WO2015094128A1

WO2015094128A1 - Process for the preparation of 4-aminodiphenylamine precursors

Info

Publication number: WO2015094128A1
Application number: PCT/SK2013/050016
Authority: WO
Inventors: Jozef Balko; Zsolt Vegh
Original assignee: Duslo, A.S.
Priority date: 2013-12-16
Filing date: 2013-12-16
Publication date: 2015-06-25
Also published as: EP3154923A1

Abstract

Process for the preparation of 4-aminodiphenylamine precursors by reacting aniline and nitrobenzene in the presence of water and a base, with controlled amount of water with respect to the base, characterised in that the mole ratio of water to the dosed base, obtained after extraction of organic impurities by an aromatic solvent of an aqueous phase from hydrogenation of a condensation mixture, is between 3.99 and 3:1 at the start of the coupling reaction, and between 0.40 and 0.59:1 at the end of the coupling reaction, and the end of the coupling reaction is indicated by full conversion of nitrobenzene or by achieving the maximum content 2 wt. % of the initial amount of nitrobenzene in the reaction mixture. The ingredients are continuously fed into reactor cascades in the required ratio to the condensation process, the mole ratio of aniline to nitrobenzene is between 1 :1 and 10:1, and hydrogenation of the condensation product in the presence of a hydrogenation catalyst and added water is followed by separation of the hydrogenation catalyst, and an organic phase, containing 4-aminodiphenylamine, is separated from the aqueous phase, containing the released base.

Description

PROCESS FOR THE PREPARATION OF 4-AMINODIPHENYL AMINE PRECURSORS

TECHNICAL FIELD , · ^*'

The invention relates to a process for the preparation of 4-aminodiphenylamine (4-ADFA) precursors, 4-nitrosodiphenylamine and/or 4-nitrodiphenylamine and/or salts thereof, wherein aniline with nitrobenzene reacts in a liquid medium with a base to obtain 4-ADFA precursors, i.e. 4-nitrosodiphenylamine (4-NODFA), 4-nitrodiphenylamine (4-N0₂DFA) and/or salts thereof, providing 4-ADFA following the hydrogenation.

BACKGROUND OF THE INVENTION

4-Aminodiphenylamines (4-ADFA) can be prepared by various methods, for example by reacting 4-chloronitrobenzene with aniline followed by hydrogenation, by nitrosation of diphenylamine to N-nitrosodiphenylamine and after rearrangement to 4- nitrosodiphenylamine by hydrogenation. Considerably more preferred methods of manufacturing 4-ADFA intermediates from both ecological and economical point of view are based on direct reaction of aniline with nitrobenzene. The reaction is initiated by bases, forming an anilide anion by reaction with aniline, which anilide anion subsequently substitutes the hydrogen in nitrobenzene by nucleophilic substitution [A; Wohl et al.: Ber. 34, 2442-2450 (1901) and A. Wohl: Ber. 36, 4135-4138 (1903)], wherein the use of solid potassium hydroxide as a base leads mainly to phenazine and phenazinoxide, and the use of sodium hydroxide leads also to 4-NODFA.

In the fifties, several authors studied and described the mechanism of Wohl-Aue nucleophilic reaction of aniline and its derivatives with aromatic nitro compounds by the action of a base (NaOH, KOH, optionally NaNH₂) in the presence of benzene, toluene and xylene, to form phenazine derivatives. A variety of other reaction products were isolated and described as well, such as 4-nitrosodiphenylamine, 4-nitro-substituted diphenylamines, azobenzenes, azoxybenzenes. [EJ. Abramov et al.: Zur. Obscej Chim. 22, 502-509 (1953); S.B. Serebrjanyj: Uspechi chimii 24, 313 -345 (1955); S.B. Serebrjanyj: Ukrain. Chlm. Zur. 21, 350-360 (1955), V.P. Cerneckij et al: Zur. Obscej Chim. 25,2161-2170 (1955)]. U.S. Patent No. 5,420,354 discloses the reaction of nitrobenzene with aniline in the presence of hydrogen, a hydrogenation catalyst, an acid co-catalyst and a hydrogenation inhibitor, providing directly 4-ADFA, but in relatively low yields (max. 12%) and at low selectivity of reaction, like in other processes already mentioned above.

Another halogen-free process for the preparation of 4-ADFA is based on the reaction of aniline with 4-(phenylazo)diphenylamine in the presence of strong bases, such as potassium t-butoxid with crown ethers or quaternary ammonium hydroxides [U.S. Patent Nos. 5,382,691, 5,633,407, 5,618,979 and 5,451,702]. The subsequent conversion of 4- FADFA to 4-ADFA can be carried out either by catalytic hydrogenation according to U.S. Patent No. 5,451,702] or by nucleophilic substitution reaction of 4-FADFA with an amine in the presence of strong bases [U.S. Patent Nos. 5,382,691, 5,633,407 and 5,618,979]. 4- ADFA can also be prepared [see U.S. Patent Nos. 5,618,979 and 5,633,407, and a publication by M.K. Stem at al.: J. Org. Chem. 59, 5627-5632 (1994)] in one step directly by reaction of azobenzene or azoxybenzene with aniline in the presence of strong basic catalysts. However, in all the above mentioned processes azobenzene is used as a starting material, which is a technically more hardly available material and, moreover, it is necessary to prepare it in advance. In addition, there is a lot of waste, which must be either further processed or disposed of.

In a number of patents of the firm Monsanto [U.S. Patent Nos. 5,117,063, 5,453,541, 5,608,111, 5,623,088] there is described a process for the preparation of 4-ADFA intermediates by direct reaction of aniline with nitrobenzene in an aprotic solvent with a controlled amount of an aprotic solvent by the action of bases, which include alkali hydroxides, alkoxides, hydrides and quaternary ammonium hydroxides with alkyl, aryl- and aralkyl-substituents, as well as alkyl-substituted di-ammonium hydroxides. Nevertheless, the reaction products could be obtained with high yields and with high selectivity only when using quaternary ammonium hydroxides. The mechanism of the reaction is known [M.K. Stem et al. in J. Am. Chem. Soc. 114, 9237-9238 (1992), and New J. Chem. 20, 259-268 (1996)].

A continuous process for the preparation of 4-ADFA is described in U.S. Patent Application No. 2009048465, where the process for the preparation of a condensation mixture is carried out in a stage reactor in the presence of various complex catalysts. The use of such complex catalysts is disadvantageous due to their costs, which are increased by adding further substances into the reaction media. The weight of the necessary catalyst per 1 mole of precursors in increased. The losses of an effective catalyst component, i.e. tetramethylammonium hydroxide, during the process are not clear from the application.

According to experiences of the authors of U.S. Patent No. 6,140,538, when carrying out the reaction in an industrial scale, there is always a certain decomposition rate of the base during the coupling reaction step.

It was found out that 4-ADFA and methanol contained in the recycled aniline and the recycled base are critical impurities for the coupling reaction, which must be maintained at a low level. According to the authors of U.S. Patent No. 6,140,538, even relatively low levels of 4-ADFA result in unacceptably low yields for the coupling reaction and severe poisoning of the hydrogenation catalyst. Citation from the Patent: "Relatively low levels of 4-ADFA result in unacceptably low yields for the coupling reaction and severe poisoning of the hydrogenation catalyst. It is surprising that such small amounts of an aromatic amine similar to aniline would have such severe consequences."

It is the aim of the present invention to provide a process for the preparation of 4- aminodiphenylamine precursors, which enables to recycle the base and the aniline with minimal loss of reactivity for the condensation of aniline with nitrobenzene.

SUMMARY OF THE INVENTION

The process for the preparation of 4-aminodiphenylamine precursors by the reaction of aniline and nitrobenzene in the presence of water and a base with controlled amount of water with respect to the base according to the invention is based on the fact that the reaction is carried out in the mole ratio of water to the dosed base, obtained after extraction of organic impurities by an aromatic solvent of an aqueous phase from hydrogenation of a condensation mixture, between 3.99 and 3:1 at the start of the coupling reaction, and between 0.40 and 0.59:1 at the end of the coupling reaction (the range of water:TMAH mole ratios), thus providing 4-nitrodiphenylamine and/or 4-nitrosodiphenylamine and/or salts thereof. The water.TMAH mole ratios are determined by taking the samples and their analysing. The end of the reaction is indicated by full conversion of nitrobenzene or by achieving the maximum content 2 wt. % of the initial amount of nitrobenzene in the reaction mixture. Following the hydrogenation, the prepared 4-nitrosodiphenylamine (4- NODFA), 4-nitrodiphenylamine (4-N0₂DFA) and/or salts thereof provide 4-ADFA.

It was found out that the mole ratio of aniline to nitrobenzene is preferably between 1 : 1 and 10:1, and the mole ratio of the base to nitrobenzene is between 0.7:1 and 4:1.

Hydrogenation of the condensation product in the presence of the hydrogenation catalyst and added water is followed by separation of the hydrogenation catalyst, separation of phases into an organic phase, containing 4-aminodiphenylamine, and an aqueous phase, containing the released base.

The aqueous phase is extracted by an aromatic solvent in order to remove 4-ADFA, aniline, azobenzene and phenazine, and this purified recycling aqueous phase can be used again in the condensation as a base after the extraction by an aromatic solvent for removing organic impurities and after supplementing the losses caused due to handling and due to base decomposition.

In the process for the preparation of the present invention, tetramethylammonium hydroxide is used as a base, and toluene, ethylbenzene, aniline, nitrobenzene or mixtures thereof are used as an aromatic solvent.

The present process for the preparation of 4-aminodiphenylamine (ADPA) precursors of the invention is advantageous particularly due to its economical attractiveness. More specifically, in its first embodiment the invention provides a process, in which the base and aniline are recycled in a way that demonstrates its economical advantageousness. It has been found out that the base and aniline can be recycled with a minimal loss of reactivity for the condensation of aniline with nitrobenzene by an appropriate controlling of impurity levels in the recycled flows. Furthermore, it has been found out that the undesired amounts of 4-ADFA from the base containing recycling aqueous phase, that get into the aqueous phase during separation of the aqueous and the organic phase after the hydrogenation, can be removed by an extraction with toluene.

EXAMPLES OF THE PREFERRED EMBODIMENTS

The following Examples are intended to further clarify the invention, but do not limit the scope of the claims in any way. Typical methods of this invention for the condensation and hydrogenation reaction are described further. Variations of 20 mole ratios and operating conditions of these processes are commented in Examples 1-4. These variations fall within the scope of the invention, except for when they are used for comparison. The relevant loads vary depending on the size of an apparatus, and at the beginning some of the reaction mixtures contained the final product from the previous reaction batch. The amount of water in the final condensation water was determined by GC-MS and GC method with TCD detector.

E x a m p l e 1

Preparation of 4-ADFA precursors

1242 g of regenerated 25 wt. % tetramethylammonium hydroxide (TMAH) aqueous solution was concentrated to about 36 wt. % at the pressure of about 7.0 kPa and at the temperature of solution increasing from 40°C to 70°C. Then 1516 g of aniline was added, and removing of water continued by distillation of an azeotropic water-aniline mixture at the pressure of about 7.0 kPa and at the temperature of solution increasing from 60°C to 75°C, until a final water/TMAH mole ratio below 3.4 was reached. 376 g of nitrobenzene was added during 145 min, wherein distillation of an azeotropic water-aniline mixture at the pressure of about 7.0 kPa continued (in the end of nitrobenzene addition, the reaction mixture had a temperature of 80°C). After the adding of nitrobenzene was completed, the batch for condensation was stirred for another 1 hour. The distillation rate was adjusted to achieve the water/TMAH mole ratio of 0.55 (or lower) in the end of the reaction (i.e. after adding the complete amount of nitrobenzene plus the time period for finishing the reaction).

Hydrogenation of 4-ADFA precursors

The condensation reaction mixture from the previous step was added with water for dilution (in the amount corresponding to 30 wt. % of the initial condensation mixture) together with 0.6 g of commercially available dry 3% Pd/C catalyst. Then the mixture was hydrogenated in the 3.75 1 autoclave at the temperature between 65 and 80°C and the hydrogen pressure of 4 MPa. The hydrogenation reaction was stopped, when the monitored hydrogen uptake was virtually nil. The HPLC analysis data on intermediates and final products were used to calculate the nitrobenzene selectivity (i.e. (NODPA+NDPA moles)formed/(nitrobenzene moles)con verted).

Processing of hydro genated mixture

The hydrogenated condensation mixture was separated into an aqueous and an organic phase . The aqueous phase was treated by extraction with toluene (optionally ethylbenzene or xylene). The extraction removed 4-aminodiphenylamine present in water. This treated aqueous phase was returned back to carry out further condensation reaction. The amount of TMAH required for another reaction was supplemented to reach the original initial amount of TMAH. An acid-base titration method was used to determine the concentration of TMAH in the aqueous solution.

The regenerated aniline was returned back to the subsequent reaction. The regeneration of aniline was carried out either by separation of the fore-runs or by returning the aniline with the fore-run into another cycle of condensation and hydrogenation.

The results are shown in Table 1.

Table 1

4-ADFA yields with respect to added nitrobenzene

E a m p l e 2a

This example illustrates that in case of using a multirecycled aqueous phase containing TMAH after condensation with aniline to a TMAH/ AN mole ratio of 3.4 according to Example 1 before adding nitrobenzene, after completion of the reaction plus the time period for its finishing (210 min), the nitrobenzene selectivity to 4-ADFA precursors was 94% with a 100% conversion of nitrobenzene. E x a m p l e 2b

This example illustrates that in case of using a multirecycled aqueous phase containing TMAH after condensation with aniline to a TMAH/AN mole ratio of 4.3 according to Example 1 before adding nitrobenzene, after completion of the reaction plus the time period for its finishing (210 min), the nitrobenzene selectivity to 4-ADFA precursors was 94% with a 100% conversion of nitrobenzene.

E x a m p l e 3

This example illustrates the influence of distillation fore-runs, obtained during regeneration of aniline, on the yield of the condensation reaction. The results in Table 2 show a slight decrease in selectivity of the condensation reaction to nitrobenzene when returning the water-aniline fore-run with the regenerated aniline to the condensation reaction.

Table 2

E x a m p l e 4

This example illustrates a possibility to prepare 4-nitroso- and 4-nitrodiphenylamine under the conditions of water/TMAH mole ratio lower than 0.6 in the end of the condensation reaction, also with the time period for finishing the reaction within 3 hours. The reaction was carried out according to Example 1, except that after adding nitrobenzene to the reaction, the operating pressure was reduced from 7.0 kPa to 2.6 kPa and a temperature of the reaction mixture was maintained at 75°C. In this way the water content of 1.15% (water/TMAH mole ratio of 0.4) was reached in the condensation mixture after 2 hours of the finishing period. The total selectivity of precursors to NB in the condensation was 94.1%. The total yield of 4-ADFA after hydrogenation of the condensation mixture was 93.4%.

E x a m p l e 5

This example illustrates the preparation of 4-nitroso-/4-nitrodiphenylamine by a continuous process in a stirred-flow reactor.

In a two flow-reactor system having an effective volume of 235 ml, the first member was loaded with a starting condensation mixture of a composition shown in Table 3. A temperature of the reaction mixture was adjusted to 72°C at the pressure of 7.0 kPa. This condensation mixture was added with nitrobenzene at a volume rate of 0.717 ± 0.008 ml/min, and the mixture of aniline/TMAH, containing 14.22 wt. % of TMAH, was added simultaneously at a volume rate of 5.0 ± 0.05 ml/min. The aniline/TMAH mixture was tempered to 70°C. The mole ratio of the incoming TMAH/NB was 1.1. The condensation mixture from the first flow reactor flowed to the second reactor, where the conditions of pressure and temperature were identical to those in the first member of the boiler system. After separation of the condensate, the aniline distilled with water returned to the first reactor.

Conversion of nitrobenzene:

The results are shown in Table 3.

Table 3

INDUSTRIAL APPLICABILITY

A process for the preparation of 4-aminodiphenylamine precursors according to the present invention can be used in industry in the production of antioxidants.

Claims

1. Process for the preparation of 4-aminodiphenylamine by the reaction of aniline and nitrobenzene in the presence of water and a base with controlled amount of water with respect to the base, characterised in that the mole ratio of water to the dosed base, obtained after extraction of organic impurities by an aromatic solvent of an aqueous phase from hydrogenation of a condensation mixture, is between 3.99 and 3:1 at the start of the coupling reaction, and between 0.40 and 0.59:1 at the end of the coupling reaction, and the end of the reaction is indicated by full conversion of nitrobenzene or by achieving the maximum content 2 wt. % of the initial amount of nitrobenzene in the reaction mixture.

2. Process for the preparation according to claim 1, characterised in that the ingredients are continuously fed into reactor cascades in the required ratio to the condensation process.

3. Process for the preparation according to claim 1 , characterised in that the mole ratio of aniline to nitrobenzene is between 1:1 and 10:1.

4. Process for the preparation according to claim 1 , characterised in that the mole ratio of the base to nitrobenzene is between 0.7:1 and 4:1.

5. Process for the preparation according to claims 1 to 4, characterised in that the hydrogenation of the condensation product in the presence of the hydrogenation catalyst and added water is followed by separation of the hydrogenation catalyst, and an organic phase, containing 4-aminodiphenylamine, is separated from an aqueous phase, containing the released base.

6. Process for the preparation according to claim 5, characterised in that the recycling aqueous phase is extracted by an aromatic solvent whereby removing 4-ADFA, aniline, azobenzene and phenazine, and this purified aqueous phase is used again in the condensation as a base after supplementing the losses caused due to handling and due to base decomposition. Process for the preparation according to claims 1 to 6, characterised in that the said base is tetramethylammonium hydroxide.

Process for the preparation according to claims 1 to 6, characterised in that the aromatic solvent is toluene or aniline or nitrobenzene.