JP3193856B2 - Method for producing alkoxy-substituted triphenylamines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improved method for producing alkoxy-substituted triphenylamines. The alkoxy-substituted triphenylamines obtained by the method of the present invention are compounds useful as intermediates in general chemical industry, especially as intermediates for dyes, agricultural chemicals, rubber chemicals and the like.

[0002]

2. Description of the Related Art Conventionally, as a method for producing triphenylamine, phenols are used as a hydrogen acceptor in the presence of a hydrogen transfer catalyst, and while reacting with diphenylamines while generating cyclohexanone in the system, triphenylamine is produced. A method for producing phenylamines is known (Japanese Unexamined Patent Publication No.
-183250). Here, diphenylamine and cyclohexanone are reacted in an excess amount of phenol in the presence of a palladium catalyst to give triphenylamine in a yield of 68.5.
% (Selectivity 85.1%).

[0003]

However, when the inventors of the present invention repeated this method using cyclohexanones and phenols having an alkoxy substituent as raw materials, it was found that triphenylamines from which the alkoxy substituent had been eliminated were used. A considerable amount of by-products could not be obtained in a satisfactory yield of the desired product, an alkoxy-substituted triphenylamine. An object of the present invention is to provide a very efficient production method for obtaining an alkoxy-substituted triphenylamine from an alkoxy-substituted phenol and a diphenylamine or aniline in a high yield.

[0004]

Means for Solving the Problems The present inventors have studied to establish a more industrially advantageous method for producing alkoxy-substituted triphenylamines. In the process,
In the presence of an alkoxy-substituted cyclohexanone corresponding to the alkoxy-substituted phenol used in the hydrogen transfer catalyst and the reaction of the catalytic amount, the alkoxy-substituted cyclohexanone is used in the system by using the alkoxy-substituted phenol as a hydrogen acceptor. When reacting with the diphenylamines or anilines while producing the above, or without leaving the above cyclohexanone in the reaction system from the beginning, the above phenol is subjected to a catalytic amount of the corresponding alkoxy-substituted cyclohexanone under a hydrogen pressure. After that, the remaining phenols are subsequently used as a hydrogen acceptor, and in the reaction with the diphenylamines or anilines while generating the above cyclohexanones in the system, a decomposition reaction by the generated hydrogen, that is, dealkoxylation Progresses, It was discovered that led to decrease in the yield of alkoxy-substituted triphenylamine, the manner products. As a result, it has been surprisingly found that the surface-supported catalyst suppresses the dealkoxylation reaction and is extremely effective as a hydrogen transfer catalyst, and that the alkoxy-substituted triphenylamines can be obtained in good yield. Reached.

That is, the present invention uses the above-mentioned alkoxy-substituted phenol as a hydrogen acceptor in the presence of a hydrogen-transfer catalyst and a catalytic amount of an alkoxy-substituted cyclohexanone corresponding to the alkoxy-substituted phenol. A method for producing alkoxy-substituted triphenylamines, which comprises using a surface-supported catalyst as a hydrogen transfer catalyst when reacting with diphenylamines or anilines while producing corresponding alkoxy-substituted cyclohexanones, And in the presence of a hydrogen transfer catalyst, the alkoxy-substituted phenols were partially converted to the corresponding alkoxy-substituted cyclohexanone under hydrogen pressure, and the remaining alkoxy-substituted phenols were subsequently used as a hydrogen acceptor, In the system, the corresponding alkoxy-substituted cyclo Upon reacting with diphenylamine or aniline while generating a Sanon acids,
A method for producing alkoxy-substituted triphenylamines, wherein a surface-supported catalyst is used as a hydrogen transfer catalyst.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The alkoxy group-substituted phenol used in the method of the present invention is a phenol having at least one alkoxy group, and further having a substituent such as an alkyl group, a phenyl group, a phenoxy group, a cyclohexyl group, or a fluorine atom. Is also good.

For example, 4-methoxyphenol, 2-methoxyphenol, 4-ethoxyphenol, 4-butoxyphenol, 4-nonyloxyphenol, 2,4
-Dimethoxyphenol, 3-methyl-4-methoxyphenol, 2-methoxy-4-phenylphenol, 3
-Methyl-4-butoxyphenol, 2-methoxy-4
-Phenoxyphenol, 2-methoxy-4-cyclohexylphenol, 2-fluoro-4-methoxyphenol, and the like, but are not limited thereto.

The amount of the alkoxy-substituted phenol used in the method of the present invention is not particularly limited as long as the alkoxy-substituted cyclohexanone coexists from the beginning. When the group-substituted phenols are used in excess as a self-solvent, the selectivity tends to be higher.
It is used in a molar amount, particularly preferably 2 to 10 times. When anilines are used, there is no particular problem as long as they are at least 2 equivalents to the anilines, but also in this case, the selectivity tends to be higher when an alkoxy-substituted phenol is used in excess as a self-solvent. The aniline is preferably used in an amount of 3 to 20 moles, particularly preferably 4 to 10 moles.

[0009] Since the alkoxy-substituted phenol in the method of the present invention is a hydrogen acceptor and a source of the resulting alkoxy-substituted cyclohexanone, the hydrogen by-produced during the reaction is reduced in the system. Used. In addition, when the alkoxy-substituted triphenylamines as the target product are taken out, the alkoxy-substituted phenols containing the alkoxy-substituted cyclohexanone to be separated can be recycled to the reaction system as a mixture. further,
When it is difficult to obtain the corresponding alkoxy-substituted cyclohexanone in the production of the alkoxy-substituted triphenylamines, if there is an alkoxy-substituted phenol, an excessive amount of the alkoxy-substituted cyclohexanone is substituted for the alkoxy-substituted cyclohexanone. Hydrogen is previously charged using phenols, and the reaction may be performed while converting a part of the alkoxy-substituted phenols into the alkoxy-substituted cyclohexanone.

As the alkoxy-substituted cyclohexanone, there can be used an alkoxy-substituted cyclohexanone corresponding to the above-mentioned alkoxy-substituted phenol.
Examples include 4-methoxycyclohexanone, 2-methoxycyclohexanone, 4-ethoxycyclohexanone,
4-butoxycyclohexanone, 4-nonyloxycyclohexanone, 3-methyl-4-methoxycyclohexanone, 2-methoxy-4-phenylcyclohexanone,
3-methyl-4-butoxycyclohexanone, 2-methoxy-4-phenoxycyclohexanone, 2-methoxy-4-cyclohexylcyclohexanone, 2-fluoro-4-methoxycyclohexanone, 2,4-dimethoxycyclohexanone, and the like. As in the case of the substituted phenols, it is not limited to these.

When diphenylamines are used, they are used in an amount of about 0.03 mole times or more of the catalyst amount to diphenylamines, and when anilines are used, they are used in an amount of about 0.03 mole times or more of the catalyst amount to anilines. No problem,
Preferably 0.05 to 0.6 based on diphenylamines.
It is 0 mole times, and 0.05 to 1.00 mole times with respect to anilines.

When the alkoxy-substituted cyclohexanone is not used from the beginning of the reaction, hydrogen is added to the alkoxy-substituted phenol in an amount corresponding to the production of the above-mentioned appropriate amount of the alkoxy-substituted cyclohexanone, ie, diphenylamine. When using anilines, it is about 0.06 mole times or more, preferably 0.10 to 2.0 mole times, and when using anilines, it is about 0.06 mole times or more, preferably 0.10 to 1.2 mole times. After the hydrogen is sealed in the reactor, a heating reaction may be performed.

The diphenylamines used as a raw material in the method of the present invention may be any known ones,
Even if unsubstituted, an alkyl group, an alkoxy group, a phenyl group,
It may be substituted with a phenoxy group, a cyclohexyl group, a carboxyl group, a hydroxyl group, a fluorine atom or the like. For example, diphenylamine in which a nucleus such as diphenylamine, 2-methyldiphenylamine, 3-methyldiphenylamine, and 2,2-dimethyl-diphenylamine is substituted with an alkyl group, diphenylamine similarly substituted with an alkoxy group,
Halogen-substituted diphenylamine, carboxylic acid group-substituted diphenylamine, nitrile group-substituted diphenylamine, p-
Phenyldiphenylamine and the like. Also, 2-
Diphenylamine having a different functional group substituted on the nucleus, such as methyl-4-chlorodiphenylamine, may be used.

The aniline used as a raw material in the method of the present invention may be any known aniline, and may be unsubstituted, such as alkyl, alkoxy, phenyl, phenoxy, cyclohexyl, carboxyl, hydroxyl, fluorine, etc. May be substituted.

For example, aniline, 2-methylaniline, 3
Alkyl-substituted aniline such as -methylaniline and 4-ethylaniline, alkoxy-substituted diphenylamine such as 4-methoxyaniline, carboxy-substituted aniline such as 4-carboxyaniline, halogen-substituted aniline such as 4-fluoroaniline, and nitrile-substituted Examples include aniline and p-phenylaniline. Also, 2-methyl-4
-An aniline having a different functional group substituted on the nucleus such as chloroaniline may be used.

In the method of the present invention, it is important to use a surface-supported catalyst as the hydrogen transfer catalyst. Specific examples include a surface-supported nickel-supported catalyst, a surface-supported cobalt-supported catalyst, a surface-supported copper catalyst, a surface-supported rhenium-supported catalyst of the Group VIII metal of the periodic table, and the like. Of these catalysts, preferred are surface-supported palladium catalysts, especially surface-supported palladium-carbon, surface-supported palladium-silica, surface-supported palladium-alumina, surface-supported palladium-diatomaceous earth, and surface-supported palladium- A palladium catalyst supported on a carrier surface such as magnesia is preferred, and a surface-supported palladium-carbon catalyst is most preferred.

Hereinafter, a description will be given by taking palladium-carbon (Pd / C) as an example. Whereas ordinary uniform Pd / C is prepared by completely impregnating the activated carbon as a carrier in an aqueous solution of a water-soluble palladium compound, the surface-supported catalyst is prepared by sufficiently drying the activated carbon as a carrier. After that, an aqueous solution of a water-soluble palladium compound, for example, palladium chloride, palladium acetate, or the like, is sprayed, or the carrier is impregnated with the palladium compound only on the surface layer of activated carbon by gradually dropping the solution with gentle stirring. , Hydrazine, formalin, formic acid or the like, or in the liquid phase, or hydrogen reduction in the gas phase, followed by washing with warm water and drying to form a palladium-carbon catalyst having palladium supported only on the surface layer. Obtainable.

The use of such a catalyst is effective in suppressing the formation of by-products due to the elimination reaction of the alkoxy group, and a high selectivity to the target product is observed. The reaction of the present invention is represented by the following reaction formula, taking the case of using methoxy-substituted phenols and anilines as an example.

[0019]

Embedded image

According to the study of the present inventors, the dealkoxylation reaction is carried out in a compound (b) in which an alkoxy group is bonded to an aromatic ring,
(D) and not at the stage of 4-methoxyphenol,
An alkoxy group bonded to an aliphatic carbon (a),
It is clear that the process mainly proceeds at the stage of (c) and the raw material 4-methoxycyclohexanone. Also,
The dehydrogenation reaction in (a) and (c) is a uniform type,
It is considered that the dehydrogenation reaction takes place at the surface of the catalyst and the dealkoxylation reaction takes place at the deep part of the catalyst, since any of the surface-supported catalysts proceeds well. That is,
Since the alkoxy group bonded to the aliphatic carbon has a high degree of freedom, when the compounds (a) and (c) come close to the catalyst, the alkoxy group may reach inside the pores, which are the deep part of the carrier surface. is there. Therefore, in the case of a uniform catalyst in which palladium is supported on the inside of the surface of the carrier, the alkoxy group reaching the deep portion undergoes dealkoxylation by the supported palladium, but the deep layer on the surface of the carrier is subjected to dealkoxylation. In the case of a surface-supported catalyst where palladium is not supported on the part,
It is considered that such a dealkoxylation reaction is suppressed, and an alkoxy group-substituted triphenylamine as a target compound can be obtained with high selectivity.

When diphenylamines are used, the amount of the catalyst used is usually 0.001 to 0.2 g atom, preferably 0.1 g, as a metal atom with respect to the diphenylamines.
When the aniline is used in an amount of 004 to 0.1 gram atom, the metal atom is usually 0.00
1 to 0.2 gram atoms, preferably 0.004 to 0.1
Gram atoms are good.

The preferred surface-supported catalyst for use in the present invention is a solid metal catalyst having about 0.5 to 10% by weight of a metal supported on a carrier powder, wherein at least 70% of the supported metal is 2 μm from the supported surface. This is an egg shell type catalyst which is supported on the supported surface layer up to the above. Particularly preferred are catalysts in which at least 80% by weight of the metal loading is supported on the support surface up to 1 μm from the support surface. The state of metal loading is determined by EPMA (Electron Probe Micro
analyzer).

In the method of the present invention, after separating the target product from the reaction mass after completion of the reaction, it is preferred that the reaction mixture is repeatedly and continuously used without separating the alkoxy-substituted cyclohexanone. In this case, it is advantageous to use the alkoxy group-substituted phenol in excess as a self-solvent, and it is not necessary to use another reaction solvent,
Of course, there is no problem even if used.

The reaction temperature is usually from 130 to 300 ° C., preferably from 180 to 250 ° C. If the temperature is lower than this, the reaction rate is low, and a large amount of by-products tends to be generated.

In the method of the present invention, when the raw materials are charged into the reaction vessel, the catalyst and the alkoxy-substituted phenol are charged into the vessel in advance, stirred and heated, and then the aniline is reacted while being added dropwise. Is a preferred embodiment. In this case, the aniline and the alkoxy-substituted cyclohexanone react in the system to produce diphenylamines, which react with the alkoxy-substituted cyclohexanone.

The reaction is advantageously carried out while removing generated water, and for this purpose, a method of separating from the reaction mixture by azeotropic distillation using a solvent such as benzene, toluene or xylene is suitable.

The resulting alkoxy-substituted triphenylamines can be obtained by subjecting the mixture after the completion of the reaction to a conventional method such as distillation, crystallization, or extraction. For example, the reaction-terminated liquid is filtered to separate the catalyst. This recovered catalyst can be reused. The filtrate is concentrated, and an excess amount of the alkoxy-substituted phenol is recovered while containing the alkoxy-substituted cyclohexanone, and the fraction is returned to the reaction system as a mixture.
The triphenylamines in the kettle are purified and separated by distillation, crystallization and the like.

[0028]

EXAMPLES The method of the present invention will be specifically described below with reference to examples.

Example 1 A 200 ml round-bottomed flask equipped with a reflux condenser equipped with a separator, a thermometer and a stirrer was charged with a 5% Pd / C (palladium carrying amount) surface-supporting type manufactured by NE Chemcat. 1.23 g of 50% by weight, p-methoxyphenol 62.07 g (0.5 mol), 3.85 g of p-methoxycyclohexanone (0.03%) Mol),
4,4'-dimethoxyphenylamine 22.93%
(0.1 mol). While stirring the inside of the reactor, 2
The temperature was raised to 00 ° C., and the reaction was performed for 9 hours. After the temperature was further raised to 230 ° C., the reaction was performed for 4 hours. The water produced during this period was charged with toluene, azeotropically charged, condensed in a reflux condenser, and then separated from the separator. Next, the reaction solution was cooled, and 5% Pd / C was separated by filtration from the reaction mixture solution. When the filtrate was analyzed using gas chromatography, it was found that 4,4′-
The conversion of dimethoxydiphenylamine is 99.2%,
The selectivity of 4,4 ', 4 "-trimethoxydiphenylamine was 91.5%. The selectivity of the dealkoxylated 4,4'-dimethoxytriphenylamine at this time was 5.4%. Met.

Examples 2 to 6 In the same manner as in Example 1, the reaction was carried out using various diphenylamines, phenols and cyclohexanones corresponding to the phenols. The results are shown in Table 1.

[Table 1]

Example 7 A stainless steel autoclave having an internal volume of 500 ml
91.7% (0.4 mol) of 4'-dimethoxyphenylamine, 248.3 g (2.0 mol) of 4-methoxyphenol, 5% P on a surface supported by NE Chemcat
d / C (at least 80% of the supported amount of palladium is supported on the supporting surface from the supporting surface to 1 μm, 50 w
et%) 4.92 g were charged. After the inside of the autoclave was replaced with nitrogen, the pressure was increased to 10 kg / cm ² G with hydrogen.
Subsequently, a heating reaction and treatment were performed in the same manner as in Example 1. As a result, the conversion of 4,4'-dimethoxydiphenylamine was 89.3%, and the selectivity of 4,4 ', 4 "-trimethoxytriphenylamine was 81.7%. The selectivity of the alkoxy form of 4,4'-dimethoxytriphenylamine was 10.7%.

Comparative Example 1 A reaction and treatment were carried out in the same manner as in Example 1 except that a uniform type 5% Pd / C manufactured by NE Chemcat was used as the hydrogen transfer catalyst. As a result,
The conversion of 4'-dimethoxydiphenylamine is 75.2.
%, The selectivity of 4,4 ′, 4 ″ -trimethoxytriphenylamine was 71.8%, and the selectivity of the dealkoxylated 4,4′-dimethoxytriphenylamine at this time was 71.8%. Was 19.4%.

Example 8 A 200 ml round bottom flask equipped with a reflux condenser equipped with a separator, a thermometer and a stirrer was charged with a surface-supported 5% Pd / C (manufactured by NE Chemcat Co.) 80% supported on the support surface from the support surface to 1 μm, 50 wet%) 1.23 g, p-methoxyphenol 99.31 g (0.8 mol), p-methoxycyclohexanone 6.41 g (0.05 mol) ), And 12.32 g of 4-methoxyaniline was added to the dropping device.
(0.1 mol). While stirring the inside of the reactor, 2
The temperature was raised to 00 ° C., and 4-methoxyaniline in the dropping device was added dropwise over 7 hours while maintaining the temperature while stirring. After completion of the dropwise addition, the temperature was further raised to 220 ° C., and the reaction was performed for 9 hours. The water produced during this period was charged with toluene, azeotropically charged, condensed in a reflux condenser, and then separated from the separator. Then, the reaction solution was cooled, and 5% Pd /
C was filtered off. When the filtrate was analyzed by gas chromatography, the conversion of 4-methoxyaniline was 9
The selectivity for 9.0% and 4,4 ', 4 "-trimethoxytriphenylamine was 84.4%. In addition, the dealkoxylated product of 4,4'-dimethoxytriphenylamine was used. The selectivity was 12.2%.

Examples 9 to 13 In the same manner as in Example 8, the reaction was carried out using various anilines, alkoxy-substituted phenols and alkoxy-substituted cyclohexanone corresponding to the alkoxy-substituted phenols. Table 2 shows the results.

[Table 2]

Example 14 In a stainless steel autoclave having an inner volume of 500 ml, 4
223.5% (1.8 mol) of methoxyphenol, 5% Pd / C, surface-carrying type manufactured by NE Chemcat
(At least 80% of the amount of palladium supported on the supporting surface from the supporting surface to 1 μm, 50 wet
%), And 44.6 g (0.2 mol) of 4-methoxyaniline was charged into the dropping device, and the inside of the autoclave was purged with nitrogen. Then, the pressure was increased to 10 kg / cm ² G with hydrogen, and 200 ° C. The temperature rose. Subsequently, a heating reaction and treatment were performed in the same manner as in Example 1. As a result, the conversion of 4-methoxyaniline was 88.5%, and the selectivity of 4,4 ′, 4 ″ -trimethoxytriphenylamine was 80.9%. The selectivity of a certain 4,4'-dimethoxytriphenylamine was 13.5%.

Comparative Example 2 A reaction and treatment were carried out in the same manner as in Example 8, except that a uniform type 5% Pd / C manufactured by NE Chemcat was used as the hydrogen transfer catalyst. As a result, 4-
The conversion of methoxyaniline is 98.3%, 4,4 ',
The selectivity for 4 "-trimethoxytriphenylamine is 5
It was 4.8%. At this time, the selectivity of 4,4′-dimethoxytriphenylamine, which is a dealkoxylated product, was 23.5%.

[0037]

According to the method of the present invention, by using a surface-supported catalyst as the hydrogen transfer catalyst, the dealkoxylation of the raw materials and intermediates is suppressed, and the desired alkoxy-substituted triphenylamine can be obtained in good yield. can get.

Continuation of the front page (56) References JP-A-61-183250 (JP, A) JP-A-5-17384 (JP, A) JP-A-4-227069 (JP, A) JP-A-61-30545 (JP) (A) JP-A-54-141706 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 217/92 B01J 23/44 C07C 213/00 C07B 61/00 300

Claims (8)

(57) [Claims] 1. The method according to claim 1, wherein said alkoxy-substituted phenol is used as a hydrogen acceptor in the presence of a hydrogen transfer catalyst and a catalytic amount of an alkoxy-substituted cyclohexanone corresponding to the alkoxy-substituted phenol used in the reaction. The reaction of the cyclohexanone with the diphenylamine while producing the alkoxy-substituted cyclohexanone from the alkoxy-substituted phenol by using a surface-supported catalyst as a hydrogen transfer catalyst. A method for producing phenylamines. 2. An alkoxy-substituted phenol is partially converted to a corresponding alkoxy-substituted cyclohexanone under hydrogen pressure in the presence of a hydrogen transfer catalyst, and then the remaining alkoxy-substituted phenol is converted to a hydrogen acceptor. And reacting the cyclohexanone with diphenylamines while generating an alkoxy-substituted cyclohexanone from the alkoxy-substituted phenol in the system, wherein a surface-supported catalyst is used as a hydrogen transfer catalyst. A method for producing an alkoxy-substituted triphenylamine. 3. The method according to claim 1, wherein the surface-supported catalyst comprises palladium supported on a carrier. 4. The method according to claim 1, wherein the carrier is carbon. 5. The method according to claim 1, wherein the diphenylamine is an alkoxy-substituted diphenylamine. 6. The method according to claim 1, wherein an aniline is used in place of the diphenylamine. 7. The method according to claim 6, wherein the reaction is carried out while dropping anilines. 8. The method according to claim 7, wherein the anilines are alkoxy-substituted anilines.