JPS6028962A - Production of indole - Google Patents

Abstract

PURPOSE:The reaction of aniline and ethylene glycol is carried out using a novel high-active catalyst at relatively low temperatures to achieve the production of the titled compound used as a raw material for perfume, dye or alkaloid in high space time yield and high selectivity. CONSTITUTION:The reaction between an aniline of formula I (R<1> is H, alkyl, alkoxy, halogen, nitro, hydroxyl; R<2> is H, alkyl) and ethylene glycol is carried out at a molar ratio of 5:1 in the presence of a catalyst of formula II (Cd is cadmium; X is at least one of elements selected from Pb, Zr, B, Cr and W; a, b and c are numbers of atoms; when a is 1, b is 0.5-4 and c is 2-8 depending on the valencies of Cd and X element), at 250-400 deg.C under elevated, normal or reduced pressure at a liquid space rate of 0.05-10l/l-catalyst.hr to give an indole.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing indoles by reacting anilines and ethylene glycol in the presence of a novel catalyst.

Indoles are fragrances, dyes, and alkaloids.

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

A method for producing indoles in which anilines and ethylene glycol are reacted in the presence of a catalyst is known.

Various proposals have also been made regarding catalysts used in this case. For example, JP-A-56-36451 discloses a dehydrogenation catalyst, JP-A-56-55366 discloses a copper-containing catalyst, and JP-A-56-53652 discloses sulfuric acid, domium and /''i !, Bamboo zinc sulfate catalyst was published in Japanese Unexamined Patent Publication No. 5
No. 6-86154 discloses a catalyst selected from cadmium phosphate, zinc phosphate, aluminum phosphate, boron phosphate and silver.

Further, JP-A-56-110672 proposes catalysts containing magnesium oxide.

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.

The present inventor searched for the catalytic activity of two different substances with the aim of developing a catalyst that has high activity and can produce indoles with a high space-time yield in a catalytic reaction between anilines and ethylene glycol. .

As a result, each oxide of cadmium, lead, zirconium, boron, chromium, tungsten, etc. shows almost no catalytic activity when used alone, but oxides containing cadmium and one or more elements other than cadmium have extremely high catalytic activity. It was discovered that this material can serve as a catalyst that can achieve the above objectives.

We have arrived at the present invention.

The present invention uses anilines and ethylene glycol using the general formula.

CdaXbO6 (In the formula, Cd is cadmium, and X is lead and zirconium.

One or more elements selected from the group consisting of boron, chromium, and tungsten, and 0 represents oxygen, and the subscripts a, b, and C represent the number of atoms, and when a is 1, 1)
=0.5 to 4, and C is a value naturally determined by the valences of cadmium and X element, and is usually 2 to 8. )
This invention relates to a method for producing indoles, which is characterized by carrying out the reaction in the presence of a catalyst represented by:

According to the present invention, at a relatively lower reaction temperature than conventionally,
In addition, the molar ratio of anilines and ethylene glycol is 5:
Indoles can be industrially produced with a high space-time yield and good yield under conditions of one degree of high concentration of ethylene glycol.

The catalyst represented by the above general formula used in the present invention is prepared according to a general method for preparing an oxide catalyst.

For example, after mixing compounds containing catalyst component elements in the presence of water and drying them by evaporation to dryness, spray drying, etc.,
It can be easily prepared by firing at temperatures of ~800°C. Examples of compounds containing catalyst component elements include cadmium compounds such as cadmium nitrate, cadmium carbonate, cadmium hydroxide, cadmium oxalate, cadmium chloride, and cadmium oxide, lead oxide, and lead hydroxide.

Lead compounds such as lead nitrate, lead carbonate, lead acetate, lead oxalate,
Zirconium compounds such as zirconium nitrate and zirconium oxide; boron compounds such as boric acid and boron oxide;
Examples include chromium compounds such as chromium nitrate, chromium carbonate, and chromium oxide, and tungsten compounds such as ammonium tungstate and tungsten oxide. Furthermore, although it is not fully understood what form of oxide each catalyst component element forms in a catalyst, it is mainly an oxide of each catalyst component alone, and a composite oxide in which multiple catalyst components are combined with oxygen. It exists in the catalyst in the form of

In the present invention, the number of X component elements such as lead, zirconium, boron, chromium, and tungsten that constitute the catalyst together with cadmium may be one or more.

Two or three types may be used, and even when multiple types are used, excellent catalytic activity is exhibited. The amount of the X component element is 0.4 to 5 gram atoms per 1 gram atom of cadmium.

If the amount of the X component element is too large or too small, the yield and space-time yield of indoles will be low.

In carrying out the present invention, the catalyst may be used alone or supported on a carrier.

Examples of carriers include silica, alumina, silical alumina, titania, zirconia, pumice,
Examples include activated carbon and silicon carbide. When used supported on a carrier, the amount of the catalyst component supported is not particularly limited, but is usually 1 to 80% by weight.

As the raw anilines, compounds represented by the following general formula are preferably used.

1℃NHRF (In formula 2, R1 represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, a nitro group, or a hydroxyl group.
2 represents a hydrogen atom or an alkyl group. ) Representative examples of anilines that are preferably used include:

7-=! J 7 r m/f ruaniline, m-ethylaniline, 0-toluidine, m-toluidine, 0-
Examples include aninsine, m-anisidine, p-anisi7+m-aminophenol, and 0-aminephenol.

Furthermore, the raw materials anilines and ethylene glycol do not need to be particularly highly pure.

The ratio of raw materials aniline and ethylene glycol introduced into the reactor is per mole of aniline.

Ethylene glycol 0.01 to 10 mol, preferably tL<0
．． It is 1 to 5 moles. In addition, the raw material has a liquid hourly space velocity (LH8V) of 0.05-10 t/l-catalyst/h
It is introduced into the reactor in advance in vapor or liquid form so that r .

The reaction is carried out at 250-400'C, preferably 280-35
It is carried out at a temperature of 0°C and the pressure is pressurized, normal pressure.

Either pressure reduction may be used.

Although the reaction can be carried out in any of the gas phase, liquid phase, or gas-liquid mixing, 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 carried out by heating vapors of anilines and ethylene glycol in the presence of the catalyst. In this case, various inert gases can be used as diluents for the raw materials. Examples of such inert gas include nitrogen gas, carbon dioxide gas, and water vapor.

Moreover, hydrogen gas or hydrogen-containing gas can also be used as a diluent. The diluent is 0.1 to 10 for arc
It can be added in a 0-fold molar amount.

The indoles produced by the reaction can be easily separated and recovered from the reaction product by conventional methods such as distillation and extraction.

Next, Examples and Comparative Examples will be shown.

Analysis of the two reaction products on each side was performed by gas chromatography. Also, the reaction rate of ethylene glycol (%
); Indole selectivity (rate) and indole yield (%) are in accordance with the following definitions.

In addition, the reactor on each side has a tube diameter of 18 rtan.
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, forming the raw material vaporization section, the second half forming the catalyst filling section, and the reaction tube outlet connected to the receiver via the water cooling section. has been done.

Example 1 Cadmium nitrate Cod(NO3)z・4H20)308
．． 55' and lead nitrate [Pb(NO3)2] 269.0
1 was dissolved in water, evaporated to dryness, and then heated to 700" in an air atmosphere.
Time baking was performed at C. Next, 1 part by weight of graphite was added and formed into pellets of 4mOX4mH. This molded product [:Ca:Pb=1:1 (atomic ratio):] 225 m
was charged into the reactor.

The temperature inside the reactor was maintained at approximately 620°C, and 12% of the mixture with anilintoethylene glycol in a molar ratio of 5:1 was added.
me/hr(L, H, S, V, = 0.481/
At the same time, hydrogen gas was introduced at a flow rate of 20 ml/min to perform one reaction.

The results are shown in Table 1.

Examples 2 to 6 Zirconium nitrate [Zr(
NO3)4・5H20], boron oxide [BzO3'll
+ Chromium nitrate [Cr(NO3)3''9Hzo]l and tungsten oxide [W03] were used, but the same method as in Example 1 was used to produce a catalyst having the composition shown in Table 1. Aniline and ethylene glycol were reacted under similar reaction conditions.The results are shown in Table 1.

Comparative Examples 1 to 6 Cadmium oxide [:Ca, O:], lead oxide [:Ca] as a catalyst
:pbo], boron oxide CB203) + tungsten oxide (WO3:), chromium oxide (Or2031:l, and zirconium oxide (:Zr02)) Alinine and ethylene glycol were reacted under the same reaction conditions as in Example 1, except that chromium oxide (Or2031:l) and zirconium oxide (:Zr02) were used. The results are shown in Table 1.

Claims (1)

[Claims] General formula for anilines and ethylene glycol. CdaXbO8 (in the formula, cd is cadmium, , a is 1, then b
=o, s~4, and C is a value naturally determined by the valences of cadmium and X element, and is usually 2 to 8. ) A method for producing indoles, characterized by carrying out the reaction in the presence of a catalyst represented by: