JPS5811419B2 - Recovery method of diarylamine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering diarylamine, and more specifically, a method for recovering diarylamine, and more particularly, a method for recovering diarylamine, which is a secondary arylamine for producing a primary arylamine corresponding to the diarylamine by reacting monohydric phenol and ammonia in the presence of a solid acid catalyst. The present invention relates to a method for recovering the resulting diarylamine as a purified diarylamine that does not become colored even when stored for a long period of time.

When monohydric phenol, such as phenol and ammonia, are reacted by passing through a solid acid catalyst layer such as silica-alumina at high temperature to produce a primary arylamine corresponding to phenol, i.e. aniline, although it varies depending on the reaction conditions, phenol is It is known that about 0.5 to 1.5 percent by weight of diphenylamine is produced as a by-product.

To recover this by-produced shifteramine, a mixture consisting of unreacted ammonia, unreacted phenol, aniline, by-produced diphenylamine, and other by-products is usually distilled from the reaction product that has passed through the catalyst layer. Unreacted ammonia and phenol, as well as aniline, the main product, are recovered, and diphenylamine and other by-products are extracted from the bottom of the distillation column as a high-boiling fraction, and this high-boiling fraction is distilled again. Diphenylamine is thereby obtained.

However, the diphenylamine thus obtained lacks storage stability and causes undesirable discoloration in early production, so the uses of the diphenylamine produced by this method have naturally been limited.

Furthermore, when toluidine, which corresponds to cresol, is produced from cresol and ammonia in a similar manner, ditolylamine, which is produced as a by-product, has the same coloring problem.

The cause of the coloration of diarylamine obtained through such a process is not clear, and the present inventor has determined that basic organic substances containing nitrogen atoms other than diphenylamine present in the high-boiling fraction mentioned above are sufficiently removed by distillation. Based on the fact that diphenylamine exists as a trace impurity without being separated, it is presumed that this impurity is the substance that causes the coloration, and the conventional representative method for removing basic organic substances containing nitrogen atoms from diarylamine is carried out using a phosphoric acid aqueous solution. (Japanese Patent Publication No. 38-10528), heating with an organic acid (Japanese Patent Application Laid-open No. 47-134322), etc., but the treatment method with an aqueous phosphoric acid solution removes diphenylamine containing impurities. This method involves an extremely complicated process of stirring with an aqueous phosphoric acid solution, separating the aqueous layer, dehydrating it, and then distilling it, which is not suitable for industrial use. According to additional tests conducted by the present inventors, it was found that diphenylamine had no effect on the treatment method and still caused early coloring.

Until now, there has been no simple method for recovering diarylamine, which is produced as a by-product during the reaction in the presence of a solid acid catalyst to produce primary arylamine corresponding to monohydric phenol, as a purified product without coloring. Ta.

However, the present inventor oxidized the high-boiling fraction or the crude diarylamine obtained by distillation from the high-boiling fraction with molecular oxygen such as air in the presence of a metal oxidation catalyst, and then processed the resulting product to be treated. The present invention was based on the discovery that diarylamine obtained by means such as distillation has good storage stability and does not become colored for a long period of time.

That is, the present invention provides a high-boiling distillate in which unreacted ammonia, monohydric phenol, and a primary arylamine corresponding to the monohydric phenol are removed by distillation from a mixture obtained by reacting monohydric phenol and ammonia in the presence of a solid acid catalyst. In a method for recovering diarylamine by-produced from water, the high-boiling fraction or the crude diarylamine obtained by distillation from the high-boiling fraction is oxidized with molecular oxygen in the presence of a metal oxidation catalyst, and then the material to be treated is The present invention relates to a method for recovering diarylamine characterized by obtaining diarylamine from.

According to the method of the present invention, a high-boiling fraction containing diarylamine or a crude diarylamine obtained by distilling a high-boiling fraction is brought into contact with air in the presence of a metal oxidation catalyst, and then the material to be treated is distilled. Purified diarylamine with good storage stability can be obtained through this extremely simple process, and the present invention has great industrial value.

The configuration of the present invention will be explained in detail below.

The diarylamine that is the object of the present invention is a diarylamine that is produced as a by-product when monohydric phenol and ammonia are reacted in the presence of a solid acid catalyst. Diarylamine is a phenyl group, and specific examples thereof include diphenylamine, ditolylamine, diarylmine, and bis(ethylated phenyl)amine, and more preferred are diphenylamine and ditolylamine. Particularly, diphenylamine is used in the present invention. Preferred as a target.

Therefore, examples of the monohydric phenol of the present invention include phenol, cresol, xylenol and ethylated phenol, preferably phenol and cresol, more preferably phenol.

The solid acid catalyst used to react monohydric phenol with ammonia is a solid acid catalyst used to produce a base arylamine corresponding to the monohydric phenol produced according to the following formula.

Ar-OH+NHs→Ar-NH2+H20 (here A
r is an aryl group.

) Solid acid catalysts include silica, alumina, silica-alumina, titania-alumina, zirconia-alumina and mixtures thereof.

Further, the reaction conditions when monohydric phenol and ammonia are reacted in the presence of the solid acid catalyst mentioned above are the usual conditions for producing the above-mentioned primary arylamine corresponding to monohydric phenol.

For example, when phenol and ammonia are reacted, the reaction is carried out under conditions such as a molar ratio of phenol and ammonia (phenol/ammonia) of 1 to -40, a temperature of 300 to 600°C, and a pressure of 5 to 50 kg/ayl (Gauge). Ru.

The reaction product of monohydric phenol and ammonia carried out under such reaction conditions is a mixture consisting of unreacted ammonia, unreacted monohydric phenol, primary arylamine, diarylamine formed as a by-product, and other by-products. is obtained.

In this mixture, the diarylamine is usually present in an amount of 0.5 to 1.5% by weight, based on the reacted monohydric phenol.

The above mixture is distilled to recover unreacted ammonia, monohydric phenol, and primary arylamine, and a high-boiling fraction is extracted from the bottom of the column.

For example, when the monohydric phenol is phenol, this high boiling point fraction has a boiling point of about 200° C. or higher and contains about 80 to 95% by weight of diphenylamine.

In the method of the present invention, a high-boiling fraction or a crude diarylamine distilled from the high-boiling fraction is oxidized with molecular oxygen in the presence of a metal oxidation catalyst.

In the present invention, this oxidation treatment is the most important structural requirement, and without this treatment, purified diarylamine cannot be obtained.

Further, better results can be obtained by oxidizing crude diarylamine that has been distilled from the high-boiling fraction rather than by directly oxidizing the high-boiling fraction.

The distillation of crude diarylamines from high-boiling fractions can be carried out either at atmospheric pressure or under reduced pressure; however, if the diarylamines have extremely high boiling points or tend to decompose at high temperatures, reduced pressure may be used. It is preferable to carry out below.

Metal oxidation catalysts used include cobalt, manganese, copper, and zinc acetates, cobalt, manganese, and copper napthenates, copper acetylacetonates, copper, cobalt, and zinc nitrates, copper and cobalt carbonates, and hydrochloric acid. Preferred examples include copper acetate, copper naphthenate, copper acetylacetonate, copper nitrate; copper chloride and mixtures thereof; among them, copper acetate, copper naphthenate, copper nitric acid More preferred are copper and mixtures thereof, particularly the use of copper acetate.

Such a metal oxidation catalyst is used as a metal component in an amount of 0.05 to 50% by weight, preferably 0.1 to 2.0% by weight, based on the diarylamine contained in the high-boiling fraction or crude arylamine.

Examples of molecular oxygen in the present invention include pure oxygen gas, air, and a mixed gas of oxygen gas and an inert gas such as nitrogen gas, but the use of air is industrially preferred.

The partial pressure of oxygen gas in the reaction system for catalytic oxidation treatment is usually 0.05 to 1.0 kg/d, preferably 0.05 to 1.0 kg/d.
1 to 0.5 kg/cyyt.

Further, the oxidation treatment is carried out under normal pressure or increased pressure in the reaction system, but it is preferably carried out near normal pressure.

The temperature of the oxidation treatment is usually carried out at a temperature at which diarylamine melts, preferably 20 to 150°C higher than the melting point of diarylamine, more preferably 50 to 100°C.

The time for contacting the high boiling point fraction or crude diarylamine with molecular oxygen depends on the partial pressure of oxygen, but is usually 10 to 100 minutes, preferably 30 to 60 minutes.

As the apparatus used in the oxidation treatment, a reaction vessel equipped with a gas blowing pipe, a gas discharge port, a catalyst addition port, a heating device, and, if necessary, a stirring device can be used.

The treatment operation can be carried out by blowing molecular oxygen into a reaction vessel containing a high-boiling fraction or crude diarylamine and a catalyst, and stirring the mixture at a predetermined temperature and for a predetermined time so that the gas and liquid are in sufficient contact with each other.

Stirring may be performed by a stirring device or by vigorously blowing molecular oxygen into the liquid through a blowing tube.

The oxidation treatment can be carried out either continuously or batchwise.

When carried out in a continuous manner, the residence time may be the contact time between the molecular oxygen and the high boiling point fraction described above.

A purified diarylamine that does not become colored even when stored for a long time can be recovered from the oxidized material by means such as distillation or recrystallization, but distillation is recommended as a means of recovery.

Distillation can be carried out either under atmospheric pressure or under reduced pressure, but in cases where the diarylamine has a very high boiling point or tends to decompose at high temperatures, it is preferably carried out under reduced pressure.

Each of the above steps can be arbitrarily selected and carried out by a continuous method, a batch method, or an appropriate combination thereof.

The present invention will now be described in detail with reference to Examples.

Example 1 Phenol and ammonia were placed in a reaction tank filled with silica-alumina catalyst at a molar ratio (phenol/ammonia) of 1/2.
0, liquid phase space velocity 0.04 hr-1°, temperature 380°C, and pressure 15 kg/cvt (gauge).

Since a considerable proportion of ammonia is dissolved in the effluent from the reaction tank, it is fractionated by distillation, and then a mixture consisting of the produced water, unreacted phenol, diphenylamine produced by aniline, and other by-products is distilled to obtain water. , phenol, and aniline were recovered.

At this time, the main product, aniline, was produced in a yield of 98% based on phenol.

The bottoms discharged from the bottom of the distillation column is a black high-boiling fraction containing 90% by weight of diphenylamine.

1 kg of this high boiling point fraction was distilled under reduced pressure to obtain 900 g of a fraction having a boiling point of 156 to 159° C./10 mmHg.

This fraction was crude diphenylamine containing 65% by weight of diphenylamine, and trace amounts of indoles and acridines were detected.

900 g of this crude diphenylamine and 4.5 g of copper acetate (the amount of copper used is equivalent to 0.18% by weight with respect to diphenylamine).

) was placed in 21 glass flasks equipped with a stirrer, a thermometer, an air blower, and an air outlet.
The oxidation treatment was carried out at 100° C. for 1 hour at normal pressure while stirring and blowing air into the mixture.

The material to be treated is further distilled under reduced pressure to a boiling point of 156 to 158.
810 g of white crystalline diphenylamine was obtained as a fraction of °C/10 mnHg at room temperature.

This fraction showed almost no discoloration even when stored indoors in an air atmosphere for one month.

In addition, the wavelength 5
Transmittance to light of 60 mμ was measured.

The results are shown in Table 1. Comparative Example 1 In Example 1, the crude diarylamine obtained by distilling the high boiling point fraction was white at room temperature immediately after distillation, but 3
The color changed to pale yellow after a day had passed, and to brown after a month.

Further, the transmittance of the crude diarylamine to light of 560 mμ was measured in the same manner as in Example 1 after 4 days and 1 month had elapsed.

The results are shown in Table 1. Comparative Example 2 The same operation as in Example 1 was performed except that no catalyst was used in the oxidation treatment step.

The obtained diphenylamine turned pale yellow after 3 days, and turned brown after a while.

Table 1 shows the transmittance.

Example 2 In Example 1, 9 g of copper naphthenate was used instead of copper acetate (the amount of copper used was equivalent to 0.23% by weight based on diphenylamine).

) was used, but the same operation as in Example 1 was performed.

The transmittance is shown in Table 1.

Example 3 In Example 1, 4.5 g of copper nitrate was used instead of copper acetate (the amount of copper used was equivalent to 0.15% by weight based on diphenylamine).

) was used, but the same operation as in Example 1 was performed.

Claims (1)

[Claims] 1. Unreacted ammonia, monohydric phenol, and primary arylamine corresponding to the monohydric phenol are removed by distillation from a mixture obtained by reacting monohydric phenol and ammonia in the presence of a solid acid catalyst. In a method for recovering diarylamine as a by-product from a high-boiling fraction, the high-boiling fraction i or a crude diarylamine obtained by distillation from the high-boiling fraction is oxidized with molecular oxygen in the presence of a metal oxidation catalyst, and then A method for recovering diarylamine, which comprises obtaining diarylamine from the obtained and treated material. 2 Paragraph 1, which indicates that the metal catalyst is used in an amount of 0.05 to 5.0% by weight of the metal based on the diarylamine present in the high-boiling fraction or the crude diarylamine obtained by distillation from the high-boiling fraction. Method described. 3. The method according to item 2, wherein the metal oxidation catalyst is copper acetate, copper naphthenate, or copper nitrate. 4. The method according to items 1 to 3, characterized in that air is used as molecular oxygen. 5. The method according to items 1 to 4, characterized in that diarylamine is obtained by distillation from the object to be treated after oxidation treatment. 6. The method according to items 1 to 5, characterized in that: 7. The method according to item 6, wherein the monohydric phenol is phenol.