JPS609739B2 - Method for producing diarylamine - Google Patents

Description

Detailed Description of the Invention Conventional methods for synthesizing diarylamines include a method in which arylamine is reacted as a hydrochloride of arylamine under pressure, PC13, CuC12, N ratio C1, BF
A method of reacting using No. 3 or the like as a catalyst is known.

However, today, when aniline is industrially produced from phenol as a raw material, it is clear that it would be advantageous in terms of raw material costs if diphenylamine could be synthesized from cheaper phenol and aniline through a dehydration condensation reaction. This does not mean that there has not been a conventional method of synthesizing diarylamine from arylamine and phenols through a dehydration condensation reaction, and there is a method using zinc chloride as a catalyst, but the disadvantage is that the yield is low. There is. As a result of the present inventors' study on the condensation catalyst of arylamine and phenols,
Compounds of the phosphoric acid family, i.e. orthophosphoric acid, pyrophosphoric acid,
I learned that metaphosphoric acid, phosphorus pentoxide, polyphosphoric acid, phosphorous acid, etc. are effective, but considering that the above dehydration condensation reaction is a reaction at high temperatures, I am looking for a catalyst that does not cause corrosion of the equipment. As a result of further studies, we discovered that when phenyl and alkylphenyl esters of phosphorous acid are used, not only is there almost no corrosion, but the yield and quality of the diarylamine obtained is particularly good. I ended up with eggplant.

A further feature of the present invention is that it is possible to synthesize asymmetric diarylamines by selecting starting materials. That is, when deammoniated condensation starts from an arylamine such as aniline and an alkylaniline, the product is a mixture of diphenylamine, monoalkyldiphenylamine and dialkyldiphenylamine, whereas starting from phenol or alkylphenol and aniline or alkylaniline, By performing dehydration condensation, it is possible to synthesize monoalkyldiphenylamines and dialkyldiphenylamines having an alkyl substituent at any position. Furthermore, the present invention is characterized in that there is no by-product of diphenyl ethers due to the condensation of phenols, which is normally expected, and only the target diarylamine is selectively produced in high yield and purity. It's in the point where you can get it. In carrying out the present invention, phenols include phenol, cresol,
Ethylphenol, xylenol, etc. can be used,
As the arylamine, aniline, ethylaniline, dimethylaniline, trimethylaniline, toluidine, etc. can be used.

Regarding the molar ratio of the raw materials phenols and arylamines, it is preferable to use 1 to 10 times the molar excess of the phenols. Particularly preferably, it is 2 to 3 times the mole amount. The catalyst concentration is preferably 0.5 to 1% by weight, and particularly preferably 2 to 5% by weight, based on the raw material mixture. The reaction temperature ranges from 200 to 450 qO, particularly preferably from 300 to 350 oC. The reaction is carried out while the produced water is successively removed from the system. Since the reaction solution contains only a very small amount of tar compound other than the reaction raw materials and the target product, a highly pure diarylamine can be easily obtained by simple distillation. The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Phenol 376.4 hours (4 hours
After charging, 186.2 moles of aniline (2 moles) and 17 moles of triphenyl phosphorite (3% to phenol and aniline) were sealed, and the temperature was raised to 33,000 mol.

The pressure at that time was approximately 17k9/earth. From then on 33-34000
The reaction was carried out for one holding while maintaining the pressure and releasing the pressure every 2 hours (approximately 20 to 16 k9/kg) to allow water to come out. When the resulting reaction solution was distilled, the resulting reaction phenol was 278.3
(2.957 mol), unreacted aniline 63.9 mol (0
．． 686 moles) were recovered and 191.6 moles of diphenylamine were recovered.
3 (1.130 mol) was obtained. Diphenylamine yield based on consumed phenol and aniline is 95.3% (vs. theory). The obtained diphenylamine was of very good quality and had an APHA70, F. P. It was 529oo. Example
2 Phenol 376.4 moles (4 mol), p-toluidine 2
14.3 (2 moles), triphenylphosphite 1
7 days were reacted in the same manner as in Example 1.

The product is 4-methyldiphenylamine and a very small amount of 4.
It was 4-dimethyldiphenylamine, and no diphenyl ether was observed. When the reaction solution was distilled, 283.4 moles (3.015 moles) of unreacted phenol and 78.9 moles (0.737 moles) of unreacted P-toluidine were recovered.
164.6 (0.899 mol) of 4-methyldiphenylamine were obtained. The theoretical yield based on consumed phenol and p-toluidine was 80%. Example 3 p-cresol 432.5 moles (4 moles), aniline 18
6.2 (2 moles), triphenylphosphite 17
When the mixture is reacted in the same manner as in Example 1, the products are 4-methyldiphenylamine and a small amount of diphenylamine,
The yield of 4-methyldiphenylamine was 76% of theory based on the consumed p-cresol and aniline, and the M circle was 89 o.

Claims (1)

[Claims] 1. A method for producing a diarylamine, which comprises dehydrating and condensing an arylamine and a phenol under pressure in a temperature range of 200 to 450°C using a phenyl or alkyl phenyl ester of phosphorous acid as a catalyst.