JPS58128371A - Preparation of indole compound - Google Patents

Abstract

PURPOSE:To prepare an indole compound in high yield and space-time yield, by contacting an aniline compound with ethylene glycol using cadmium sulfate catalyst and a catalyst containing thallium sulfate and vanadyl sulfate. CONSTITUTION:Indole is prepared by contacting the aniline compound of formula (R<1> is H, alkyl, alkoxy, halogen, tc.; R<2> is H or alkyl) with ethylene glycol. The reaction is carried out in the presence of a catalyst composed of cadmium sulfate and a catalyst containing thallium sulfate and vanadyl sulfate, at 250- 450 deg.C, preferably 300-400 deg.C. The yield and the space-time yield of the reaction are as high as about >=70% and about >=35g/1-catalyst, hr, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing indoles.

Indoles are fragrances, dyes, and alkaloids.

It also has various industrial uses as a raw material for the essential amino acid tryptophan.

Conventionally, anilines and ethylene glycol were used.

Methods for producing the indoles to be contacted are well known, and various proposals have been made for the catalysts used. For example, JP-A-5
No. 6-36451 discloses a dehydrogenation catalyst,
No. 55366 discloses a copper-containing catalyst disclosed in JP-A-56-53.
No. 652 discloses cadmium sulfate and/or zinc sulfate catalysts, and JP-A-5'6-86154 discloses cadmium phosphate, zinc phosphate, aluminum phosphate,
Catalysts selected from boron phosphate and silver have each been proposed.

However, in all methods using these catalysts, the yield of indoles is low, and the yield per unit catalyst (
Space-time yield, 5TY) is low. For example, JP-A-56-36
In the case of using a dehydrogenation catalyst in JP-A No. 451, the yield of indoles is as low as about 10-60%, and in the case of using a cadmium sulfate and/or zinc sulfate catalyst in JP-A-56-53652, , the yield of indoles is 60-70%, but the space-time yield is 1
0 to 207/hr per catalyst, which is extremely low.

The present inventors aimed to develop a catalyst capable of producing indoles in a high yield and space-time yield in a catalytic reaction between anilines and ethylene glycol, and the catalytic activity of two various substances was determined. searched. As a result, it was found that a catalyst containing cadmium sulfate and one portion of thallium sulfate and/or vanadyl sulfate would achieve the objective.

That is, the present invention provides an extremely industrially excellent method for producing anilines and ethylene glycindoles.

In the present invention, indoles can be produced with a high yield of about 70 t or more, and a high space-time yield of about 35y7 per hr per catalyst, compared to the use of known catalysts.

The composition of the catalyst in the present invention is cadmium sulfate 1
Thallium sulfate and/or vanadyl sulfate are used in an amount of 0.01 to 5 mol per 0 mol.

In addition, sodium, potassium, lithium, cesium,
By adding one or more sulfates of alkali metals such as rubidium as the sixth component of the catalyst, the yield and selectivity of indoles can be further increased. These third ingredients are.

5 moles or less per 10 moles of cadmium sulfate.

Preferably it is used in an amount of 0.005 to 1 mol.

The catalyst in the present invention is prepared by adding a small amount of water to cadmium sulfate, thallium sulfate and/or vanadyl sulfate and optionally an alkali metal sulfate, which are anhydrous or contain water of crystallization. It can be prepared by uniformly mixing the mixture by, for example, dehydrating and drying the mixture.

Further, the catalyst of the present invention can be used after being formed into any shape, and if necessary, it can be formed into silica, alumina, silica-alumina, titania, or zirconia.

It can also be used by being supported on common carriers such as pumice, diatomaceous earth, activated carbon, and silicon carbide.

When the catalyst component is supported on a carrier, there is no particular restriction on the amount supported, but it is usually preferable that the catalyst component be supported on the carrier in an amount of about 1 to 80 wt%.

Although the method of the present invention can be carried out in any of the gas phase, liquid phase, or gas-liquid mixed phase, 9 it is usually carried out in the gas phase.

When carried out in the gas phase, it can be carried out in a fixed bed, fluidized bed or moving bed, and involves heating the vapors of anilines and ethylene glycol in the presence of a catalyst containing cadmium sulfate and thallium sulfate and/or vanadyl sulfate. It will be implemented accordingly. At this time, two kinds of inert gaseous substances can coexist as diluents for the raw materials. Examples of such inert gas include nitrogen gas, carbon dioxide gas, and water vapor. Further, hydrogen gas or hydrogen-containing gas may also be used as a diluent. Diluent is 0.1 to aniline
It can be added in a 100-fold molar amount.

Anilines and ethylene glycol, which are raw materials for the reaction, do not need to be particularly highly pure.

As the raw material anilines, compounds represented by the following general formula are useful.

1 ΣNHR2 (However, in formula 2, R1 represents a hydrogen atom, an alkyl group, an alkoxy group, a rogen atom, or a nitro group, and R2 represents a hydrogen atom or an alkyl group.) Anilines and ethylene introduced into the reactor The ratio of glycol is 0.01 to 10 moles, preferably <uo, 0.5 to 5 moles of ethylene glycol, per mole of aniline. In addition, the raw material has a liquid hourly space velocity (L, H,
S, V,) is 0.05 to 10 t/L-catalyst, hr, and is introduced into the reactor in vapor or liquid form in advance.

The reaction of the present invention is carried out at 250-450'C, preferably at 30
It is carried out at a temperature of 0 to 400°C, and the pressure is increased.

Either normal pressure or reduced pressure may be used.

After the reaction, the indoles are extracted from the reaction product by distillation,
It can be easily separated and purified by conventional methods such as extraction.

Next, examples and comparative examples of the present invention will be shown.

In addition, as a reactor on each side, a stainless steel U-shaped reaction tube with a tube diameter of 18-U was used. The first half of this reactor is connected to the raw material insertion pipe and the diluent gas introduction pipe, and constitutes the raw material vaporization section, the second half constitutes the catalyst filling section, and the two reaction tube outlet sections pass through the water cooling section and into the receiver. is connected to.

Example 1 Cadmium sulfate (CdSO4.-H2O) 256. i
f.

Add 25.2 f of thallium sulfate (T4SO4) and 6 g of senlum sulfate (C!52sO4) to 50 m/! of water!
After addition, the mixture was sufficiently mixed using a kneader, and then dehydrated and dried at 200°C for 15 hours. Next, after crushing to 14 mesh or less, 3 weights of graphite were added to make it 4 mm 5%
It was molded into pellets of 4 myn H. This molded product 25
ml was charged into two reactors.

The temperature inside the reactor was maintained at approximately 350°C, and a mixture of aniline and ethylene glycol with a molar ratio of 10:1 was poured into 15 m
l/hr (L, H, S, V, = 0.6 L/
L-catalyst.

At the same time, hydrogen gas was introduced at a flow rate of 40 me/min.

The reaction was analyzed by gas chromatography. The results are shown in Table 1.

Examples 2 to 6 and Comparative Examples 1 to 5 Various catalysts were prepared in the same manner as in Example 1, and using 25 mg of each catalyst, in the same manner as in Example 1,
produced indole.

The results are shown in Table 1.

(9)-597

Claims (1)

[Claims] A method for producing cadodols of sulfate from anilines and ethylene glycol.