JPH0434977B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing 5-ethylidene-2-norbornene, and more specifically, a method for producing 5-ethylidene-2-norbornene in the presence of a specific catalyst.
The present invention relates to a method for producing 5-ethylidene-2-norbornene (hereinafter referred to as ENB), which is characterized by isomerizing vinyl-2-norbornene (hereinafter referred to as VNB). ENB is a synthetic rubber ethylene-propylene-diene monomer terpolymer, so-called
It is a very useful compound as the third component of EPDM, and is usually produced by isomerizing VNB obtained by the reaction of 1,3-butadiene and cyclopentadiene in the presence of a catalyst. As a catalyst for such an isomerization reaction, a liquid base,
For example, mixtures of alkali metal hydroxides and aprotic organic solvents, alkali metal amides and amines, or organic alkali metals and aliphatic amines are known. However, in the method using such a liquid base reagent, the catalytic activity is insufficient,
In addition to requiring large quantities of expensive reagents,
It is difficult to separate and recover the reagent from the reaction mass;
There is a problem that not only a complicated separation and recovery process is required but also a large amount of energy is saved. As solid isomerization catalysts, catalysts in which alkali metals are dispersed in carriers with large surface areas, such as activated carbon, silica gel, alumina, etc., are known (J.Am.Chem.Soc. 82 387 (1960)). . However, in such a solid catalyst, the alkali metal itself is simply finely dispersed on a carrier, and when it comes into contact with air, it ignites and becomes deactivated, so it is difficult to operate.
There were major problems in terms of safety. Also, the isomerization ability was unsatisfactory. The present inventors have already developed a new catalyst using alumina, alkali metal hydroxide, and an alkali metal as raw materials, and a new catalyst using hydrous alumina and an alkali metal as raw materials, as efficient catalysts that do not have the problems of isomerization catalysts. In addition, we discovered that these solid base catalysts are safer even in the air without the risk of ignition, and are industrially superior as catalysts for the isomerization of olefins such as VNB. Special Publication No. 50-3274, Special Publication Sho
57-21378 No. 0). The present inventors used such a solid base catalyst.
Further research into the isomerization of VNB revealed that the temperature at which the raw material, hydrated alumina, and the alkali metal are heated is particularly important, and if adjusted to a specific temperature, the catalytic activity can be significantly improved.
They discovered that the isomerization of VNB proceeds efficiently with a small amount of catalyst, and completed the present invention after further various studies. That is, in the present invention, when producing 5-ethylidene-2-norbornene by isomerizing 5-vinyl-2-norbornene in the presence of a catalyst in an inert gas atmosphere, the present invention uses water-containing alumina as a catalyst to produce 5-ethylidene-2-norbornene. A solid base on which an alkali metal is reacted in an amount of 1.01 to 2 times the molar amount, and the temperature at which the alkali metal is reacted with the alkali metal in an amount exceeding the equivalent amount relative to the molar amount of water in the alumina is 180 to 350°C. The present invention provides a method for producing 5-ethylidene-2-norbornene, which is characterized by using a solid base. As the hydrated alumina that is the raw material for the solid base catalyst in the present invention, various forms of hydrated alumina other than α-alumina are used. Alumina is usually produced by firing aluminum hydroxide, but it is known that alumina exists in various forms, taking various metastable structures and varying amounts of water depending on the firing temperature and time. It is being In the present invention, such alumina is mainly used. Especially γ−, χ−,
High surface area hydrated alumina such as ρ-type is preferably used. Hydrous materials containing alumina, such as kaolin and alumina silicate, can also be used, but the alumina is particularly preferred. Furthermore, as the firing temperature increases, alumina will eventually reach α
- It is said that the weight loss on heating of alumina is eliminated by switching to alumina. Although it is not so easy to measure the amount of water contained in alumina, it can be expressed by the loss of water on heating until the initial various forms of alumina are converted to α-alumina. The water content of the hydrated alumina is usually in the range of 1.3 to 10% by weight, preferably 2 to 7% by weight. Further, examples of the alkali metal which is the other raw material of the catalyst used in the present invention include sodium, potassium, rubidium, etc. of Group 1 of the periodic table. Two or more of these alkali metals may be used, or an alloy thereof, such as an alloy of sodium and potassium, may be used. The alkali metal is used in an amount of 1.01 to 2 times the molar amount of water in the hydrated alumina. The adjustment temperature of the catalyst used in the present invention, that is, the temperature at which the hydrated alumina and the alkali metal are made to interact with each other, is extremely important.In particular, the amount of the alkali metal that exceeds the equivalent amount of water in the hydrated alumina is made to act on the catalyst. Temperature has a significant effect on catalyst activity. The temperature is 180 to 350°C, more preferably 200 to 330°C. By adjusting the catalyst to such a temperature, a catalyst with extremely high activity never seen before can be obtained, and the desired reaction can be efficiently completed with a small amount of catalyst. When making an alkali metal act on hydrated alumina, a predetermined amount of the alkali metal may be added at once, or the remaining alkali metal may be added after adding an amount equivalent to the water content of the hydrated alumina and causing a sufficient reaction. . In the latter case, the alkali metal added first and the alkali metal added later may be different.
In the latter case, the first temperature and the second temperature may be different, and the first temperature in this case is also preferably
The temperature ranges from 180 to 350°C. The catalyst used in the present invention is prepared by making the above-mentioned hydrated alumina and alkali metal interact with each other at a specific temperature in an inert gas atmosphere. ,
Examples include argon. Heating time varies depending on the selected temperature conditions, but
Usually 15 minutes to 10 hours is sufficient. In this way, a catalyst can be obtained which is safer than known solid base catalysts without the risk of ignition, and has significantly higher activity. The present invention uses such a solid base catalyst to produce VNB.
The amount of solid base catalyst used is usually 1/1 of VNB.
3000 to 1/50 weight, preferably 1/2000
The weight is 1/100 to 1/100. Regarding the isomerization temperature, there is no need to particularly heat the reaction because the reaction proceeds sufficiently at room temperature, but heating may be used depending on the purpose. Usually -30 to 120℃, preferably -10 to 120℃
Performed in a temperature range of 100°C. If necessary an inert medium such as pentane, hexane, heptane,
Although the reaction can be carried out by diluting with a hydrocarbon such as dodecane, it is sufficient to use no medium. The method of the present invention can be carried out in either a batch method or a continuous method, and it is also effective to pre-treat VNB with a desiccant such as alumina in advance for isomerization. In order to carry out isomerization more safely and reliably, it may be carried out under an inert gas atmosphere. The isomerization reaction products and the like are analyzed by known methods such as gas chromatography, and separated from the catalyst by filtration or the like. In this way, ENB, which is the object of the present invention, is obtained. According to the method of the present invention, the isomerization reaction of VNB can be completed extremely efficiently even with a significantly smaller amount of catalyst than in known methods, and by-products such as polymers can be completed. ENB can be obtained in high yield with almost no oxidation.
Furthermore, the reaction can proceed safely without any dangers such as ignition, so it is extremely advantageous as an industrial manufacturing method for ENB. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to examples, but the present invention is not limited only to the examples. Reference example 1 30.0g of γ-alumina containing 2.2% water by weight
was placed in a 100 ml flask and heated to 300°C while stirring under nitrogen gas flow. metallic sodium
1.2g was introduced, stirred at the same temperature for 1 hour, and then allowed to cool. 30.9 g of a gray-blue catalyst was obtained. Example 1 0.25 g of the solid base prepared in Reference Example 1 was placed in a 200 ml flask under a nitrogen atmosphere, and 64.5 g of 5-vinyl-2-norbornene (hereinafter referred to as VNB) was added to this.
was added and stirred at 15-20°C for 8 hours. After the reaction, the catalyst was removed by filtration to obtain 63.9 g of reaction solution. When this product was analyzed by gas chromatography, it was found to be 0.4% VNB and 99.5% 5-ethylidene-2-norbornene (hereinafter referred to as ENB). Reference Examples 2 to 10 The solid base catalysts shown in Table 1 were obtained in the same manner as in Reference Example 1 except for the conditions shown in Table 1. Examples 2 to 6, Comparative Examples 1 to 4 Using the solid base catalysts prepared in Reference Examples 2 to 10, the same procedure as in Example 1 was performed except for the conditions shown in Table 2.
Isomerization of VNB was performed. The results are shown in Table-2. Reference Example 11 50 g of γ-type alumina with a water content of 6.0% was placed in a 100 ml flask and heated to 200° C. with stirring in a nitrogen atmosphere. At the same temperature, 4.0 g of metallic sodium was added in small pieces over 20 minutes. After stirring for 1 hour, gradually heat to 300℃.
It was set to At 300°C, 1.9 g of metallic sodium was further added in small pieces over 10 minutes, and the mixture was stirred at the same temperature for 3.5 hours. Thus 54.2 g of solid base was obtained. Reference Example 12 50 g of γ-type alumina with a moisture content of 6.0% was placed in a 100 ml flask and heated to 200° C. with stirring in a nitrogen atmosphere. At the same temperature, 4.0 g of metallic sodium was added in small pieces over 20 minutes. After continuing stirring for 1 hour, the mixture was gradually heated to 400°C. At 400°C, 1.9 g of metallic sodium was added in small pieces over 10 minutes, and stirring was continued for 3.5 hours at the same temperature. Thus 54.1 g of solid base was obtained. Example 7 Reference Example-11 in a 200ml flask under nitrogen atmosphere
Add 0.25g of solid base prepared in
62.5 g of VNB was added and stirred at 15-20°C for 8 hours. After the reaction, the catalyst was removed by filtration to obtain 62.0 g of reaction solution.
When this product was analyzed by gas chromatography, it was found to be 0.3% VNB and 99.5% ENB. Comparative Example 5 Reference Example-12 in a 200ml flask under nitrogen atmosphere
Add 0.25g of solid base prepared in
62.5g of VNB was added and stirred at 15-20°C for 8 hours. After the reaction, the catalyst was removed by filtration to obtain 61.9 g of reaction solution.
When this product was analyzed by gas chromatography, it was found that VNB was 40.1% and ENB was 59.8%.

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Claims (1)

[Claims] 1 In producing 5-ethylidene-2-norbornene by isomerizing 5-vinyl-2-norbornene in the presence of a catalyst in an inert gas atmosphere, a catalyst is added to hydrated alumina based on the molar amount of water in the alumina. A solid base on which 1.01 to 2 equivalents of alkali metal is reacted at a temperature of 180 to 350°C at which the alkali metal is reacted in an amount exceeding the equivalent amount relative to the molar amount of water in the alumina. A method for producing 5-ethylidene-2-norbornene, characterized by using.