JPS5931494B2 - Houkou Zokudai 3 Kiyuu Aminno Seizou Hou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an aromatic tertiary amine.

Specifically, the present invention relates to a method for producing a corresponding aromatic tertiary amine by reacting an aromatic primary or secondary amine or a precursor thereof with an aldehyde and hydrogen. It is known to react aromatic primary amines or secondary amines with aldehydes and hydrogen in the presence of hydrogenation catalysts to produce the corresponding aromatic tertiary amines.

This reaction proceeds easily in an organic solvent, but it is difficult to proceed in an aqueous solvent unless a large amount of hydrogenation catalyst is used, and moreover, there are many intermediate products and other by-products.

The present inventors investigated a method for industrially advantageously carrying out this reaction in an aqueous solvent, and found that by proceeding the reaction while sequentially supplying aldehyde to the reaction system, the corresponding aromatic product could be produced in high yield. The present invention was completed by discovering that tertiary amines can be produced.

To explain the present invention in detail, the present invention relates to an improved method for producing an aromatic tertiary amine by reacting a conventionally known aromatic primary or secondary amine with an aldehyde and hydrogen.

The aromatic primary or secondary amine used as a raw material has at least one solubilizing substituent selected from a carboxyl group, a hydroxyl group, and a sulfonic acid group.

In addition to the above-mentioned substituents, the aromatic amine as a raw material may have a substituent inert to the reaction, such as an alkyl group, an alkoxy group, or a halogen atom. Such aromatic amines include 2-aminophenol, 3-aminophenol, 4-aminophenol, 4.6-cyclo2-
Aminophenol, 2,4-diaminophenol, N-
Methyl-4-aminophenol, N-ethyl-4-aminophenol, 3-amino-1-naphthol, N-methyl-4-amino-1-naphthol, 2-aminoresorcin, 4-aminoresorcin, 4-amino-1.2-dioxy- Aminophenols such as naphthalene, 2-aminobenzoic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, N-methyl-2-aminobenzoic acid, 2, 3-diaminobenzoic acid, 2-chloro-4-aminobenzoic acid acid, 4-amino-2-methylbenzoic acid, 4-aminonaphthoic acid, 5
- Aromatic aminocarboxylic acids such as aminonaphthoic acid, 2
-Aminobenzenesulfonic acid, 3-aminobenzenesulfonic acid, 4-aminobenzenesulfonic acid, 2-methyl-
5-aminobenzenesulfonic acid, N-methyl-2-aminobenzenesulfonic acid, 1-aminonaphthalene-2-sulfonic acid, 5-aminonaphthalene-1-sulfonic acid, 2
-Aminobenzenesulfonic acids such as aminonaphthalene-1,5-disulfonic acid, 4-chloro2-aminobenzenesulfonic acid, 2-aminoanthraquinone-3-sulfonic acid, and 6-amino-anthraquinone-2-sulfonic acid are mentioned. .

Precursors of these aromatic amines, ie, nitro compounds that are hydrogenated in the reaction system to form these amines, can also be used as raw materials.

These aromatic amines and their precursors may be subjected to the reaction in free form, but it is preferable to use them in the form of alkali salts so that they are well soluble in water ~ As aldehydes used in the method of the present invention Examples include aliphatic aldehydes such as formaldehyde and acetaldehyde, and aromatic aldehydes such as benzaldehyde.

In addition, as a hydrogenation catalyst, any catalyst commonly used in hydrogenation reactions can be used, such as Raney nickel, platinum oxide, copper monochromium oxide, nickel, platinum, palladium, or other metal-supported catalysts. can do.

The reaction easily proceeds by adding an aromatic amine to an aqueous solvent in which a catalyst is suspended, maintaining the temperature at room temperature to 150°C, preferably 70 to 100°C, and supplying aldehyde and hydrogen thereto.

The reaction system usually has a pH of 6. O~9.5, preferably 7.0~
Keep it at 9.0. Normal pressure to 10 kg/CTn is usually sufficient for the hydrogen pressure in the reaction system. Of course, even higher hydrogen pressures can be used as long as side reactions do not occur. The concentration of the raw material amine in the water solvent is preferably determined such that both the raw material and the product are dissolved in the water solvent.

The aqueous solvent may contain an organic solvent that is miscible with the aqueous solvent, but this is not preferred since it requires recovery of the solvent and other incidental operations. In the present invention, it is necessary to supply the aldehyde to the reaction system not at once but sequentially.

Here, "sequentially" means that aldehyde is supplied to the reaction system continuously or intermittently during the progress of the reaction. Usually, it is fed at a constant rate over most of the reaction period, or fed in a fixed amount at fixed time intervals, and after the end of the feeding, the reaction is terminated after a certain amount of reaction time has elapsed. Alternatively, the reaction may be started by first supplying aldehyde in an amount of % or less of the theoretical amount based on the raw material amine, and the remaining aldehyde may be supplied sequentially as described above. In any case, it is preferable to feed 9% to 9% of the theoretical amount of aldehyde based on the raw amine into the reaction system by the time the total reaction time reaches the middle (
. If the aldehyde feed rate to the reaction system is faster than this, the advantages of sequentially feeding aldehyde according to the present invention will not be realized. If the feed rate is slower than this, the reaction rate will decrease and the ratio of aldehyde to raw material amine will become too large in the late stage of the reaction, which may lead to an increase in by-products. The amount of aldehyde supplied to the reaction system is preferably from the theoretical amount to 1.2 times the amount of the raw material amine. Although it is possible to use larger amounts of aldehyde, it is usually not necessary. The time required for the reaction depends on the type of raw amine and the reaction conditions, but usually 2 to 3 hours is sufficient.

After the reaction is completed, the catalyst is removed by filtration and the slurry is acidified to precipitate the aromatic tertiary amine product.

According to the method of the present invention, aromatic tertiary amines can be easily produced in high yield using water as a solvent and a small amount of hydrogenation catalyst.

The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example 1 In a flask with an internal volume of 11, 27.4 m-aminobenzoic acid was added.
7. Add 8.07ml of caustic soda and 200ml of water, m
-Aminobenzoic acid was dissolved.

To this was added 3.07 g of 5% palladium-carbon, and the temperature was raised to 80 DEG C. while supplying hydrogen at a rate of 1.2'/min. To this solution, the theoretical amount of formalin required to convert amino groups into dimethylamino groups was added in % amounts.

One supply was carried out for 15 minutes, and the next supply was carried out 45 minutes after the end of the supply.

After reacting for 3 hours, the reaction solution was thoroughly filtered to separate the catalyst.
10% sulfuric acid was added to the slurry to adjust the pH to 3 to precipitate the amine.

The crystals were separated by filtration, washed twice with 100 ml of water, and then dried in vacuo.

Results for N-N-dimethyl-m-aminobenzoic acid 32.3
7 was obtained (yield 98%).

This product has a melting point of 150-150.5℃ and is a pure N-N
The spectrum matched the IR and NMR spectra of -dimethyl-m-aminobenzoic acid.

In addition, no primary or secondary amines were detected in chemical analysis. Comparative example: 1 internal volume 1f? ．． 27.47 m-aminobenzoic acid, 8.07 ml of caustic soda, and 200 ml of water were added to the flask to dissolve m-aminobenzoic acid.

Add to this 5%-palladium-carbon 3.0y and 37%
100ml of formalin was added. Add 1.0% hydrogen to this solution.
The reaction was carried out at 80°C for 7 hours while introducing at a rate of 21/min.

After the reaction was completed, the reaction solution was filtered to remove the catalyst, and then 10% sulfuric acid was added to the solution to adjust the pH to 3 to precipitate the amine.

The crystals were separated by filtration, washed twice with 100 ml of water, and then dried in vacuo.

The yield of crystals was 29.67, of which 40% was N・N-
dimethyl-m-aminobenzoic acid, and the rest is raw material and N
-Methyl-m-aminobenzoic acid.

Example 2 Internal volume 1f! 27. m-aminobenzoic acid into a flask.
4y, 8.07ml of caustic soda, and 200ml of water were added to dissolve m-aminobenzoic acid.

Add 5%-palladium-carbon 3.07 to this,
It was heated to 40° C. while supplying hydrogen.

37% formalin was continuously added dropwise to this solution at a rate of 10 ml/hour over 3 hours to carry out the reaction at 40°C. After reacting for 4 hours, the same treatment as in Example 1 was performed to obtain crystals 32 of N-N-dimethyl-m-aminobenzoic acid.
．． 7y was obtained (yield 99%).

The melting point of this crystal was 150 to 150.5°C, and the IR and M were consistent with those of the pure product. Further, as a result of chemical analysis, no primary or secondary amines were detected. Example 3 Internal volume 1
1 flask, 33.4 f m-nitrobenzoic acid, 2 ml water
00ml and 8.0y' of caustic soda were added to dissolve the m-nitrobenzoic acid.

Add 2%-palladium-carbon 0.757 to this,
The mixture was heated to 80° C. while supplying hydrogen at a rate of 1.51/min, and reacted at this temperature for 6 hours.

Next, this was reacted in exactly the same manner as in Example 1 while adding formalin, to obtain crystals 321 of N-N-dimethyl-m-aminobenzoic acid (yield 97%).
IR of this crystal. The NMR spectrum matched that of the pure product, and no primary or secondary amines were detected in chemical analysis.

Claims (1)

[Claims] 1. A method for producing a corresponding aromatic tertiary amine by reacting aminobenzoic acid or nitrobenzoic acid with an aldehyde and hydrogen in the presence of a hydrogenation catalyst in an aqueous solvent, in which the aldehyde is sequentially added to the reaction system. A method characterized by allowing the reaction to proceed while supplying.