JPS63196562A - Production of indoles - Google Patents

Abstract

PURPOSE:To obtain indoles useful as raw material for tryptophan, etc., in high yield and efficiency, by the catalytic dehydrogenation cyclization reaction of N-ethylanilines using a catalyst containing groups Ib, IIb and/or VIII metal elements of the periodic table. CONSTITUTION:N-ethylanilines are subjected to dehydrogenative cyclization by contacting with a catalyst containing at least one kind of metal element selected from groups Ib, IIb and VIII metal elements of the periodic table, especially selected from Ru, Pt, Pd, Cu, Zn, Cd and Ag, especially ruthenium supported on activated carbon, palladium supported on activated carbon, zinc, zinc supported on ZSM-5 zeolite, etc., preferably in the presence of hydrogen. Various kinds of indoles can be produced from not only N-ethylaniline but also N-ethylanilines having various substituent groups at a low temperature in high yield compared with conventional thermal decomposition process. The addition of hydrogen suppresses the formation of polymer and remarkably improves the catalytic life.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing indoles, and more specifically, for example, as raw materials for various chemical products such as tryptophan for animal feed and pigments. This invention relates to a method for producing indoles that can be widely used in various fields such as the biochemical industry.

[Prior art and its problems 1 There have been no reports of patents for producing indoles by the dehydrocyclization reaction of N-ethylanilines, but there is no report on patents for producing indoles by dehydrocyclization reaction of N-ethylanilines. (page 87) reports that indole is obtained by passing N-ethylaniline through a red-hot tube. However, this pyrolysis method requires extremely high temperatures;
In addition, the yield of indole is low and cannot be put to practical use. Therefore, if we can find a suitable catalyst and find a way to obtain indole in a high yield at a lower temperature by catalytic dehydrocyclization. If so, it would be possible to provide a new and practically excellent method for producing indole. Furthermore, this method can be expected to be developed into a new method for efficiently obtaining various corresponding indoles not only from N-ethylaniline but also from N-ethylaniline having various substituents.

[Object of the Invention] The present invention was made in view of the above-mentioned circumstances, and its purpose is to solve the above-mentioned problems and to provide high yields from ethylanilines such as N-ethylaniline by catalytic dehydrocyclization reaction. An object of the present invention is to provide a novel method for producing indoles, which can obtain indoles such as indole.

[Means for solving problems] The inventors aimed to solve the above problem.

Instead of the traditional method of thermally decomposing N-ethylaniline,
As a result of extensive research on methods for catalytic dehydrocyclization, we found that by using a catalyst containing a specific metal element, we were able to dramatically increase the yield of indole at a lower temperature than with conventional thermal decomposition methods. Furthermore, we found that it is possible to increase the

According to this knowledge, we discovered that not only N-ethylaniline but also various indoles can be produced in high yields from N-ethylanilines with specific structures, and based on these findings, we completed this invention. I ended up doing it.

That is, the present invention is characterized in that N-ethylanilines are brought into contact with a catalyst containing at least one metal element selected from group Ib, IIb, and VIII metal elements of the periodic table to undergo dehydrocyclization. The present invention provides a method for producing indoles.

The present invention will be explained in detail below.

The N-ethylanilines used as reaction raw materials in the method of the present invention have the following general formula (Formula [11)] (wherein R1, R2 and R3 are hydrogen atoms or alkyl groups, preferably represents a hydrogen atom or a methyl group, particularly preferably a hydrogen atom, and R4, R5 and R6 are
A hydrogen atom or an alkyl group, preferably a hydrogen atom, a methyl group or an ethyl group, is shown in blue, and R7 represents 1, a hydrogen atom, a methyl group or an ethyl group, preferably a hydrogen atom.

In addition, each group of said R1-R1 may be the same type of group, or may be a different type of group.) It is a compound represented by these.

Note that some of the compounds represented by Formula 11 above should be classified as general N-furkyanilines other than N-ethylanilines if the nomenclature of organic compounds is strictly applied. Kimono is also included, but here, for convenience, they are regarded as alkyl substituted products of N-ethylaniline, and N-ethylaniline is
- Shown as ethylanilines.

Specific examples of the N-ethylanilines are shown merely for purposes of illustration and not limitation, such as 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-)limethylphenylamine, N-
Ethyl-2,3,4-)diethylphenylamine, 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-methylphenyl, amine, 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-)diethylphenylamine, 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 -) luidine, N-ethyl-N-methyl-m-
) luidine, 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-methylethylmethylethyl)-m-)luidine, N-(1-methylethyl)-0-)luidine, 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)-
〇-Ethylaniline, N-(1-methylethyl)-N-
Methylaniline, N-(1-methylethyl)-N-methyl-p-toluidine, N-(l-methylethyl)-N
-Methyl-m-)luidine, N-(1-methylethyl)
-N-Methyl-〇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 the 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 (however, 2
, 6-excluding isomers. ), etc.

Among these, N-ethylaniline, N-ethyl-m-
) luidine, 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-) luidine, 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-)luidine, etc. are preferred, and N-ethylaniline is particularly preferred.

Incidentally, these compounds may be used alone or in combination of 28 or more.

In the method of this invention, a solid substance containing at least one metal element selected from metals of Group Ib, Group Nb, and Group II of the Periodic Table is used as a catalyst. Specific examples of these metal elements include copper, silver, zinc, cadmium, iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, and platinum. Among them, ruthenium, palladium, and platinum , copper, silver, zinc, cadmium, etc. are preferable, and ruthenium, platinum, palladium, zinc, etc. are particularly preferable.

These metal elements can be used as components in various types and states in the catalyst to be used or the catalyst precursor that can be used as its precursor, and further in the stage of raw materials for their preparation.

Note that the catalyst precursor is one that can exhibit catalytic activity through physical or chemical activation treatment such as heat treatment, reduction treatment, treatment with a reactant, or the like.

The type and state of the component containing the metal element that can be used in the above sense is not particularly limited as long as it contains at least one metal element,
For example, elemental metals, atomic metals, clustered metal alloys, composite metal clusters or intermetallic compounds, amorphous metal ruthenic acids, metal blacks such as platinum black, palladium black, or other partially oxidized metal-like substances; oxides, aluminates, silicates, metallosilicates, chromates, nitrates, phosphates, carbonates, sulfates,
Complex oxides or oxyacids such as carboxylates such as borates and acetates, carbides or acetylides, nitrides,
Various inorganic or organometallic compounds such as borides, sulfides, alkyl compounds, alkoxides, aryl oxides, halides; halogen complexes such as aqua complexes, ammine complexes, halogenated metal acids or their salts, cyano complexes, acetylacetate complexes , amine complexes, nitro complexes, nitride complexes, nitrosyl complexes, nitrile complexes, isonitrile complexes, incyanato complexes, carbonyl complexes,
Halogenated carbonyl complexes, carbide complexes, carbonylphosphine complexes, other l-substituted carbonyl complexes, phosphine complexes, hydride complexes, olefin complexes, polyene complexes such as diene complexes, acetylene complexes, allyl complexes, aryl complexes, cyclopentadienyl complexes, etc. Various complexes or complex salts can be mentioned, and these can be used as compounds or components in various complex states such as cluster compounds such as dinuclear complexes, double salts, and composite complexes, or as various mixtures or components. They can be used in combination, and furthermore, they can be used partially or entirely supported on various carriers.

However, in the method of the present invention, examples of catalysts that can be suitably used include those in which the metal element is
So-called compatible metals that are in a high surface area metal state such as metal colloid, metal ultrafine particles, highly dispersed metal, ultrahighly dispersed metal, or in a high surface area metal-like state that is partially oxidized. Catalysts, complex oxide catalysts containing the above-mentioned metal elements in a partially reduced state, or mixtures thereof can be mentioned, and in particular, when group (I) elements such as ruthenium, platinum, and palladium are used. It is usually preferable to use it as the above-mentioned supporting metal catalyst.

On the other hand, in the case of using metal elements of group Ib or group IIb such as copper or zinc, it is usually preferable to use them as the above-mentioned composite oxide.

The catalyst precursor that can be suitably used in the method of the present invention can be led to the above-mentioned supported metal catalyst or composite metal oxide catalyst by an activation treatment such as heat treatment or treatment with a reduction treatment 1 reactant. I can list things that can be done.

Specific examples of compounds or components containing the metal elements that can be suitably used as raw materials for the preparation of catalysts or catalyst precursors such as these supported metal catalysts or composite oxide catalysts are given for the purpose of illustration only and not for limitation. and halogenated rutheniums, such as ruthenium trichloride, ruthenium tribromide, ruthenium triiodide, and ruthenium trifluoride; Its salts: Ruthenium red, ruthenium hydroxide, diruthenium trioxide, ruthenium dioxide, ruthenium tetroxide, ruthenates such as potassium ruthenate, ruthenium dicarbonyl iodide, decarbonyl triruthenium, dodecacarbonyl tetrahydride tetraruthenium chloride Ruthenium carbonyl complexes such as carbonylruthenium, ruthenium complexes such as ruthenocene, dicyclooctadicilthenium, or ruthenium cluster compounds, ruthenium complex salts such as hexaammineruthenium (■) trichloride, ruthenium black, laney ruthenium, ruthenium colloid, ruthenium ultrafine particles, Ruthenium metal, rhodium halides such as rhodium trichloride, hexachlororhodic acid or its ammonium salt or alkali metal salt, rhodium hydroxide, dirhodium trioxide: hexaammine, rhodium complex salts such as rhodium (■) trichloride, tris(trichloride), Rhodium complexes or rhodium cluster compounds such as phenylphosphine)hydridocarbonium rhodium and dodecacarbonyltetrarhodium, rhodium black, Raney palladium, rhodium colloid, rhodium metal: palladium fluoride, palladium chloride, palladium bromide, palladium iodide, etc. Inorganic and organic acid salts of palladium such as palladium halides, palladium nitrate, palladium sulfate, palladium acetate, palladium acetylacetonate, palladium sulfide; tetraamine palladium dichloride, hexachloropalladate, hexachloropalladate sodium salt, Palladium inorganic complex compounds such as tetrachloropalladate and dinitrodiammine palladium dichloride; palladium oxide, palladium hydroxide [Pd(GO)Cu2] 2, [Pd(GO)z (
Palladium carbonyl complexes such as 4112, palladium diisonitrile complexes, [PdCjLz (olefin) 12
, [Pd(PPh3) 2 (olefin)], [
PdCR(ηs −Cs Hs )12[Pd(η
Palladium olefin or allyl complexes such as [η3-CsHsPdC]2, palladium phosphine complexes such as [Pd(PPh3)41, [(CH3)2Pd PP]
h3] [CH3Pd 0 Palladium compounds such as various organic palladium compounds such as palladium alkyl complexes, palladium aryl complexes, palladium acyl complexes, palladium hydride complexes such as COCI31; Highly dispersed palladium such as palladium black, palladium colloid, palladium ultrafine particles: dioxide Osmium oxides such as osmium and osmium tetroxide; osmium halides such as osmium trichloride; osmic acids or salts thereof such as hexachloroosmium (IV) acid or its ammonium salts or alkali metal salts; decacarbonyltriosmium;
Various osmium complexes such as carbonyl osmium chloride or osmium cutister compounds: osmium black,
Osmium colloid, osmium metal, iridium halides such as iridium oxide, iridium hydroxide, iridium trichloride, iridium salts such as hexachloroiridate (ff) acid or its ammonium salt or alkali metal salt: hexaammineiridium (m) trichloride Organic iridium compounds or iridium cluster compounds such as iridium complex salts nidodecacarbonyl iridium; iridium rings, iridium colloids, iridium metal; platinum halides such as platinum dichloride, platinum tetrachloride, platinum dibromide, platinum diodide; Chloroplatinum (n)
Acids, platinic acids or platinates such as hexachloroplatinic (N) acid or their ammonium salts or alkali metal salts: platinum oxides such as platinum oxide (■), platinum oxide (ff), platinum hydroxide, platinum disulfide, Platinum complex compounds such as platinum (n) ammine complex, platinum 7-cetylacetonate complex,
Various organic platinum compounds or platinum cluster compounds such as bis(triphenylphosphine)platinum dichloride, dinitrodiaminoplatinum, platinum nitrile complexes, platinum nitrosyl complexes, platinum carbonyl clusters, zinc hydroxide, zinc oxide: zinc nitrate, sulfuric acid 1 Zinc salts or zinc complex oxides such as lead, zinc phosphate, zinc acetate, zinc carbonate, zinc chloride, zinc bromide, zinc iodide, zinc fluoride, zinc cyanide, zinc chromate, jetoxyzinc, tetraaqua Zinc complex compounds such as zinc hydroxide, tetraammine zinc, hydroxide, sodium tralacyanozincate, sodium zincate; organic zinc compounds such as diethylzinc and diallylzinc; zinc metals such as electrolytic zinc; cadmium nitrate, cadmium sulfate, carbonate Cadmium, cadmium acetate, cadmium hydroxide, cadmium oxide, cadmium chloride, and other cadmium halides and cadmium metals; copper nitrate, copper sulfate, copper acetate, copper chloride, copper bromide, copper iodide, copper carbonate, basic copper carbonate ,
Copper salts such as copper chromate, or copper complexes such as copper complex oxides, tetraammine copper (■) chloride, tetraammine copper (n) sulfate, tetraammine copper (■) nitrate, and tetraammine copper (n) hydroxide. Compounds, copper oxide (■), copper (I) oxide, copper hydroxide: organic copper compounds such as copper atylide, copper acetylacetonate, Raney copper, copper colloid, ultrafine copper particles, copper metal: nickel nitrate, Nickel salts such as nickel sulfate, nickel phosphate, nickel chloride, nickel bromide, nickel acetate, nickel formate, nickel oxalate, nickel carbonate: nickelcene, nickel diacetylacetonate, dicyclooctadiene copper, diallyl nickel,
Organic nickel compounds such as nickel carbonyl; nickel oxide, nickel hydroxide: Raney nickel, urushihara nickel, nickel colloid, nickel ultrafine particles, metallic nickel; silver salts such as silver nitrate, silver fluoride, silver carbonate, silver sulfate, diamine silver (I ) Silver complex compounds such as chloride, diamine silver CI) hydroxide: Cobalt salts such as cobalt chloride, cobalt bromide, cobalt nitrate, cobalt sulfate, cobalt acetate, cobalt formate, and cobalt carbonate: cobalt hydroxide, cobalt oxide) (n), cobalt oxide (■, ■), cobalt oxide (■), organic cobalt compounds such as cobalt niacetylacetonate, cobalt carbonyl; Raney cobalt, cobalt colloid, ultrafine cobalt particles, metallic cobalt: iron nitrate (■), Iron salts such as iron nitrate (m), iron chloride (■), iron chloride (■), iron sulfate (■), iron sulfate (■), iron acetate: iron hydroxide (■), iron hydroxide (■) , iron oxide (■),
Iron oxide (■, ■), iron oxide (■), hexadi-7 iron (■
Examples include various iron complex compounds such as potassium hexadi-7ferrate (■), and organic iron compounds such as iron acetylacetonate, iron carbonyl, and ferrocene.

Among these, from the viewpoint of ease of preparation, ruthenium halides such as ruthenium trichloride permanent hydrate or its hydrochloric acid solution, rhodium halides such as rhodium trichloride hydrate, palladium halides such as palladium dichloride, etc. or its hydrochloric acid solution, tetrachloropalladate or its ammonium salt or sodium salt, palladium nitrate, palladium sulfate, palladium acetate, osmium halide or its hydrochloric acid solution such as osmium trichloride hydrate, osmium tetroxide, iridium trichloride, or Its hydrochloric acid solution, platinum chloride or its hydrochloric acid solution, tetrachloroplatinic acid, hexachloroplatinic acid or its alkali metal salts such as ammonium salt or sodium salt, water-soluble lead salts such as zinc nitrate and zinc chloride, cadmium nitrate, cadmium chloride water-soluble cadmium salts such as copper nitrate, copper sulfate, copper chloride, water-soluble nickel salts such as nickel nitrate, nickel sulfate, nickel chloride, cobalt nitrate, cobalt sulfate, cobalt chloride,
Examples include water-soluble cobalt salts such as cobalt acetate, water-soluble iron salts such as iron nitrate, iron sulfate, iron chloride, and potassium hexadipenferrate, and are particularly preferred from the viewpoint of catalytic activity of the metal component. Examples include ruthenium trichloride hydrate or its hydrochloride, palladium chloride or its hydrochloric acid solution, tetrachloropalladate or its ammonium salt, palladium nitrate, platinum chloride or its hydrochloric acid solution, hexachloroplatinic acid, tetrachloroplatinic acid, or Examples include its ammonium salt.

The various compounds or components described above can be used as anhydrides, hydrates, Lewis base complexes such as ether complexes, and in the form of aqueous solutions, non-aqueous solutions, slurries, or pastes.

Furthermore, these compounds or components may be used alone, or in combination of two or more, in combination, or in a stepwise combination.

The carrier is not particularly limited, and metal oxide carriers, composite metal oxide carriers, carbon carriers or carbonaceous carriers, metal nitride carriers, and metal boride carriers are commonly used as carriers for supported catalysts. Various carriers can be used, such as carriers, metal carbide carriers, metal phosphate carriers, organic polymer carriers, ion exchange resins, and the like.

Among these, porous or high surface area oxide or composite oxide carriers, and high surface area carbon or carbonaceous carriers are preferably used.

Specific examples include alumina such as γ-alumina and η-alumina, silica such as silica gel Vycol glass, magnesia, titania, zirconia, niobium oxide, thoria, boria, chromia, ceria, lanthanum oxide,
Ittria, zinc oxide, tin oxide, tungsten oxide,
Oxides such as molybdenum oxide; silica alumina, alumina boria, alumina galia, silica magnesia, chromia alumina, molybdena alumina, tungsten oxide
Amorphous composite oxides such as alumina, silica titania, silica zirconia, etc.: A-type zeolite, X-type zeolite,
ZSM type zeolites such as L type zeolite, Y type zeolite, omega type zeolite, ultra stable Y type zeolite, ZSM-5 type zeolite, ZSM-11 type zeolite, various dealuminated zeolites, high silica zeolite, mordenite, dealuminated mordenite , high-silica mordenite, silicalite, and other synthetic zeonites or synthetic crystalline aluminosilicates; gallosilicate, aluminogallosilicate, iron silicate, iron aluminosilicate, and other crystalline silicates, crystalline metallosilicates, and metal-replaced aluminosilicates. ; Natural zeolite or natural crystalline aluminosilicate such as clinoptilolite, chabasite, erionite, faujasite; ; Quasi-crystalline composite oxides such as cane earth, activated clay, clay, micas, celite, pumice, asbestos, etc. :
Crystalline or non-crystalline acid phosphates such as crystalline aluminum phosphate (albo), amorphous aluminum phosphate, crystalline zirconium phosphate, amorphous zirconium phosphate:
Perovskite-type composite oxides such as perovskite, sealite-type composite metal oxides such as sealite: spinel-type composite oxides; cordierite: heteropolyacids or their salts, etc.: amorphous carbon carriers such as activated carbon and charcoal, carbon fibers, Examples include carbonaceous carriers such as carbon cross carbon black; polymer carriers such as polystyrene, nylon, and Nafion, and ion exchange resins.

Among these, γ-alumina, η-alumina, silica alumina, silica pal, silicalite, Synthetic zeolites such as aluminum mordenite, steam-treated zeolite, high-silica zeolite, aluminogallosilicate, etc. or synthetic crystalline metal silicates, etc. Carbon or carbonaceous supports such as activated carbon can be suitably used for the synthesis of ZSN-5 type zeolite, etc. Zeolites such as silica gel and activated carbon are particularly preferably used.

Some of these carriers include, for example, zeolites, silicates, crystalline aluminosilicates, etc.
Some products have cation exchange ability, and the cation components of such products include nonmetallic cations such as hydrogen ions, ammonium ions, secondary to quaternary ammonium ions, and other oxonium ions. Alkali metal and alkaline earth metal ions such as sodium ion, potassium ion, lithium ion, cesium ion, beryllium ion, magnesium ion, calcium ion, strontium ion, barium ion, rare earth element ion such as lanthanum ion, cerium ion, iron ion , cobalt ions, manganese ions, nickel ions, copper ions, plate ions, palladium ions, platinum ions, ruthenium ions, rhodium ions, tridylam ions, osmium ions, ruthenium ions, chromium ions, etc., or their various transition metal ions. complex ions, zinc ions, cadmium ions, thallium ions,
It may be one type or 214 or more cations selected from various metal ions such as typical metal ions such as tin ions or complex ions thereof.

Furthermore, the carrier may be subjected to two/element 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
- Wire treatment 1 It may be used by subjecting it to chemical or physical treatment to adjust its surface chemical properties, pore diameter, pore distribution, etc.

In addition, these carriers may be used alone.

Two or more types may be used in combination.

Specific examples of compatible metal catalysts or composite metal oxide catalysts that can be suitably used in the method of the present invention are shown merely for the purpose of illustration and not limitation, such as 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 Particularly preferred examples include ruthenium-supported activated carbon, palladium-supported activated carbon, zinc or zinc-supported ZSN-5 zeolite, and the like. Note that these catalysts may be used alone or in combination of two or more.

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

The preparation method is not particularly limited, and various methods used for the preparation of ordinary metal catalysts, oxide catalysts, supported catalysts, composite oxide catalysts, etc. can be used, such as aqueous solutions, slurries, etc. Impregnation method using paste etc., ion exchange method, ligand substitution method, adsorption method, deposition method, precipitation method, coprecipitation method, drying method, encapsulation method, injection method, coating method,
Mixing method, mechanical mixing method, gas phase adsorption method using gas phase components, vapor deposition method, CVD method, various methods similar to these methods, dry mixing method, attrition method, etc., or a combination of these methods. I can list the following. Among these, impregnation methods, adsorption methods, ion exchange methods, etc. are preferred from the viewpoint of ease of preparation.

The catalyst or catalyst precursor thus obtained can be used as is; however, it is usually preferable to perform an activation treatment such as a thermal decomposition treatment or a reduction treatment, especially an activation treatment by a reduction treatment. .

This reducing gas may be a wet reduction method using aldehydes such as sodium formate or formaldehyde, an aqueous or alkaline solution such as oxalic acid or hydrazine, or an amine such as carbon oxide, hydrogen, ethylene, ammonia, or a reaction material. Conventional reduction methods can be used, such as dry reduction with reducing gases such as .

The wet reduction treatment is performed at a temperature of 0 to 100°C, preferably room temperature to
It can be carried out at 90°C. Note that this wet reduction treatment may be carried out simultaneously with the preparation of the catalyst, or may be carried out before drying the prepared solid. The solid obtained by this wet reduction treatment is usually separated from the solution by a separation method such as filtration, and then dried by a normal drying method such as vacuum drying, heat drying, gas flow drying, etc. It can also be used in reactions as

On the other hand, in the dry reduction treatment or thermal decomposition treatment, 3! l!
1. Usually after separating the liquid such as a solution or solvent by filtration or impregnation to dryness.

If necessary, the obtained solid is further dried by a conventional drying method, for example, at 100 to 800°C, preferably at 300°C.
This can be carried out by heat treatment at a temperature of 50 to 650° C. in the aforementioned reducing gas or an inert gas such as nitrogen or helium, or under vacuum. However, a method using hydrogen is particularly suitable for the reduction treatment.

Through such treatment, highly dispersed metal components are generated on the catalyst carrier, and so-called compatible metal catalysts can be prepared. The supported metal catalyst prepared in this way can be used as a catalyst in the reaction as it is, or after being subjected to pretreatment such as reduction treatment or activation treatment with hydrogen gas or the like, if necessary, before the reaction. can.

By appropriately selecting and adjusting the preparation raw materials, type of carrier, TI4 production method, reduction treatment method, and their conditions, the degree of dispersion, surface area, etc. of active components such as metal components in the catalyst to be used are adjusted. By,
The activity, selectivity, lifespan, etc. of the catalyst can be improved.

The appropriate range of the content of the metal element contained in the catalyst used in the method of this invention cannot be uniformly defined because it varies depending on the type, structure, form, surface concentration of the metal element component, degree of dispersion, etc. of the catalyst used. is usually 0.01% by weight or more (preferably 0.1% by weight or more), and in the case of a compatible metal catalyst, it is usually 0.01-15% by weight (preferably 0.1-5% by weight). ), and in the case of a composite oxide catalyst, it is usually about 1 to 50% by weight (preferably 5 to 30% by weight).

If this content is less than the above range, the activity may not be sufficient. On the other hand, if it exceeds the above range, catalytic activity commensurate with the content may not be expected, or hydrogenolysis reactions etc. Side reactions may occur.

The shape of the carrier, catalyst precursor, or catalyst is not particularly limited, and examples include extrusion molded products, press molded products, beads, pellets, tablets, granules, cylinders, columns, granules, and strips. , plate-like, film-like, thin-film-like, powder-like, fine-powder-like, ultrafine-particle-like, long-fiber-like, short-fiber-like, hollow-fiber-like,
It can be used in various shapes and particle sizes such as hollow cylinders, hollow beads, hollow columns, crosses, tubes, nets, and monoliths, and in various molded products. a
Various binders may be used for different purposes or for molding purposes.

These carriers, catalyst precursors, or catalysts are appropriately selected from natural products, synthetic products, commercial products, or those used in conventional reactions, such as dehydration reactions and hydrogenation reactions. They may be used, or they may be used after being subjected to appropriate physical or chemical treatment, or they may be freshly prepared and used.

In the method of the present invention, indoles are produced by dehydrocyclizing the ethylanilines in the presence of the catalyst. The reaction of this dehydrocyclization reaction (here, R1-R1 in formula 21 is the R1-R1 in formula 11)
represents R7, and R8-R14 correspond to R1-17, respectively, if no other side reactions occur. however,
When a side reaction such as a dealkylation reaction or an alkyl transfer reaction occurs, R8-R14 does not necessarily correspond to R1-R7, but may correspond to hydrogen or a lower alkyl group such as a methyl group or an ethyl group, or an alkenyl group. It may happen. ) etc. However, No.
When R7 in formula 21 is a hydrogen atom, 7 of the benzene ring
Indoles cyclized at the two ortho positions to the mino group are obtained. In general, in addition to the above, complex side reactions and sequential reactions such as polymerization reactions and decomposition reactions may occur. Anilines etc. may be obtained.

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

That is, for example, it is preferable to carry out the reaction by adding hydrogen to this reaction system, separately from the hydrogen produced, usually about 1 to 20 moles per mole of N-ethylaniline used. If the ratio is less than the above value, polymer by-products will be noticeable and the life of the catalyst may be shortened, while if it exceeds the above value, by-products from hydrogenolysis reactions will increase. , the selectivity to indoles may decrease.

Furthermore, if necessary, an inert gas such as helium or nitrogen or a diluent gas such as steam can be added to this reaction system to carry out the reaction. The rate of addition of this steam is usually 1 to 2 per mole of N-ethylaniline used.
It is preferable to set it to about 0 mol, and by adding steam! ! It is possible to suppress the production of anilines other than the X material.

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

The reaction pressure is usually 1, reduced pressure to 50 Kg/am? (
gauge pressure), preferably normal pressure to 15 Kg/c 2 (
Since the unreacted reaction is a dehydrogenation reaction, low pressure is preferable from this point of view, but in consideration of catalyst life, etc., it is preferable to carry out the reaction under slightly increased pressure.

There are no particular restrictions on the reaction operation method, reaction system, etc., and any operation method or system used for ordinary gas phase catalytic reactions, especially dehydrogenation reactions, etc. can be used. In other words, reaction operation method 1 can be carried out using any method such as batch method, semi-batch method, continuous flow method, intermittent flow method, etc. using fixed bed, moving bed, fluidized bed, etc., but usually A continuous flow method using a fixed bed or the like is preferably used.

When carrying out the reaction using this continuous flow method.

The proportion of catalyst using feed rate of feedstock is determined by liquid hourly space velocity (L
H5V, that is, N- supplied to the catalyst layer per unit time.
Usually, the LOI is calculated by dividing the volume of ethylaniline as a liquid by the apparent volume of the catalyst layer used.
50 hr-1, preferably 0.1-10 brl.

By-products such as indoles, by-product anilines, and unreacted N-ethyl-7-nilines obtained by such methods are separated from the reaction products by conventional separation and purification methods such as distillation and extraction. It can be purified and recovered. .

Note that the hydrogen used, the hydrogen generated by the dehydrogenation reaction, and the unreacted N-ethylanilines can be purified to a necessary degree and recycled to the reaction system for use.

Further, the catalyst whose activity has deteriorated can be regenerated or activated using a regeneration gas such as air, steam, hydrogen gas, or inert gas, as necessary, and used for repeated reactions.

9. Anilines such as by-produced aniline.

It can be used for various purposes, and if necessary, it can be converted into N-ethylanilines by alkylation reaction, etc.
It can also be used as 9 again as a reaction raw material.

By such a method, N such as N-ethylaniline can be
-Ethylaniline! It has now become possible to efficiently produce indoles such as indole and substituted indoles catalytically. The obtained indoles are, for example,
It can be suitably used as a raw material for various compounds such as tryptophan for animal feed, various pigments, etc., and as a reagent.

[Effect of the invention] According to the present invention, indoles such as indole can be produced in high yield and catalytically efficiently from N-ethylanilines such as %N-ethylaniline. A method for producing indoles can be provided.

Moreover, by carrying out the reaction in the presence of hydrogen, excellent effects such as significantly increasing the life of the catalyst can be achieved.

[Example] (Catalyst temperature 4 Example 1/Preparation of ruthenium carbon catalyst ■) Coal-based granular activated carbon (1) IAHOPEOO8: manufactured by Mitsubishi Chemical Industries, Ltd. Soak 14.7 g in a 10 G water bath, and add RuC Ko 3 11! lH2O (Ru containing i44-45
%) was added and left to stand for 4 hours. I took this while taking a hot bath! After removing water while stirring, 1
Dry at 20°C day and night, and then dry at 500°C in a hydrogen stream for 2 hours.
A 3% Ru-carbon catalyst was obtained by time-based processing.
When subjected to the reaction, pretreatment was carried out for 1 hour in a hydrogen stream.

(Catalyst temperature Example 2; Palladium/carbon catalyst temperature S!j
! In Reference Example 1, 12.0 g of activated carbon, Ru C; 1
3. A 5% Pd-carbon catalyst was obtained by performing the same operation except that Pd Cu21-Og was used instead of nH20. When subjected to the zero reaction, pretreatment was performed for 1 hour in a hydrogen stream. .

(Touch-Example 3: Oxidation-Example of Preparation of ZSM-5 Catalyst) Zn
(103) 2 @8H207-3g water 150s + J
Dissolve in L and soak ZSM-520.0g in it for 80 minutes.
Stir at ℃ for 4 hours. Furthermore, after removing moisture while stirring in a warm bath, it was dried at 120°C overnight and heated to 600°C in the air.
C. for 6 hours to obtain 10%-ZnO-ZSM-5.

(Catalyst Preparation Example 4; Copper/ZS) l-5 Catalyst Preparation) Copper nitrate Cu (NOx) 2.3H202-3g was mixed with water 15
After removing the moisture, add 520 g of ZS) and heat and stir at 80°C for 6 hours.
Dry at 120℃ for one day and then dry at 600℃ in a hydrogen stream.
, and calcined for 6 hours to obtain a 3% Cu-ZSM-5 catalyst.

(Example 1) A fixed bed flow reaction tube was filled with 2.0 g of the ruthenium carbon catalyst obtained in Catalyst Preparation Example 1, and the reaction temperature was set to 55.
While maintaining the temperature at 0° C., the reaction was carried out with N-ethylaniline and hydrogen at a molar ratio of 1/1 G under normal pressure at L)ISV-0.1 hrl. As a result, the yield of indole was 23.5%.
(value after 2 hours of reaction) was obtained.

(Examples 2.3 and 4) The same operation as in Example 1 was performed except that the reaction temperature in Example 1 was changed to 400°C, 500°C, and 600°C.

The results are shown in Table 1.

(Examples 5, 6.7 and 8) Where a ruthenium/carbon catalyst was used in Example 1, a palladium/carbon catalyst in Catalyst Preparation Example 2, a zinc oxide/ZSN-5 catalyst in Catalyst Preparation Example 3, and a platinum/alumina catalyst The same operation as in Example 1 was performed except that the catalyst was changed to (0.5% pt, manufactured by Engelhard) and the copper/ZS)15 catalyst of Catalyst Preparation Example 4. The results are shown in Table 2.

1st Table 1 550°C 23.5 2 400 10.9 4 800 18.3 2nd Table 1 Ruthenium/carbon 23.55 Palladium/carbon 16.7B Zinc oxide-Z
SM-58,0 7 Platinum/Alumina 12.38 Copper-Z
SN-59,2 (Example 9) The same operation as in Example 1 was performed except that the molar ratio of N-ethylaniline and nitrogen was set to 1/10. As a result, indole was obtained in a yield of 15.2% (value after 2 hours of reaction).

Claims (3)

[Claims] (1) N-ethylanilines are listed in periodic table Ib, IIb,
A method for producing indoles, which comprises bringing them into contact with a catalyst containing at least one metal element selected from Group VIII metal elements, and dehydrocyclizing them. (2) Claim 1, which adds hydrogen to the reaction system
Method for producing indoles as described in Section. (3) 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. A method for producing indoles.