JPH0347264B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing indoles from anilines and ethylene glycols. (Prior art and their problems) Indoles are known as raw materials for the chemical industry, and indoles in particular have recently become important substances as raw materials for perfumes and amino acid synthesis. There have been many attempts to synthesize indoles in the past, but all of them had problems such as a large number of by-products, expensive raw materials, and complicated manufacturing processes. Recently, a catalyst system has been discovered that is effective in the reaction of synthesizing indoles using inexpensive raw materials anilines and ethylene glycols and in a short process. For example, Cu-Cr, Cu-Co, Pd/
Examples include SiO ₂ , Pt/SiO ₂ , CdS, etc., but all catalyst systems have drawbacks such as severe reduction in reaction activity and low reaction activity, and cannot be used as practical catalysts. The present inventors have conducted various studies on this reaction and have already clarified that the performance of the reaction can be improved by adding water to the reaction system, carrying out the reaction under pressure, etc. Furthermore, the present inventors have found that a catalyst system containing any one of Cu, Ag, and Au, which are elements of group b of the periodic table, is effective for the production of indoles and lasts for a long time. It has been found that the reaction can be carried out. An object of the present invention is to provide an industrial method for producing indoles that can be used repeatedly by regenerating and activating the degraded catalyst used in the reaction in such a method for producing indoles. (Means for Solving the Problems) The present inventors have diligently studied methods for solving the above problems, and have regenerated the catalyst by bringing the deteriorated catalyst into contact with a gas containing oxygen at a temperature of 200 to 450°C. Furthermore, they discovered a method of reductively activating the regenerated catalyst and completed the present invention. That is, in the method of the present invention, anilines and ethylene glycols are used as raw materials, and in the presence of a catalyst containing a Group B metal of the Periodic Table of Elements to produce indoles, the method uses anilines and ethylene glycols as raw materials more than once in the reaction. This method for producing indoles is characterized in that the catalyst is regenerated and subjected to reduction activation treatment when used repeatedly in reactions. The anilines used in the method of the present invention have the general formula () (wherein R represents a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group, or an alkoxy group). For example, aniline, o
-・m-・or p-toluidine, o-・m・
Alternatively, examples thereof include p-haloaniline, o-, m-, or p-hydroxyaniline, o-, m-, or p-anisidine, and the like. Ethylene glycols include ethylene glycol, propylene glycol, 1,2-butanediol, 1,2,4-butanetriol, glycerol, 2,3-butanediol, diethylene glycol, and the like. The catalyst used in the method of the present invention is a catalyst system containing one or more selected from group B elements Cu, Ag, and Au as an active ingredient, and elements that can be combined with these include B, C, O, Mg, Al,
Si, P, S, Ca, Ti, Cr, Mn, Fe, Co, Ni,
Zn, Ga, Ge, Se, Sr, Zr, Mo, Ru, Rh, Pd,
Cd, In, Sn, Sb, Te, Ba, La, Ce, W, Ir,
Examples include Pt, Tl, Pb, Bi, and Th. The aforementioned catalysts may be used alone or in the presence of common carriers such as diatomaceous earth, activated clay, zeolite, silica,
It is used supported on alumina, silica-alumina, titania, chromia, thoria, magnesia, calcia, zinc oxide, etc. Raw materials for Group B elements include nitrates, sulfates, phosphates, carbonates, halides, organic acid salts, etc. for Cu and Ag, and chloroauric acid, chlorauric acid, etc. for Au.
Alkali metal chloroaurates, gold cyanide, alkali metal gold cyanide, etc. can generally be used. As a method for preparing the catalyst, the usual kneading method, coprecipitation method, impregnation method, and a method combining the above-mentioned methods can be applied. For example, a method of mixing various raw materials, adding a small amount of water, and kneading with a kneader, etc., a method of making various raw materials into an aqueous solution, adding a precipitant to this, and co-precipitating as an insoluble precipitate; It can be prepared by impregnating raw materials. The obtained catalyst composition is usually dried at 180° C. or lower, and suitable granulation additives, molding aids, etc. are added and molded, or the catalyst composition is crushed and used as it is. In the method of the present invention, such a catalyst is used in the production of indoles and is deteriorated. The catalyst is subjected to a regeneration treatment as described below, followed by a reduction activation treatment, and then used repeatedly. In the method of the present invention, the reaction between anilines and ethylene glycols is carried out in the gas phase in the presence of a catalyst, but any reaction mode such as a fixed bed, fluidized bed or moving bed is possible. The anilines and ethylene glycols introduced into the reactor are in the range of 0.01 to 5 mol of ethylene glycol per 1 mol of aniline, preferably
It is in the range of 0.05 to 1 mole. The amount of introduced raw materials anilines and ethylene glycols is 0.01 to 0.01 in terms of liquid hourly space velocity (LHSV).
It is in the range of 10 hr ^-1 and is introduced into the reactor after being vaporized in an evaporator. Further, at that time, water vapor, hydrogen, carbon monoxide, carbon dioxide, methane, nitrogen, neon, argon, etc. may be entrained as a carrier gas. Among them, water vapor, hydrogen, and carbon monoxide are preferable because they have the effect of increasing the service life of the catalyst. The reaction temperature ranges from 200 to 600℃, preferably 250℃
~500℃ range. The reaction can be carried out under reduced pressure, normal pressure, or increased pressure, but normal pressure or increased pressure is preferable. The catalyst used more than once for the production of indoles under the above conditions is subjected to regeneration treatment and then reduction activation treatment as follows. That is, in the regeneration process, the deteriorated catalyst is regenerated by burning off carbonaceous substances deposited on the catalyst. Examples of the regeneration method include a method of bringing the deteriorated catalyst into contact with an inert gas containing 5 vol% or less of oxygen at a temperature range of 200 to 450°C. In this regeneration method, the oxygen concentration is preferably 2% or less, and the inert gas used is nitrogen, argon, helium, carbon monoxide, water vapor, or the like. As needed,
Subsequently, heat treatment may be performed. However, the regeneration method is not limited to the above regeneration method. Then, when the regenerated catalyst is to be used repeatedly, it is subjected to the following reduction activation treatment before starting the reaction. In this reduction activation treatment, hydrogen, carbon monoxide, methanol, ammonia, hydrazine, etc. are used as a reducing agent. Usually, when producing indoles, a hydrogen-containing gas is often used as a carrier, so it is convenient to use hydrogen as a reducing agent. Reduction activation temperature is 100-500℃, preferably 200℃
-450°C, more preferably 300-400°C.
The processing pressure may be increased pressure, reduced pressure, or normal pressure. The reduction treatment time may be as long as desired, but the catalyst performance becomes constant at 2 hours or more. Usually, under pressure or normal pressure, the time is at least 1 minute, preferably 30 minutes or more. The above reducing agent may be used alone or after being diluted with an inert gas. (Operation and Effects of the Invention) When a deteriorated catalyst is regenerated as in the present invention and the regenerated catalyst is repeatedly used, it is possible to perform reduction activation treatment in advance so that it can be used more than once for the production of indoles and deteriorated. However, the activity of the regenerated catalyst is further improved. The activity expressed by reductive activation is extremely stable, and the reaction can be continued for a long time. That is, the method of the present invention provides an industrial method for producing indoles in which the catalyst used is regenerated, activated, and repeatedly used in a method for producing indoles from anilines and ethylene glycols. (Examples) Hereinafter, the present invention will be explained in detail with reference to Examples and Comparative Examples. Example 1 and Comparative Example 1 A stainless steel reaction tube with an inner diameter of 20 mm was filled with 400 c.c. of a commercially available tablet-formed SiO ₂ catalyst with a diameter of 3 mm and a height of 2.5 mm, which supported 13% silver. Keep the reaction tube at 350℃ and pre-vaporize aniline,
Ethylene glycol and water molar ratio: 12:
The indole synthesis reaction was carried out under normal pressure by supplying 1:30 raw materials at 300 g/hr and simultaneously supplying hydrogen gas at 60 STP/hr to the reaction tube. After reacting for a certain period of time, the conditions for regenerating the catalyst were as follows: the inlet temperature of the oxygen-containing gas was 300℃, the oxygen concentration was 1.5vol%, and the cylinder linear velocity.
Regeneration was performed at 15Ncm/sec. 500 more after playing
The catalyst was heat treated for 15 hours at °C under an air atmosphere. After that, the temperature was increased to 320℃ under N ₂ atmosphere, and H ₂ was added at 2/min.
The mixture was sent for 1 hour and subjected to reduction treatment, and then the reaction was performed again under the same conditions as before regeneration. Table 1 shows the conversion rate of ethylene glycol in the reaction and the yield of indole produced. In addition,
The conversion rate of ethylene glycol and the yield of indole follow the definitions below. Conversion rate of ethylene glycol = Number of moles of ethylene glycol consumed/Number of moles of ethylene glycol supplied x 100 Yield of indole = Number of moles of indole produced/Number of moles of ethylene glycol supplied x 100 Also, Example 1 The reaction was carried out according to the method shown in , without performing the high-temperature reduction activation treatment before the reaction.

[Table] conversion rate
Yield of indole Example 2 and Comparative Example 2 The reaction was carried out according to the method shown in Example 1 and Comparative Example 1, except that only the catalyst was changed. The catalyst was the same as the catalyst carrier used in Example 1, with 2.5% copper supported thereon. Table 2 shows the conversion rate of ethylene glycol in the reaction and the yield of indole produced.

[Table] conversion rate
is the yield of indole

Claims (1)

[Claims] 1. A method for producing indoles using anilines and ethylene glycols as raw materials and subjecting them to a gas phase catalytic reaction in the presence of a catalyst containing a metal from Group B of the Periodic Table of the Elements, in which the catalyst used in the reaction is heated at 200 to 450°C.
The catalyst is regenerated by contacting with an inert gas containing 5 vol% or less of oxygen at a temperature range of 100 to 500 °C, and then subjected to a reduction activation treatment at a temperature range of 100 to 500 °C.The regenerated catalyst is then subjected to a reaction. A method for producing an indole compound.