JPH07149695A - Production of 4-aminodiphenylamine - Google Patents

Abstract

PURPOSE:To efficiently obtain the compound at low cost in high yield and selectivity through a few processes and useful as an intermediate for rubber antioxidants or azo dyes, without the need for using any noble metal catalyst, by reaction between an aniline and an azobenzene. CONSTITUTION:This compound can be obtained by reaction between an aniline of formula I (R<1> is H, 1-4C alkyl, 1-4C alkoxyl, halogen, cyano, etc.) and an azobenzene of formula II (R<2> and R<3> are each the same as R<1>, etc., not substituting at p-site) in the presence of a base such as potassium t-butoxide pref. in a solvent, an aprotic dipolar solvent such as glyme (derivative).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing 4-aminodiphenylamines by reacting anilines with azobenzenes.

[0002]

BACKGROUND OF THE INVENTION 4-Aminodiphenylamines are important compounds as intermediates for rubber antiaging agents and azo dyes, and have been conventionally produced by various methods.

For example, in JP-A-59-82349, diphenylamine is reacted with an acid and a nitrite to produce N.
-Nitrosation, Fischer-He in the presence of hydrogen chloride
A method for producing 4-nitrosodiphenylamine by pp rearrangement and reducing it to produce 4-aminodiphenylamine is described.

In addition, Ger. Patent 18566
Japanese Patent Publication No. 3 describes a method for producing 4-aminodiphenylamine by reacting p-nitrochlorobenzene with aniline to produce 4-nitrodiphenylamine and reducing it.

U. S. P. In the publication 5117063,
Reaction of aniline and nitrobenzene in the presence of a base such as tetramethylammonium hydroxide 4
A method for producing 4-nitrodiphenylamine and 4-nitrodiphenylamine and reducing them to produce 4-aminodiphenylamine is described.

[0006]

In such prior art, the method disclosed in Japanese Patent Laid-Open No. 59-82349 has a high yield, but not only many reaction steps are required but also a stoichiometrically large amount is required. Secondary materials are used and they generate wastes, and their disposal is expensive.

Further, Ger. Patent 185663
The method disclosed in Japanese Patent Publication uses p-nitrochlorobenzene as a raw material, but in this production, by-production of o-nitrochlorobenzene is unavoidable, and a balance with demand is required, which is economically unfavorable. .

Further, U. S. P. The method shown in Japanese Patent No. 5117063 is performed with nitrobenzene and aniline which are easily available as starting materials, but for example, a large amount of expensive and thermally unstable tetramethylammonium hydroxide is used as a catalyst, It is difficult to collect and use this.

Therefore, in each of the above-mentioned prior arts, it is necessary to produce 4-nitrosodiphenylamine or 4-nitrodiphenylamine as an intermediate and reduce these, which not only increases the number of steps but also requires an expensive noble metal catalyst. There was a problem that it had to be used.

According to the present invention, it is possible to efficiently produce 4-aminodiphenylamines without reducing the number of steps to produce an intermediate, and without using an expensive precious metal catalyst, and to use a small amount of auxiliary materials. The purpose is to prevent the generation of waste and to improve the economic efficiency by not producing by-products.

[0011]

As a result of various investigations in view of such circumstances, the present inventors have found that 4-aminodiphenylamines are directly produced in a single step by reacting anilines and azobenzenes in the presence of a base. The present invention was discovered, and it was found that 4-aminodiphenylamines were produced in high yield by selecting a solvent, and the present invention was completed.

[0012]

The present invention is a method for producing 4-aminodiphenylamines, which comprises reacting anilines with azobenzenes in the presence of a base. In this case, the reaction formula is as shown in [Chemical Formula 1].

[0013]

[Chemical 1]

The anilines used in the present invention are compounds represented by the general formula [Chemical Formula 2].

[0015]

[Chemical 2] In the formula, R ¹ is hydrogen, an alkyl group having 1 to 4 carbon atoms, and 1 carbon atom
To alkoxy groups, halogen groups, cyano groups and the like. Specific examples include o-toluidine, m-toluidine, p-toluidine, o-anisidine, m-anisidine, p-anisidine, o-aminobenzonitrile, m-.
Aminobenzonitrile, p-aminobenzonitrile, o
-Chloroaniline, m-chloroaniline, p-chloroaniline and the like can be mentioned.

As the azobenzenes used in the present invention, compounds represented by the general formula [Chemical Formula 3] having no substituent at the para position are used.

[0017]

[Chemical 3] In the formula, R ² and R ³ include hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen group, a cyano group and the like. Specific examples include 2,2'-dimethylazobenzene, 3,3'-dimethylazobenzene, 2,2'-dimethoxyazobenzene, 3,3'-dimethoxyazobenzene and the like.

As the base used in the present invention, alkali and alkaline earth metals, alkali and alkaline earth amides, alkali and alkaline earth alkoxides, alkali and alkaline earth hydroxides,
Examples thereof include alkali metal amide, alkali metal hydride, and alkali metal alkoxide. Preferred are metal potassium, potassium hydroxide, cesium hydroxide, t-BuOK, and the like.

The amount of the base used is not particularly limited, but
It is preferable to use azobenzenes in a molar ratio of 0.5 or more.

In the above reaction, the desired product can be obtained without a solvent, but by selecting and using an appropriate catalyst, the formation of 2-aminodiphenylamines as a by-product can be suppressed and 4-aminodiphenylamine can be obtained. It is preferable to use a solvent because the yield of the compounds can be significantly increased.

As such a solvent, an aprotic dipolar solvent is preferable, and specific examples thereof include glymes and derivatives thereof, and examples thereof include diglyme and derivatives thereof, more preferably triglymes and derivatives thereof.

The amount of the solvent used is not particularly limited, but the solvent /
It is preferable to use 5 or more in terms of molar ratio of azobenzenes.

The reaction temperature is generally room temperature or higher, preferably 100 ° C. or higher, and particularly preferably 1
It is 20 ° C to 180 ° C. Generally, the higher the reaction temperature is, the higher the yield can be. However, if the reaction temperature is too high, decomposition may be considered.

The molar ratio of aniline to azobenzene may be any, but it is preferable to use the aniline / azobenzene molar ratio of 5 to 20 times.

The reaction atmosphere may be an inert gas atmosphere such as nitrogen, argon or helium. Particularly, the reaction in a hydrogen atmosphere enhances the yield of 4-aminodiphenylamines. You can

The 4-aminodiphenylamines produced by the above reaction can be easily separated and obtained by distillation.

[0027]

EXAMPLES Examples 1 to 14 of the present invention are shown below, and the results are summarized in Table 1. In Table 1, Azo is azobenzene, 4A is 4-aminodiphenylamine, and 2A.
Is 2-aminodiphenylamine, 4-PADPA is 4-
Indicates phenylazodiphenylamine. Further, in Table 1, 4A selectivity = 4A yield / (4A yield + 2A yield)
Representing × 100, 4A component yield = 4A yield + 4
It represents the PADPA yield. The present invention is not limited to the examples shown below.

(Example 1) Stirrer, reflux condenser,
In a four-neck round bottom flask equipped with a thermometer and a nitrogen introduction tube, 18.2 g (0.1 mol) of azobenzene, t-BuOK
11.2 g (0.1 mol), 93 g (1.0 mol) of aniline and 75 ml of ethylene glycol dimethyl ether (monoglyme) as a solvent were charged, and nitrogen gas was 50 m.
The reaction was carried out at 140 ° C. for 5 hours while flowing at a flow rate of 1 / min. The reaction product was quantitatively analyzed by gas chromatography, and its identification was carried out by comparing retention times of gas chromatograms and using GC / MS. As a result of analysis, unreacted azobenzene was not detected, and the product was 4-aminodiphenylamine 26% and 2-aminodiphenylamine 20%.
%, 4-phenylazodiphenylamine 33% (all are yields based on azobenzene). The selectivity of 4A was 56%.

Example 2 The same conditions as in Example 1 were used except that the solvent was ethylene glycol diethyl ether (a derivative of monoglyme). Unreacted azobenzene was not detected and the product was 4-aminodiphenylamine 3
The yield was 8%, 2-aminodiphenylamine 19%, and 4-phenylazodiphenylamine 23% (all yields based on azobenzene). The selectivity of 4A was 67%.

Example 3 The same conditions as in Example 1 were carried out except that the solvent was ethylene glycol di-n-butyl ether (a derivative of monoglyme). Unreacted azobenzene was not detected, and the products were 4-aminodiphenylamine 31%, 2-aminodiphenylamine 25%, and 4-phenylazodiphenylamine 20% (all yields based on azobenzene). Moreover, the selection rate of 4A is 55.
%Met.

Example 4 Example 1 except that the solvent was diethylene glycol dimethyl ether (diglyme).
The same conditions were used. Unreacted azobenzene was not detected and the product was 4-aminodiphenylamine 50%, 2
-Aminodiphenylamine was 8% and 4-phenylazodiphenylamine was 26% (all are based on azobenzene). The selectivity of 4A was 87%.

Example 5 The same conditions as in Example 1 were carried out except that the solvent was diethylene glycol diethyl ether (a derivative of diglyme). Unreacted azobenzene was not detected, and the product was 4-aminodiphenylamine 5
The yield was 5%, 2-aminodiphenylamine 5%, and 4-phenylazodiphenylamine 12% (all are based on azobenzene). The selectivity of 4A was 92%.

(Example 6) The same conditions as in Example 1 were carried out except that the solvent was diethylene glycol di-n-butyl ether (derivative of diglyme). Unreacted azobenzene was not detected, and the products were 4-aminodiphenylamine 48%, 2-aminodiphenylamine 9%, and 4-phenylazodiphenylamine 10% (all yields based on azobenzene). Also, the selectivity of 4A is 85%
Met.

(Example 7) The same conditions as in Example 1 were carried out except that the solvent was triethylene glycol dimethyl ether (triglyme). Unreacted azobenzene and 2
-Aminodiphenylamine was not detected and the product was 4
-Aminodiphenylamine was 64% and 4-phenylazodiphenylamine was 17% (both were yields based on azobenzene). The selectivity of 4A was 100%.

Example 8 The same conditions as in Example 1 were used except that the solvent was triethylene glycol diethyl ether (a derivative of triglyme). Unreacted azobenzene and 2-aminodiphenylamine were not detected, and the products were 4-aminodiphenylamine 65% and 4-phenylazodiphenylamine 5% (all yields based on azobenzene). The selectivity of 4A was 100%.

(Example 9) The same conditions as in Example 1 were carried out except that the solvent was triethylene glycol di-n-butyl ether (derivative of triglyme). Unreacted azobenzene was not detected and the products were 4-aminodiphenylamine 50%, 2-aminodiphenylamine 4%, 4-
The amount of phenylazodiphenylamine was 22% (all are based on azobenzene). Also, the selection rate of 4A is 9
It was 3%.

Example 10 The same conditions as in Example 1 were carried out except that the solvent was tetraethylene glycol dimethyl ether (tetraglyme). Unreacted azobenzene was present at 15%, and the products were 4-aminodiphenylamine 24% and 2-aminodiphenylamine 6% (all yields based on azobenzene). The selectivity of 4A was 79%.

(Example 11) The same conditions as in Example 7 were carried out except that the solvent was diethoxymethane and the reaction temperature was 115 ° C. Unreacted azobenzene 17% was present, and the products were 4-aminodiphenylamine 11%, 2-aminodiphenylamine 32%, and 4-phenylazodiphenylamine 36% (all are yields based on azobenzene). The selectivity of 4A was 26%.

Example 12 A 500 ml pressure-resistant autoclave was used in a reaction vessel, and hydrogen gas was supplied at 10 kg / cm ^2.
The same procedure as in Example 7 was performed except that the pressure was increased to G. Unreacted azobenzene was not detected, and the product was only 4-aminodiphenylamine 82% (yield based on azobenzene).

Example 13 The procedure of Example 7 was repeated, except that a 500 ml pressure-resistant autoclave was used in the reaction vessel, the reaction temperature was 120 ° C., and hydrogen gas was injected under pressure up to 10 kg / cm ² G. Unreacted azobenzene was not detected,
The products were 66% of 4-aminodiphenylamine, 1% of 2-aminodiphenylamine, and 18% of 4-phenylazodiphenylamine (all were yields based on azobenzene).

(Example 14) Example 12 was repeated except that nitrogen gas was pressurized to 10 kg / cm ² G as an atmosphere gas.
I went the same way. Unreacted azobenzene was not detected, and the products were 4-aminodiphenylamine 52%, 2-aminodiphenylamine 1%, and 4-phenylazodiphenylamine 32% (all yields based on azobenzene).

[0042]

[Table 1]

From Table 1, by selecting the solvent, 4
-The yield of aminodiphenylamines can be varied and can be obtained in high yield. Also, it can be seen that the 4A yield is higher in the reaction under the hydrogen gas atmosphere than in the reaction under the nitrogen gas atmosphere.

Example 15 1.0 mol of aniline, 0.1 mol of azobenzene (Azo), base (t-BuOK)
The case was investigated in which the reaction temperature and the solvent were changed at 0.1 mol and a reaction time of 5 hours. The results are shown in Table 2 below.
Shown in.

[0045]

[Table 2]

From Table 2, the higher the temperature, the higher the 4A yield and the higher the 4A.
In many cases, the A selectivity was good. Also, 4A yield and 4
It was Triglyme that had both good A selectivities.

Example 16 Azobenzene (Azo)
The case was investigated in which the mixing ratio of aniline, triglyme, and t-BuOK was changed at 0.1 mol, a reaction temperature of 120 ° C., and a reaction time of 5 hours. The results are shown in Table 3 below.

[0048]

[Table 3]

From Tables 1 to 4, it can be seen that the more triglyme, the better the 4A yield and 4A selectivity. Also,
From 5 to 7 in Table 3, the higher aniline yielded 4A yield and 4
It can be seen that the A selectivity is good. In addition, it can be seen from Tables 8 to 9 that the higher the amount of base, the better the 4A yield and 4A selectivity. However, from the comparison between 0.1 mol and 0.2 mol of the base, the amount of the base may be about equimolar to azobenzene.

(Example 17) 1.82 g (0.01 mol) of azobenzene and 1.12 g of t-BuOK were placed in a four-necked round bottom flask equipped with a stirrer, a reflux condenser and a thermometer.
(0.01 mol), p-toluidine (0.1 mol) as an aniline, and 10 g of triglyme were charged,
The reaction was carried out at 160 ° C. for 3 hours while flowing nitrogen gas.

As a result of the analysis, unreacted azobenzene was present at 7%, and 4-amino-4'-methyldiphenylamine 73
% (Both are based on azobenzene).

(Example 18) p-aminobenzonitrile was used as the aniline, diglyme was used as the solvent,
Example 1 was repeated except that the reaction time was 8 hours. As a result of the analysis, 31% of unreacted azobenzene was present,
32% of 4-amino-4′-cyanodiphenylamine (based on azobenzene) was produced.

Example 19 Example 19 was repeated except that p-chloroaniline was used as the aniline and the reaction time was 8 hours. As a result of analysis, unreacted azobenzene 23%, 4-amino-4′-cyanodiphenylamine 3
8% (based on azobenzene) was produced.

Example 20 As azobenzenes 3,
The same procedure as in Example 1 was performed except that aniline was used as 3'-dimethylazobenzene as the aniline. As a result of analysis, unreacted 3,3′-dimethylazobenzene was present at 1%, and 2-methyl-4-aminodiphenylamine was at 76%.
(3,3′-dimethylazobenzene standard) was produced.

Example 21 As azobenzenes 3,
3'-Dimethylazobenzene as p- as aniline
The same procedure as in Example 1 was carried out except that chloroaniline was used and the reaction time was 8 hours. As a result of analysis, unreacted 3,3 '
-24% dimethylazobenzene, 4-amino-
3-Methyl-4'-chlorodiphenylamine 33%
(3,3′-dimethylazobenzene standard) was produced.

[0056]

INDUSTRIAL APPLICABILITY According to the present invention, 4-aminodiphenylamines can be efficiently and inexpensively produced in a small number of steps without using an expensive noble metal catalyst and without producing an intermediate. Economical because no by-products and wastes are generated, and monoglyme as a solvent,
By selecting diglyme, triglyme, or tetraglyme, the yield and selectivity of 4-aminodiphenylamines can be increased, and particularly when triglyme is used, extremely high yield and selectivity can be obtained. It can produce the effect.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masaki Sasaki, 1-1533 Yanagizaki, Kawaguchi City, Saitama Prefecture Seiko Chemical Co., Ltd. (72) Harukichi Kano, 1-33, Yanagizaki, Kawaguchi City, Saitama Prefecture Kagaku Kagaku Co., Ltd. (72) Inventor Yataro Ichikawa 1-35 Yanagizaki, Kawaguchi City, Saitama

Claims (10)

[Claims] 1. A process for producing 4-aminodiphenylamines, which comprises reacting anilines with azobenzenes in the presence of a base. 2. The method for producing 4-aminodiphenylamines according to claim 1, wherein the base is an alkali metal alkoxide. 3. The method for producing 4-aminodiphenylamines according to claim 2, wherein the base is t-BuOK. 4. The method for producing 4-aminodiphenylamines according to claim 1, 2 or 3, wherein the reaction is carried out in the presence of a solvent which is an aprotic dipolar solvent. 5. The method for producing 4-aminodiphenylamines according to claim 4, wherein the solvent used in the reaction is monoglyme or a derivative thereof. 6. The method according to claim 4, wherein the solvent used in the reaction is diglyme or a derivative thereof.
-A method for producing aminodiphenylamines. 7. The method for producing 4-aminodiphenylamines according to claim 4, wherein the solvent used in the reaction is triglyme or a derivative thereof. 8. The method for producing 4-aminodiphenylamines according to claim 4, wherein the solvent used in the reaction is tetraglyme or a derivative thereof. 9. The method for producing 4-aminodiphenylamines according to claim 1, wherein the reaction is carried out in a hydrogen gas atmosphere. 10. The reaction according to claim 1, 2, 3, 4, 5, 6, wherein the reaction is carried out at a temperature of about 120 to 180 ° C.
7. A method for producing 4-aminodiphenylamines according to 7, 8 or 9.