A method for reducing the by-product azobenzene in the RT-ferment condensate

Abstract

The application discloses a method for reducing by-product azobenzene in RT-PCR condensation liquid, and the method comprises the following steps: inputting tetramethylammonium hydroxide, aniline, nitrobenzene and polyethylene imine type activated carbon into the condensation reaction; catalyzing the condensation reaction of aniline and nitrobenzene by the tetramethylammonium hydroxide to obtain a condensation liquid; separating the polyethylene imine type activated carbon and the condensation liquid; using the polyethylene imine type activated carbon for the condensation reaction; and preparing RT-PCR by catalyzing hydrogenation of the condensation liquid. The application greatly reduces the generation of by-product azobenzene in the condensation reaction by using the polyethylene imine type activated carbon, improves the selectivity of the condensation reaction, simultaneously reduces the absorption of carbon dioxide in the air by the system material, slows down the increase of tetramethyl carbonate, prolongs the catalytic life of the tetramethylammonium hydroxide, saves the raw material cost, and has a good application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fine chemical industry, and particularly relates to a method for reducing by-product azobenzene in RT-PS condensation liquid. BACKGROUND

[0002] RT-PS (p-aminodiphenylamine) is widely used in rubber additives, dyes, textiles, printing and pharmaceutical industries, and is mainly used in rubber antioxidant 4010NA, 6PPD, etc.

[0003] At present, the production process of RT-PS (p-aminodiphenylamine) prepared by nitrobenzene method mainly uses nitrobenzene and aniline as raw materials, and tetramethylammonium hydroxide as a condensation catalyst. After the condensation is completed, the condensation liquid is input into a reduction device, and methanol is added in the presence of a reduction catalyst. After reduction is completed, filtration and separation are performed, the organic base and solvent methanol are recovered from the water phase, and the organic phase is input into a rectification process to obtain the product RT-PS.

[0004] As shown in the following formula, under the catalysis of tetramethylammonium hydroxide, nitrobenzene and aniline condensation not only generates the target product 4-nitrodiphenylamine (D) and 4-nitrosodiphenylamine (C), but also generates by-products azobenzene (B) and phenazine (A).

[0005]

[0006] Chinese patent CN1735587A discloses a method for preparing an intermediate of 4-aminodiphenylamine, which reacts aniline or its derivative with nitrobenzene in a defined area in the presence of a mixture containing an alkali and an oxidant containing hydrogen peroxide, wherein the amount of hydrogen peroxide is about 0.01 mol to 0.60 mol per mol of nitrobenzene. The use of hydrogen peroxide has the advantage of greatly reducing the generation amount of azobenzene. Without adding hydrogen peroxide, the mass content of azobenzene in the condensation liquid is 2.01%, and by adding 5% to 35% of different mass concentrations of hydrogen peroxide aqueous solution, the mass content of azobenzene in the condensation liquid is 0.79% to 1.22%. The mass content of hydrogen peroxide solution used in the patent is greater than 8%, which is an explosive chemical, and hydrogen peroxide is in the list of class III carcinogens.

[0007] The generation of by-products affects the selectivity of the condensation reaction, increases the production cost of RT-PS, increases the difficulty of subsequent rectification and separation, and affects the quality of RT-PS product. SUMMARY

[0008] The application aims to provide a method for reducing by-product azobenzene in RT-PS condensation liquid, which is intended to solve the problems of high generation amount of by-product azobenzene in the existing RT-PS condensation reaction and low selectivity of the condensation reaction, and improve the quality of RT-PS.

[0009] The application discloses a method for reducing byproduct azobenzene in RT-PEPS condensation liquid, and mainly adds polyethylene imine type activated carbon in the condensation reaction to reduce the generation of byproduct azobenzene in the condensation reaction, and improve the selectivity of the condensation reaction.

[0010] The polyethylene imine contains a large number of amine groups, including primary amine, secondary amine and tertiary amine, which can effectively reduce the free nitrobenzene in the condensation liquid to attack the complex formed by the combination of the negatively charged aniline and nitrobenzene, reduce the formation of nitrosobenzene, thereby reducing the azobenzene generated by the combination of nitrosobenzene and aniline; meanwhile, the polyethylene imine type activated carbon can adsorb acidic substances in the system materials, slow down the increase of tetramethylammonium salt, prolong the catalytic life of tetramethylammonium hydroxide, and save the raw material cost.

[0011] Generally, the polyethylene imine type activated carbon treatment step is as follows: 1) preparing a solution by using polyethylene imine, diethylenetriamine and ethanol; 2) immersing activated carbon in the prepared solution; 3) taking out the soaked activated carbon and solidifying; and 4) constant temperature drying the solidified product to obtain the polyethylene imine type activated carbon.

[0012] Further, the polyethylene imine type activated carbon treatment step is as follows: 1) preparing a solution by using 10-30 parts of polyethylene imine, 1-5 parts of diethylenetriamine and 67-87 parts of ethanol; 2) immersing activated carbon in the prepared solution for 4-8 hours; 3) taking out the soaked activated carbon and solidifying at a temperature of 70-90 DEG C for 1.5-3.5 hours; and 4) constant temperature drying the solidified product at a temperature of 70-90 DEG C to obtain the polyethylene imine type activated carbon.

[0013] Generally, the method for reducing byproduct azobenzene in RT-PEPS condensation liquid is as follows: inputting tetramethylammonium hydroxide, aniline, nitrobenzene and polyethylene imine type activated carbon into a condensation reactor, catalyzing the condensation reaction of aniline and nitrobenzene by the tetramethylammonium hydroxide to obtain a condensation liquid, separating the polyethylene imine type activated carbon from the condensation liquid, using the polyethylene imine type activated carbon for the condensation reaction, and preparing RT-PEPS by catalytic hydrogenation of the condensation liquid.

[0014] Further, the aniline is fresh aniline and / or recycled aniline, and the tetramethylammonium hydroxide is fresh tetramethylammonium hydroxide and / or recycled tetramethylammonium hydroxide.

[0015] Further, the condensation reaction temperature is 60-80 DEG C.

[0016] Further, the condensation reaction is carried out under a certain vacuum, and the vacuum pressure is-0.088 MPa to-0.094 MPa.

[0017] Compared with the prior art, the application has the following advantages:

[0018] 1. By using polyethylene imine type activated carbon, the generation of by-product azobenzene in the RT-Persee condensation solution can be reduced, and the selectivity of the RT-Persee condensation reaction can be improved.

[0019] 2. The polyethylene imine type activated carbon can protect the condensation reaction catalyst tetramethyl ammonium hydroxide, improve the service life and selectivity of the catalyst, reduce the conversion of tetramethyl ammonium hydroxide into tetramethyl carbonate, and reduce the cost of raw materials. Embodiment

[0020] The application will be described in detail below with reference to examples.

[0021] (The percentages below are all mass percentages)

[0022] Comparative Example (without using polyethylene imine type activated carbon)

[0023] Fresh tetramethyl ammonium hydroxide solution 25% 118.5 g, fresh aniline 150.0 g, nitrobenzene 40.0 g were added to the reactor, and the condensation reaction was carried out under the control of reaction vacuum pressure-0.092 MPa and reaction temperature 70°C, and the condensation reaction time was 4 h. The condensation solution was obtained, and the content of each substance in the condensation solution was analyzed by liquid chromatography: aniline 47.32%, nitrobenzene 0.31%, 4-nitrosodiphenylamine 28.86%, 4-nitrodiphenylamine 2.71%, azobenzene 2.19%, phenazine 0.25%. The selectivity of the target products 4-nitrosodiphenylamine and 4-nitrodiphenylamine was calculated to be 92.00%, the selectivity of azobenzene was 6.99%, and the content of tetramethyl carbonate was 0.81% after 5 times of tetramethyl ammonium hydroxide reuse.

[0024] Example 1

[0025] Preparation of polyethylene imine type activated carbon: 20 parts of polyethylene imine, 3 parts of diethylenetriamine, and 77 parts of ethanol were prepared into a solution; the activated carbon was immersed in the prepared solution, and the soaking time was 6 h; the soaked activated carbon was taken out and solidified, the solidification temperature was 80°C, and the solidification time was 2.5 h; the solidified product was subjected to constant temperature drying, and the drying temperature was 80°C, to obtain the polyethylene imine type activated carbon.

[0026] The polyethyleneimine type activated carbon prepared above 40 g, fresh tetramethylammonium hydroxide 25% solution 118.5 g, fresh aniline 150.0 g, nitrobenzene 40.0 g were added to the reactor, the reaction vacuum pressure was controlled at -0.092 MPa, the reaction temperature was 70°C, the condensation reaction was carried out, the condensation reaction time was 4 h, after the reaction was completed, the polyethyleneimine type activated carbon and the condensation liquid were separated, the organic matter content in the condensation liquid was analyzed by liquid chromatography: aniline 47.13%, nitrobenzene 0.29%, 4-nitrosodiphenylamine 30.11%, 4-nitrosodiphenylamine 1.32%, azobenzene 0.80%, phenazine 0.24%, the selectivity of the target product 4-nitrosodiphenylamine and 4-nitrosodiphenylamine was calculated to be 96.51%, the selectivity of azobenzene was 2.68%, and the tetramethylammonium carbonate content was 0.20% after the tetramethylammonium hydroxide was reused for 5 times.

[0027] Example 2

[0028] The polyethyleneimine type activated carbon prepared in Example 1 40 g, fresh tetramethylammonium hydroxide 25% solution 118.5 g, fresh aniline 150.0 g, nitrobenzene 40.0 g were added to the reactor, the reaction vacuum pressure was controlled at -0.094 MPa, the reaction temperature was 65°C, the condensation reaction was carried out, the condensation reaction time was 4 h, after the reaction was completed, the polyethyleneimine type activated carbon and the condensation liquid were separated, the organic matter content in the condensation liquid was analyzed by liquid chromatography: aniline 47.28%, nitrobenzene 0.33%, 4-nitrosodiphenylamine 30.17%, 4-nitrosodiphenylamine 1.29%, azobenzene 0.71%, phenazine 0.21%, the selectivity of the target product 4-nitrosodiphenylamine and 4-nitrosodiphenylamine was calculated to be 96.90%, the selectivity of azobenzene was 2.38%, and the tetramethylammonium carbonate content was 0.19% after the tetramethylammonium hydroxide was reused for 5 times.

[0029] Example 3

[0030] The polyethyleneimine type activated carbon prepared in Example 1 40 g, fresh tetramethylammonium hydroxide 25% solution 118.5 g, fresh aniline 150.0 g, nitrobenzene 40.0 g were added to the reactor, the reaction vacuum pressure was controlled at -0.088 MPa, the reaction temperature was 75°C, the condensation reaction was carried out, the condensation reaction time was 4 h, after the reaction was completed, the polyethyleneimine type activated carbon and the condensation liquid were separated, the organic matter content in the condensation liquid was analyzed by liquid chromatography: aniline 46.12%, nitrobenzene 0.29%, 4-nitrosodiphenylamine 29.96%, 4-nitrosodiphenylamine 1.35%, azobenzene 0.87%, phenazine 0.27%, the selectivity of the target product 4-nitrosodiphenylamine and 4-nitrosodiphenylamine was calculated to be 96.17%, the selectivity of azobenzene was 2.91%, and the tetramethylammonium carbonate content was 0.22% after the tetramethylammonium hydroxide was reused for 5 times.

[0031] Example 4

[0032] Polyethyleneimine type activated carbon 40 g prepared in Example 1, recycled tetramethylammonium hydroxide 25% solution 118.5 g, recycled aniline 150.0 g, nitrobenzene 40.0 g were added to the reactor, the condensation reaction was carried out by controlling the reaction vacuum pressure-0.092 MPa and the reaction temperature 70°C, the condensation reaction time was 4 h, after the reaction was completed, the polyethyleneimine type activated carbon and the condensation liquid were separated, the organic matter content in the condensation liquid was analyzed by liquid chromatography: aniline 46.09%, nitrobenzene 0.31%, 4-nitrosodiphenylamine 29.13%, 4-nitrodiphenylamine 1.34%, azobenzene 0.83%, phenazine 0.25%, the selectivity of the target products 4-nitrosodiphenylamine and 4-nitrodiphenylamine was calculated to be 96.27%, the selectivity of azobenzene was 2.86%, and the tetramethyl carbonate content was 0.21% after the tetramethylammonium hydroxide was reused for 5 times.

[0033] Example 5

[0034] Preparation of polyethyleneimine type activated carbon: a solution was prepared by using 25 parts of polyethyleneimine, 5 parts of diethylenetriamine and 70 parts of ethanol; the activated carbon was immersed in the prepared solution, the soaking time was 8 h; the soaked activated carbon was taken out and solidified, the solidification temperature was 88°C, and the solidification time was 1.5 h; the solidified product was subjected to constant temperature drying at a drying temperature of 88°C to obtain the polyethyleneimine type activated carbon.

[0035] Polyethyleneimine type activated carbon 30 g prepared above, fresh tetramethylammonium hydroxide 25% solution 118.5 g, fresh aniline 150.0 g, nitrobenzene 40.0 g were added to the reactor, the condensation reaction was carried out by controlling the reaction vacuum pressure-0.092 MPa and the reaction temperature 70°C, the condensation reaction time was 4 h, after the reaction was completed, the polyethyleneimine type activated carbon and the condensation liquid were separated, the organic matter content in the condensation liquid was analyzed by liquid chromatography: aniline 47.15%, nitrobenzene 0.28%, 4-nitrosodiphenylamine 30.14%, 4-nitrodiphenylamine 1.29%, azobenzene 0.77%, phenazine 0.23%, the selectivity of the target products 4-nitrosodiphenylamine and 4-nitrodiphenylamine was calculated to be 96.64%, the selectivity of azobenzene was 2.58%, and the tetramethyl carbonate content was 0.18% after the tetramethylammonium hydroxide was reused for 5 times.

[0036] Example 6

[0037] Polyethyleneimine type active carbon 40 g prepared in Example 5, fresh tetramethylammonium hydroxide 25% solution 118.5 g, fresh aniline 150.0 g, nitrobenzene 40.0 g were added to a reactor, and condensation reaction was performed under the conditions of vacuum pressure -0.094 MPa and reaction temperature 68°C for 4 hours. After the reaction, polyethyleneimine type active carbon and condensation liquid were separated, and the content of organic substances in the condensation liquid was analyzed by liquid chromatography: aniline 47.01%, nitrobenzene 0.23%, 4-nitrosodiphenylamine 30.04%, 4-nitrodiphenylamine 1.27%, azobenzene 0.69%, phenazine 0.22%. The selectivity of the target products 4-nitrosodiphenylamine and 4-nitrodiphenylamine was 96.92%, and the selectivity of azobenzene was 2.33%. Tetramethylammonium hydroxide was reused 5 times, and the content of tetramethylammonium carbonate was 0.17%.

[0038] Example 7

[0039] Polyethyleneimine type active carbon 50 g prepared in Example 5, recycled tetramethylammonium hydroxide 25% solution 118.5 g, recycled aniline 150.0 g, nitrobenzene 40.0 g were added to a reactor, and condensation reaction was performed under the conditions of vacuum pressure -0.092 MPa and reaction temperature 69°C for 4 hours. After the reaction, polyethyleneimine type active carbon and condensation liquid were separated, and the content of organic substances in the condensation liquid was analyzed by liquid chromatography: aniline 45.13%, nitrobenzene 0.29%, 4-nitrosodiphenylamine 29.15%, 4-nitrodiphenylamine 1.36%, azobenzene 0.73%, phenazine 0.24%. The selectivity of the target products 4-nitrosodiphenylamine and 4-nitrodiphenylamine was 96.64%, and the selectivity of azobenzene was 2.52%. Tetramethylammonium hydroxide was reused 5 times, and the content of tetramethylammonium carbonate was 0.15%.

[0040] The present application can be summarized with other specific forms not departing from the spirit or main features of the present application. Therefore, the above-described embodiments of the present application can be considered as a description of the present application rather than a limitation of the present application, and the claims indicate the scope of the present application, and the above-described description does not indicate the scope of the present application, and thus any change within the meaning and scope equivalent to the claims of the present application should be considered as included in the scope of the claims.

Claims

1. A method for reducing the amount of by-product azobenzene in a RT- PEST condensate, characterized in that The polyethylene imine type activated carbon is input into the RT PEST condensation reaction, the generation of by-product azobenzene in the condensation reaction is reduced, and the selectivity of the condensation reaction is improved. Specifically, tetramethylammonium hydroxide, aniline, nitrobenzene and polyethylene imine type activated carbon are input into the condensation reactor. The tetramethylammonium hydroxide catalyzes the condensation reaction of aniline and nitrobenzene to obtain a condensation liquid. The polyethylene imine type activated carbon is separated from the condensation liquid. The polyethylene imine type activated carbon is used for the condensation reaction. The condensation liquid is used for catalytic hydrogenation to prepare RT PEST. The polyethylene imine type activated carbon treatment step is: 1) a solution is prepared from 10-30 parts of polyethylene imine, 1-5 parts of diethylenetriamine and 67-87 parts of ethanol; 2) the activated carbon is immersed in the prepared solution, and the immersion time is 4-8 hours; 3) the immersed activated carbon is taken out and solidified, the solidification temperature is 70-90 DEG C, and the solidification time is 1.5-3.5 hours; and 4) the solidified product is subjected to constant temperature drying, the drying temperature is 70-90 DEG C, and the polyethylene imine type activated carbon is obtained.

2. The method of claim 1, wherein the reducing of the byproduct azobenzene in the RT-ferment condensate is characterized by The aniline is fresh aniline and / or recycled aniline, and the tetramethylammonium hydroxide is fresh tetramethylammonium hydroxide and / or recycled tetramethylammonium hydroxide.

3. The method of claim 1, wherein the reducing of the byproduct azobenzene in the RT-ferment condensate is characterized by The condensation reaction temperature is 60-80 DEG C.

4. The method of claim 1, wherein the reducing of the byproduct azobenzene in the RT- PEST condensate is characterized by The condensation reaction is carried out under a vacuum pressure of -0.088 MPa to -0.094 MPa. ​

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