g of 10% Pd / C, seal the reaction device, and evacuate it for half an hour. Introduce hydrogen at atmospheric pressure and stir the reaction at 55 °C for 15 hours. After the reaction is completed, filter to remove the Pd / C catalyst, pour the filtrate into ice-cold deionized water, and filter the precipitated solid particles; liquid chromatography-mass spectrometry shows that the conversion rate of 3,3'-dinitrophenolphthalein is 100%, but the selectivity is 38%. By separating and purifying the crude product by silica gel column chromatography and analyzing it using mass spectrometry and nuclear magnetic resonance hydrogen spectroscopy, the by-product is 2-(bis(3-amino-4-hydroxyphenyl)methyl)benzoic acid.

[0042] Comparative Example 2

[0043] Weigh 6.0 g of 3,3′-dinitrophenolphthalein and place it in a 300 mL high-pressure reactor. Add 36 mL of tetrahydrofuran and stir to dissolve the dinitrophenolphthalein. Then add 0.6 g of 10% Pd / C, tighten the reactor lid, and fill it with nitrogen to check the airtightness. After replacing the air with nitrogen three times, introduce hydrogen. After replacing nitrogen with hydrogen three times, fill the hydrogen pressure to 1.0 MPa, turn on the stirrer with a rotation speed of 650 r / min, and the reaction temperature is 55 °C. After reacting for 2 h, the pressure in the reactor remains unchanged. Take a small amount of sample from the discharge pipe for thin-layer chromatography detection and analysis. The analysis shows that there is a by-product 2-(bis(3-amino-4-hydroxyphenyl)methyl)benzoic acid generated. Open the reaction kettle, pour out the reaction product, filter to remove the Pd / C catalyst, pour the filtrate into ice-cold deionized water, precipitate solid particles, filter, wash with ice-cold deionized water, and place it in a vacuum oven at 55 °C for drying. The crude product is separated and purified by silica gel column chromatography to obtain 1.79 g of 3,3’-diaminophenolphthalein with a yield of 35%.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A preparation method of 3,3'-diaminophenolphthalein, characterized in that, Comprising: 3,3'-dinitrophenolphthalein, Pd / C catalyst and tetrahydrofuran are mixed and subjected to a hydrogenation reaction to obtain a reaction solution containing 3,3'-diaminophenolphthalein; the temperature of the hydrogenation reaction is 20°C - 25°C; the pressure of the hydrogenation reaction is 0.3 MPa - 5 MPa; the structural formula of 3,3'-diaminophenolphthalein is shown as formula I below:

2. The preparation method of 3,3'-diaminophenolphthalein according to claim 1, characterized in that, The Pd / C catalyst is a 5% or 10% Pd / C catalyst.

3. The preparation method of 3,3'-diaminophenolphthalein according to claim 1 or 2, characterized in that, The dosage of the Pd / C catalyst is 5% - 10% of the mass of 3,3'-dinitrophenolphthalein.

4. The preparation method of 3,3'-diaminophenolphthalein according to claim 1, characterized in that, The Pd / C catalyst is removed from the reaction solution containing 3,3'-diaminophenolphthalein, the filtrate after removing the Pd / C catalyst is mixed with water at 2°C - 5°C, allowed to stand for precipitation, and filtered and dried to obtain 3,3'-diaminophenolphthalein.

5. The preparation method of 3,3'-diaminophenolphthalein according to claim 4, characterized in that, The drying temperature is 50°C - 55°C.

6. The preparation method of 3,3'-diaminophenolphthalein according to claim 1, 2, 4 or 5, characterized in that, The hydrogenation reaction is carried out in a self-priming stirring reactor.

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