JPH078842B2 - Method for purifying p-nitrodiphenylamine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for purifying crude p-nitrodiphenylamine produced using a copper-based catalyst.

(Prior Art) p-Nitrodiphenylamine is an important intermediate of N-alkyl-N'-phenyl-p-phenylenediamine, which is widely used as a stabilizer against oxidative deterioration or ozone deterioration of rubber. As a typical method for producing N-alkyl-N′-phenyl-p-phenylenediamine from p-nitrodiphenylamine, alkylation reaction of p-nitrodiphenylamine and ketones in the presence of hydrogen with a catalyst such as platinum charcoal is carried out. It is known how to do this. As a result of various studies on this production method, the present inventors have conducted a crude p-production by reacting p-halonitrobenzene and aniline in the presence of a neutralizing agent and a solubilizing agent using a copper compound as a catalyst. It has been found that when -nitrodiphenylamine is used as a raw material, a trace amount of copper root or tar content mixed therein adversely affects the alkylation reaction. In particular, since the platinum catalyst used for the above alkylation reaction is expensive, it is necessary to repeatedly use such a platinum catalyst as an industrial production method. However, when the above crude p-nitrodiphenylamine is used as a raw material, Since there is a problem that the catalytic activity is drastically reduced by the repeated use of about once or twice and the yield is extremely lowered, it is necessary to purify it by some method.

By the way, a distillation method is known as a method for purifying such crude p-nitrodiphenylamine (British Patent No. 834,510).
issue). However, when p-nitrodiphenylamine is produced by the reaction of p-halonitrobenzene and aniline as described above, a thermally unstable by-product such as 4,4'-dinitrotriphenylamine is produced. However, the distillation treatment of crude p-nitrodiphenylamine containing such by-products is not preferable as an industrial refining method because it involves a risk of explosion and the like.

As another purification method, there is also known a method in which crude p-nitrodiphenylamine is recrystallized in a methanol solvent for purification (British Patent No. 798,148). However, as a result of additional tests conducted by the present inventors, this method also shows that the precipitated crystal form is extremely fine and inferior in passivity, the hue of p-nitrodiphenylamine obtained is black green, and the purity is 95 to 97%. It was not satisfactory as a refining method because it was low and there was a problem that copper roots of about 300 to 800 ppm remained in the cake after separation.

<Problems to be Solved by the Invention> From the above, the present inventors have an industrially advantageous purification method for removing tar and copper roots from the crude p-nitrodiphenylamines produced by the above method. As a result of the investigation, the present invention was achieved.

<Means for Solving the Invention> That is, the present invention is a crude p-nitro obtained by reacting p-halonitrobenzene and aniline in the presence of a neutralizing agent and a solubilizing agent using a copper compound as a catalyst. In purifying diphenylamine, the crude -p-nitrodiphenylamine is treated with an aqueous mineral acid solution in the presence or absence of an aromatic or aliphatic hydrocarbon solvent substituted with at least one or more halogen atoms, and then the solvent is used. The present invention provides a method for purifying p-nitrodiphenylamine, which is characterized in that it is recrystallized.

The crude p-nitrodiphenylamine used in the present invention is produced by reacting p-halonitrobenzene and aniline with a copper compound as a catalyst in the presence of a neutralizing agent and a solubilizing agent. .

Usually, this reaction requires a high temperature and a long time, and the obtained crude p-
Nitrodiphenylamine contains many tar-like byproducts and a small amount of copper compounds.

The copper compound used in this reaction is copper cyanide, basic copper carbonate, copper iodide, copper chloride, copper powder, copper oxide, etc., and the neutralizing agent is caustic soda, sodium bicarbonate, sodium carbonate, caustic potash, heavy copper. Examples of potassium carbonate, potassium carbonate and the like, and examples of the solubilizer include polyoxyethylene, polyoxypropylene, polyoxyethylene mono- or dialkyl ether and the like.

The reaction is usually carried out under normal pressure or slightly reduced pressure, the reaction temperature is usually 170 to 220 ° C., the reaction time is usually 10 to 20 hours, and generally, the water produced is drained out of the reaction system at appropriate times. Be seen.

After completion of the reaction, a solid substance in the reaction solution is removed, and then low boiling components such as unreacted aniline are distilled off to obtain crude p-nitrodiphenylamine.

In the purification method of the present invention, such crude p-nitrodiphenylamine is first washed with a mineral acid aqueous solution.

Examples of the mineral acid used here include sulfuric acid, hydrochloric acid, phosphoric acid and the like, and sulfuric acid is particularly preferably used.
Such a mineral acid is usually used as an aqueous solution having a concentration of 0.2 to 20% by weight.

Here, if the concentration is less than 0.2% by weight, the treatment efficiency is poor and
When it exceeds the weight%, no significant difference is observed in the treatment efficiency with the increase of the concentration.

The amount of the aqueous mineral acid solution used is not particularly limited and can be arbitrarily selected depending on the concentration of the aqueous mineral acid solution and the like, but is usually in the range of 0.2 to 10 times by weight with respect to the crude p-nitrodiphenylamine,
For example, when a mineral acid aqueous solution having a concentration of 1 to 3% by weight is used, a sufficient treatment effect can be expected by using 0.5 to 2 times by weight of the aqueous solution.

The treatment with the aqueous solution of mineral acid can be performed in the absence of a solvent, but it is more preferable to perform the treatment in the presence of a solvent from the viewpoint of workability and recrystallization treatment in the next step.

As the solvent used here, an aromatic hydrocarbon or aliphatic hydrocarbon solvent substituted with at least one halogen is used, and such solvent includes 1,1-dichloroethane, 1,2- Dichloroethane, 1,2-dichloropropane, 1,3-dichloropropane, 2,2-dichloropropane, monochlorobenzene, o-dichlorobenzene, p-
Dichlorobenzene, p-chlorotoluene, o-chlorotoluene and the like are exemplified, but monochlorobenzene is particularly preferably used.

When a solvent is used, its amount is usually 0.1 to 5 times the weight of the crude p-nitrodiphenylamine.

The treatment temperature varies depending on whether or not a solvent is used, the type of solvent used, and the like. When a solvent is used, it is limited by the boiling point thereof and the like, but is usually 20 to 150 ° C. at normal pressure. Of course, it can also be performed under pressure. When no solvent is used, the treatment is usually performed under pressure at a temperature equal to or higher than the melting point of the crude p-nitrodiphenylamine.

After such treatment, the oil layer is separated from the water layer by liquid separation,
The oil layer may be further washed with water, and a small amount of alkali may be added to the oil layer to adjust the liquidity.

The above oil layer is then subjected to recrystallization treatment, but when the solvent is contained in the oil layer, that is, when the oil layer obtained when the above treatment with a mineral acid aqueous solution is carried out in the presence of a solvent is targeted. In the case of a recrystallization treatment by cooling the oil layer according to a general method, and when the oil layer does not contain a solvent, that is, when the treatment with a mineral acid aqueous solution is performed in the absence of a solvent. Obtained oil layer (high temperature)
In the case of the above, the recrystallization treatment is performed after adding the same amount of the same solvent as described above to the oil layer.

Incidentally, before such recrystallization treatment, acid clay, activated clay,
Treatment with activated carbon or the like may be performed in advance.

The p-nitrodiphenylamine deposited by the above recrystallization treatment is recovered due to excess.

The liquid is usually purified and then reused.
It is preferable to reuse a part of the filtrate as it is in order to increase the recovery yield of nitrodiphenylamine.

By such recrystallization treatment, extremely high quality p-nitrodiphenylamine having a purity of 99% or more and a copper content of 2 ppm or less can be obtained as yellow flaky crystals.

The purified p-nitrodiphenylamine thus obtained can be reacted with ketones in the presence of hydrogen using a catalyst such as platinum charcoal to produce N-alkyl-N'-phenyl-p-phenynediamine.

The reductive alkylation reaction is carried out in a conventional manner.

For example, commercially available platinum charcoal or sulfided platinum charcoal is used as a catalyst, and acetone or methyl isobutyl ketone is used as a ketone, and charged into a reactor together with purified p-nitrodiphenylamine, heated to a predetermined temperature, and hydrogen is heated under a predetermined pressure. It is done by introducing.

The method for repeatedly using the catalyst is not particularly limited and may be any method.

For example, after the reaction is completed, the reaction product is taken out of the reactor, then the catalyst is separated due to excess or the like, and then charged into the reactor again to carry out the reductive alkylation reaction, or after the reaction is completed, the reaction product is taken out of the reactor and the catalyst is removed. Is left in the reactor and the reductive alkylation reaction is carried out again.

The reductive alkylation reaction proceeds easily by repeatedly using the catalyst without using a completely new catalyst for each reaction.

<Effects of the Invention> Thus, according to the present invention, high-quality purified p-nitrodiphenylamine can be obtained from crude p-nitrodiphenylamine, and as a result, catalysts such as platinum charcoal in the reductive alkylation reaction using this as a raw material can be obtained. It can be used repeatedly, and N-alkyl-N'-phenyl-p-phenylenediamine can be produced very industrially with great advantage.

<Example> Hereinafter, the present invention will be described with reference to Examples.

Reference example 1 126 g of p-chloronitrobenzene in a 500 cc reaction flask,
Charge 149 g of aniline, 55 g of anhydrous potassium carbonate, 8 g of copper oxide and 5 g of commercially available polyether (PEG-2000) and stir 180-
The reaction was carried out at 190 ° C. under a reduced pressure of 760 to 600 mmHg for 12 hours.

During this time, water produced during the reaction was azeotropically distilled off together with aniline, and the aniline was returned to the reaction system after liquid separation.

After completion of the reaction, water was added to the obtained reaction mixture, and the mixture was washed with water and then passed through an oil layer to remove residual catalyst. The oil layer was subjected to simple distillation to remove low boiling components such as unreacted aniline to obtain crude p-nitro. 165.5 g of diphenylamine was obtained. The p-nitrodiphenylamine purity of this product is 88.9%, and the copper root is 620p.
pm contained.

Example 1 150 g of crude p-nitrodiphenylamine in a 500 cc flask,
150 g of monochlorobenzene and 150 g of a 3% sulfuric acid aqueous solution were charged, and the mixture was kept at 85 to 90 ° C for 1 hour while stirring. After keeping warm,
The aqueous layer was removed by liquid separation, 150 g of water was added, and the mixture was stirred.
It was washed with water at 85 to 90 ° C. After washing with water, the water layer is removed by liquid separation,
The oil layer was slowly cooled with stirring to precipitate crystals of p-nitrodiphenylamine.

After cooling to 5 ° C., the precipitated crystals were separated by filtration and washed with 50 g of monochlorobenzene.

The amount of purified p-nitrodiphenylamine after drying is 123.5 g.
The purity was 99.9% and the copper content was 0.3 ppm.

Example 2 Crude p-nitrodiphenylamine 1 in a 500cc autoclave
Charge 50g and 150g of 3% sulfuric acid aqueous solution and stir at 130 ~ 13
Incubated at 5 ° C for 1 hour. After completion of heat retention, the aqueous layer was removed by liquid separation, 150 g of water was newly added, and the mixture was washed with water at 130 to 135 ° C with stirring. After washing with water, the water layer is removed by liquid separation and the oil layer is heated to 100 ° C.
After cooling to 150 g, monochlorobenzene (150 g) was added to obtain a uniform solution.

The mass was cooled slowly to precipitate crystals of p-nitrodiphenylamine.

Thereafter, the same procedure as in Example 1 was performed to obtain purified p-
121.9 g of nitrodiphenylamine was obtained. Purity 99.8
%, And the copper content was 0.9 ppm.

Examples 3 and 4 The same processes as in Example 1 were carried out except that the solvents shown in Table 1 were used instead of monochlorobenzene, and the results shown in Table 1 were obtained.

Examples 5 to 9 The same treatment as in Example 1 was carried out except that 50% of the crystallization liquid recovered in Example 1 was recycled as the crystallization solvent and new monochlorobenzene was replenished as a solvent shortage.
(Example 5). Thereafter, the same treatment as in Example 1 was repeated except that 50% of the recovered crystallization liquid in the previous treatment was recycled and the solvent shortage was replenished with new monochlorobenzene (Examples 6 to 9).

The results are shown in Table-2.

Comparative Example 1 A 500 cc flask was charged with 150 g of crude p-nitrodiphenylamine and 150 g of methanol, the temperature was raised to the reflux temperature to completely dissolve it, and then slowly cooled to precipitate crystals.

Thereafter, the post-treatment was carried out according to Example 1 (however, methanol was used as a solvent for crystal washing) to obtain p-nitrodiphenylamine. The results are shown in Table-3.

Comparative Example 2 p-Nitrodiphenylamine was obtained in the same manner as in Example 1 except that toluene was used instead of monochlorobenzene as the solvent. The results are shown in Table-3.

Comparative Example 3 p-Nitrodiphenylamine was obtained in the same manner as in Comparative Example 1 except that monochlorobenzene was used instead of methanol as the solvent. The results are shown in Table-3.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ebina Millennial 3-1,98 Kasugade, Konohana-ku, Osaka City, Osaka Prefecture Sumitomo Chemical Co., Ltd. (72) Inventor, Akira Yamada Kasuga, Konohana-ku, Osaka City, Osaka Prefecture Ichinaka 3-chome No. 98 Sumitomo Chemical Co., Ltd.

Claims (1)

[Claims] 1. A p-halonitrobenzene and aniline,
When purifying crude p-nitrodiphenylamine obtained by reacting a copper compound as a catalyst in the presence of a neutralizing agent and a solubilizing agent, the crude -p-nitrodiphenylamine is substituted with at least one halogen atom. A method for purifying p-nitrodiphenylamine, which comprises treating with an aqueous solution of a mineral acid in the presence or absence of an aromatic or aliphatic hydrocarbon solvent, and then performing recrystallization treatment with the solvent.