JPH0482136B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a process for producing an iron catalyst-free rubber antioxidant diaryl-P-phenylenediamine.

[Conventional technology]

A method for removing an iron catalyst from a mixture of condensation reaction products of aromatic amines and hydroquinone is described in U.S. Pat.
It is described in 35862 etc. No. 3,305,584 discloses that an insoluble salt of iron is formed by adding an aqueous solution of an alkali metal salt to a mixture of condensation reaction products, and then after distilling off the water by heating and vacuum. , relates to a method for filtering out insoluble iron salts from said mixture. Furthermore, in Japanese Patent Publication No. 57-35862, anhydrous calcium hydroxide is used instead of an aqueous alkali metal salt solution. In the former example, the iron content rate of the obtained diamine antioxidant is limited to 30 to 60 ppm, and in the latter example, it is extremely difficult to obtain an iron content rate of 100 ppm or less.

[Problem to be solved by the invention]

Since iron tends to accelerate the oxidative deterioration of organic matter, it is desirable that the iron content of the diamine antioxidant be as low as possible. However, as mentioned above, in the known technology, the iron content is limited to 30 to 100 ppm.
It is extremely difficult to obtain lower contents. On the other hand, if the mixture resulting from the condensation reaction is washed with a large amount of water, it is possible to obtain a product with a content of 10 ppm, but this is not industrially advantageous because a large amount of wastewater with a high load is generated.

[Means for solving problems]

Therefore, as a result of intensive research to obtain a product with a low iron content that does not have these problems, the present inventor found that
When adding an aqueous alkali metal salt solution to the mixture of condensation reaction products, by adding activated clay,
The present invention was achieved by discovering a method for obtaining diaryl-P-phenylenediamine having an extremely low iron content of 5 ppm or less. That is, the present invention is based on the general formula () General formula () (In the formula, R ₁ and R ₂ are each independently a hydrogen atom or
Production of diaryl-P-phenylenediamine, which comprises reacting an aromatic amine represented by _C1 - _C3 alkyl group) with hydroquinone in the presence of an iron halide condensation catalyst at a temperature range of 100-350°C. In the method, an aqueous solution of an alkali metal salt and activated clay are added to the mixture resulting from the condensation reaction, water is distilled out of the system, and the solution of the mixture is filtered,
The present invention provides a method for producing diaryl-P-phenylenediamine that does not contain an iron catalyst and is characterized by removing insoluble iron salts.

Examples of the aromatic amine represented by the general formula () of the present invention include aniline, toluidine, ethylaniline, xylidine, and diethylaniline. The reaction between the aromatic amine alone or a mixture thereof and hydroquinone is carried out in the presence of an iron halide condensation catalyst. As the iron halide condensation catalyst, ferrous chloride or ferric chloride is used. The reaction may be carried out under normal pressure or under increased pressure, but it is preferable to take measures to remove the produced water from the system. The reaction temperature is preferably in the range of 100 to 350°C, and particularly preferably in the range of 190 to 250°C in view of reaction time and the like. Reaction time is 5-20 hours. The amount of aromatic amine used relative to hydroquinone is desirably 1.6 mol or more, particularly preferably 1.8 to 2.2 mol, per 1 mol of hydroquinone. In the present invention, for example, toluene, xylene, etc. can be used during azeotropic distillation for the purpose of dehydration.

Alka metal salts that can be used in the present invention include sodium carbonate (Na ₂ CO ₃ ), potassium carbonate (K ₂ CO ₃ ), sodium sulfate (Na ₂ SO ₄ ), potassium sulfate (K ₂ SO ₄ ), and acidic sodium sulfate. Examples include aqueous alkali metal salts such as (NaTSO ₄ ) and sodium thiosulfate (Na ₂ S ₂ O ₃ ). Any commercially available activated clay may be used, and thus the effect of fixing iron in the reaction mixture resulting from the condensation reaction as an insoluble iron salt can be enhanced. Water is distilled out of the system by azeotropic distillation or the like, and then the anhydrous reaction mixture is filtered to remove insoluble iron salts, yielding diaryl-P-phenylenediamine with an extremely low iron content. At this time, due to the adsorption effect of activated clay, diaryl-P-phenylenediamine with a low content of impurities insoluble in the solvent can be obtained, and in addition, a large amount of waste water is not produced as in the water washing method.

〔Example〕

Next, examples of the present invention will be shown.

Example 1 110 g of hydroquinone, 75 g of orthotoluidine,
Pour 169.5 g of mixed xylidine into a 500 ml four-necked flask, and add 13 g of 41.7% ferric chloride aqueous solution while stirring.
Add.

The reaction is continued while gradually heating and distilling water such as produced water out of the system, and the reaction is completed at 250°C. The reaction solution was cooled to 120° C., 120 ml of xylene was added as a diluting solvent, and 6 g of Activated Shirato Kou (manufactured by Nippon Shakuto Shirado Co., Ltd.) was added.

Next, 50 g of a 15.7% aqueous sodium carbonate solution was added at 90°C, and after stirring at 100°C for 4 hours, water was distilled out of the system, and the internal temperature became 140°C. After that, the reaction solution was filtered, and then xylene and unreacted amines were distilled off under reduced pressure to obtain 285 g of diaryl-P-phenylenediamine mixture.The iron content was measured by atomic absorption spectrometry. Then,
It was 2.2ppm. After dissolving 20 g of the obtained diaryl-P-phenylenediamine mixture in 300 ml of toluene and filtering it through a membrane filter with a pore size of 1.0 μm, the toluene insoluble content was determined from the increase in dry weight of the membrane filter taken out.
It was 0.001%.

Example 2 3g of filter aid Daicalite Pearlite (manufactured by Daicalite Orient Co., Ltd.) along with activated clay strong ○
The experiment was carried out in the same manner as in Example 1 except for the use of the following materials. The obtained diaryl-P-phenylenediamine mixture was 283 g, had an iron content of 2.1 ppm, and had a toluene insoluble content of 0.001%.

Example 3 An experiment was carried out in exactly the same manner as in Example 2, except that 2.5 g of activated clay strong ○ and 3 g of dicalite pearlite were used.

The resulting product weighed 285 g, with an iron content of 3.4 ppm and a toluene insoluble content of 0.001%.

Comparative Example 1 An experiment was carried out in exactly the same manner as in Example 1, except that 6 g of dicalite pearlite was used instead of activated clay strong ○.

The obtained product was 285g, iron content was 33.5ppm,
The toluene insoluble content was 0.004%.

〔Effect of the invention〕

As mentioned above, the use of activated clay has a clear iron removal effect and a solvent-insoluble removal effect, and the iron content is
It was possible to obtain less than 10 ppm of diaryl-P-phenylenediamine. Moreover, unlike the washing method, it does not generate large amounts of wastewater, which has a high load.

Claims (1)

[Claims] 1 General formula () (In the formula, R ₁ and R ₂ are each independently a hydrogen atom or
Production of diaryl-P-phenylenediamine, which comprises reacting an aromatic amine represented by _C1 - _C3 alkyl group) with hydroquinone in the presence of an iron halide condensation catalyst at a temperature range of 100-350°C. In the method, an aqueous solution of an alkali metal salt and activated clay are added to the mixture resulting from the condensation reaction, water is distilled out of the system, and the solution of the mixture is filtered,
A method for producing diaryl-P-phenylenediamine that does not contain an iron catalyst, characterized by removing insoluble iron salts.