JPH0714902B2 - Process for producing N-alkyl substituted aminophenols - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to reductive alkylation of aminophenols and aldehydes or aminophenols and ketones in the presence of an organic solvent, a reducing catalyst and hydrogen. N-
It relates to a method for producing alkyl-substituted aminophenols. N-alkyl-substituted aminophenols are industrially extremely important compounds as intermediates for heat-sensitive / pressure-sensitive paper dyes, xanthene dyes, fluorescent dyes and the like.

<Prior art> Conventionally, aminophenols and aldehydes, or aminophenols and ketones, an organic solvent, a reduction catalyst,
And N-in the presence of hydrogen to undergo a reductive alkylation reaction.
Methods for producing alkyl-substituted aminophenols are known.

However, since platinum-based, palladium-based, and other noble metal catalysts that have been conventionally used for reductive alkylation reactions have the ability to reduce aromatic rings, when used as they are, depending on the reaction conditions, As a side reaction, nuclear hydrogenation of an aromatic ring occurs, and as a result, there is a problem that the yield of N-alkyl-substituted aminophenols, which is a target product, decreases. Further, industrially, since these noble metal catalysts are expensive, it is usually essential to repeatedly use the catalyst.However, when the catalyst is repeatedly used, other than the hydrogenation of the aromatic ring, , Aminophenols and aldehydes, or a heavy reaction between aminophenols and ketones occurs, and by-products of alcohol increase due to reduction of aldehydes or ketones. was there.

Among the above problems, for alcohol by-product, for example, JP-A-57-165349, JP-A-58-26844,
Japanese Patent Application Laid-Open No. 58-194843 describes a technique for suppressing the by-product of alcohol by adding a solid sulfur compound or using a platinum sulfide catalyst during the reductive alkylation reaction.

However, this technique can suppress alcohol by-product to some extent, but at the same time, it also suppresses the reaction rate of the main reaction, reductive alkylation reaction, so that the unstable Schiff-based heaviation reaction of aminophenols can be suppressed. However, when the catalyst is used repeatedly, the desorption of sulfur from the catalyst makes it difficult to control the reaction.

Furthermore, these prior arts hardly describe a technique for suppressing the nuclear hydrogenation of an aromatic ring, and in particular, regarding the technique for suppressing the nuclear hydrogenation in the production method of N-alkyl-substituted aminophenols, Was not known.

<Problems to be Solved by the Invention> The present invention suppresses undesired side reactions such as the nuclear hydrogenation reaction and the heavy reaction of the aromatic ring, and the catalyst can be repeatedly used under high yield. That is, industrially very advantageous N-
The main object is to provide a method for producing alkyl-substituted aminophenols.

<Means for Solving the Problems> The inventors of the present invention, in order to achieve the above-mentioned object, as a result of diligent studies, platinum contact-treated with a solution containing a specific metal element selected from the periodic table or The present invention has been achieved by finding that the purpose can be achieved by using a palladium catalyst.

That is, in the present invention, in producing an N-alkyl-substituted aminophenol by a reductive alkylation reaction from an aminophenol and an aldehyde, or an aminophenol and a ketone, in the presence of an organic solvent and hydrogen, the activated carbon is supported. The platinum or palladium catalyst
N is characterized by being subjected to a contact treatment with a solution containing at least one metal element selected from Group IB, Group IIB, Group IVB, Group VB and Group VIB, and then subjected to the reductive alkylation reaction. -The present invention relates to a method for producing an alkyl-substituted aminophenol.

The details will be described below.

The aminophenols of the present invention are specifically o-aminophenol, m-aminophenol, p-aminophenol and the like.

Examples of the aldehydes include aliphatic aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde and isovaleraldehyde, cyclic aldehydes such as cyclohexylaldehyde and furfural, benzaldehyde and aromatic aldehydes such as p-tolualdehyde. .

Ketones include acetone, 2-butanone, 4-methyl-
Aliphatic ketones such as 2-pentanone, cyclopentanone,
Cyclic ketones such as cyclohexanone, acetophenone, p
-Aromatic ketones such as methylacetophenone are exemplified.

The N-alkylaminophenols are N-monoalkyl such as N-ethylaminophenol, N-propylaminophenol, N-butylaminophenol, N-cyclohexylaminophenol, N-benzylaminophenol and N-isopropylaminophenol. Examples include N, N-dialkylaminophenols such as aminophenols, N, N-diethylaminophenol, N, N-dibutylaminophenol, N-ethyl-N-isobutylaminophenol and N-ethyl-N-isoamylaminophenol. To be done.

As the organic solvent used in the present invention, an aliphatic alcohol such as methanol or ethanol is used.

The greatest feature of the present invention is that the reduction catalyst is subjected to the reaction after being subjected to the contact treatment characteristic of the present invention.

That is, a platinum or palladium catalyst supported on activated carbon was prepared by using Group IB, Group IIB, Group IVB, Group VB or Group IB of the periodic table.
It is necessary to carry out contact treatment with a solution containing one or more metal elements selected from the VIB group, and then subject it to a reductive alkylation reaction.

Specific examples of metal elements selected from the periodic table include Cu, Z
Examples include n, Cd, Sn, Pb, As, Sb, Se, Te and the like.

As the contact treatment in the present invention, a metal salt containing a metal element selected from the periodic table is added to a slurry liquid consisting of an organic solvent used in a reductive alkylation reaction and a platinum or palladium catalyst supported on activated carbon. There is a method of subjecting the obtained catalyst slurry to the reductive alkylation reaction as it is, or a method of subjecting the solid catalyst obtained by filtering the catalyst slurry to the reductive alkylation reaction.

Specific examples are as follows. In the case of 1, a new catalyst or a catalyst once used for the reaction and recovered may be charged together with an organic solvent, and then the metal salt may be added alone or as an organic solvent solution with stirring. This operation is carried out under an inert gas atmosphere, under N ₂ pressure, H ₂
The treatment may be carried out under pressure, and the temperature and time during the treatment are not particularly limited, but normally room temperature to 90 ° C. and 5 minutes to 2 hours are sufficient. Considering that this contact treatment is subjected to a reductive alkylation reaction, it is desirable to perform the treatment in an autoclave at room temperature and atmospheric pressure.

In the case of, a new catalyst or a catalyst that was once used in the reaction and collected was charged together with a solvent, and then the metal salt was added alone or as a solution with stirring, and after stirring, the solid catalyst was collected by filtration. You can do it. This operation may be carried out under atmospheric pressure of an inert gas atmosphere or under N ₂ pressure, and the temperature and time during the treatment are not particularly limited, but usually from room temperature to
90 ° C and 5 minutes to 2 hours are sufficient.

In the reducing catalyst contact-treated by the above method or, generally, almost all of the metal element used in the contact treatment is contained on the reducing catalyst.

In the case of the method (1), the solvent used to generate the catalyst slurry does not necessarily have to be an organic solvent used in the reductive alkylation reaction, but considering the problem of contamination of the reaction system of the reductive alkylation reaction, The solvent is preferably the same solvent as the organic solvent used in the reductive alkylation reaction or water.

The metal salt used to obtain the catalyst slurry, oxides, chlorides, bromides of metal elements selected from the periodic table,
Examples thereof include sulfates, nitrates, phosphates, acetates and oxalates, with acetate being most preferred from the viewpoint of uniformly adsorbing a metal element on a platinum or palladium catalyst.

The amount of the metal element used in the contact treatment is preferably 0.001 to 0.5 part by weight, and more preferably 0.005 to 0.2 part by weight, per 1 part by weight of platinum or palladium. If it is less than 0.001 part by weight, the effect of suppressing the nuclear hydrogenation of the aromatic ring may be insufficient. On the other hand, if it exceeds 0.5 parts by weight, the activity of the reducing catalyst for the reductive alkylation reaction, which is the main reaction, decreases, and as a result, aminophenols and aldehydes, or aminophenols and ketones are condensed, The heaviness may increase.

The reaction of the present invention is a reaction for obtaining an N-alkyl-substituted aminophenol by a reductive alkylation reaction from an aminophenol and an aldehyde, or an aminophenol and a ketone, in the presence of the organic solvent, hydrogen and a reducing catalyst. Is. This reaction can be carried out by charging aminophenols, an organic solvent and a reducing catalyst and continuously supplying aldehydes or ketones under a pressure of hydrogen or supplying them all at once, but the reaction is carried out more smoothly. For this purpose, it is preferable to continuously supply the aldehydes or ketones, and it is more preferable to continuously add a small amount of organic carboxylic acids such as acetic acid in accordance with the supply of the aldehydes or ketones. Usually, a reaction temperature of room temperature to 150 ° C. and a reaction pressure of ^{2 to} 30 kg / cm ² G are sufficient.

The amount of the reducing catalyst used is 1 part by weight of aminophenols as a raw material, and the amount of platinum or palladium in the catalyst is 0.
0001-0.02 parts by weight is preferable, more preferable range is 0.00
1 to 0.01 parts by weight. If it is less than 0.0001 part by weight, the rate of the main reaction is slowed down, and the heavy reaction of the side reaction may be promoted. If it exceeds 0.02 part by weight, the reduction of the aromatic ring may be promoted. The reducing catalyst may be used only once, but is industrially usually used repeatedly. In particular, the reducing catalyst used in the present invention is used repeatedly because the metal element selected from the periodic table remains almost entirely on the catalyst even after being subjected to the reaction once. In that case, no special processing is required, and the effects of the present invention are connected. In case of repeated use, there is a loss due to refining of the catalyst and a loss at the time of filtration and recovery.In order to carry out the reaction stably, a small amount of new catalyst should be added if necessary. It can also be subjected to a reductive alkylation reaction.

At this time, it is also possible to add a metal element selected from the periodic table in an amount commensurate with the new catalyst to be added.

<Example> Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 A SUS 500cc autoclave equipped with a stirrer was charged with methanol 18
5.5g, 5wt% platinum supported activated carbon catalyst 1.6g, lead acetate 0.015g
Was charged and stirred at room temperature for 1 hour. After that, 32.7 g (0.30 mol) of m-aminophenol was charged, and the hydrogen pressure was 10 kg /
While keeping the cm ² constant, 67.5 g of a methanol solution containing 45% by weight of acetaldehyde (0.69 mol of acetaldehyde) and 0.20 g of acetic acid (0.0033 mol) were continuously introduced at 40 ° C. for 1 hour. After the introduction of acetaldehyde, the mixture was kept at the same temperature for 90 minutes, cooled, and the reaction solution obtained by filtering and separating the catalyst was analyzed by gas chromatography, liquid chromatography, and GPC (gel permeation chromatography). As a result, the conversion rate of m-aminophenol (consumed m-aminophenol /
Charged m-aminophenol x 100) 100%, 3- (diethylamino) phenol selectivity 94.5%, benzene ring nuclear hydrogenation product (nuclear hydrogenation product 3- (diethylamino) -2-hexen-1-one) selection The rate was 1.7%, and the selectivity for heavy substances was 3.4% (selectivity is a value for m-aminophenol).

Example-2 The reaction was performed in the same manner as in Example-1, except that the catalyst recovered after use in Example-1 was not treated with lead acetate again. As a result of the analysis, the conversion rate of m-aminophenol was 100%, the selectivity of 3- (diethylamino) phenol was 94.5%, the selectivity of nuclear hydrogenated products of benzene ring was 1.3%, and the selectivity of heavy substances was 2.9%.

Comparative Example-1 The reaction was performed in the same manner as in Example-1, except that the catalyst was used once in the reaction without any treatment with lead acetate, and the catalyst was not newly treated with lead acetate. . As a result of the analysis, the conversion rate of m-aminophenol was 100%, the selectivity of 3- (diethylamino) phenol was 87.8%, the selectivity of the nuclear hydrogenated products of the benzene ring was 7.2%, and the selectivity of the heavy substances was 3.3%.

Comparative Example-2 Using the catalyst recovered in Comparative Example-1, the reaction was performed in the same manner as in Example-1, except that the treatment with lead acetate was not performed again. As a result of the analysis, the conversion rate of m-aminophenol was 100%, the selectivity of 3- (diethylamino) phenol was 87.8%, the selectivity of nuclear hydrogenated product of benzene ring was 7.0%, and the selectivity of heavy substances was 3.5%.

Example-3 A 200 cc glass round bottom flask was charged with 1.6 g of 5% platinum-supported activated carbon catalyst and 100 g of water to prepare a catalyst slurry, 0.015 g of lead acetate was added, and the mixture was heated and stirred at 80 ° C. for 1 hour. After cooling the catalyst slurry, suction filtration was performed, the catalyst was washed twice with 50 g of water, and then the solid catalyst was recovered. The reaction was carried out in the same manner as in Example 1 except that the thus obtained catalyst was used. As a result, the conversion of m-aminophenol was 100%, and 3-
The selectivity of (diethylamino) phenol was 94.8%, the selectivity of benzene ring nuclear hydrogenated products was 2.8%, and the selectivity of heavy substances was 1.7%.

Example-4 Using the catalyst recovered after use in Example-3, the reaction was performed in the same manner as in Example-1 without performing treatment with lead acetate again. As a result of the analysis, the conversion of m-aminophenol was 100%, the selectivity of 3- (diethylamino) phenol was 95.0%, the selectivity of the nuclear hydrogenated product of the benzene ring was 3.0%, and the selectivity of the heavy product was 1.5%.

Examples-5 and 6 The reaction was performed twice in the same manner as in Examples-1 and 2 except that copper acetate was used instead of lead acetate.

Examples-7 and 8 The reaction was performed twice in the same manner as in Examples-1 and 2 except that zinc acetate was used instead of lead acetate.

Examples-9, 10 Reactions were carried out twice in the same manner as in Examples-1, 2 except that arsenic acetate was used instead of lead acetate. The results of Examples 5 to 10 are shown in Table-1.

Example-11, 12 Example-1 except that 103.8 g (n-butyraldehyde 0.72 mol) of a methanol solution containing 50% by weight of n-butyraldehyde was used in place of the methanol solution containing 45% by weight of acetaldehyde. The reaction was performed twice in the same manner as in 2.

The results are shown in Table-2.

Examples 13 and 14, except that 70.6 g of a methanol solution containing 50% by weight of cyclohexanone (0.72 mol of cyclohexanone) was used instead of the methanol solution containing 45% by weight of acetaldehyde,
The reaction was performed twice in the same manner as in Examples-1 and 2. The results are shown in Table-3.

Examples-15 and 16 The same operation as in Examples-1 and 2 was performed to synthesize 3- (N-ethyl-N-isobutylamino) phenol. In a SUS 500cc autoclave equipped with a stirrer, methanol 185.5g, 5% platinum-supported activated carbon catalyst 1.6g, lead acetate 0.015g
Was charged and stirred at room temperature for 1 hour. After that, 32.7 g (0.30 mol) of m-aminophenol was charged, and the hydrogen pressure was 10 kg /
While keeping the cm ² constant, add 47.6 g of methanol solution containing isobutyraldehyde (0.33 mol of isobutyraldehyde) at 40 ° C to 3
Continuous introduction was performed over 0 minutes. After the completion of the isobutyraldehyde introduction, the mixture was kept at the same temperature for another hour, and then continuously introduced with 41.1 g of methanol solution containing 45% by weight of acetaldehyde (0.42 mol of acetaldehyde) and 0.20 g of acetic acid (0.0033 mol) over 30 minutes. After the introduction of acetaldehyde, the temperature was maintained for another 70 minutes. After cooling, the catalyst was separated by filtration to obtain a reaction liquid, which was analyzed by gas chromatography, liquid chromatography, and GPC (gel permeation chromatography). The results are shown in Table-4.

Example-17, 18 56.8 g of a methanol solution containing 50% by weight of isovaleraldehyde in place of the methanol solution containing 50% by weight of n-butyraldehyde (0.33 mol of isovaleraldehyde)
Reaction was performed twice by the same operation as in Examples-15 and 16 except that the above was used. The results are shown in Table-5.

<Effects of the Invention> As described above, according to the present invention, an aminophenol and an aldehyde, or an aminophenol and a ketone are subjected to a reductive alkylation reaction in the presence of an organic solvent, a reducing catalyst and hydrogen. In a method for producing N-alkyl-substituted aminophenols, N-alkyl-substituted aminophenols can be obtained in high yield by suppressing the nuclear hydrogenation or heavier reaction of aromatic ring, which is a side reaction. In particular, when the reducing catalyst is repeatedly used, it is industrially extremely advantageous to obtain N.
It has been possible to provide a method for producing alkyl-substituted aminophenols.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B01J 23/89 X 8017-4G // C07B 61/00 300 C07C 213/02

Claims (4)

[Claims] 1. In producing an N-alkyl-substituted aminophenol by a reductive alkylation reaction from an aminophenol and an aldehyde, or an aminophenol and a ketone in the presence of an organic solvent and hydrogen, it is supported on activated carbon. A platinum or palladium catalyst
An N-alkyl-substituted aminophenol characterized by being subjected to a reductive alkylation reaction after being contact-treated with a solution containing one or more metal elements selected from Group IIB, Group IVB, Group VB and Group VIB. Manufacturing method. 2. The solution used for the contact treatment is a metal salt of a metal element selected from the periodic table according to claim 1 and soluble in an organic solvent or water used in the reductive alkylation reaction. The method according to claim 1, which is a solution. 3. The method according to claim 1 or 2, wherein the amount of the metal element used in the contact treatment is 0.001 to 0.5 part by weight per 1 part by weight of platinum or palladium. 4. A metal element selected from the periodic table is lead,
The method according to claim (1), (2) or (3), which is copper, zinc or arsenic.