JPS6048501B2 - Method for producing N-alkyl aromatic amine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing N-alkyl aromatic amines from aromatic primary amines and alcohols and/or ethers.

More specifically, the present invention relates to a catalyst that can produce particularly N-alkyl aromatic amines in good yields. N-alkyl aromatic amines are compounds useful as intermediates in the production of color formers for color photography, medicines, agricultural chemicals, dyes, rubber drugs, and the like.

Conventionally, when producing this N-alkyl aromatic amine from an aromatic primary amine and alcohols and/or ethers, nickel- or cobalt-containing catalysts, copper-chromium catalysts, sulfuric acid, phosphoric acid, etc. have been used as catalysts. The method to do this is well known. In addition, alumina, silica gel, and other metal oxides can be used as catalysts for this reaction, and the catalytic activity is particularly high when alumina is used.Also, when methyl alcohol is used as an alkylating agent, the main product is is an N,N-dimethyl aromatic amine,
When an alcohol with more carbon atoms than methyl alcohol, such as ethanol, is used as an alkylating agent, the
As the amount of ethyl aromatic amines produced increases, the amount of nuclear alkylated by-products also increases, according to Institutional & Engineering. Chemistry (1st,
Eng, Chem,) UN1579-1584 (195
1). When using any of these conventionally known catalysts and using methyl alcohol or dimethyl ether as the alkylating agent, N
, N-dimethyl aromatic amine is almost selectively obtained as the main product, but when an alcohol having 2 or more carbon atoms is used as an alkylating agent, N-alkyl As more aromatic amines are produced than N,N-dialkyl aromatic amines, more nuclear alkylated products and other high boiling point products are produced as by-products.
Therefore, the method using these catalysts is a method for industrially producing N-alkyl aromatic amines from aromatic primary amines and alcohols having 2 or more carbon atoms or ethers having 4 or more carbon atoms. It is hard to say that it is sufficient. The present inventors have made extensive efforts to develop a method for selectively producing N-alkyl aromatic amines by reacting primary aromatic amines with alcohols having 2 or more carbon atoms or ethers having 4 or more carbon atoms. As a result of the study, it was found that using silica alumina with a silica component content within a specific range as a catalyst suppresses nuclear alkylation reactions and by-products of high-boiling substances, and improves selectivity to N-alkyl aromatic amines. The present invention was achieved by observing that the yield was improved along with the method.

The product obtained by the process of the present invention is a mixture of N-alkyl aromatic amines and small amounts of N,N-dialkyl aromatic amines, with almost no nuclear alkylation products or high-boiling by-products. No byproducts. That is, the present invention provides an aromatic primary amine, an alcohol having 2 or more carbon atoms, and/or an alcohol having 4 carbon atoms in the presence of a silica-alumina catalyst containing a silica component in the range of 1 to 10% by weight.
N characterized by reacting with the above ethers
- A method for producing an alkyl aromatic amine.

Specifically, the aromatic primary amines used as raw materials in the method of the present invention include aniline, o-toluidine, m-toluidine, p-toluidine, o-3 ethylaniline, m
-Ethylaniline, p-ethylaniline, o-n-propylaniline, m-n-propylaniline, p-n-propylaniline, o-isopropylaniline, m-isopropylaniline, p-isopropylaniline, 2,3
4. -xylidine, 3,4-xylidine, 2,6-xylidine, 2,4-xylidine, 3,5-xylidine, 2
, 5-xylidine, pseudocumidine, methidine, etc.

Also, a mixture of two or more of these aromatic primary amines,
For example, it is also possible to use isomeric mixtures. Among these aromatic primary amines, it is particularly preferable to apply the method of the present invention to toluidine or aniline. Examples of alcohols having 2 or more carbon atoms used as raw materials in the method of the present invention include ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, Sec-butyl alcohol, isobutyl alcohol, amyl alcohol, and isoamyl alcohol. Examples include alcohol, hexyl alcohol, cyclohexyl alcohol, and benzyl alcohol.

Among these alcohols, it is particularly preferable to use ethyl alcohol. In addition, examples of ethers having 4 or more carbon atoms include diethyl ether, di-n-propyl ether, diisopropyl ether, and di-n-propyl ether.
-butyl ether, diSec-butyl ether, diisobutyl ether, and the like. Among these ethers, it is particularly preferred to use diethyl ether. It is also possible to use mixtures of the alcohols and ethers mentioned, for example mixtures of ethyl alcohol and diethyl ether. The catalyst used in the process of the invention contains 1 to 1% by weight of silica component.
The most important requirement is that the content of the silica component be within this range.

Even if the content of the silica component is less than 1% by weight, or even if it is more than 1% by weight, the selectivity to N-alkyl aromatic amines decreases and the yield thereof also decreases. For example, alumina containing almost no silica component has a particularly low selectivity to N-alkyl aromatic amines and a low yield thereof, and also has a low catalytic activity. Further, ordinary silica alumina containing a large amount of silica component in the range of 60 to % by weight has low selectivity to N-alkyl aromatic amines. Among the catalysts of the present invention, when silica alumina containing a silica component in the range of 1.5 to 5% by weight is used in the process of the present invention, the selectivity to N-alkyl aromatic amines and the yield thereof are improved. This is particularly preferable because it further improves. In addition, among the silica alumina catalysts of the present invention, when a silica alumina catalyst whose silica component is adjusted to the above range by pretreatment with an organic acid such as acetic acid or an inorganic acid such as sulfuric acid is used, it produces an N-alkyl aroma. It is more preferable since the selectivity to group amines is improved. The reaction of the present invention can be carried out by either a liquid phase method or a gas phase method.

When carrying out the liquid phase method, a mixture consisting of an aromatic primary amine, an alcohol and/or an ether, the silica-alumina catalyst and, if necessary, a solvent is heated under pressure at a temperature of usually 150 to 300°C. The reaction proceeds easily by stirring. The silica alumina catalyst is normally used in an amount of 1 to 50% by weight based on the aromatic primary amine. After the catalyst is removed from the reaction mixture, the target N-alkyl aromatic amine can be obtained by treating the mixture according to a conventional method such as distillation or crystallization. In addition, when carrying out the method of the present invention in a gas phase method, for example, a mixed gas consisting of a fixed bed packed with the silica-alumina catalyst, aromatic amines, alcohols and/or ethers, and optionally a diluent is used. normal pressure to 10k9/c eG) preferably 3 to 7k9/c
The reaction can easily proceed by contacting the mixture under pressure (usually 200 to 400°C), preferably at a temperature in the range of 250 to 350°C. The feed rate of raw materials varies depending on the reaction temperature and each raw material component used in the reaction, but is usually 100 to 6000 hr at GHSV.
-゛, preferably in the range of 500 to 3000 hr-''. By treating the distillate after the completion of the reaction in the same manner as in the liquid phase reaction, an N-alkyl aromatic amine can be obtained. The method is preferably carried out by a gas phase method from the viewpoint of regeneration and life of the catalyst.Next, the method of the present invention will be specifically explained with reference to Examples.

Examples 1 to 14, Comparative Examples 1 to 6 A quartz tube with an inner diameter of 28wi and a length of 850TfUn, which was equipped with a raw material supply port, a carrier gas supply port, and a reaction product receiver, was used as a gas phase reactor.

The central part of this reactor was filled with the catalyst 6y shown in Table 1,
While flowing nitrogen gas as a carrier gas at a flow rate of 101'/Hr, a mixed solution (
The molar ratio of alcohol to aromatic primary amine is 2.
0, the molar ratio of ethers is 1.0) shown in Table 1.
The temperature of the reaction tube was kept constant as shown in Table 1 by feeding the reaction tube so as to achieve SV and heating the reaction tube in an electric furnace. The products distilled from 2 to 6 hours after starting the supply of raw materials were collected, and the amounts of raw materials and products contained therein were analyzed by gas chromatography.
The results are shown in Table 1. Product yield is expressed as mole percent of product relative to the charged primary aromatic amine, and selectivity is expressed as mole percent of product relative to the modified aromatic primary amine. Example 1 Comparative Examples 7 to 14 A stainless steel autoclave with an internal volume of 100 square meters equipped with a magnetic stirrer was charged with 20 mm of m-toluidine, 30 mm of ethyl alcohol, and the catalyst shown in Table 2, and heated to 10 k9/cm with nitrogen gas. After pressurizing cl-G, 22
Heated at 0'C for 1 hr with stirring.

Claims (1)

[Claims] 1. In the presence of a silica alumina catalyst containing a silica component in the range of 1 to 10% by weight, an aromatic primary amine and an alcohol having 2 or more carbon atoms and/or an alcohol having 4 carbon atoms.
N- characterized by reacting with the above ethers
A method for producing an alkyl aromatic amine. 2. The method according to claim 1, characterized in that silica alumina containing a silica component in the range of 1.5 to 5% by weight is used as a catalyst. 3. The method according to claim 1 or 2, characterized in that the reaction is carried out in a gas phase. 4. Process according to claims 1 to 3, characterized in that the reaction is carried out in the gas phase at a temperature of 250 to 350°C. 5 Claims 1 to 4 characterized in that toluidine or aniline is used as the aromatic primary amine.
the method of. 6. The method according to claims 1 to 5, characterized in that ethyl alcohol is used as the alcohol having 2 or more carbon atoms. 7 Claims 1 to 5 characterized in that ethyl ether is used as the ether having 4 or more carbon atoms.
the method of.