JPH11217358A - Method for producing diarylamines - Google Patents

Abstract

(57) [Summary] [PROBLEMS] An arylamine is used as a raw material in the presence of a catalyst.
Provided is a catalyst capable of improving productivity when producing diarylamines under a pressurized liquid phase. A SiO ₂ / Al ₂ O ₃ molar ratio of 5 to 18
Are used as solid acid catalysts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing diarylamines, which are raw materials for rubber drugs, medicines, dyes and the like. More specifically, the present invention relates to a method for producing a diarylamine under a pressurized liquid phase in the presence of a solid acid catalyst using an arylamine as a starting material.

[0002]

2. Description of the Related Art Conventionally, as a method for producing diphenylamine using aniline as a starting material, hydrochloric acid, P ₂ O ₅ ,
A pressurized liquid phase method (for example, JP-A-51-138628, JP-A-53-40697) using a catalyst such as PCl ₃ , AlCl ₃ , BF ₃ , NH ₄ BF _4, etc. Fixed bed gas phase method using γ-alumina (for example, JP-A-61-103857, JP-B-3-1694)
No. 3). In addition, Japanese Patent Publication 52-15
No. 585, Japanese Patent Application Laid-Open No. 54-135728,
A fixed bed pressurized liquid phase method using a silica-alumina based synthetic solid acid catalyst is disclosed. Further, U.S. Pat.
No. 538 discloses a fixed bed pressurized liquid phase method for synthesizing diarylamines using a solid acid catalyst comprising β-zeolite and activated alumina.

[0003]

However, the pressurized liquid phase method has disadvantages in that the catalyst is corrosive, so that a highly corrosion-resistant container is required, and that separation and recovery of the catalyst are difficult. Further, the fixed bed gas phase method has disadvantages in that the size of the reaction apparatus becomes large and the catalytic activity is significantly reduced due to the adhesion of the tar by-product generated during the reaction to the catalyst surface. On the other hand, in the fixed bed pressurized liquid phase method, in the case of a silica-alumina catalyst, the activity is low and the conversion is low. Therefore, it has disadvantages such as low productivity and the need to collect and recycle a large amount of raw material aniline. Although the method using a solid acid catalyst comprising β-zeolite and activated alumina has a high catalytic activity, it cannot be said that it is sufficient for industrial practice. Under such circumstances, the present inventors have conducted intensive studies on the pressurized liquid phase method using a solid acid catalyst which is considered to be advantageous in terms of catalytic activity. As a result, the β-zeolite catalyst SiO ₂ / Al ₂ The inventors have found that the reaction activity is significantly improved by lowering the O ₃ molar ratio, and completed the present invention.

[0004]

That is, the present invention relates to a method for producing diarylamines from an arylamine as a raw material under a pressurized liquid phase, wherein the molar ratio of SiO ₂ / Al ₂ O ₃ is 5 or more and less than 20. An object of the present invention is to provide a method for producing a diarylamine, which comprises using a range of β-zeolites as a solid acid catalyst.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The method of the present invention will be specifically described below. In carrying out the method of the present invention, it is essential to use a β-zeolite catalyst as a solid acid catalyst.
Acid points are present in zeolite as a solid acid catalyst, and these acid points are preferably H-type or NH ₄ -type. Of course, as long as the applicable zeolite is in a range having a function as a solid acid catalyst, it may contain Na type and K type.
It is of course possible to use zeolite as a solid acid catalyst as long as the conversion is not significantly reduced as a solid acid catalyst. Generally, the number of acid sites in a zeolite catalyst is SiO ₂ /
It is known that the lower the Al ₂ O ₃ molar ratio, the higher the molar ratio.
_{The 2} / Al ₂ O ₃ molar ratio is applied in the range of 5 or more and less than 20, more preferably 5 to 18 for high activation.

The β-type zeolite catalyst may be any one obtained by a generally known production method, and the production method is not particularly limited. The shape of the zeolite catalyst at the time of use is not particularly limited, and it can be used in various shapes such as powder, granules, and tablets, but from the viewpoint of handling, granules or tablets are recommended. You. In molding, various materials can be used as a binder, but alumina, silica, diatomaceous earth and the like are usually used.

In the present invention, the arylamines used are represented by the following general formulas [1] and [2] wherein R ₁ to
R ₁₀ may be the same or different,
Each of hydrogen, alkyl having 1 to 12 carbons, 1 to 1 carbon
12 alkoxy, phenyl, hydroxy, amino, nitro or C1-C12 alkoxy, hydroxy or phenyl-substituted alkyl having 1 to 12 carbons]. The arylamine is reacted in the presence of a solid acid catalyst comprising the above-mentioned β-type zeolite to give the following general formula [3] (the symbols and conditions in the formula are the same as those of the above general formulas [1] and [2]) Diarylamine can be obtained.

[0008]

The above-mentioned general formulas [1] and [2] as raw materials
Specific examples of the arylamine represented by aniline,
Toluidine, ethylaniline, cumidine, xylidine,
Examples thereof include butylaniline, anisidine, fluoroaniline, bromoaniline, iodoaniline, and fluorodimethylaniline. Of these, aniline, toluidine, cumidine, and xylidine are preferable. In the reaction, general formulas [1] and [2] may of course be the same, for example, only aniline.

In carrying out the present reaction method, the reaction can be carried out as it is or by adding water to the starting arylamine. Regarding the addition of water during the reaction, silica-
Japanese Patent Application Laid-Open No. 54-135728 discloses that a composite oxide catalyst such as alumina has an effect of improving the conversion rate. However, apart from the effect, a β-zeolite is used as a solid acid catalyst. In this system, the starting arylamines may be reacted in the presence of water. The method of adding water and the amount of addition in this case are described in
A prescription similar to that of JP-A-135728 can be applied.

This reaction is carried out in a temperature range of 300 to 400 ° C.
It is desirably carried out under a temperature condition of 330 to 360 ° C. When the temperature is lower than 300 ° C., the reaction proceeds slowly, which is not suitable for practical use. On the other hand, if the temperature is 400 ° C. or higher, a large amount of by-products is generated, and when a low-boiling raw material such as aniline is used as the raw material, a high pressure is required to maintain the liquid, which is not preferable.

The pressure in the practice of the present invention may be any pressure as long as it can release the generated ammonia and maintain the liquid phase of the reaction phase at the above reaction temperature. This pressure increases in proportion to the reaction temperature and decreases as the mole fraction of arylamines in the reaction phase decreases as the reaction proceeds. In addition, this pressure may generally correspond to the saturated vapor pressure of the arylamine at the reaction temperature. For example, in the case of aniline, it is usually 10 to 40 kg at the above-mentioned reaction temperature.
/ Cm ² G.

In the method of the present invention, after the reaction, unreacted arylamines are simply fractionated from the reaction product, and then the desired diarylamines can be easily obtained by separating them as high-boiling by-products. Can be. When water is added during the reaction, most of the water is recovered at the same time as the arylamines during the fractionation of the unreacted arylamines, so that the fractionated arylamines are appropriately adjusted in water content. Can be reused.

The method of the present invention can be carried out by a batch method or a continuous method. However, industrially, a continuous method of continuously supplying the starting material arylamines and water and continuously extracting the reactants while controlling the pressure is advantageous in terms of work efficiency.

[0015]

According to the present invention, the molar ratio of SiO ₂ / Al ₂ O ₃ is 5 or more in the production of diarylamines under a pressurized liquid phase using arylamines as raw materials. By using a β-zeolite in a range of less than 20 as a solid acid catalyst, it is possible to greatly improve its productivity, and its industrial value is extremely large.

[0016]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Example 1 In a 500 mL stainless steel autoclave, 50 g of H
-Β zeolite (Si / Al = 12.5, N-Chemcat Corporation, trade name H-β) catalyst powder, 200
g of aniline and 2 g of water were added, the air in the autoclave was replaced with nitrogen, and then heated at 350 ° C. for 3 hours in a sealed system. After cooling the reaction product, it was taken out of the autoclave, the catalyst was filtered, and the reaction solution was analyzed using a gas chromatograph. As a result, the diphenylamine concentration in the reaction solution was 43.7%.

Comparative Example 1 In a 500 mL stainless steel autoclave, 50 g of H
-Β zeolite (Si / Al = 25.0, manufactured by JGC Universal Co., Ltd., trade name BETA) catalyst powder, 200 g
Of aniline and 2 g of water were added thereto, and the air in the autoclave was replaced with nitrogen, followed by heating at 350 ° C. for 3 hours in a sealed system. After cooling the reaction product, it was taken out of the autoclave, the catalyst was filtered, and the reaction solution was analyzed using a gas chromatograph. As a result, the diphenylamine concentration in the reaction solution was 27.1%.

Claims (4)

[Claims] 1. A method for producing a diarylamine from an arylamine as a raw material under a pressurized liquid phase, wherein SiO _{2 is used.}
A method for producing diarylamines, comprising using a β-zeolite having a / Al ₂ O ₃ molar ratio of 5 or more and less than 20 as a solid acid catalyst. 2. The method according to claim 1, wherein the β-zeolite has a SiO ₂ / Al ₂ O ₃ molar ratio of 5 to 18. 3. The β-zeolite catalyst is H-type or NH-form.
The method according to claim 1, which is a type ₄ catalyst. 4. A method for producing a diarylamine represented by the following general formula [3] by reacting an arylamine represented by the following general formula [1] with an arylamine represented by the following general formula [2]. The method of claim 1, wherein: [Wherein, R _{1 to} R ₁₀ may be the same or different, and each represents hydrogen, alkyl having 1 to 12 carbons, alkoxy, phenyl, hydroxy, amino, nitro or carbon having 1 to 12 carbons. Alkoxy of formulas 1 to 12,
C1-C1 substituted by hydroxy or phenyl
Selected from the group consisting of 2 alkyls)