JPH0528216B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides an industrially advantageous improvement for obtaining N-alkyldiphenylamines or nuclear substituted products thereof (hereinafter abbreviated as N-alkyldiphenylamines). The present invention relates to a manufacturing method.

More specifically, in the presence of a catalyst and a phenol or its nuclear substituted product (hereinafter abbreviated as phenols), N-alkylanilines or its nuclear substituted products (hereinafter abbreviated as N-alkylamines) and a phenol corresponding to The present invention relates to a method for producing N-alkyldiphenylamines by reacting cyclohexanones, condensation reaction, and intermolecular hydrogen transfer.

N-alkyldiphenylamines are extremely useful as intermediates for organic compounds such as synthetic dyes and rubber drugs.

Conventional technology Conventionally, N-alkyldiphenylamines can be obtained by a method such as a reaction between diphenylamine and an alkyl halide, dialkyl sulfuric acid, or trialkyl phosphate, or a reaction between a hydrochloride of diphenylamine and an alcohol. Although this method is well known, it cannot be said to be an advantageous method as an industrial method.

A method similar to the method of the present invention is patented in the United States.
3219704 In the specification, in the presence of a palladium catalyst,
A method is described in which N-methyldiphenylamine is obtained by dehydrogenation of Schiff's base obtained by a heated reaction of N-methylaniline and cyclohexanone. However, in this method, the dehydrogenation reaction is carried out in the absence of a hydrogen acceptor, so the yield is only about 47%, even though N-methylaniline and cyclohexanone are used in approximately equivalent ratios. It wasn't satisfying.
Furthermore, when using cyclohexanones, which are difficult to obtain by such a method, in the reaction, it is necessary to synthesize them from the corresponding phenols in a separate step.

Means for Solving the Problems In order to improve these points, the present inventors have intensively studied industrially advantageous methods, and found that in the presence of a hydrogen transfer catalyst and phenols, N-alkylamines and phenols By heating and reacting cyclohexanones corresponding to the above, an intermediate is produced by a condensation reaction between N-alkylamines and cyclohexanones, and this dehydrogenation reaction occurs, and at the same time, a proportion equivalent to the cyclohexanones consumed in the condensation is generated. The present invention was achieved by discovering that phenols can be easily reduced to produce cyclohexanones in the same reaction system.

That is, in the method of the present invention, in the presence of a hydrogen transfer catalyst,
Phenols, N-alkylanilines, and cyclohexanones corresponding to the phenols used in the reaction are reacted by heating, or phenols are charged in excess without coexisting cyclohexanones in the reaction system from the beginning. Production of N-alkyldiphenylamines, which is characterized in that a part of the N-alkylamines is converted into the corresponding cyclohexanones under hydrogen pressure, and then heated and reacted with phenols and N-alkylamines. It's a method.

The method of the present invention not only provides satisfactory results in terms of reaction rate and selectivity to the desired product, but also dehydrogenates the intermediates produced by the reaction of N-alkylamines and cyclohexanones. The generated hydrogen is extremely efficient because it is all used in the same reaction system for the reduction of phenols, that is, the production of cyclohexanones. Furthermore, in the production of certain types of nuclear-substituted N-alkyldiphenylamines, even if it is difficult to obtain suitable corresponding cyclohexanones, excess amounts of phenols can be used instead of cyclohexanones as long as phenols are available. It is sufficient to charge hydrogen in advance and convert some of the phenols into cyclohexanones before reacting, which has many advantages such as a wide range of applications. In addition, since phenols are hydrogen acceptors and are also a source of the cyclohexanones produced as a result, phenols containing cyclohexanones are separated when the target product N-alkyldiphenylamines are extracted. The mixture is recycled and reused in the reaction system.

Phenols used as raw materials in the method of the present invention include phenol, methylphenol, ethylphenol, isopropylphenol, butylphenol, 2,4-dimethylphenol, 2,4,6-trimethylphenol, 2,
Alkylphenols such as 6-di-t-butyl-4-methylphenol, 3-methoxyphenol, 4
- Alkoxyphenols such as methoxyphenol and the like. If the cyclohexanones are coexisting from the beginning, there is no particular problem with the amount used as long as it is equivalent to or more than the N-alkylaniline, but it is usually advantageous to use it as a solvent, and it is 2 to 20 mol relative to the amine. excess of 4 to 10 times, preferably 4 to 10 times
It is better to use double the mole.

As N-alkylamines, N-methyl-
Aniline, N-ethyl-aniline, N-propyl-aniline, N-isopropyl-aniline, N-
Isobutyl-aniline, 2-methyl-N-methylaniline, 4-ethyl-N-methylaniline,
Alkyl in the nucleus, such as 4-dodecyl-N-methyl-aniline, 4-decyl-N-methyl-aniline, 3,4-dimethoxy-N-methyl-aniline, 2-methyl-4-methoxy-N-methyl-aniline, etc. and/or N-alkyl- having an alkoxy group
Aniline, N-alkyl compound of O-aminobenzoic acid or its ester, 4-cyclohexyl-
N-methyl-aniline, 4-benzyl-N-methyl-aniline, 4-phenoxy-N-methyl-aniline, 2-fluoro-N-methyl-aniline, 4
-Hydroxy-N-methyl-aniline, N-alkyl compounds of α-aminonaphthalene, and the like.

As the cyclohexanones, cyclohexanones corresponding to the above-mentioned phenols are used, and there is no particular problem as long as the amount used is about 0.03 times the catalytic amount or more by mole relative to the N-alkylamines, but preferably 0.05 to 0.40 moles. Double is better. If the amount used is less than this, the reaction rate will decrease, and if it is more than this, the yield of the target N-alkyldiphenylamine will decrease, which is not preferable.

In addition, if cyclohexanones are not used from the beginning of the reaction, an amount equivalent to producing the appropriate amount of cyclohexanones, based on the phenols,
That is, about 0.06 mole or more, preferably 0.10 to 0.80 mole times, of hydrogen may be sealed in a reactor and then heated and reacted.

The catalyst used in the method of the present invention must have the functions of both a dehydrogenation reaction and a reduction reaction, and normally suitable hydrogenation reduction reaction catalysts are also suitable for the dehydrogenation reaction. Specifically, Raney nickel, reduced nickel or nickel supported catalysts, taneh cobalt, reduced cobalt or cobalt supported catalysts, Raney copper, reduced copper or copper supported catalysts, noble metal catalysts of group 8 of the periodic table or noble metals as supports, carbon , catalysts supported on alumina, barium carbonate, etc., rhenium catalysts such as rhenium-carbon, copper-chromium oxide catalysts, and the like. Among these catalysts, palladium is preferred, and palladium catalysts supported on carriers such as palladium-carbon, palladium-alumina, and palladium-magnesium oxide are particularly preferred. The amount used is usually 0.001 to 0.2 gram atoms as metal atoms, preferably
0.004-0.1 gram atom is good.

In the method of the present invention, it is advantageous to use phenols as self-solvents, and there is no need to use other reaction solvents, although there is of course no problem in using them.

The temperature during the reaction is important and is usually between 100℃ and 200℃.
℃, preferably selected in the range of 130℃ to 200℃.

The produced diphenylamines can be obtained by treating the mixture after the completion of the reaction according to conventional methods such as distillation, crystallization, and extraction. For example, the catalyst that has passed through the reaction completion liquid is separated. This recovered catalyst can be reused. Concentrate the liquid and recover phenols containing cyclohexanones. The fraction can be reused as a mixture. Diphenylamines in the pot can be used as raw materials for the next reaction as the case may be, but if necessary, they can be purified by distillation, crystallization, etc.

Next, the method of the present invention will be specifically explained using examples.

[Example 1] 24.2 g of 2-methyl-N-methyl-aniline (0.2
mol), 94.1 g (1.0 mol) of phenol, 2.0 g (0.02 mol) of cyclohexanone, and 1.07 g of 5% palladium-carbon (manufactured by Nippon Engelhard Co., Ltd.). After replacing the inside of the autoclave with nitrogen, 150
The reaction mixture was heated to 0.degree. C. and reacted at that temperature for 8 hours with stirring. After cooling to room temperature, the reaction mixture was filtered to separate the catalyst. A portion of the liquid was collected and analyzed by gas chromatography to quantify unreacted raw materials and products. As a result, unreacted 2-methyl-N
-Methyl-aniline remained in an amount of 0.8 g (conversion rate 96.7%), and 2-methyl-N-methyl-diphenylamine was produced in an amount of 33.8 g (selectivity 88.7%). The liquid was concentrated and distilled to separate and collect a fraction of 75.8 g of phenol containing cyclohexquinone. The concentration of cyclohexanone in it was 2.2%, which corresponded to 83.4% of the amount of cyclohexanone charged.

Subsequently, no cyclohexanone was newly added to the recovered phenol fraction containing the recovered catalyst and cyclohexanone, and the selectivity of 20.0 g of phenol and 2-methyl-N-methyl-diphenylamine was 90.0%. The concentration of cyclohexanone in the recovered phenol fraction was 2.4%.

[Example 2] The reaction and treatment were carried out in the same manner as in Example-1, except that 5% palladium-magnesium oxide was used instead of the 5g palladium-carbon used in Example-1. As a result, 1.2 g (conversion rate 95.0%) of unreacted 2-methyl-N-methyl-aniline remained, and 2-methyl-N-methyl-aniline remained.
33.1g of N-methyl-diphenylamine (selectivity
88.4%).

[Example 3] Except for the absence of cyclohexanone in the initial preparation,
It was prepared as in Example-1. After purging the inside of the autoclave with nitrogen, it was pressurized to 5 kg/cm ² G with hydrogen. This amount of hydrogen corresponds to about 0.3 mole times that of 2-methyl-N-methyl-aniline. continuation,
The reaction and treatment were carried out in the same manner as in Example-1. the result,
2-Methyl-N-methyl-diphenylamine was produced with a selectivity of 90.5%. Furthermore, cyclohexanone was present in the recovered phenol fraction, and its concentration was 3.0%.

[Example 4] The reaction and treatment were carried out in the same manner as in Example 1, except that the reaction temperature was 250° C. for 3 hours. As a result, 2-
Methyl-N-methyl-diphenylamine has selectivity
Although it was produced at 76.3%, increasing the reaction temperature was detrimental to the reaction.

[Example 5] The reaction and treatment were carried out in the same manner as in Example 3 except that the phenol was 3,5 dimethyl-phenol. There are a few unresponsive responses. The conversion rate of 2-methyl-N-methyl-aniline was 85.6%, and the selectivity of the desired product was 89.0%.

[Example 6] The reaction treatment was carried out in the same manner as in Example 1 except that 2-methyl-N-methyl-aniline was 2-methyl-4-methoxy-N-methyl-aniline. As a result, the desired product was obtained with a conversion rate of 97.5% and a selectivity of 89.0%.

[Example 7] Example-1 except that 2-methyl-N-methyl-aniline is 2-chloro-N-methyl-aniline
The reaction was carried out in the same manner as above. As a result, the conversion rate was 96.7%
The desired product was obtained with a selectivity of 89.5%.

[Example 8] The reaction treatment was carried out in the same manner as in Example 1, except that 2-methyl-N-methyl-aniline was 4-ethoxy-N-ethyl-aniline. As a result, the conversion rate
At 93.3%, the desired product was obtained with a selectivity of 86.2%.

Claims (1)

[Claims] 1. Phenol or its nuclear substituted product, N-alkylanilines or its nuclear substituted product, and cyclohexanones corresponding to the phenol or its nuclear substituted product used in the above reaction in the presence of a hydrogen transfer catalyst. A method for producing N-alkyldiphenylamine or a nuclear substituted product thereof, which comprises carrying out a heating reaction. 2. In the presence of a hydrogen transfer catalyst, an excess amount of phenol or its nuclear substituted product is converted into a phenol by partially converting it into the corresponding cyclohexanone under hydrogen pressure in an N-alkylaniline or its nuclear substituted product. A method for producing an N-alkyldiphenylamine or a nuclear substituted product thereof, which comprises carrying out a heating reaction with N-alkylaniline or a nuclear substituted product thereof. 3. After separating the N-alkyldiphenylamine or its nuclear substituted product obtained from the heated reaction mass, the phenol or its nuclear substituted product containing by-products cyclohexanones is recycled to the reaction system for reuse. The method according to scope 1 or 2. 4. The method according to claim 1 or 2, wherein the heating reaction temperature is 130 to 200°C. 5. The method according to claim 1 or 2, wherein the hydrogen transfer catalyst is palladium. 6 Phenol or its nuclear substituted product is added to N-alkylanilines or its nuclear substituted product in 2 to
The method according to claim 1 or 2, in which a 20-fold molar excess is used. 7. The method according to claim 1 or 29, wherein the cyclohexanones are present in an amount of 0.05 to 0.40 moles relative to the N-alkylamines.