JPS58109471A - Preparation of indole compound - Google Patents

Abstract

PURPOSE:To prepare the titled compound useful as a raw material of perfume, dye, alkaloid, etc., economically, in an industrial scale, in high yield, by contacting an aniline compound with ethylene glycol using a material containing cadmium chloride as a catalyst. CONSTITUTION:An aniline compound is made to react with ethylene glycol in the presence of a catalyst containing cadmium chloride, preferably in vapor phase, at 250-450 deg.C, especially at 300-400 deg.C to obtain the objective compound. The aniline compound used as the raw material is preferably the compound of formula (R<1> is H, alkyl, alkoxy, halogen, etc.; R<2> is H or alkyl). The amount of the ethylene glycol introduced into the reactor is 0.01-10 moles, preferably 0.05-5mol per 1mol of the aniline compound. The catalyst is prepared usually by dehydrating and drying cadmium chloride having water of crystallization.

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.

The method for producing the indoles to be contacted is well known, and various proposals have been made regarding the catalyst. For example,
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-56-86154 discloses cadmium phosphate, zinc phosphate, and aluminum phosphate catalysts. Umm.

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-56-16
In the case of using a dehydrogenation catalyst in JP-A No. 451, the yield of indoles is as low as about 10 to 60t16, and in the case of using a cadmium sulfate and/or zinc sulfate catalyst in JP-A-56-53652, Although the yield of indoles is 60 to 70%, the space-time yield is extremely low at 10 to 20 f/hr per catalyst.

The present inventors aimed to develop a catalyst that can produce indoles in high yield and high space-time yield in the catalytic reaction between anilines and ethylene glycol. searched. As a result, they discovered that cadmium chloride is a catalyst that can achieve this purpose.

That is, in the present invention, anilines and ethylene glycol are brought into contact under a catalyst containing cadmira chloride. This provides an extremely industrially excellent method for producing indoles.

The present invention has a high yield of about 70% or more, about Ofl/l.
- Indoles can be produced with a high air sowing yield of more than catalyst + hr.

Furthermore, in addition to cadmium chloride, cesium, rubidium, bismuth, vanadium, thallium, cerium, beryum,
Chlorides or sulfates of metals selected from neodymium,
and cadmium sulfate. These third components are 100 mol or less, preferably 0.0001 to 50 mol, more preferably 0.0001 to 50 mol, per 1 mol of cadmium chloride.
．． 005 to 20 moles are used.

The catalyst in the present invention is usually prepared by dehydrating and drying cadmium chloride (CdC42.2.5H2o) containing water of crystallization. In addition, when using the above third component together, cadmium chloride containing crystal water and the sixth component anhydrous or containing crystal water are added with a small amount of water and mixed in a catcher, a kneader, a further kneader, etc. After uniformly mixing, it can be prepared by dehydrating and drying.

The catalyst of the present invention can also be used after being molded into any shape, if necessary, such as silica, alumina, silica-alumina, titania, and zirconia.

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

When supporting the catalyst component on a carrier, there is no particular restriction on the amount of the catalyst component supported, but it is generally preferred 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, 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 is carried out by heating vapors of anilines and ethylene glycol in the presence of a catalyst containing cadmium chloride. At this time, two kinds of inert gaseous substances can coexist as diluents for the raw materials. Such inert gases include nitrogen gas and carbon dioxide gas.

Examples include water vapor. Further, hydrogen gas or hydrogen-containing gas may also be used as a diluent. The diluent can be added in a molar amount of 0.1 to 100 times the amount of aniline.

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.

(However, in formula 1, R1 represents a hydrogen atom, an alkyl group, an alkoxy group, or a rogene atom or a nitro group. + R2 represents a hydrogen atom or an alkyl group. ) fuglycol 0.01-10 mol, preferably 0.05
~5 moles. In addition, the raw material has a liquid hourly space velocity (L, H, S, V,) of 0. Os ~ + o l/ is introduced into the reactor in advance in a vapor state or in a liquid state so that one angle m1 h r is obtained.

The reaction of the present invention is carried out at 250-450°C, preferably at 300°C.
It is carried out at a temperature of ~400C, and the pressure may be either pressurized, normal pressure, or reduced pressure.

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, the reactor on each side has a tube diameter of 18 mynl.
A stainless steel U-shaped reaction tube 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 After dehydrating and drying cadmium chloride (CaCl2.2.5 R20), 2 parts by weight of raglanite were added, and 4 min.
It was molded into MH pellets. Fill a Yume reactor with 2.45 ml of this molded product, maintain the temperature inside the reactor at approximately 335°C, and add 10 ml of a mixture of aniline and ethylene glycol in a molar ratio of 10:1.
l /hr (L, H, S, V, = 0.4 t /
L-catalyst, hr), and at the same time nitrogen gas was passed at a flow rate of 2 oml/min.

As a result of analyzing the reaction product by gas chromatography, the reaction rate of ethylene glycol was 93. Bl) The selectivity of indole based on 1 ethylene glycol was 75.6%, and the yield of indole was 70.956 (space-time yield: 28
．． 4? / was one catalyst + hr″y′c.

Example 2 Chlorinating power)” Mi17mu (OdC12・2.5H20)
228.39 and cadmium sulfate (CdS04., H2
O) After adding a small amount of water to 12.8 f and thoroughly mixing with a kneader.

It was dehydrated and dried at 200C for 15 hours. Next, after pulverizing to 14 mesocy or less, 2% by weight of graphite was added and formed into pellets of 4 ρX 4 MH.

25 ml of this molded product was filled into 9 reactors.

The temperature inside the reactor was maintained at approximately 340°C, and a mixture of aniline and ethylene glycol with a molar ratio of 10:1 was heated to 12.5°C.
me/hr (L, H, S, V, = 0.5 t/
1-catalyst, hr), and at the same time hydrogen gas was passed at a flow rate of 40 me/min.

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

Examples 3 to 12 Catalysts containing cadmium chloride and various sixth components were prepared by the same method as in Example 2, and using the catalyst 25m#,
Indole was produced in the same manner as in Example 2.

The results are shown in Table 1.

Comparative Example 1 Commercially available Cu-0r catalyst (manufactured by JGC Chemical Co., Ltd., trade name N-N-
The experiment was conducted in the same manner as in Example 2, except that 201)25 was used.

The results are shown in Table 1.

Chapter 1 Table *: Values in parentheses indicate 1 molar ratio.

Comparative Example 2 By the same method as Example 2, CdSO4 and ZnS
A catalyst with an O4 molar ratio of 4:1 was prepared. This catalyst 25
The experiment was conducted in the same manner as in Example 1, except that me was used.

Conclusion 1. The reaction rate of ethylene glycol is 80.8,
The selectivity of indole based on ethylene glycol is 73.
251), and the yield of indole was 59.1% (space-time yield: 21.5y/z-catalyst 1hr).

Patent applicant Ube Industries Co., Ltd.

Claims (1)

[Claims] A method for producing indoles, which comprises bringing anilines and ethylene glycol into contact under a catalyst containing cadmium chloride.