JPH0813800B2 - Indole manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing indras, and more specifically, for example, tryptophan for animal feed,
The present invention relates to a method for producing indoles, which can be widely used in various fields such as chemical industry and biochemical industry as raw materials for various chemical products such as dyes.

[Prior Art and its Problems] Although no report has been made on a patent for producing an indole by a dehydrocyclization reaction of N-ethylanilines, a chemical dictionary (published in 1969, vol. 8). (Page 87)
It is reported that indole is obtained by passing N-ethylaniline through a red-hot tube. However, this pyrolysis method requires significantly higher temperatures,
Moreover, the yield of indole is low, and it is not practical.

Therefore, if a suitable catalyst can be found and a method for obtaining an indole at a lower temperature and a high yield by catalytic dehydrocyclization can be found, a novel and practically excellent indole is obtained. It is thought that the manufacturing method of can be provided. Furthermore, this method can be expected to develop into a novel method for efficiently obtaining not only N-ethylaniline but also various corresponding indoles from N-ethylaniline having various substituents.

[Object of the Invention] The present invention has been made under the above circumstances, and an object thereof is to solve the above problems and to obtain a high yield from ethylanilines such as N-ethylaniline by a catalytic dehydrocyclization reaction. The present invention is to provide a novel method for producing indoles such as indoles.

[Means for Solving the Problems] In order to solve the above problems, the present inventors have diligently studied a method of catalytic dehydrocyclization, instead of the conventional method of thermally decomposing N-ethylaniline. As a result, it was found that by using a catalyst containing a specific metal element, the yield of indole can be dramatically increased at a lower temperature as compared with the conventional thermal decomposition method. According to this finding, it was also found that not only N-ethylaniline but also various indoles are produced from N-ethylanilines having a specific structure in high yield, and the present invention was completed based on these findings. Came to do.

That is, the present invention comprises contacting N-ethylanilines with a catalyst containing at least one metal element selected from the group Ib, IIb, and VIII metal elements of the periodic table for dehydrocyclization. A method for producing a characteristic indole is provided.

 The present invention will be described in detail below.

The N-ethylanilines used as a reaction raw material in the method of the present invention are represented by the following general formula (first [1]) (In the formula [1], R ¹ , R ² and R ^{3 each} represent a hydrogen atom or an alkyl group, preferably a hydrogen atom or a methyl group, particularly preferably a hydrogen atom, and R ⁴ , R ⁵ and R 3
⁶ represents a hydrogen atom or an alkyl group, preferably a hydrogen atom, a methyl group or an ethyl group, and R ⁷ represents a hydrogen atom, a methyl group or an ethyl group, preferably a hydrogen atom. The groups R ^{1 to} R ⁷ may be the same type of groups or different types of groups. ).

When the nomenclature of organic compounds is strictly applied to the compounds represented by the above formula [1], they should be classified into general N-alkylanilines other than N-ethylanilines. Are also included here, but for convenience, they are regarded as alkyl-substituted N-ethylaniline,
-Shown as ethylanilines.

Specific examples of the N-ethylanilines are not limited,
For illustration purposes only, for example, N-ethylaniline, N-ethyl-m-toluidine, N-ethyl-p-toluidine, N-ethyl-o-toluidine, N-ethyl-
3,4-xylidine, N-ethyl-3,5-xylidine, N-
Ethyl-2,3-xylidine, N-ethyl-2,4-xylidine, N-ethyl-2,5-xylidine, N-ethyl-3,4,5
-Trimethylphenylamine, N-ethyl-2,3,4-trimethylphenylamine, N-ethyl-2,3,5-trimethylphenylamine, N-ethyl-2,4,5-triphenylamine, N-ethyl -2,3,4,5-tetramethylphenylamine, N-ethyl-p-ethylaniline, N-ethyl-m-ethylaniline, N-ethyl-3-methyl-4
-Ethylphenylamine, N-ethyl-3,4-diethylphenylamine, N-ethyl-3-ethyl-4-methylphenylamine, N-ethyl-3-ethyl-5-methylphenylamine, N-ethyl-3 -Methyl-5-ethylphenylamine, N-ethyl-3,5-diethylphenylamine, N-ethyl-2-ethylphenylamine, N-
Ethyl-2-methyl-3-ethylphenylamine, N-
Ethyl-2-methyl-4-ethylphenylamine, N-
Ethyl-2-methyl-5-ethylphenylamine, N-
Ethyl-3,4,5-triethylphenylamine, N-ethyl-3-methyl-4,5-diethylphenylamine, N-
Ethyl-3-ethyl-4,5-dimethylphenylamine,
N-ethyl-3,5-dimethyl-4-ethylphenylamine, N-ethyl-3,5-diethyl-4-methylphenylamine, N-ethyl-N-methylaniline, N-ethyl-N-
Methyl-p-toluidine, N-ethyl-N-methyl-m
-Toluidine, N-ethyl-N-methyl-3,4-xylidine, N-ethyl-N-methyl-3,5-xylidine, N
-Ethyl-N-methyl-2,3-xylidine, N-ethyl-N-methyl-2,4-xylidine, N-ethyl-N-methyl-2,5-xylidine, N-ethyl-N-methyl-3
-Methyl-4-ethylphenylamine, N- (1-methylethyl) aniline, N- (1-methylethyl) -p-toluidine, N- (1-methylethyl) -m-toluidine, N- (1- Methyl ethyl) -o
-Toluidine, N- (1-methylethyl) -3,4-xylidine, N- (1-methylethyl) -3,5-xylidine, N- (1-methylethyl) -2,4-xylidine, N
-(1-methylethyl) -2,5-xylidine, N- (1
-Methylethyl) -2,3-xylidine, N- (1-methylethyl) -3,4,5-trimethylphenylamine, N-
(1-methylethyl) -p-ethylaniline, N- (1
-Methylethyl) -m-ethylaniline, N- (1-methylethyl) -o-ethylaniline, N- (1-methylethyl) -N-methylaniline, N- (1-methylethyl) -N-methyl -P-toluidine, N- (1-methylethyl) -N-methyl-m-toluidine, N- (1-methylethyl) -N-methyl-o-toluidine, N- (1
-Methylethyl) -N-methyl-3,4-xylidine, N
-(1-methylethyl) -N-methyl-3,5-xylidine, N-propylaniline, N-propyl-toluidine,
N-propylxylidine (excluding 2,6-isomer) N-propyl-3,4,5-trimethylbenzene, N
-Propyl-N-methylaniline, N-propyl-N-
Methyltoluidine, N-propyl-N-methylxylidine (excluding 2,6-isomer), N- (1-methylpropyl) aniline, N- (1-methylpropyl) toluidine, N- (1 -Methylethyl) -N-methylaniline, N, N-diethylaniline, N, N-diethyltoluidine, N, N-diethylxylidine (excluding 2,6-isomer). .

Among these, N-ethylaniline, N-ethyl-m
-Toluidine, N-ethyl-p-toluidine, N-ethyl-3,4-xylidine, N-ethyl-3,5-xylidine,
N-ethyl-3,4,5-trimethylphenylamine, N-
Ethyl-p-ethylaniline, N-ethyl-m-ethylaniline, N-ethyl-N-methylaniline, N-ethyl-N-methyl-p-toluidine, N-ethyl-N-methyl-m-toluidine, N -Ethyl-N-methyl-3,4
-Xylidine, N-ethyl-N-methyl-3,5-xylidine, N- (1-methylethyl) aniline, N- (1-
Methylethyl) -p-toluidine and the like are preferable, and N-ethylaniline and the like are particularly preferable.

In addition, these compounds may be used individually by 1 type or in mixture of 2 or more types.

In the method of the present invention, a solid substance containing at least one metal element selected from the group Ib, IIb, and VIII metal elements of the periodic table is used as a catalyst. Specific examples of these metal elements include, for example, copper, silver, zinc, cadmium, iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium,
Platinum and the like can be mentioned, and among them, ruthenium, palladium, platinum, copper, silver, zinc, cadmium and the like are preferable, and ruthenium, platinum, palladium and zinc are particularly preferable.

These metal elements are used as a catalyst or a catalyst precursor that can be used as a precursor thereof,
Further, they can be used as components of various kinds and states at the stage of their raw materials for preparation.

In addition, the catalyst precursor refers to a substance that can exhibit catalytic activity by a physical or chemical activation treatment such as heat treatment, reduction treatment, and treatment with a reaction product.

The kind and state of the component containing the metal element that can be used in the above meaning is not particularly limited as long as it contains at least one kind of the metal element, and for example, simple metal, atomic metal, Cluster-like metal alloys, complex metal clusters or intermetallic compounds, amorphous metal ruthenium black, platinum black, palladium black and other metal blacks or other partially oxidized metal-like substances; oxides, aluminates, silicates, metallo Silicates, chromates, nitrates, phosphates, carbonates, sulfates, borates, complex oxides such as carboxylates such as acetates, oxyacid salts, carbides or acetylides, nitrides, borides, sulfides, Various inorganic or organometallic compounds such as alkyl compounds, alkoxides, aryl oxides and halides Aqua complex, ammine complexes,
A halogen complex such as a metal halide acid or a salt thereof,
Cyano complex, acetyl acetate complex, amine complex, nitro complex, nitrito complex, nitrosyl complex, nitrile complex, isonitrile complex, isocyanato complex, carbonyl complex, carbonyl halide complex, carbide complex, carbonylphosphine complex, other substituted carbonyl complex, phosphine complex , Hydride complex, olefin complex, polyene complex such as diene complex, acetylene complex, allyl complex, aryl complex, various complexes or complex salts such as cyclopentadienyl complex, and these are dinuclear complex etc. Can be used as compounds or components in various complex states such as cluster compounds, double salts, complex complexes, etc., or as various mixtures or combinations, and further, a part or whole thereof can be supported on various carriers. It can be used Te.

However, in the method of the present invention, as a catalyst that can be preferably used, for example, the metal element is a metal colloid, a metal ultrafine particle, a highly dispersed metal,
A high surface area metal state such as ultra-high dispersion metal or a so-called supported metal catalyst supported as a high surface area metal-like state in a partially oxidized state thereof, or
The metal oxide may be a complex oxide-based catalyst contained as a partially reduced state, or a mixture thereof, and in particular, when a Group VIII element such as ruthenium, platinum or palladium is used, it is usually It is preferably used as the above-mentioned supported metal catalyst, while copper, zinc, etc.
When a group b or II b metal element is used, it is usually preferable to use it as the above composite oxide.

And, as the catalyst precursor which can be preferably used in the method of the present invention, the above-mentioned supported metal catalyst or the composite metal oxide-based catalyst can be introduced by activation treatment such as heat treatment, reduction treatment and treatment with a reactant. It can include those that can.

Specific examples of the compound or component containing the metal element that can be preferably used as a raw material for preparing a catalyst such as a supported metal catalyst or a composite oxide catalyst or a catalyst precursor, and are shown only for the purpose of illustration, not limitation. When,
For example, ruthenium trichloride, ruthenium tribromide, ruthenium triiodide, ruthenium trifluoride, and the like; pentachlororuthenium (III) acid and its ammonium salt, alkali metal salts, and the like, and ruthenium halides and salts thereof. Ruthenium red, ruthenium hydroxide, diruthenium trioxide, ruthenium dioxide, ruthenium dioxide, ruthenium tetraoxide, potassium ruthenate, ruthenium salts, ruthenium dicarbonyl iodide, decarbonyl triruthenium, dodecacarbonyl tetrahydridotetraruthenium, carbonyl ruthenium chloride Ruthenium carbonyl complex, ruthenocene, ruthenium complex such as dicyclooctadisilthenium, or ruthenium cluster compound, hexaammineruthenium (III) trichloride, etc. Ruthenium complexes, ruthenium black, Raney ruthenium, ruthenium colloids, ruthenium nanoparticles, the ruthenium metal trihalide rhodium such as rhodium chloride, or hexachlororhodate,
Ammonium salts or alkali metal salts, rhodium hydroxide, dirhodium trioxide; rhodium complex salts such as hexaammine and rhodium (III) trichloride; rhodium complexes such as tris (triphenylphosphine) hydridocarbonium rhodium and dodecacarbonyltetrarhodium; or Rhodium cluster compounds, rhodium black, Raney palladium, rhodium colloid, rhodium metal; palladium halides such as palladium fluoride, palladium chloride, palladium bromide, palladium iodide, palladium nitrate, palladium sulfate, palladium acetate, palladium acetylacetonate, Inorganic or organic acid salts of palladium such as palladium sulfide; tetraamine palladium dichloride,
Hexachloropalladic acid, hexachloropalladic acid sodium salt, tetrachloropalladic acid, dinitrodiamminepalladium dichloride and other palladium inorganic complex compounds; palladium oxide, palladium hydroxide [Pd (CO) C
l ₂ ] ₂ , Pd (CO) ₂ Cl] _{2 and} other palladium carbonyl complexes, palladium isonitrile complexes, [PdCl ₂ (olefin)] ₂ , [Pd (PPh ₃ ) ₂ (olefin)], [PdCl (η ₃ − _{C 3 H 5)] 2 [} Pd (η 5 -C 3 H 5) 2] palladium olefin or allyl complexes such _{as, [η 3 -C 5 H 5} PdCl] 2 , etc. palladium cyclopentadienyl complexes of, [Pd (PPh ₃ ) ₄ ] and other palladium phosphine complexes, [(CH ₃ ) ₂ Pd PPh ₃ ] [CH ₃ Pd OCOCH ₃ ] and other palladium alkyl complexes, palladium aryl complexes, palladium acyl complexes, palladium hydride complexes, and various other compounds. Palladium compounds such as organopalladium compounds; highly dispersed palladium such as palladium black, palladium colloids and palladium ultrafine particles; osmium oxide such as osmium dioxide and osmium tetroxide; trichloride Osmium halides such as smium, osmium acid such as hexachloroosmium (IV) acid or its ammonium salts or alkali metal salts or salts thereof; various osmium complexes or osmium cluster compounds such as decacarbonyltriosmium and carbonylosmium chloride; osmium black , Osmium colloid, osmium metal, iridium oxide, iridium hydroxide, iridium halides such as iridium trichloride, hexachloroiridium (IV) acid or its iridium salts such as ammonium salts or alkali metal salts; hexaammineiridium (III) trichloride Iridium complex salts such as compounds; organic iridium compounds such as dodecacarbonyliridium or iridium cluster compounds; iridium black, iridium colloids, Rijiumu metal; platinum dichloride, platinum tetrachloride, dibromide platinum,
Platinum halide such as platinum diiodide; Platinic acid or platinate such as tetrachloroplatinate (II) acid, hexachloroplatinum (IV) acid or their ammonium salts or alkali metal salts; Platinum oxide (II), Platinum oxide Platinum oxide such as (IV), platinum hydroxide, platinum disulfide, platinum complex compound such as platinum (II) ammine complex, platinum acetylacetonato complex, bis (triphenylphosphine) platinum dichloride, dinitrodiaminoplatinum, platinum Various organic platinum compounds or platinum cluster compounds such as nitrile complex, platinum nitrosyl complex, platinum carbonyl cluster, zinc hydroxide,
Zinc oxide; zinc salts such as zinc nitrate, zinc sulfate, zinc phosphate, zinc acetate, zinc carbonate, zinc chloride, zinc bromide, zinc iodide, zinc fluoride, zinc cyanide, zinc chromate, etc., or zinc complex oxidation. Compounds, zinc complex compounds such as diethoxyzinc, tetraaqua zinc hydroxide, tetraammine zinc, hydroxide, sodium tralacyanozincate and sodium zincate; organic zinc compounds such as diethylzinc and diallylzinc; zinc metal such as electrolytic zinc Cadmium nitrate, cadmium sulfate, cadmium carbonate, cadmium acetate, cadmium hydroxide, cadmium oxide, cadmium chloride and other halogenated cadmium, cadmium metal; copper nitrate, copper sulfate,
Copper salts such as copper acetate, copper chloride, copper bromide, copper iodide, copper carbonate, basic copper carbonate and copper chromate, or copper complex oxides,
Tetraammine copper (II) chloride, tetraammine copper (I
I) Copper complex compounds such as nitrate, tetraammine copper (II) nitrate, and tetraammine copper (II) hydroxide, copper oxide (I
I), copper (I) oxide, copper hydroxide; organic copper compounds such as copper acetylide, acetylacetonato copper, Raney copper, copper colloid, copper ultrafine particles, copper metal; nickel nitrate, nickel sulfate, nickel phosphate, chloride Nickel salts of nickel, nickel bromide, nickel acetate, nickel formate, nickel oxalate, nickel carbonate, etc .; nickel nickel, organic nickel compounds such as diacetylacetonatomic nickel, dicyclooctadiene copper, diallyl nickel, nickel carbonyl; nickel oxide , Nickel hydroxide: Raney nickel, lacquer nickel, nickel colloid, nickel ultrafine particles, metallic nickel; silver salts such as silver nitrate, silver fluoride, silver carbonate, silver nitrate, diammine silver (I) chloride, diammine silver (I) hydroxide Complex compounds such as cobalt; cobalt chloride, cobalt bromide, cobalt nitrate Cobalt salts such as cobalt oxide, cobalt sulfate, cobalt acetate, cobalt formate, and cobalt carbonate; cobalt hydroxide, cobalt oxide (II), cobalt oxide (I
I, III), cobalt (IV) oxide; organic cobalt compounds such as acetylacetonatocobalt and cobalt carbonyl; Raney cobalt, cobalt colloid, cobalt ultrafine particles, metallic cobalt; iron nitrate (II), iron nitrate (III),
Iron salts such as iron (II) chloride, iron (III) chloride, iron (II) sulfate, iron (III) sulfate, and iron acetate; iron (II) hydroxide, iron (III) hydroxide, iron (II) oxide , Iron (II, III), iron (III) oxide, potassium hexacyanoferrate (II), potassium hexacyanoferrate (III), and other iron complex compounds; organic iron such as iron acetylacetona, iron carbonyl, and ferrocene Various things such as compounds can be mentioned.

Among them, ruthenium halides such as ruthenium trichloride hydrate or its hydrochloric acid solution, rhodium halides such as rhodium trichloride hydrate, halogenated halides such as palladium dichloride, etc. Palladium or its hydrochloric acid solution, tetrachloropalladic acid or its ammonium salt or sodium salt,
Osmium halides such as palladium nitrate, palladium sulfate, palladium acetate, osmium trichloride hydrate or its hydrochloric acid solution, osmium tetraoxide, iridium trichloride or its hydrochloric acid solution, platinum chloride or its hydrochloric acid solution, tetrachloroplatinic acid, hexachloro Platinic acid or its alkali metal salts such as ammonium or sodium salts, water-soluble lead salts such as zinc nitrate and zinc chloride,
Water-soluble cadmium salt such as cadmium nitrate and cadmium chloride, water-soluble copper salt such as copper nitrate, copper sulfate and copper chloride, water-soluble nickel salt such as nickel nitrate, nickel sulfate and nickel chloride, cobalt nitrate, cobalt sulfate and cobalt chloride , Water-soluble cobalt salts such as cobalt acetate, water-soluble iron salts such as iron nitrate, iron sulfate, iron chloride, potassium hexacyanoferrate, etc., and particularly preferable from the viewpoint of catalytic activity of metal components. As ruthenium trichloride hydrate or its hydrochloride, palladium chloride or its hydrochloric acid solution, tetrachloropalladic acid or its ammonium salt, palladium nitrate, platinum chloride or its hydrochloric acid solution, hexachloroplatinic acid, tetrachloroplatinic acid or its An ammonium salt etc. can be mentioned.

The various compounds or components may be anhydrides, hydrates, Lewis base complexes such as ether complexes, and the like.
It can be used as an aqueous solution, a non-aqueous solution, a slurry or a paste state. Further, these compounds or components may be used alone, or two or more kinds may be mixed, combined, or stepwise combined and used.

The carrier is not particularly limited and is usually used as a carrier for a supported catalyst, such as a metal oxide carrier, a composite metal oxide carrier, a carbon carrier or a carbonaceous carrier, a metal nitride carrier, and a metal boride carrier. Various carriers such as a carrier, a metal carbide carrier, a metal phosphate carrier, an organic polymer carrier, an ion exchange resin and the like can be used.

Among them, porous or high surface area oxide or complex oxide type carriers, and high surface area carbon or carbonaceous type carriers are preferably used.

As specific examples, for example, γ-alumina, alumina such as η-alumina, silica such as silica gel Vycor glass, magnesia, titania, zirconia, niobium oxide, thoria, boria, chromia, ceria, lanthanum oxide, yttria, zinc oxide, Oxides such as tin oxide, tungsten oxide and molybdenum oxide; non-crystalline composite oxides such as silica alumina, alumina boria, alumina garia, silica magnesia, chromia alumina, molybdena alumina, tungsten oxide-alumina, silica titania, silica zirconia, etc. Material: A type zeolite, X type zeolite, L type zeolite, Y type zeolite, Omega type zeolite, Ultrastable Y type zeolite, ZSM-5 type zeolite, ZSM-11 type zeolite and other ZSM type zeolite, various dealuminated zeolite Synthetic zeonite or synthetic crystalline aluminosilicates such as high-silica zeolite, mordenite, dealuminated mordenite, high-silica mordenite, silicalite; crystalline silicates such as gallosilicate, aluminogallosilicate, iron silicate, iron aluminosilicate, and crystalline metallo Silicates and metal-substituted aluminosilicates; natural zeolites or natural crystalline aluminosilicates such as clinobutilite, chabazite, erionite, faujasite; diatomaceous earth, activated clay, clay, mica, celite, pumice, asbestos Quasi-crystalline composite oxides such as; crystalline or non-crystalline acid phosphates such as crystalline aluminum phosphate (alpo), non-crystalline aluminum phosphate, crystalline zirconium phosphate, non-crystalline zirconium phosphate; Perovskite-type complex oxides such as rovskite, celite-type complex metal oxides such as celite; spinel-type complex oxides; cordierite; heteropolyacid or salts thereof; activated carbon, charcoal, etc. Carbonaceous carriers such as carbon cross carbon black; polymer carriers such as polystyrene, nylon and Nafion, ion exchange resins and the like. Among these, γ-alumina, η-alumina, silica alumina, silica bar, silicalite, X type zeolite, Y type zeolite, ultrastable Y type zeolite, L type zeolite, mordenite, ZSM-5 type zeolite, dealuminated zeolite, Carbon or carbonaceous carrier such as dealuminized mordenite, steam treated zeolite, high silica zeolite, aluminogallosilicate or other synthetic zeolite or synthetic crystalline metal silicate such as activated carbon can be preferably used, and ZSM-5 type zeolite or the like Synthetic zeolites such as silica gel and activated carbon are particularly preferably used.

Among these carriers, for example, zeolites,
Some silicates, crystalline aluminosilicates and the like have a cation exchange ability, and the cation component of such substances is hydrogen ion, ammonium ion, secondary to quaternary ammonium ion, etc. Non-metallic cations such as oxonium ions, sodium ions, potassium ions, lithium ions, cesium ions, beryllium ions, magnesium ions, calcium ions, strontium ions, alkali metal or alkaline earth metal ions such as barium ions, lanthanum Ion, rare earth element ion such as cerium ion, iron ion, cobalt ion, manganese ion, nickel ion, copper ion, silver ion, palladium ion, platinum ion, ruthenium ion, rhodium ion, tridium ion, osmium ion Emissions, ruthenium ion, various transition metal ions or their complex ions, such as chromium ions, zinc ions, cadmium ions, thallium ions,
It may be one or more cations selected from typical metal ions such as tin ions or various metal ions such as complex ions thereof.

Further, the carrier, if necessary, fluorine or fluoride treatment, chlorine or chlorine compound treatment, silylation treatment,
Silicon compound treatment such as tetraalkoxysilane treatment, acid treatment, alkali treatment, dehydration treatment, hydrothermal treatment, steam treatment, phosphine modification, X-ray treatment, ion beam treatment, γ
-Chemical or physical treatment such as linear treatment, partial reduction treatment, oxygen treatment, heat treatment, and grinding treatment may be performed to adjust the surface chemical properties, pore diameter, pore distribution, etc. .

These carriers may be used alone or in combination of two or more.

In the method of the present invention, specific examples of supported metal catalysts or mixed metal oxide catalysts that can be preferably used are shown for the purpose of illustration only, and, for example, ruthenium-supported activated carbon, palladium-supported activated carbon, platinum-supported activated carbon, Nickel-supported activated carbon, cobalt-supported activated carbon, ruthenium-supported silica gel, palladium-supported silica gel, platinum-supported silica gel, ruthenium-supported zeolite, palladium-supported zeolite, platinum-supported zeolite, zinc or zinc oxide-supported zeolite, copper or copper oxide-supported zeolite, zinc oxide / silica gel. And so on,
Particularly preferred examples include, for example, ruthenium-supported activated carbon, palladium-supported activated carbon, zinc or zinc-supported ZSM-5 zeolite, and the like. These catalysts may be used alone or in combination of two or more.

The catalyst or catalyst precursor used in the method of the present invention is
It can be prepared using the compound or component containing the metal element, or these and the carrier.

The preparation method is not particularly limited, and various methods that are used for the preparation of ordinary metal catalysts, oxide catalysts, supported catalysts, complex oxide catalysts, and the like can be used, for example, aqueous non-aqueous solution, slurry, Impregnation method using paste, ion exchange method, ligand substitution method, adsorption method, deposition method, precipitation method, coprecipitation method, dry solidification method, embedding method, injection method, coating method, kneading method, or mechanical method Examples thereof include a mixing method, a gas phase adsorption method using a gas phase component, a vapor deposition method, a CVD method or various methods similar thereto, a dry mixing method, an attrition method, or a combination thereof. Among these, the impregnation method, the adsorption method, the ion exchange method and the like are preferable from the viewpoint of easy preparation.

The catalyst or catalyst precursor thus obtained is
Although it can be used as it is, it is usually desirable to carry out an activation treatment such as a thermal decomposition treatment or a reduction treatment, particularly an activation treatment by a reduction treatment before use.

Examples of the reduction method include aldehydes such as sodium formate and formaldehyde, wet reduction method using an aqueous solution or alkali solution such as oxalic acid and hydrazine, and amines such as carbon monoxide, hydrogen, ethylene, ammonia, and reaction materials. An ordinary reduction method such as a dry reduction method using a reducing gas can be used.

The wet reduction treatment is 0 to 100 ° C., preferably room temperature to 9
It can be performed at 0 ° C. The wet reduction treatment may be performed at the same time as the preparation of the catalyst, or may be performed before drying the prepared solid. The solid obtained by performing this wet reduction treatment is usually separated by a separation method such as filtration, and then separated from the solution, and then dried by a normal drying method such as reduced pressure drying, heat drying, and gas flow drying to obtain a catalyst. Can also be used in the reaction.

On the other hand, in the dry reduction treatment or thermal decomposition treatment, the prepared solid is usually separated by separating the liquid such as a solution or a solvent by filtration or impregnation to dryness, and then dried by a usual drying method, if necessary. Then, the obtained solid can be heat treated, for example, at a temperature of 100 to 800 ° C., preferably 350 to 650 ° C. under the reducing gas or an inert gas such as nitrogen or helium, or under vacuum. However, a method using hydrogen as the reduction treatment is particularly preferable.

By such a treatment, a highly dispersed metal component is produced on the catalyst carrier, and a so-called supported metal catalyst or the like can be prepared. The supported metal catalyst thus prepared may be used as it is or as a catalyst after a pretreatment for reduction treatment or activation treatment with hydrogen gas or the like before the reaction. it can.

Then, by appropriately selecting and adjusting the preparation raw material, the type of carrier, the preparation method, the reduction treatment method and the conditions thereof, the dispersity and surface area state of the active component such as the metal component in the catalyst to be used are adjusted. By,
The activity, selectivity and life of the catalyst can be improved.

Suitable range of the content of the metal element contained in the catalyst used in the method of the present invention, the type of catalyst used, structure,
It cannot be regulated uniformly because it depends on the form, the surface concentration of metal element components, the degree of dispersion, etc., but it is usually 0.01% by weight or more (preferably 0.1% by weight or more). ~ 15% by weight (preferably
0.1 to 5% by weight), and in the case of a complex oxide catalyst,
For example, it is usually about 1 to 50% by weight (preferably 5 to 30% by weight).

If the content is less than the above range, the activity may not be sufficient, on the other hand, if the content exceeds the above range, catalytic activity commensurate with the content cannot be expected, or
Side reactions such as hydrogenolysis may occur.

The shape of the carrier, the catalyst precursor or the catalyst,
There is no particular limitation, for example, extruded products, press-formed products, beads, pellets, tablets, fruit granules, cylinders,
Columnar, granular, strip, plate, film, thin film, powder, fine powder, ultrafine particle, long fiber, short fiber, hollow fiber, hollow cylinder, hollow bead, hollow column , Cross,
Various shapes and particle sizes such as tubular, mesh, monolith, etc.
It can be used as various molded products and the like, and various binders may be used for adjusting the shape and particle size or for molding.

And, these carriers, catalyst precursors or catalysts,
Natural products, synthetic products, commercially available products or those conventionally used in other reactions such as dehydration reaction and hydrogenation reaction may be appropriately selected and used. It may be chemically treated before use,
Alternatively, it may be newly prepared and used.

In the method of the present invention, the ethylanilines are dehydrocyclized in the presence of the catalyst to produce indoles. The reaction formula of this dehydrocyclization reaction is, for example, formally the general formula of the formula [2]. (Here, R ^{1 to} R ⁷ in the formula [2] respectively represent R ^{1 to} R ⁷ in the formula [1], and R ^{8 to} R ¹⁴ are the cases where other side reactions do not occur. Respectively correspond to R ^{1 to} R ^7. However, when side reactions such as dealkylation reaction and alkyl transfer reaction occur, R ^{8 to} R ¹⁴ do not necessarily correspond to R ^{1 to} R ^7. Instead, it may be hydrogen or a lower alkyl group such as a methyl group or an ethyl group, or an alkenyl group.) Etc. However, when R ⁷ in the formula [2] is a hydrogen atom, indoles cyclized at two ortho positions with respect to the amino group of the benzene ring can be obtained. In general, in addition to the above, complicated side reactions such as polymerization reaction and decomposition reaction or sequential reaction may occur. For example, in addition to indoles, aniline and N-alkyl having a different structure from the starting material Anilines may be obtained.

These side reactions can be suppressed by adjusting various factors such as the type of catalyst used, structure, reaction conditions, reaction atmosphere, and selection of reaction raw materials.

That is, for example, it is preferable to add hydrogen to the reaction system separately from the produced hydrogen, usually about 1 to 20 mol per mol of the N-ethylanilines used. If the addition ratio of hydrogen is less than the above value, the by-product of the polymer becomes remarkable and the life of the catalyst may be shortened. On the other hand, if it exceeds the above value, by-products due to hydrocracking reaction and the like may occur. The number of organisms may increase and the selectivity for indoles may decrease.

In addition, this reaction system, if necessary, helium,
The reaction can be carried out by adding an inert gas such as nitrogen or a diluent gas such as steam. The addition ratio of this steam is usually 1 to 1 mol of N-ethylaniline used.
It is preferably about 20 mol. The addition of steam can suppress the production of anilines other than the raw materials.

The reaction temperature in carrying out the reaction cannot be uniformly specified because it varies depending on the type of catalyst used and various other conditions, but is usually 100 to 650 ° C, preferably 400 to 650 ° C,
Particularly preferably, the temperature is set to 450 to 600 ° C.

The reaction pressure is usually set to a reduced pressure to 50 kg / cm ² (gauge pressure), preferably a reduced pressure to 15 kg / cm ² (gauge pressure). Since this reaction is a dehydrogenation reaction, low pressure is preferable from this point of view, but it is preferable to carry out slightly pressurizing in consideration of the life of the catalyst and the like.

The reaction operation method and reaction method are not particularly limited, and the operation method and method used for ordinary gas phase catalytic reaction, in particular dehydrogenation reaction and the like can be used. That is, as the reaction operation method and the reaction method, for example, a fixed bed, a moving bed,
It can be carried out by any method such as a batch method using a fluidized bed, a semi-batch method, a continuous flow method, an intermittent flow method, etc. Usually, a continuous flow method using a fixed bed is preferably used.

When carrying out the reaction by the continuous flow method, the ratio of the catalyst using the feed rate of the raw material is set to the liquid hourly space velocity (LHSV, that is, the volume of the N-ethylaniline to be fed to the catalyst layer per unit time as a liquid is used. (Value divided by the apparent volume of the catalyst layer), which is usually set to 0.01 to 50 hr ^-1 , preferably 0.1 to 10 hr ^-1 .

The indole obtained by such a method, by-products such as by-product aniline, and unreacted N-ethylaniline are separated and purified from the reaction product by a usual separation and purification method such as distillation and extraction. And can be collected.

The hydrogen used, the hydrogen generated by the dehydrogenation reaction, or the unreacted N-ethylaniline can be purified to the required extent and recycled to the reaction system.

In addition, the catalyst whose activity has deteriorated can be used for repeated reactions by regenerating or activating it with a regenerating gas such as air, steam, hydrogen gas, or an inert gas, if necessary.

Further, anilines such as aniline produced as a by-product can be used for various purposes, and if necessary, they can be used again as N-ethylanilines by an alkylation reaction or the like as a reaction raw material.

By such a method, it became possible to catalytically and efficiently produce indoles such as indoles and substituted indoles from N-ethylanilines such as N-ethylaniline. The obtained indoles can be suitably used, for example, as raw materials for various compounds such as tryptophan for animal feed and various pigments, and as reagents.

EFFECTS OF THE INVENTION According to the present invention, novel indoles such as indole can be efficiently produced catalytically and efficiently from N-ethylanilines such as N-ethylaniline in a high yield. A method for producing indoles can be provided.

Further, by carrying out the reaction in the coexistence of hydrogen, excellent effects such as a marked increase in the life of the catalyst can be achieved.

[Example] (Catalyst preparation example 1; Preparation example of ruthenium / carbon catalyst) Coal-based granular activated carbon (DIAHOPE008: manufactured by Mitsubishi Kasei) 14.
Soak 7 g in 100 ml of water and add RuCl ₃ · nH ₂ O (Ru content 44 ~ 45
%) 1.0 g of an aqueous solution was added and the mixture was allowed to stand for 4 hours. This was stirred in a hot water bath to remove water, dried at 120 ° C. for a whole day and night, and further reduced in a hydrogen stream at 500 ° C. for 2 hours to obtain a 3% Ru-carbon catalyst. Prior to the reaction, reduction pretreatment was carried out in a hydrogen stream for 1 hour.

(Catalyst Preparation Example 2; Preparation Example of Palladium / Carbon Catalyst) The same operation was performed except that 12.0 g of activated carbon was used in Reference Example 1 and 1.0 g of PdCl ₂ was used instead of RuCl ₃ .nH ₂ O. A 5% Pd-carbon catalyst was obtained. Prior to the reaction, reduction pretreatment was carried out in a hydrogen stream for 1 hour.

The; (Catalyst Preparation Example 3 Preparation of zinc oxide ZSM-5 _{catalyst) Zn (NO 3) 2 ·} 6H 2 O7.3g was dissolved in water 150 ml, this ZS
Dip 20.0 g of M-5 and stir at 80 ° C. for 4 hours. After removing water while stirring in a hot water bath, it is dried at 1200 ° C for 24 hours and baked in air at 600 ° C for 6 hours to obtain 10% -ZnO-ZSM-
Got 5.

The; (Catalyst Preparation Example 4 Preparation of copper · ZSM-5 catalyst) of copper nitrate _{Cu (NO 3) 2 · 3H} 2 O2.3g was dissolved in water 150 ml, 60 hours at 80 ° C. To this was added ZSM-520 g , Heat and stir. After removing water, the product was dried at 120 ° C for a whole day and night, and further calcined in a hydrogen stream at 600 ° C for 6 hours to obtain a 3% Cu-ZSM-5 catalyst.

(Example 1) A fixed bed flow type reaction tube was filled with 2.0 g of the ruthenium-carbon catalyst obtained in Catalyst Preparation Example 1, and the reaction temperature was 550 ° C.
While maintaining the N-ethylaniline and hydrogen molar ratio
The reaction was carried out at LHSV = 0.1 hr ⁻¹ under normal pressure at 1/10. As a result, indole was obtained with a yield of 23.5% (reaction time value of 2 hours).

(Examples 2, 3 and 4) In Example 1, the reaction temperatures were 400 ° C, 500 ° C and 600 ° C.
The same operation as in Example 1 was carried out except that the temperature was changed to ° C.

 The results are shown in Table 1.

(Examples 5, 6, 7 and 8) When the ruthenium / carbon catalyst was used in Example 1, the palladium / carbon catalyst of Catalyst Preparation Example 2, the zinc oxide / ZSM-5 catalyst of Catalyst Preparation Example 3, and the platinum / alumina catalyst were used. (0.5% Pt, manufactured by Engelhardt) and the same operation as in Example 1 was carried out except that the copper / ZSM5 catalyst of Catalyst Preparation Example 4 was used. Table 2 shows the results.

(Example 9) The same operation as in Example 1 was performed except that the molar ratio of N-ethylaniline and nitrogen was changed to 1/10. As a result, indole was obtained with a yield of 15.2% (value after 2 hours of reaction).

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Claims (3)

[Claims] 1. N-ethylanilines are represented by the periodic table Ib, II.
A process for producing an indole, which comprises contacting with a catalyst containing at least one metal element selected from Group b and Group VIII metal elements for dehydrocyclization. 2. The method for producing an indole according to claim 1, wherein hydrogen is added to the reaction system. 3. The claim 1 or 2 wherein the metal element is at least one metal element selected from the group consisting of ruthenium, platinum, palladium, copper, zinc, cadmium, and silver. The method for producing indoles according to 1.