JPS6130657B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing indole or indole derivatives. In more detail,
The present invention relates to a method for producing indole or an indole derivative by reacting N-β-hydroxyethylaniline or a nuclear substituted derivative thereof in a hydrogen atmosphere using copper as a main catalyst.

Various methods for producing indole have been proposed for a long time, and its derivatives have also been studied. In the case of compounds having a substituent, such as a phenyl group or a methyl group, at the 2-position of the indole, excellent synthetic methods are available and industrial production is relatively easy. However, an industrially advantageous method for producing indole itself or a compound having a substituent only on the benzene ring is not yet known. For example, a method is known in which ortho-toluidine is obtained by reducing ortho-nitrotoluene, N-formylated, and then melted with caustic alkali to obtain indole through several steps. Such methods have various drawbacks, such as problems with the quantitative balance between the ortho and para isomers of the starting materials, and complicated steps such as handling of molten salts.

The quantitative balance between ortho and para isomers is a major problem in industrial mass production, and handling of molten salts is also difficult on an industrial scale.

The present inventors have conducted various studies on the production method of indole or indole derivatives with the aim of providing a production method of indole or indole derivatives without the above-mentioned drawbacks, and have developed a method for producing indole or indole derivatives using N-β-hydroxyethylaniline or a nuclear substituted derivative. It was discovered that when brought into contact with a heated copper-containing catalyst, the desired product was produced in a single reaction operation, and a patent application has already been filed (Japanese Patent Application No. 54-14343 (Sho 55-108850)).

The method of the present invention is a further improvement on the method of the above application, and its purpose is to
The object of the present invention is to provide a method for converting β-hydroxyethylaniline or a nuclear-substituted derivative into indole or an indole derivative in a single reaction operation and in high yield.

As a result of research into a method for obtaining indoles in high yield from N-β-hydroxyethylaniline or nuclear substituted derivatives, the present inventors found that CuO-
Conventionally, by reacting N-β-hydroxyethylaniline or a nuclear substituted derivative in a hydrogen atmosphere using a catalyst consisting of MgO- _NnO2 - _SiO2 ,
The present invention was completed based on the discovery that indoles can be obtained in much higher yields than known methods.

That is, the method of the present invention uses N-β-hydroxyethylaniline or a nuclear substituted derivative thereof.
This is a method for producing indole and indole derivatives by reacting in a hydrogen atmosphere using a catalyst consisting of CuO-MgO- _MnO2 - _SiO2 .

According to the method of the present invention, it is possible to produce indole or an indole derivative at a high yield unimaginable by conventional methods, and it is industrially very advantageous. That is, in the method of the present invention, the starting material can be used in a simple manner that does not have problems with ortho-para isomer balance, does not involve complicated steps such as handling molten salt, and can produce the desired product in high yield. can get.

In the method of the present invention, the raw material N-β
-Hydroxyethylaniline is easily obtained in high yield from aniline and ethylene oxide.
Aniline and ethylene oxide are available as industrial raw materials in large quantities at low cost, so they are extremely advantageous as starting materials for indole. Furthermore, starting materials for nuclear substitution derivatives can also be obtained in exactly the same manner.

The catalyst used in the method of the present invention is composed of CuO-MgO-MnO ₂ -SiO ₂ with copper as the main catalyst, and each of the catalysts has a composition of CuO (10 to 10
40 mol%), MgO (10~30 mol%), MnO2 ( ₂ ~
20 mol%) and _SiO2 (10 to 78 mol%).

The catalyst is prepared by a dipping method, for example, by dissolving water-soluble copper salts and manganese salts in silica gel or silica magnesia gel, and performing dipping, drying, and thermal decomposition. Alternatively, use the coprecipitation method, for example, add water glass to a mixed aqueous solution of copper nitrate, magnesium nitrate, and manganese nitrate while stirring to precipitate silica gel. A coprecipitate is formed, and the precipitate is separated by filtration.
Prepared by washing, drying and baking.
The amount of each metal salt to be used is determined so as to achieve the composition described above. Drying of the precipitate takes several hours to one day and night at room temperature.
It is preferable to carry out the reaction at 100 to 200°C for several hours and at 350 to 350°C for several hours. It is preferable that the precipitate dried at 100 to 200°C be shaped into tablets prior to firing.

The catalyst is usually reduced by a conventional method before carrying out the reaction. The reduction treatment is carried out by, for example, increasing the temperature little by little while flowing a mixed gas of hydrogen and nitrogen through the catalyst bed, and maintaining the temperature at 250 to 350°C for several hours.

To carry out the method of the present invention, the raw material N-β-anilinoethanol or N-
This is carried out by heating and vaporizing an aniline solution of β-anilinoethanol and bringing it into contact with the heated catalyst in an atmosphere of hydrogen, or hydrogen and a hydrogen-containing gas such as nitrogen or methane. The catalyst during the reaction is copper oxide reduced to metallic copper or a mixture of metallic copper and cuprous oxide, manganese oxide as Mn ₂ O ₃ , or
It is presumed to be in the Mn ₃ O ₄ state, but details are unknown.

The feed rate of the raw material to the catalyst bed is usually in the range of 0.1 to 2 when expressed in liquid hourly space velocity LHSV. The temperature of the catalyst bed is 200~500℃, especially 250~
A range of 400°C is preferred. There are various types of catalyst beds, usually fixed beds. The reaction is usually carried out at normal pressure, but can also be carried out under increased pressure or reduced pressure.

The reaction product flowing out of the reactor is collected in a cooled trap, and indole or an indole derivative is obtained by a conventional method such as distillation.

The present invention will be explained below with reference to Examples.

Example 1 A reactor made of Pyrex glass having an inner diameter of 12 m/m was filled with 7.5 ml of a catalyst having a particle size of 1 to 2 m/m and subjected to a reaction. The catalyst was prepared by a coprecipitation method, and its composition was 30 mol% CuO, 15 mol% MgO,
It contains 5 mol% MnO ₂ and 50 mol% SiO ₂ , and its BET surface area is 200 m ² /g.

A mixed gas consisting of 0.1 part of hydrogen gas and 0.9 parts of nitrogen gas was supplied to the reaction tube at 100 ml/min, and the catalyst bed temperature was gradually raised from room temperature to 300°C for 1 hour at 300°C.
The mixture was kept at 330°C for 1 hour to reduce the catalyst. After the reduction, a mixed gas consisting of 0.5 parts of hydrogen gas and 0.5 parts of nitrogen gas was supplied to the reaction tube at 50 ml/min, and 15 wt of N-β-hydroxyethylaniline was added.
% aniline solution was supplied to the vaporizer at a rate of 7 ml/Hr, introduced into the reaction tube, and reacted. Catalyst bed temperature is 340℃
I kept it.

Analysis of the reaction liquid collected in a trap that had been cooled between 4 and 6 hours after the start of the reaction revealed that raw material N
- Conversion rate of β-hydroxyethylaniline 94%,
The target indole was produced with a selectivity to indole of 80 mol%.

Example 2 A reaction was carried out using the same catalyst and reaction method as in Example 1, except that the raw material used was changed to N-β-hydroxyethyl-meta-toluidine.

The raw material was supplied to the catalyst bed as a 15 wt% ortho-toluidine solution of N-β-hydroxyethyl-ortho-toluidine at LHSV, 0.9 Hr ^-1 .

When the collected reactor distillate was fractionated, N-
90% conversion of β-hydroxyethyl-ortho-toluidine, selectivity to 7-methyl-indole
The target product was produced at 73 mol%.

Claims (1)

[Claims] 1. A method for producing indole or an indole derivative, which comprises reacting N-β-hydroxyethylaniline or a nuclear substituted derivative thereof in a hydrogen atmosphere using a catalyst consisting of CuO-MgO- _MnO2 - _SiO2 .