JPH11222466A - Method for producing diarylamines - Google Patents

Abstract

(57) [Summary] [Problem] To prepare aniline as a raw material in the presence of a solid acid catalyst,
In producing diphenylamine under a pressurized liquid phase, the conversion of aniline to diphenylamine is increased, and the productivity is improved. SOLUTION: A catalyst comprising β-zeolite and silica is used as a solid acid catalyst.

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 from an arylamine as a starting material under a pressurized liquid phase in the presence of a solid acid catalyst.

[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 ,
Pressurized liquid phase method using PCl ₃ , AlCl ₃ , BF ₃ , NH ₄ BF ₄ or the like as a catalyst (for example, see JP-A-51-138628).
JP-A-53-40697) and a fixed-bed gas phase method using acid-treated γ-alumina (for example, JP-A-61-103857, JP-B-3-16943).
And fixed bed pressurized liquid phase method using a silica-alumina synthetic solid acid catalyst (for example, Japanese Patent Publication No. 52-1558).
No. 5, JP-A-54-135728) and the like.

[0003]

However, the pressurized liquid phase method has the drawback that the catalyst is corrosive, so that a highly corrosion-resistant container is required, and that the separation and recovery of the catalyst are difficult. . In addition, the fixed bed gas phase method has disadvantages in that the reactor becomes large and equipment cost increases, and that tar by-products generated during the reaction adhere to the surface of the catalyst, resulting in a significant decrease in catalytic activity. On the other hand, in the fixed bed pressurized liquid phase method, in the case of a silica-alumina catalyst, the activity is low,
Low conversion. Therefore, it has disadvantages such as low productivity and the need to collect and recycle a large amount of the raw material aniline. In view of such circumstances, the present inventors have conducted intensive studies on a pressurized liquid phase method using a solid acid catalyst, and as a result, β
-It has been found that the conversion of arylamine to diarylamine is remarkably improved by using a solid acid catalyst composed of zeolite and silica, and the present invention has been completed.

[0004]

That is, the present invention relates to the use of a solid acid catalyst comprising β-zeolite and silica in the production of diarylamines from an arylamine as a raw material under a pressurized liquid phase. To provide a method for producing diarylamines characterized by the following.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The method of the present invention will be specifically described below. In carrying out 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, if the applicable zeolite is in a range having a function as a solid acid catalyst, Na type and K type may be contained.

[0006] It is, of course, possible to use zeolite as a solid acid catalyst as long as the conversion is not significantly reduced. In the method of the present invention, the molar ratio of SiO ₂ / Al ₂ O ₃ of the β-zeolite is preferably 5 to 10
It is in the range of 0, more preferably in the range of 20 to 50. When the SiO ₂ / Al ₂ O ₃ molar ratio is lower than this range, the reaction activity increases, but the amount of generated impurities increases. Conversely, when the molar ratio is higher than this range, the reaction activity decreases.
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 in use is not particularly limited, and it can be used in various shapes such as powder, granules, tablets, etc., but from the viewpoint of handling, it is formed into granules or tablets. Is recommended. When molding the zeolite catalyst, various materials such as alumina and silica can be usually used as a binder, but silica is used in the method of the present invention. The amount of silica used is preferably 10 to 70%,
More preferably, it is selected from the range of 20 to 50%. If the amount of silica used is less than this range, the strength of the molded catalyst will be insufficient, and if it is greater than this range, the β-zeolite concentration will decrease, and the activity per unit molded catalyst will be low.

In the present invention, an arylamine represented by the following general formula [1] and an arylamine represented by the following general formula [2] wherein R _{1 to} R ₁₀ are the same or different. Respectively, hydrogen, carbon number 1 to
12 alkyl, alkoxy having 1 to 12 carbons, phenyl, hydroxy, amino, nitro or alkyl having 1 to 12 carbons substituted with alkoxy having 1 to 12 carbons, hydroxy or phenyl] and Is reacted in the presence of a solid acid catalyst comprising β-zeolite and silica to obtain a diaryl represented by the following general formula [3] (wherein symbols and conditions are the same as those of general formulas [1] and [2]): Produce amine.

[0009]

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, and fluorodimethylaniline. Of these, aniline, toluidine, cumidine, and xylidine are preferred. Formulas (I) and (I
I) may, of course, be the same, for example only aniline.

In carrying out the present reaction method, the raw material arylamine can be reacted as it is or by adding water. 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 the method of the present invention, the starting arylamine may be reacted in the presence of water. The method and amount of water addition in this case are described in
The same formulation as in the method described in JP-A-4-135728 can be applied.

In the present invention, β of the starting arylamines
-The reaction in the pressurized liquid phase in the presence of a solid acid catalyst composed of zeolite and silica is carried out in a temperature range of 300 to 400C, preferably in a temperature range of 330 to 360C.
If the temperature is lower than 300 ° C., the progress of the reaction is slow. If the temperature exceeds 400 ° C., a large amount of by-products is generated. If a low-boiling raw material such as aniline is used as the raw material, the temperature is high to maintain the liquid. Requires pressure.

The pressure in the present invention may be any pressure that can release ammonia generated by the reaction from the reaction system and keep the reaction phase in a liquid state at the 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, the pressure is generally in the range of 10 to 40 kg / cm ² G at the above-mentioned reaction temperature.

In the process of the present invention, the desired diarylamines can be easily obtained by fractionating unreacted arylamines from the reaction product after the reaction and then separating high-boiling by-products as residues. . 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 process of the present invention can be carried out by either a batch process or a continuous process. However, industrially, a continuous process in which the raw materials, arylamines and water are continuously supplied and the reaction product is continuously withdrawn while controlling the pressure. Is advantageous in terms of work efficiency.

[0016]

According to the method of the present invention described in detail above, a solid acid catalyst comprising β-zeolite and silica is used for producing diarylamines from an arylamine as a raw material under a pressurized liquid phase. By doing so, it is possible to improve the product quality, and its industrial value is extremely large.

[0017]

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 25 g of H was placed in a 500 mL stainless steel autoclave.
-Β zeolite (Si / Al = 25.0, silica 20%
After containing 200 g of aniline and replacing the air in the autoclave with nitrogen, the autoclave was 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 25.0%.

Comparative Example 1 In the method of Example 1, 50 g of the following silica-alumina catalyst (manufactured by JGC Corporation) was used as a catalyst.
The same operation as in Example 1 was performed except that 2 g of water was added. After cooling the obtained reaction product, it was taken out of the autoclave, the catalyst was filtered, and the reaction solution was analyzed using a gas chromatograph. Table 1 shows the results. Silica alumina (Si / Al = 6.5): trade name N63
3L silica alumina (Si / Al = 2.6): trade name N63
2NH

[0020]

[Table 1]

Claims (4)

[Claims] 1. A method for producing diarylamines, which comprises using a solid acid catalyst comprising β-zeolite and silica in producing diarylamines from an arylamine as a raw material under a pressurized liquid phase. . 2. The method according to claim 1, wherein the β-zeolite is an H type or NH ₄ type catalyst. 3. SiO ₂ / Al ₂ O _{3 of} β-zeolite
The molar ratio is 5-100, and the silica content is 10-70% by weight.
2. A solid acid catalyst which is:
The described method. 4. A method of reacting an arylamine represented by the following general formula (1) with an arylamine represented by the following general formula (2) to produce a diarylamine represented by the following general formula (3). 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)