JPS6251949B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to a novel method for producing indole or indole derivatives. More specifically, the present invention relates to a method for producing indole or an indole derivative by reacting hydrogen, nitrobenzenes, and ethylene glycol in the presence of a Group 8 metal and/or an activated carbon-containing catalyst. Indole is known as a raw material for the chemical industry, and has become an important substance particularly in recent years as a raw material for perfumery and amino acid synthesis. Conventional techniques and problems to be solved by the invention There have been several attempts to synthesize indole in the past, but all of them produced many by-products,
Many of them are expensive in terms of raw materials, and the process to reach indole is long and the operations are complicated. An object of the present invention is to produce indole or indole derivatives with high selectivity in a single step using inexpensive raw materials. Means for Solving the Problems As a result of intensive studies to achieve this objective, the present inventors have developed a method based on a completely new reaction that was previously unknown, that is, a method based on a completely new reaction between hydrogen, nitrobenzenes, and ethylene glycol. The inventors have discovered that the desired product, indole or indole derivative, can be produced with high selectivity by catalytically reacting the compound with a Group 8 metal and/or activated carbon-containing catalyst, and have completed the method of the present invention. That is, according to the method of the present invention, for example,
Indole can be obtained by reacting hydrogen, nitrobenzene, and ethylene glycol, and 5-methylindole can be obtained by reacting hydrogen and paranitrolethylene glycol. The catalyst used in the method of the present invention is a catalyst containing a Group 8 metal of the Periodic Table of Elements and/or activated carbon. That is, it contains a Group 8 metal or activated carbon, each alone, or a mixture of two or more, and each of these contains another compound. For example, iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, etc.
Platinum, activated carbon, or a Group 8 metal and/or activated carbon in the periodic table, or a mixture of a Group 8 metal and/or activated carbon and other compounds. It is an activated carbon-containing catalyst. Other compounds used in combination with Group 8 metals and/or activated carbon include lithium, sodium,
Potassium, magnesium, calcium, strontium, barium, copper, silver, mercury, aluminum, tin, iron, cobalt, nickel, chromium, manganese, lead, molybdenum, halides, nitrates, sulfates, carbonates, organic acid salts, These include oxides, hydroxides, and metals. As the carrier for supporting the catalytic material (hereinafter referred to as the 8th metal of the periodic table of elements and activated carbon) or the catalytic material and other compounds, any of those commonly used as a carrier for supported catalysts may be used. Generally, diatomaceous earth, pumice, titania, silica alumina, alumina, magnesia, silica gel, activated carbon, activated clay, asbestos, etc. are used. A supported catalyst is prepared by supporting the catalyst substance on these carriers by a conventional method. According to the immersion method, for example, a water-soluble Group 8 metal salt is dissolved in water and immersed in a carrier such as activated carbon or alumina, then dried,
Manufactured by thermal decomposition and reduction operations.
Alternatively, according to a precipitation method, for example, a carrier such as activated carbon or silica gel is added to an aqueous solution of nitrate of one or more Group 8 metals, and an alkaline substance is added while stirring to form a precipitate. It is prepared by filtering, washing, drying, calcining and reducing the precipitate. In addition, there are various catalyst preparation methods, and the method for preparing the catalyst is not limited. Further, there is no particular restriction on the amount of the catalyst substance supported on the carrier, and usually an appropriate amount depending on the carrier, for example,
0.01-50% of said catalyst material may be supported. In the present invention, activated carbon alone can be used as a catalyst, but when the activated carbon supports a group 8 metal of the periodic table of elements, its catalytic activity increases.
The activated carbon used in the present invention includes various activated carbons. Examples include activated carbon made from coconut shells, wood, sawdust, lignin, coal, blood char, bone char, petroleum carbon, and the like. Commercially available activated carbon is usually powdered carbon, crushed carbon, or molded carbon shaped into a spherical or cylindrical shape, and the shape of the activated carbon used in the present invention is not particularly limited. The nitrobenzenes used in the present invention include nitrobenzene, ortho-nitrotoluene, meta-
Includes nuclear substituted derivatives of nitrobenzene such as nitroluene, para-nitroluene, ortho-nitrophenol, meta-nitrophenol, para-nitrophenol, ortho-nitroanisole, meta-nitroanisole, and para-nitroanisole. In the method of the present invention, the reaction can be carried out in a gas phase, a liquid phase, or a gas-liquid mixed phase, but it is usually carried out in a gas phase. When carried out in the gas phase, it can be carried out in fixed bed, fluidized bed or moving bed reactors, in which a gas mixture of nitrobenzenes, ethylene glycol and hydrogen gas is heated in the presence of a group 8 metal and/or activated carbon containing catalyst. It is implemented by At this time, various inert gaseous substances may be present as diluents for the raw materials. Examples of such inert gaseous substances include nitrogen gas, carbon dioxide, water vapor, and vapors of compounds inert to this reaction. Furthermore, hydrogen gas or hydrogen-containing gas may be used as the diluent. In this reaction, the nitrobenzenes and ethylene glycol charged into the reactor are at a ratio of 0.05 to 5 moles of ethylene glycol per mole of nitrobenzene, and the liquid hourly space velocity relative to the catalyst is 0.01 to 5/.
-Catalyst/hr, either in vapor form or directly charged to the reactor in liquid form. Further, hydrogen gas to be mixed with nitrobenzenes and ethylene glycol is charged into the reactor at a ratio of 0.1 to 100 moles, preferably 1 to 30 moles, per mole of nitrobenzenes. The reaction temperature is in the range of 200-500°C, preferably
It is in the range of 250-400℃. If the temperature is below 200°C, the reaction will hardly proceed, and if it is above 400°C, a large amount of by-products will be produced, which is not preferable. Further, the reaction pressure may be increased pressure, normal pressure, or reduced pressure. From the reaction products in these various methods,
Indole or an indole derivative can be easily separated and purified by a suitable method, for example, a conventional method such as distillation. Effects The advantages of the method of the present invention are as follows. First, the raw materials are very cheap, such as nitrobenzene. Second, indole or an indole derivative is produced from the raw materials in one step. Thirdly, there are very few by-products, the selectivity is very good, and therefore highly pure indole can be obtained. Examples Hereinafter, the method of the present invention will be explained in detail with reference to Examples. Example 1 Cylindrical palladium-carbon catalyst (PD content 0.5
%) was filled into a 25 mm Pitx glass flow-through reactor. The front part of this reactor is connected to a raw material insertion pipe and a gas introduction pipe to constitute a raw material vaporization part, and the rear part is connected to a receiver via an air cooling part.
In the reaction section, the internal temperature of the reactor was maintained at 325°C, and hydrogen gas was passed into the reactor to reduce the catalyst for about 1 hour.
123 g (1 mole) of nitrobenzene and 6.2 g of ethylene glycol at a liquid hourly space velocity of 0.1/-catalyst/hr.
(0.1 mol) is inserted through the raw material insertion tube,
At the same time, 10 times the molar amount of hydrogen relative to the raw material nitrobenzene was passed under normal pressure. When the reaction products condensed through the reactor are analyzed using a gas chromatograph,
8.5 g of indole was produced, with a conversion rate of 88.3% and a selectivity of 82.6% based on ethylene glycol, with very little by-products. Examples 2 to 10 In Example 1, the reaction was carried out in the same manner as in Example 1 in the same reaction apparatus as in Example 1, using the catalysts shown in Table 1 instead of the PD-C catalyst. I went. The results are shown in Table-1.

【table】

[Table] Example 11 In Example 1, granular activated carbon was used instead of the PD-C catalyst, and the reaction temperature was 375°C.
The reaction was carried out in the same manner as in Example 1 using the same reaction apparatus as in Example 1. As a result, 3.1 g of indole was obtained. The conversion rate was 31.6% and the selectivity was 82.5% based on ethylene glycol. Example 12 In Example 1, a reaction was carried out in the same manner as in Example 1, except that 137 g (1 mol) of para-nitrotoluene was used in place of nitrobenzene. the result
1.7 g of 5-methylindole was obtained. Conversion rate 25.1%, selectivity based on ethylene glycol
It was 50.2%. Example 13 A reaction was carried out in the same manner as in Example 1 except that 153 g (1 mol) of para-nitroanisole was used in place of nitrobenzene. the result
1.8 g of 5-methoxyindole was obtained. Conversion rate 23.8%, selectivity based on ethylene glycol
It was 51.3%.

Claims (1)

[Claims] 1. A method for producing indole or an indole derivative, which comprises subjecting hydrogen, nitrobenzenes, and ethylene glycol to a gas phase reaction in the presence of a Group 8 metal and/or activated carbon-containing catalyst.