RU2369595C1 - Method of obtaining 4-aminodiphenylamine and intermediate products of its synthesis - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to obtaining 4-aminodiphenylamine and intermediate products of its synthesis, chosen from 4-nitrodiphenylamine and 4-nitrosodiphenylamine by reacting aniline and nitrobenzene in the presence of a catalyst, containing a quaternary ammonium group with formation of 4-nitrodiphenylamine and 4-nitrosodiphenylamine as intermediate products, with subsequent hydrogenation of the said intermediate products of the reaction after their extraction or directly in the reaction mass in the presence of a hydrogenation catalyst and a solvent in form of a lower alcohol or water, separation of the hydrogenation catalyst from the reaction mixture, obtaining aqueous and organic phases, which are separated with extraction of 4-aminodiphenylamine from the organic phase. The method is distinguished by that, the catalyst used at the stage for reacting aniline with nitrobenzene is a polymer high-basic anionite in OH-form, containing a quaternary ammonium group N(CH₃)₃ ⁺, and the reaction takes place in the presence of a base. The preferred molar ratio of aniline and nitrobenzene ranges from 3:1 to 7:1 and the ratio of base to nitrobenzene ranges from 0.9:1 to 1.5:1.

EFFECT: new compounds have useful biological properties.

3 cl, 3 tbl, 5 ex

Description

The invention relates to a low-waste method for producing 4-aminodiphenylamine (4-ADPA). The invention also relates to methods for producing 4-nitrodiphenylamine and / or 4-nitrosodiphenylamine, which are intermediates in the synthesis of 4-ADPA and alkylated n-phenylenediamines.

4-Aminodiphenylamine is widely used as an intermediate in the preparation of alkylated derivatives of 4-ADPA used as antiozonants, antioxidants and stabilizers of monomers and various polymeric materials.

A known method of producing 4-ADPA (US patent No. 5608111), in which aniline and nitrobenzene react in the presence of a base. Then water was added to the product, and the resulting reaction mixture was catalytically hydrogenated. The catalyst, which is usually a noble metal on a support, is removed from the hydrogenation reaction mixture. To isolate 4-ADPA, the organic phase is separated, and the aqueous phase, which contains the base, is returned to another cycle of the initial reaction mixture. In working examples, aniline and nitrobenzene are reacted in the presence of tetramethylammonium hydroxide (GTMA) used as a base, and water and aniline are removed during the condensation reaction as an azeotropic mixture.

US patent No. 5739403 describes a condensation reaction and subsequent catalytic hydrogenation, where the amount of added water is from 25 to 80 wt.% Relative to the weight of the condensation reaction mixture. After hydrogenation, toluene is added, the catalyst is filtered off and the organic and aqueous phases are separated. Example 1 indicates that: “Analysis of the aqueous phase shows that 99.7% of the incoming GTMA can be isolated. The resulting aqueous phase can be returned to the reaction without loss of reactivity. "

The disadvantage of this method is that the reactivity of the base recovered in the described method is in fact unknown. GTMA is an unstable compound and decomposes in a concentrated form and increases in temperature; therefore, it is forced to store and use it in the form of dilute aqueous solutions. But even in aqueous solutions at temperatures above 80 ° C, it decomposes with the formation of (CH ₃ ) ₃ N and CH ₃ OH, which leads to its loss and higher cost of the target product due to the high cost of GTMA (see Chemical encycl .. T .1, ed. Council. Enz., M., 1988, p. 152).

A known method (Russian patent No. 2225387), in which it was shown (example 7) that the degree of decomposition of GTMA at 80 ° C depends on the molar ratio of water to GTMA and is 2 and 0.2% in 2 hours at a molar ratio of water to GTMA equal to 5 and 2.7, respectively.

Known methods in which instead of expensive and unstable GTMA was proposed to use tetramethylammonium chloride (Russian patents No. 2265590, No. 2247712), various salts of quaternary ammonium bases (US patents No. 6395933, No. 6583320) in combination with a strong base, complex catalysts (US patents No. 7176333, No. 7235694), consisting of tetraalkylammonium hydroxide, alkali metal hydroxide and tetraalkylammonium salt.

The closest analogue (prototype) of the present invention is US patent 7235694, June 26, 2007, C07C 209/00. According to the prototype 4-ADPA obtained from aniline and nitrobenzene in 5 technological stages. At the first stage, aniline is condensed with nitrobenzene in the presence of a complex basic catalyst, at the second stage, the resulting reaction mixture is diluted with a solvent, which use lower alcohols or water, and hydrogenated with a nickel-aluminum catalyst at 50-100 ° C and 0.2- 3 MPa. The third stage of the process is the separation, recovery of the complex base catalyst and the powdered hydrogenation catalyst. These catalysts can be reused in the process. In the fourth stage, separation and purification of unreacted aniline is carried out for reuse; on the fifth, the purification of crude 4-ADPA to produce a marketable product. The disadvantage of this method is the use of thermally unstable quaternary ammonium compounds - GTMA and its salts as components of a complex main catalyst of the condensation stage. This imposes very strict requirements for maintaining the temperature regime in the first three stages of the technological process. Overheating of the reaction mass above 80 ° C leads to a significant acceleration of the decomposition of the catalyst, the formation of by-products and a decrease in the selectivity of the condensation and hydrogenation processes (see Russian patent 2225387). In addition, the use of organic polyesters at the stage of separation of the complex main catalyst leads to their accumulation in the recycling system, which in turn leads to additional costs for their separation and disposal, contamination of the product.

The objective of the present invention is to develop a method for producing 4-ADPA using a heterogeneous condensation catalyst, which will significantly simplify its separation from the reaction mass, remove strict technological limitations at other stages of the process, and improve technical and economic performance of the production. It is solved by carrying out the condensation process in the presence of a catalyst, which is used as a highly basic anion exchange resin containing a quaternary ammonium group ~ -N (CH ₃ ) ₃ ⁺ .

The invention and its distinguishing features

In accordance with the present invention, a method for producing 4-ADPA includes the following process steps:

1. The interaction of nitrobenzene with aniline in an alkaline medium in the presence of a polymer condensation catalyst, which is used as a highly basic anion exchange resin containing a quaternary ammonium group ~ -N (CH ₃ ) ₃ ⁺ .

2. Catalytic hydrogenation of the reaction products of stage (1) in the presence of a solvent, which is used as lower alcohols or water.

3. The separation of the hydrogenation catalyst from the reaction mixture and the regeneration of its properties.

4. Separation of the reaction mixture into aqueous and organic phases, extraction of excess aniline from the organic phase, purification and concentration of the aqueous phase in order to regenerate the alkaline agent.

5. Isolation from the remaining organic phase of marketable 4-ADPA and disposal of by-products.

A significant difference of the proposed method from the prototype is the use of highly basic anion exchange resin containing a quaternary ammonium group ~ -N (CH ₃ ) ₃ ⁺ as a condensation catalyst.

The use of a polymer catalyst eliminates the stage of its separation from the reaction mass, removes the stringent temperature and concentration restrictions at the subsequent stages of the process of obtaining 4-ADPA.

The method allows to reduce the cost of raw materials through the use of anion exchange resin, to reduce energy costs for the separation of reaction products. As a condensation catalyst, known highly porous strongly basic anion exchangers, such as AV-17P (Encyclopedia of Polymers. T.1, ed. Council, enz., M., 1974, p. 168; Slavinskaya G.V., Selemenev V .F., Kuznetsova N.S., Ponamarev A.N., Merzlikina A.A. Equilibrium of sorption of fulvic acids of natural waters by anion exchangers // Bulletin of the Voronezh State University. Series: Chemistry. Biology. Pharmacy. 2003. No. 2. P.66- 70), Amberlyst A26, Amberlyst A27 (product catalog of a subsidiary of the Dow Chemical Company - http://www.amberlyst.com/sba.htm), DOWEX MARATHON MSA, DOWEX UPCORE Mono MA-600, DOWEX MSA-1C, DOWEX MONOSPHERE MP-725A (Dow Chemical Com product catalog pany - http://www.dow.com/liquidseps/prod/sbati.htm), Tulsion A-74 MP (Thermax Limited product catalog -www.swtsamara.ru/files/catalog.doc), Purolite A500 (catalog Purolite products - http://www.purolite.com/ProductID/203/FolderID/60/Page Vars / Library / Products / ProductDetails.htm). Our studies have shown that the use of gel highly basic anion exchangers such as AB-17-8 leads to a decrease in their catalytic activity in the condensation reaction, due to the strong adsorption of the reaction products and the low mass transfer rate.

The condensation reaction of aniline with nitrobenzene can be carried out in a batch or continuous manner. The reaction unit consists of at least two main apparatuses: a reactor and a stripping vessel. As a reactor, you can use a reactor with a stirrer and a catalyst dispersed in the reaction mass or a shelf apparatus with a fixed catalyst bed. In the distillation tank, the azeotropic aniline-water mixture is distilled off under vacuum. The use of auxiliary distillation tank allows you to maintain optimal temperature conditions in the condensation reactor and removes the harsh temperature and concentration restrictions when removing water from the reaction mass.

When choosing the conditions for the condensation process, we took into account the results and recommendations of the above patents.

The molar ratio of aniline to nitrobenzene is from 1: 1 to 10: 1. Preferably, this ratio is in the range of 3: 1 to 7: 1. Aqueous solutions of sodium or potassium hydroxides are usually used as the base. For practical purposes, at the beginning of the process it is recommended to use a 30-40 wt.% Aqueous solution of sodium hydroxide.

For a more complete conversion of nitrobenzene and to prevent side reactions, during the reaction of aniline with nitrobenzene, water is distilled off and the molar ratio of water to base is carefully regulated. Since aniline is present in the reactor in a molar excess relative to nitrobenzene, water can be distilled off in the form of an azeotropic mixture of water and aniline. The molar ratio of water to base at the beginning of the condensation reaction is at least 4.5: 1, and at the end of the condensation reaction, when the degree of conversion of nitrobenzene is 98% or higher, this ratio is at least 1.0: 1. The process of removing water can be controlled by measuring the mass or volume of water in the distillate. It should be borne in mind that when calculating the components, the amount of base is the total amount of base present in the reactor, i.e. free base and / or base included in the salts of 4-nitroso and / or 4-nitrodiphenylamine. The amount of water includes water, which comes with the base, and water, which is formed during the condensation process.

The molar ratio of base to nitrobenzene can be in the range from 0.7: 1 to 4: 1, preferably in the range from 0.9: 1 to 1.5: 1. The temperature in the condensation reactor may vary from 20 to 60 ° C, preferably from 50 to 60 ° C; in a distant vessel from 50 to about 150 ° C, preferably from about 70 to 100 ° C. The pressure in the condensation step is maintained in the range of 20 to 200 mbar, preferably in the range of 50 to 150 mbar.

The condensation reaction time includes the time of addition of nitrobenzene plus the exposure time and it is 3.5-6 hours. The reaction mixture is stirred during the entire course of the condensation reaction. Mixing and circulation of the reaction mass in the reaction unit of the reactor - distillation tank is carried out using a circulation pump.

The reaction mixture was diluted with water and hydrogenated on a nickel-aluminum catalyst at 50-100 ° C and 0.2-3 MPa.

The separation of the hydrogenation catalyst from the reaction mixture and the regeneration of its properties is carried out by known methods.

Due to the absence of quaternary ammonium compounds in the reaction mass, its separation into the aqueous and organic phases proceeds much more efficiently than in the prototype. This, in turn, eliminates the use of organic polyesters at the separation stage, which improves the quality of the product and reduces its cost.

The absence of quaternary ammonium compounds in the reaction mass greatly facilitates the process of concentration of the aqueous phase in order to regenerate the alkaline agent.

Isolation from the remaining organic phase of commercial 4-ADFA and the disposal of by-products are carried out by analogy with the method described in the prototype.

The following are the results of experiments explaining the essence of the present invention.

Example 1

The condensation reaction of aniline with nitrobenzene, using anionite AB-17P in the OH form as a catalyst, was carried out on a batch unit at a temperature in the catalyst zone of 58 ± 1 ° C for 5 hours. The installation included a circulation pump and a three-necked flask equipped with: a nozzle-reactor and a dropping funnel; separator nozzle and reflux condenser; siphon for recycling the reaction mixture. The reactor nozzle had a jacket for temperature control of the catalyst bed. The volume of anion exchange resin in the reactor is 25 cm ³ . 11.5 g of a 35 wt% NaOH solution (0.0936 mole of NaOH), 37.8 g (0.4065 mole) of aniline were charged into the flask and heated to a temperature of 60 ° C. The installation was evacuated to a residual pressure of 120-170 mbar, the circulation pump was turned on, the reaction mass was circulated from the distillation flask to the reactor 100 cm ³ / h, and the dosage of nitrobenzene was started in an amount of 10 g (0.0813 mol). The duration of dosing of nitrobenzene is 90 minutes. The temperature in which the azeotropic aniline-water mixture was continuously distilled was maintained in the distillation flask. Anilin constantly returned to the distillation flask. The total amount of water distilled during the condensation process (in all experiments) was 6.7 g. The condensation process was monitored by thin layer chromatography and electron spectroscopy. After each synthesis, the exchange capacity of the anion exchange resin was determined in accordance with GOST 17552-72 (Ion-exchange membranes. Methods for determining the total and equilibrium exchange capacity. GOST 17552-72).

The results of a series of sequential syntheses are presented in Table 1. The results obtained indicate that during a series of sequential syntheses there is a slight decrease in the exchange capacity of anion exchange resin (within 5-6% for 10 syntheses), most likely due to adsorption of by-products on active centers. In this case, there is practically no change in the degree of conversion of nitrobenzene and the selectivity of the process.

Example 2

The condensation reaction of aniline with nitrobenzene was carried out using other known highly porous strongly basic anion exchangers as a catalyst. The conditions of the experiments and loading are the same as in example 1. The results are presented in table 2. The results obtained indicate that the known highly basic anion exchangers containing the quaternary ammonium group ~ -N (CH ₃ ) ₃ ⁺ can serve as catalysts for the condensation of aniline with nitrobenzene with the formation of 4-nitrodiphenylamine and 4-nitrosodiphenylamine.

Example 3

The condensation reaction of aniline with nitrobenzene was carried out under the conditions of experiments of example 1. The volume of anion exchange resin in the reactor 25 cm ³ . The amount of nitrobenzene was 10 g (0.0813 mol), the molar ratio of aniline: nitrobenzene varied from 3: 1 to 7: 1 and the molar ratio of NaOH: nitrobenzene varied from 0.9: 1 to 1.5: 1. The results are presented in table 3. The obtained results indicate that at the indicated molar ratios of aniline: alkaline agent: nitrobenzene, the process of condensation of aniline with nitrobenzene can be carried out with the formation of 4-nitrodiphenylamine and 4-nitrosodiphenylamine.

Example 4

The condensation reaction of aniline with nitrobenzene, using anionite AB-17P in the OH form as a catalyst, was carried out on a batch unit at a temperature in the catalyst zone of 58 ± 1 ° C for 6 hours. The volume of anion exchange resin in the reactor is 25 cm ³ . 9.77 g of a 40 wt.% NaOH solution (0.0976 mol of NaOH), 9.07 g (0.0976 mol of) aniline were loaded into the flask and heated to a temperature of 60 ° C. The installation was evacuated to a residual pressure of 120-170 mbar, the circulation pump was turned on, the reaction mass was circulated from the distillation flask to the reactor at 50 cm ³ / h, and the dosage of nitrobenzene was started in an amount of 10 g (0.0813 mol). The duration of dosing of nitrobenzene is 90 minutes. The temperature in which the azeotropic aniline-water mixture was continuously distilled was maintained in the distillation flask. Anilin constantly returned to the distillation flask. The total amount of water distilled during the condensation process was 5.1 g. The condensation process was monitored by thin layer chromatography and electron spectroscopy. Analysis of the reaction mass showed: nitrobenzene conversion 82%, the selectivity of the process by the sum of the two products of 4-nitrodiphenylamine and 4-nitrosodiphenylamine 92%.

At the end of the process, the reaction mass was cooled, the catalyst was washed with 6 portions of a 1 mol / L 25 cm ³ NaOH solution. Wash solutions were attached to the reaction mixture, the resulting solution was partially neutralized with concentrated hydrochloric acid to a pH of 10.5–11 (by pH meter), cooled to 2–5 ° C, and the precipitated 4-nitrodiphenylamine was filtered off. The filtrate is treated with concentrated hydrochloric acid to a pH of 6-7, which causes the precipitation of 4-nitrosodiphenylamine. The precipitate was filtered off and dried at 100 ° C. Products are identified by IR and PMR spectra. The melting point of the obtained 4-nitrodiphenylamine is 133-134 ° C. The melting point of the obtained 4-nitrosodiphenylamine 141-142 ° C. The final yield of the isolated substances with respect to the reacted nitrobenzene is 63% for 4-nitrodiphenylamine and 29% for 4-nitrosodiphenylamine. This example shows the conditions for the isolation and yields of intermediates of 4-nitrodiphenylamine and 4-nitrosodiphenylamine.

Example 5

To the reaction mass obtained in the condensation step under the conditions of Example 1 using an used catalyst (the catalyst was used in 6 syntheses without alkali regeneration), 10 g of water and 3.7 g of the hydrogenation catalyst — skeleton nickel — were added. The resulting mixture was loaded into the reactor and hydrogenated with hydrogen at a temperature of 75-80 ° C and a pressure of 1.5 MPa until the absorption of hydrogen ceased, which lasted 1.5-2 hours. Upon completion of the reaction, the mixture was cooled to 20-30 ° C, discharged from the reactor, the catalyst was separated from the liquid phase, the catalyst was washed with three 10 cm ³ portions of water. Wash water was added to the liquid phase of the hydrogenation step (hydrogenate).

The hydrogenation catalyst is reused.

32.5 g of water, 24.04 g of toluene were added to the hydrogenate, the mixture was stirred, settled and the aqueous and organic phases were separated. The aqueous phase - 4.5-5% NaOH solution can be reused at the stage of condensation or for the regeneration of the condensation catalyst (highly basic anion exchange resin). The results of our experiments show that more than 99% NaOH can be returned to the process for reuse. Concentration of an aqueous NaOH solution to the desired concentration was carried out by evaporation in vacuo.

Analysis of the organic phase showed that the yield of 4-ADPA on loaded nitrobenzene is 96.9%. The organic phase was subjected to fractional distillation. Toluene and aniline, which can be reused, were distilled off at atmospheric pressure. The residue was distilled on a distillation column at 6-25 mbar. Get 4-ADPA with a melting point of 66-67 ° C and a mass fraction of the main substance of 99.8%. This example shows the specific conditions for the individual stages of the process of obtaining the target product 4-ADPA.

Achievable technical result

The above examples show that the use of highly basic anion exchange resin as a catalyst for the condensation of aniline with nitrobenzene in an alkaline medium removes temperature restrictions at the subsequent stages of the 4-ADPA production process, increases its efficiency, and greatly facilitates the phase separation of the reaction mixture and the alkaline solution regeneration.

Table 1
Effect of the number of sequential syntheses on the degree of conversion and selectivity of the process of condensation of aniline with nitrobenzene Experience number The degree of conversion of nitrobenzene Process selectivity * Full static exchange capacity, mEq / cm ³ ** one 0,992 0.982 0,990 2 0,990 0.988 0.976 3 0.987 0,992 0.973 four 0.989 0.978 0.969 5 0.986 0.984 0.976 6 0.986 0.987 0.961 7 0.988 0.986 0.947 8 0.987 0.981 0.947 9 0.989 0.978 0.954 10 0.986 0.976 0.947 * - the selectivity of the process was determined by the formula selectivity = (the sum of moles of 4-nitrodiphenylamine and 4-nitrosodiphenylamine) / (number of moles of reacted nitrobenzene)
** - total static exchange capacity of anion exchange resin AB-17P in the initial state 994 mEq / cm ³ table 2
The effect of the type of polymer catalyst on the degree of conversion and selectivity of the process of condensation of aniline with nitrobenzene Experience number Anion exchange resin The degree of conversion of nitrobenzene Process selectivity one Amberlyst A26 OH 0.982 0.984 2 DOWEX Marathon MSA 0.988 0.976 3 Tulsion A-74 MP 0.986 0.982 four Purolite A500 0,990 0.972 Table 3
The effect of the molar ratio of the regents on the degree of conversion, selectivity and yield of the process of condensation of aniline with nitrobenzene Experience number Molar ratio The degree of conversion of nitrobenzene Process selectivity Product Yield * aniline / nitrobenzene NaOH / Nitrobenzene one 5 1,2 0.984 0.984 0.968 2 3 1,2 0.954 0.944 0.901 3 7 1,2 0.988 0,994 0.982 four 5 0.9 0.936 0.962 0,900 5 5 1,5 0.976 0.968 0.945 * - the sum of the outputs of 4-nitrodiphenylamine and 4-nitrosodiphenylamine

Claims (3)

1. The method of obtaining 4-aminodiphenylamine and its intermediate synthesis products selected from 4-nitrodiphenylamine and 4-nitrosodiphenylamine by the interaction of aniline and nitrobenzene in the presence of a catalyst containing a quaternary ammonium group with the formation of 4-nitrodiphenylamine and 4-nitrosodiphenylamine as intermediate products, followed by hydrogenation of these intermediate reaction products after their isolation or directly in the reaction mass in the presence of a hydrogenation catalyst and a solvent, as which use lower alcohol or water, separating the hydrogenation catalyst from the reaction mixture to obtain an aqueous and organic phase, which are separated with the separation of 4-aminodiphenylamine from the organic phase, characterized in that a polymer of high basic anion exchange resin in OH is used as a catalyst in the reaction of aniline and nitrobenzene a form containing a quaternary ammonium group N (CH ₃ ) ₃ ⁺ , and the reaction is carried out in the presence of a base. 2. The method according to claim 1, characterized in that the molar ratio of aniline and nitrobenzene is from 3: 1 to 7: 1. 3. The method according to claim 1, characterized in that the molar ratio of base to nitrobenzene is from 0.9: 1 to 1.5: 1.