JPH0820574A - Production of 3-methylpiperidine - Google Patents

Abstract

PURPOSE:To obtain the subject compound which is a precursor of methylpyridine to be a raw material for nicotinic acid (amide) in high yield by carrying out the cyclodehydrogenation of methylglutaronitrile in the presence of ammonia using rhodium as a catalyst. CONSTITUTION:This method for producing 3-methylpiperidine comprises carrying out the cyclodehydrogenation of (A) 2-methylglutaronitrile in the presence of (B) ammonia using (C) rhodium as a catalyst. Furthermore, the rhodium catalyst is preferably used in the form supported on a metallic black an/or a carrier. The ammonia is used in a molar amount of 10-200 times based on the component (A) and the reactional temperature in the cyclodehydrogenation is preferably 60-130 deg.C. The partial pressure of hydrogen is preferably 1-200kg/cm<2>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing 3-methylpiperidine, which is a precursor of 3-methylpyridine which is a raw material for nicotinic acid and nicotinic acid amide useful as vitamins and feed additives. 3-Methylpiperidine is easily converted to 3-methylpyridine by dehydrogenation.

[0002]

2. Description of the Related Art Conventionally, various methods for producing 3-methylpyridine have been proposed. Among them, a method has been proposed in which 2-methylglutaronitrile, which is a by-product when producing adiponitrile, which is a hydrogenated raw material of hexamethylenediamine, which is a raw material of 6,6-nylon, is used as a starting material. There is. This method is noteworthy because it does not produce pyridine other than 3-methylpyridine and is highly economical.

A method for obtaining 3-methylpyridine from 2-methylglutaronitrile is disclosed in JP-A-57-1506.
No. 63 discloses a method of carrying out hydrogenation, cyclization, and dehydrogenation reaction in one step in the gas phase using palladium-alumina as a catalyst. However, this method is difficult to carry out industrially because the space-time yield is low and the catalyst life is short.

A method for producing 3-methylpiperidine, which is a precursor of 3-methylpyridine, from 2-methylglutaronitrile has also been proposed. For example, JP-A-51-122
In No. 074, 2-methylglutaronitrile was hydrogenated with a nickel catalyst in the presence of ammonia to give 3 at a yield of 90% or more.
-Methylpiperidine is obtained. However, when the present inventors repeated this method, the main product of the actual reaction was 2-
It was methyl-1,5-pentanediamine.

In US Pat. No. 3,975,392,
Hydrogenation was carried out in the presence of ammonia in the first step using a nickel catalyst to obtain 2-methyl-1,5-pentanediamine. Subsequently, in the second step, the temperature was raised in the absence of hydrogen and ammonia to perform deamine secondary cyclization. 3-methylpiperidine is obtained. The amount of 3-methylpiperidine produced can be increased to some extent by this method. However, the deamined secondary product of 2-methyl-1,5-pentanediamine is not limited to 3-methylpiperidine, which is a cyclic amine deamined in the molecule, and intermolecular deamined polyamines are often produced.
Therefore, this method is not an efficient method for producing 3-methylpiperidine.

Further, in Japanese Patent Laid-Open No. 51-136672, 2
2-methyl-1,5-pentanediamine or 2-methyl-1, which is the hydrogenation product of methylglutaronitrile
A method of obtaining 3-methylpyridine by cyclization dehydrogenation of a mixture of 5-pentanediamine and 3-methylpiperidine in a gas phase using palladium-alumina as a catalyst is disclosed. In addition, the special publication No. 3-505877 and the special publication No. 3
No. 505878 discloses a metal oxide other than an alkali metal or a transition of copper-chromium or molybdenum to obtain 3-methylpyridine by cyclodehydrogenation of 2-methyl-1,5-pentanediamine in a gas phase. A method of using a metal oxide as a catalyst is described. These methods are 2-methyl-
Cyclodehydrogenation of 1,5-pentanediamine is to be carried out in a single step, but 2-methyl-
Since it is a polyamine that is by-produced by intermolecular deamine of 1,5-pentanediamine, it has a drawback that the catalyst is poisoned and its life is short. Therefore, in an example in which a metal oxide other than an alkali metal or a transition metal oxide of copper-chromium or molybdenum is used as a catalyst, a fluidized bed reactor is used to carry out the reaction while regenerating the catalyst. Further, in order to reduce the frequency of catalyst regeneration, the reaction must be carried out at a very high temperature of 500 to 600 ° C.

[0007]

Although many methods for obtaining 3-methylpyridine from 2-methylglutaronitrile have been proposed, the yield is not satisfactory, the catalyst life is short, and the like. There are many problems such as severe reaction conditions. It is known that 3-methylpiperidine can be easily quantitatively converted into 3-methylpyridine by a dehydrogenation reaction. Therefore, if a method for industrially producing 3-methylpiperidine from 2-methylglutaronitrile can be established, an advantageous industrial production method for 3-methylpyridine can be constructed. An object of the present invention is to provide a method for efficiently and industrially producing 3-methylpiperidine from 2-methylglutaronitrile.

[0008]

Means for Solving the Problems As a result of diligent studies on the method for producing 3-methylpiperidine from 2-methylglutaronitrile, the present inventors have found that 2-methylglutaronitrile is hydrolyzed in the presence of ammonia using rhodium as a catalyst. The present inventors have found that 3-methylpiperidine can be obtained in high yield by cycloaddition, and have reached the present invention. That is, the present invention is characterized in that, when hydrogenating cyclization of 2-methylglutaronitrile to synthesize 3-methylpiperidine, the reaction is carried out using rhodium as a catalyst in the presence of ammonia.
It is a method for producing methylpiperidine. When nickel, cobalt or ruthenium is used as a catalyst, the main product of the hydrogenation reaction of 2-methylglutaronitrile is 2-methyl-1,
It was 5-pentanediamine, and the amount of 3-methylpiperidine produced was small even when the reaction conditions were changed such as increasing the temperature, and more polyamine was produced as a by-product. On the other hand, if the rhodium catalyst of the method of the present invention is used, 3-methylpiperidine can be efficiently produced.

The rhodium catalyst used in the present invention is used in the form of being supported on metal black and / or a carrier. As the catalyst carrier, diatomaceous earth, silica, alumina, silica-alumina and carbon are preferably used.
The amount of rhodium supported is not particularly limited, but 0.1 to 5.0% by weight is preferable in terms of economical amount and reaction results.

In the present invention, it is necessary to use ammonia as a reaction solvent. The reaction proceeds even without ammonia to produce 3-methylpiperidine, but polyamine is also produced at the same time, so that the yield is lowered, and the catalyst life is shortened due to poisoning of polyamine. The coexistence of ammonia solves these problems. The amount of ammonia used is 0.01 times mol or more based on 2-methylglutaronitrile. From the viewpoint of productivity and reaction results, the range of 10 to 200 times mol is usually preferable. When the amount is 0.01 times or less, the amount of polyamine produced increases, which is not preferable.

The reaction solvent in the present invention may be only ammonia, but other solvents may be used in combination. As the reaction solvent used in combination, for example, water, methanol,
Ethanol, 1-propanol, 2-propanol, 1
-Alcohols such as butanol and 2-butanol: Aliphatic hydrocarbon ethers such as dimethyl ether, methyl ethyl ether, diethyl ether and diisopropyl ether: Aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene and pseudocumene: Methyl acetate, ethyl acetate , And esters such as ethyl benzoate. The amount of the reaction solvent used in combination is not particularly limited, but is usually 0 to 100 parts by weight, preferably 0 to 50 parts by weight, relative to 1 part by weight of the starting material, 2-methylglutaronitrile.

The reaction temperature for the hydrogenation cyclization is 60 to 130 ° C. Under these conditions, a sufficient yield can be obtained in a short time.
The reaction proceeds even at a critical temperature of ammonia higher than this, but the reaction pressure becomes unnecessarily high, which is not preferable. The hydrogen partial pressure required to carry out the hydrogenation reaction is 1 to 100.
The reaction rate is 0 kg / cm ² , and the higher the hydrogen partial pressure, the higher the reaction rate, but a sufficient yield can be obtained at 1 to 200 kg / cm ² .

The reaction system in the present invention can be carried out by either a liquid phase batch slurry system or a fixed bed flow system.
Since a supported catalyst is used in the present invention, an irrigation type reaction system using a fixed bed flow reactor is simpler as an industrial production method.

[0014]

EXAMPLES The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these examples. The results of each Example and Comparative Example are shown in Tables 1 and 2, and the symbols used in each table are as follows. 2MGN: 2-methylglutaronitrile 3-MP: 3-methylpiperidine MPDA: 2-methyl-1,5-pentanediamine C9: pseudocumene

Example 1 An SUS reaction tube having an inner diameter of 16 mmφ and a length of 960 mmL was charged with 30 g of 2.0 wt% rhodium / alumina (made by NE Chemcat) having a particle size of 12 to 20 mesh. Raschig rings were filled in the upper part of the catalyst layer at a height of 200 mm to form a preheating part. Before the start of the reaction, the catalyst was reduced with 5% hydrogen gas (diluted with nitrogen) at 200 ° C. until the production of water was stopped and used. The reaction tube is set to 125 ° C, hydrogen gas is introduced from the upper part of the reaction tube, and the total pressure is 125 kg / cm.
Hold on to ² . Then, from the upper part of the reaction tube, a raw material liquid (2-methylglutaronitrile: 16.7% by weight, ethanol 1
6.7% by weight, ammonia 66.6% by weight) 90 g /
The hydrogenation reaction was performed by supplying at a rate of hr. The reaction product liquid was separated into liquid and gas in the high-pressure gas-liquid separator, and the liquid was further collected as a sample after evaporating ammonia in the atmospheric gas-liquid separator. The obtained sample was subjected to GC analysis of 3-methylpiperidine produced by distillation, and polyamine was quantified from the residual weight of the kettle to obtain a reaction result. The results are shown in Table 1. According to this result, the selectivity to 3-methylpiperidine is very high, and the production of by-products 2-methyl-1,5-pentanediamine and polyamine is small.

Example 2 A reaction was carried out in the same manner as in Example 1 except that pseudocumene was used instead of ethanol as a reaction solvent. The results are shown in Table 1.

Example 3 30 g of 2.0 wt% rhodium / activated carbon (manufactured by NE Chemcat) crushed to a particle size of 12 to 20 mesh was used as a catalyst in Example 1 except that methanol was used as a reaction solvent. Reacted in the same manner. The results are shown in Table 1.

Comparative Example 1 A raw material liquid containing no ammonia in Example 1 (2-methylglutaronitrile: 50.0% by weight, ethanol 5
(0.0% by weight) was fed at a feed rate of 30 g / hr to carry out the hydrogenation reaction, and the reaction was carried out in the same manner. The results are shown in Table 1. This result shows a significant increase in polyamine production.

Comparative Example 2 Nickel-diatomaceous earth (manufactured by JGC Chemical Co., Ltd.) 30 crushed to a particle size of 12 to 20 mesh as a catalyst in Example 1
The reaction was performed in the same manner except that g was used. Table 2 shows the results
Shown in The main product of this result is 2-methyl-1,5-pentanediamine, and polyamine is often produced.

Comparative Example 3 2.0 wt% ruthenium / as a catalyst in Example 1
The reaction was carried out in the same manner except that 30 g of alumina (manufactured by NE Chemcat) was used. Table 2 shows the results. The main product of this result is 2-methyl-1,5-pentanediamine, and polyamine is often produced.

Comparative Example 4 The reaction was carried out in the same manner as in Example 1 except that 30 g of 0.5 wt% platinum / alumina (manufactured by NE Chemcat) was used as a catalyst. Table 2 shows the results. The main product of this result was 3-methylpiperidine, but a large amount of polyamine was produced.

Comparative Example 5 0.5 wt% palladium / catalyst in Example 1
The reaction was carried out in the same manner except that 30 g of alumina (manufactured by NE Chemcat) was used. Table 2 shows the results. The main product of this result is the polyamine, with little formation of 3-methylpiperidine.

[0023]

[Table 1] Example 1 Example 2 Example 3 Comparative Example 1 Catalyst 2wt% Rh 2wt% Rh 2wt% Rh 2wt% Rh / Al2O3 / Al2O3 / C / Al2O3 Reaction solvent Ethanol C9 Methanol Ethanol Ammonia Yes Yes Yes Yes Yes No 2MGN reaction rate% 99.8 100.0 100.0 100.0 3-MP selectivity% 86.3 85.8 86.1 34.5 MPDA selectivity% 11.8 11.4 11.7 0.0 Polyamine selectivity% 1.90 2.80 2.20 65.5

[0024]

[Table 2] Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Catalyst Ni / 2wt% Ru 0.5wt% Pt 0.5wt% Pd Diatomaceous earth / Al2O3 / Al2O3 / Al2O3 Reaction solvent Ethanol Ethanol Ethanol Ethanol Ammonia Yes Yes Yes Yes Yes Yes 2MGN reaction rate% 100.0 98.3 98.7 98.1 3-MP selectivity% 18.3 11.8 64.4 10.3 MPDA selectivity% 72.2 80.4 1.98 0. 0 polyamine selectivity% 9.48 7.79 33.6 89.7

[0025]

As is apparent from the examples, according to the method of the present invention, 2-methylglutaronitrile as a raw material reacts almost completely and the selectivity to 3-methylpiperidine is very high. A very high yield of 3-methylpiperidine is obtained. According to the method of the present invention, 3-methylpiperidine, which is a precursor of 3-methylpyridine, which is a raw material of nicotinic acid and nicotinic acid amide, can be efficiently industrially produced from 2-methylglutaronitrile. As such, its significance is extremely large.

Claims (1)

[Claims] 1. A method for producing 3-methylpiperidine, which comprises reacting rhodium as a catalyst in the presence of ammonia when hydrogenating and cyclizing 2-methylglutaronitrile to synthesize 3-methylpiperidine.