JPH0784420B2 - Process for producing orthoalkylated aromatic amines - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an orthoalkylated aromatic amine selectively and in high yield using a catalyst having a long life. More specifically, the aromatic amines having at least one hydrogen atom in the ortho position and the primary alcohol or secondary alcohol are heated in the presence of a metal oxide catalyst obtained by two-step calcination under specific conditions. It relates to a method for producing ortho-alkylated aromatic amines by reacting below.

The ortho-alkylated aromatic amines are useful as intermediates for the production of medicines, agricultural chemicals, dyes, stabilizers for resins, compounding agents for rubber and the like.

(Prior Art) Conventionally, as a method for producing alkylated aromatic amines such as o-toluidine and 2,6-dimethylaniline, o
It is known to react the corresponding alkylated phenols such as cresol and 2,6-xylenol with ammonia or amine under heating in the presence of a dehydration catalyst such as alumina or silica-alumina. However, the reaction of these phenols having an alkyl group at the ortho position with ammonia or amine has an extremely slow reaction rate as compared with the reaction of the phenol with ammonia or amine, and thus the reaction with ortho-alkylated aromatic amines is selected. And the yield is low. Moreover, since the activity of the dehydration catalyst is remarkably reduced, it cannot be said that the method is suitable as an industrial method for producing orthoalkylated aromatic amines.

Also, a method of reacting an aromatic amine such as aniline with an olefin or alcohol in the presence of a Friedel-Crafts type catalyst such as Lewis acid is described by GAOlah, “Fr.
iedel Crafts and Related Reactions, Vol.2, Paet
1 ”, published by Interscience Publishers (1964). However, in this method, N-alkylated aromatic amines such as N-monoalkyl aromatic amines or N, N-dialkyl aromatic amines are used when the amino groups of the aromatic amines are not substituted. As the main product, and the nuclear alkylated aromatic amines as a by-product only slightly, and as the nuclear alkylated aromatic amines, ortho-alkylated aromatic amines and para-alkylated aromatic amines. A mixture with aromatic amines is formed, and the production rate of ortho-alkylated aromatic amine is low. This tendency is particularly remarkable when alcohol is used as the alkylating agent.

In addition, as a method of improving the drawbacks of this method,
No. 4569 discloses a method of reacting an aromatic amine such as aniline with an olefin in the presence of a Friedel-Crafts type catalyst under conditions of high temperature and high pressure. However, although this method slightly improves the selectivity to orthoalkylated aromatic amines, it still produces a large amount of N-alkylated aromatic amines as a by-product, and selectively produces orthoalkylated aromatic amines. However, this method is not completely satisfactory as a method for industrially producing orthoalkylated aromatic amines.

Further, as another method for producing orthoalkylated aromatic amines, U.S. Pat.No. 2,814,646 discloses that an aromatic amine such as aniline is reacted with an olefin in the presence of a catalyst composed of aluminum anilide under heating. A method of reacting an alkylaluminum halide with an aromatic amine such as aniline, and then reacting the mixture thus produced with an olefin is proposed in JP-B-4724014. Has been done,
Further, JP-A-50-137934 proposes a method of reacting an aromatic amine such as aniline with a lower olefin in the presence of a catalyst consisting of aromatic aminoaluminum and a halogenated hydrocarbon. Among these methods, the method described in U.S. Pat. No. 2,814,646 has a drawback that the orthoalkylated aromatic amines in the product have high selectivity, but the reaction activity is low. In addition, Japanese Patent Publication No. 47-24014 and Japanese Unexamined Patent Publication No. 50-13793.
All of the methods described in Japanese Patent Publication No. 4 have high reaction activity, and also have the advantage of high selectivity for orthoalkylated aromatic amines in the product, but the reaction is performed under conditions of high temperature and high pressure. Since it is a reaction of the reaction is disadvantageous in terms of a reaction apparatus, since a considerable amount of an aluminum compound is used as a catalyst, a post-treatment operation for separating and removing the aluminum compound from the mixture after the reaction is complicated, etc.
There are many problems in industrialization. Further, as a matter of course, since olefins are used as alkylating agents in these methods, ortho-methylated aromatic amines such as methylaniline and dimethylaniline or orthomethylated aromatic amines having an alkyl group having 3 or more carbon atoms are used. Unable to produce -n-alkylated aromatic amines.

Therefore, in view of the above-mentioned circumstances of the conventional method, the present inventors have searched for a method suitable as a method for producing orthoalkylated aromatic amines selectively and on an industrial scale, and as a result, have found that transitions containing iron oxide A method for reacting an aromatic amine having at least one hydrogen atom at the ortho position with a primary alcohol or a secondary alcohol in the presence of a metal oxide catalyst was developed, and a patent application was previously filed (Japanese Patent Laid-Open Publication No. Sho. 56-110652).

(Problems to be Solved by the Invention) This prior application method is an excellent method in which the drawbacks of the conventional method are eliminated, but in view of the implementation situation after that, a catalyst having a long life and further improved durability of the catalyst Has been requested.

In response to this demand, the present invention intends to improve the durability of the catalyst used in the prior application method to prolong the catalyst life, and thus to more efficiently produce orthoalkylated aromatic amines. is there.

(Structure and Effect of the Invention) The present invention is a method for reacting an aromatic amine (a) having at least one hydrogen atom in the ortho position with a primary alcohol or a secondary alcohol (b) under heating to obtain an orthoalkylated aroma. When a group amine is produced, it is obtained by calcining a small amount of a chromium compound and germanium oxide together with an iron compound as a catalyst, then impregnating and supporting an aqueous solution of a salt of chromium, aluminum or magnesium, and further calcining. A method for producing orthoalkylated aromatic amines is characterized by using an iron-germanium-chromium oxide catalyst containing iron oxide as a main component.

The aromatic amines (a) used as a raw material in the present invention are aromatic amines having at least one hydrogen atom in the ortho position with respect to the amino group or the substituted amino group. The aromatic amines (a) may be aromatic amines whose aromatic nucleus is represented by any of a benzene ring, a naphthalene ring, an anthracene ring and a phenanthrene ring, and the aromatic amines (a) are It does not matter whether the aromatic amines are monoaromatic amines, secondary aromatic amines or tertiary aromatic amines. Further, the aromatic amines (a) may be any other aromatic amines (a) on the benzene ring, naphthalene ring, anthracene ring, or phenanthrene ring as long as they have at least one hydrogen atom in the ortho position with respect to the amino group or the substituted amino group. 1 for a carbon atom
It does not matter even if one or more substituents are bonded. Specifically as a substituent, an alkyl group,
Examples thereof include an aryl group, an alkoxyl group, an aryloxyl group, an acyl group, an acyloxyl group, a halogen atom and a hydroxyl group. Specific examples of aromatic amines include aniline, o-toluidine, m-toluidine, and p.
-Toluidine, o-ethylaniline, m-ethylaniline, p-ethylaniline, o-isopropylaniline,
m-isopropylaniline, p-isopropylaniline, 2,3-xylidine, 2,4-xylidine, 2,5-xylidine, 3,5-xylidine, 2,3-diethylaniline, 2,4
-Diethylaniline, 2,5-diethylaniline, 3,5-diethylaniline, 2,3-diisopropylaniline, 2,4-
Diisopropylaniline, 3,5-diisopropylaniline, N-methylaniline, N-ethylaniline, N-isopropylaniline, N, N-dimethylaniline, N, N-diethylaniline, N, N-diisopropylaniline, N-
Methyl-o-toluidine, N-methyl-2,3-xylidine, N-methyl-2,4-xylidine, N-methyl-2,5-
Xylidine, N-methyl-3,5-xylidine, N, N-dimethyl-o-toluidine, N, N-dimethyl-m-toluidine, N, N-dimethyl-p-toluidine, N, N-dimethyl-
2,3-xylidine, N, N-dimethyl-2,4-xylidine,
N, N-dimethyl-2,5-xylidine, N, N-dimethyl-3,5
-Xylidine, N-ethyl-o-ethylaniline, N-
Ethyl-m-ethylaniline, N-ethyl-p-ethylaniline, N-ethyl-2,3-diethylaniline, N-
Ethyl-2,4-diethylaniline, N-ethyl-2,5-diethylaniline, N-ethyl-3,5-diethylaniline, N, N-diethyl-o-ethylaniline, N, N-diethyl-m- Examples thereof include ethylaniline, N, N-diethyl-p-ethylaniline, α-naphthylamine and β-naphthylamine. Of these aromatic amines, it is preferable to apply the method of the present invention to aniline or o-alkylaniline.

Alcohol (b) used as a raw material in the present invention
Is a primary alcohol or secondary alcohol, usually a primary lower alcohol or secondary lower alcohol having 1 to 6 carbon atoms. Specifically as the primary alcohol,
Examples thereof include methanol, ethanol, n-propanol, n-butycohol, isobutycohol, n-pentyl alcohol, isopentyl alcohol, n-hexyl alcohol, and isohexyl alcohol. Specific examples of the secondary alcohol include isopropanol, sec-butyl alcohol, sec-pentyl alcohol, sec-hexyl alcohol, cyclohexyl alcohol and the like. Among these alcohols, it is preferable to use an alcohol having 1 to 3 carbon atoms, and it is particularly preferable to use methanol, ethanol or isopropanol. The proportion of these alcohols used is usually 1 to 10 mol, preferably 3 to 6 mol, per 1 mol of the aromatic amines.

The catalyst used in the present invention is an iron oxide obtained by calcining a small amount of chromium compound and germanium oxide together with an iron compound, then impregnating and supporting an aqueous solution of a salt of chromium, aluminum or magnesium, and further calcining. It is an iron / germanium / chromium oxide catalyst containing as a main component. Examples of the iron and chromium compounds include various salts, for example, salts of inorganic acids such as hydrochlorides, sulfates and nitrates, organic acid salts such as acetates and oxides.

The catalyst used in the present invention thus contains 2 iron compounds.
It is obtained by stage firing. The first stage firing is usually
It is carried out at a temperature in the range 400 to 850 ° C, preferably 550 to 800 ° C. The second-stage firing is carried out by impregnating the fired product obtained in the first-stage firing with an aqueous solution of a salt of chromium, aluminum or magnesium and supporting it thereon, and then, usually at 400 to 850 ° C., preferably at 550 to 800 ° C. It is carried out at a range of temperatures. Examples of the aqueous salt solution used here include various aqueous solutions such as salts of inorganic acids such as metal nitrates, hydrochlorides and sulfates, or salts of organic acids such as acetates. Among these, it is preferable to use nitrate.

In the present invention, the amount of chromium, aluminum and magnesium supported on the first-stage fired product prior to the second-stage firing is such that the metal is a metal per 100 parts by weight of the first-stage fired product. It is usually in the range of 0.05 to 10% by weight, preferably 0.5 to 4% by weight. If the amount of the metal supported deviates from this range, the durability of the resulting catalyst and the activity of forming orthoalkylated aromatic amines are deteriorated, which is not preferable.

By such two-step calcination, the iron and chromium compounds and the impregnated salts such as chromium are changed to oxides, and the catalyst used in the present invention is obtained. Further, in the present invention, since iron oxide and chromium oxide are mixed with germanium oxide, the selectivity for ortho-alkylated aromatic amines is high and the decomposition of alcohol during the reaction can be suppressed.

In the method of the present invention, the catalyst may be used by itself, or may be supported on various carriers or used as a molded article to which various binders are added.

The catalyst calcination carried out in the method of the present invention is carried out in an atmosphere of air or nitrogen gas in both the first-stage calcination and the second-stage calcination. Is adopted.

In the method of the present invention, an aromatic amine (a) having at least one hydrogen atom at the ortho position and the primary alcohol in the presence of the two-stage calcined iron-germanium-chromium oxide catalyst; By reacting the secondary alcohol (b) under heating, orthoalkylated aromatic amines are selectively produced. This reaction can be carried out by a liquid phase reaction or a gas phase reaction, but is preferably carried out by a gas phase reaction.

In the method of the present invention, when the reaction is carried out by a gas phase method, the reaction temperature is usually 200 to 500 ° C., preferably
It is in the range of 250 to 450 ° C. Liquid space velocity of the feedstock when the reaction is carried out (LHSV) to not usually 0.05 10 hr ^-1, preferably in the range from 0.2 to 4.0hr ^-1. The reaction can be carried out either under reduced pressure or under increased pressure, but preferably atmospheric pressure or 30
It is carried out under a pressure in the range 0 kg / cm ² -G. After the reaction, the unreacted alcohol is separated from the mixture, and the unreacted starting aromatic amines are recovered, and then treated by a conventional method such as distillation, crystallization, or extraction to obtain an orthoalkylated aromatic amine. Kind is obtained. The recovered unreacted alcohol and aromatic amines having ortho hydrogen are recycled to the reaction.

(Examples and Comparative Examples) Example 1 To an aqueous solution 2 in which 202 g of ferric nitrate nonahydrate and 4.3 g of chromium nitrate nonahydrate were dissolved was added 0.5 an aqueous solution in which 2.53 g of germanium oxide was dissolved. Then, 25% aqueous ammonia was gradually added to adjust the pH of the solution to 9. The precipitate formed was washed with water, filtered, dried at 90 ° C for 24 hours and then calcined at 550 ° C for 3 hours to obtain Fe ₂ O.
_A catalyst containing ₃・ GeO ₂・ Cr ₂ O ₃ was obtained.

After crushing this into 6 to 10 mesh, 30 g of the crushed product was immersed in 100 ml of an aqueous solution in which 0.81 g of chromium nitrate nonahydrate was dissolved. The water was distilled off with a rotary evaporator, and the mixture was calcined at 600 ° C. for 3 hours to obtain a catalyst.

10 ml of the catalyst was filled in a Pyrex reaction tube having an inner diameter of 30 mm and then heated to 360 ° C. After reaching the predetermined temperature, a mixture of aniline: methanol: H ₂ O with a molar ratio of 1: 5: 2 was added at 3 ml / hr.
The reaction was carried out by feeding at a rate of. The results are shown in Table 1.

In Example 2 Example 1, Fe was 3hr calcined at _{550 ℃ 2 O 3 · GeO 2} · C
A catalyst was prepared and reacted under the same conditions except that the amount of chromium nitrate nonahydrate impregnated in r ₂ O ₃ was changed to 1.62 g. The results are shown in Table 1.

Example 3 The reaction was performed under the same conditions as in Example 2, except that methanol was changed to ethanol. The results are shown in Table 1.

Example 4 Example 1, Fe was 3hr calcined at _{550 ℃ 2 O 3 · GeO 2} · C
A catalyst was prepared and reacted under the same conditions except that the chromium nitrate nonahydrate impregnated in r ₂ O ₃ was changed to 0.76 g of aluminum nitrate nonahydrate. The results are shown in Table 1.

Example 5 A catalyst was prepared and reacted under the same conditions as in Example 4, except that 0.76 g of aluminum nitrate nonahydrate was changed to 0.52 g of magnesium nitrate hexahydrate. The results are shown in Table 1.

Comparative Example 1 In Example 1, Fe ₂ O ₃ · GeO ₂ · C fired at 550 ° C. for 3 hours
The reaction was performed under the same conditions except that r ₂ O ₃ was used as the catalyst.
The results are shown in Table 1.

Claims (5)

[Claims] 1. An orthoalkylated aromatic amine is produced by reacting an aromatic amine (a) having at least one hydrogen atom in the ortho position with a primary alcohol or a secondary alcohol (b) under heating. In doing so, as a catalyst,
Iron containing iron oxide as a main component obtained by calcining a small amount of chromium compound and germanium oxide together with an iron compound, then impregnating and supporting an aqueous solution of a salt of chromium, aluminum or magnesium, and further calcining. A method for producing ortho-alkylated aromatic amines, which comprises using a germanium-chromium oxide catalyst. 2. The method according to claim 1, wherein the aromatic amine (a) having at least one hydrogen atom in the ortho position is aniline or o-alkylaniline. 3. The method according to claim (1) or (2), wherein the alcohol is methanol, ethanol or isopropanol. 4. A method according to claim 1, wherein the reaction is carried out in a gas phase.
The method according to any one of items 1 to 3. 5. The method according to any one of claims (1) to (4), wherein the reaction is carried out at a temperature in the range of 250 to 450 ° C.