KR950003114B1 - Process for preparing 5-ethylidene-2-norbornene - Google Patents

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Description

Method for preparing 5-ethylidene-2-norbornene

The present invention relates to a process for producing 5-ethylidene-2-norborene (hereinafter referred to as "ENB"). In particular, the present invention relates to a process for producing ENB by isomerizing 5-vinyl-2-norbornene (hereinafter referred to as "VNB") in the presence of a particular solid base catalyst.

ENB is the most promising compound as the tertiary monomer of terpolymers of ethylene, propylene and diene monomers (EPDM rubber) and is prepared by isomerizing VNB in the presence of a catalyst. VNB is produced by reacting 1,3-butadiene and cyclopentadiene.

As isomerization catalysts, liquid bases such as mixtures of alkali metal hydroxides and aprotic organic solvents, mixtures of alkali metal amides and amines, and mixtures of organic alkali metal compounds and aliphatic amines are known. However, these liquid bases do not have sufficient catalytic activity and therefore expensive catalysts must be used in large quantities. In addition, it is very difficult to separate and recover the catalyst components from the reaction mixture, which requires complicated separation and recovery steps and consumes a large amount of energy.

Alkali metals (eg, activated carbon, silica, gels, alumina, etc.) supported on solid isomerization catalysts, for example, anhydrous carriers having a large area, are also known. J. Am. Chem. Soc., 82, 387 (1960). However, these solid catalysts are difficult to handle and less stable because they ignite on contact with air and lose activity. This is because the alkali metal is finely dispersed in the carrier. In addition, the solid carrier has insufficient isomerization activity.

The inventors have proposed a solid base catalyst which isomerizes olefins such as VNB, which does not have the drawbacks of known isomerization catalysts. This proposed catalyst is made from alumina, alkali metal hydroxides and alkali metals or from hydrous alumina and alkali metals. Solid base catalysts have high stability to air and have an isomerization activity of olefins (e.g. VNB) superior to alkali metal dispersion catalysts [cf. Japanese Patent Publication Nos. 3274/1975 and 21378/1982].

It is an object of the present invention to provide an improved catalyst for isomerizing VNBs to produce ENBs.

It is still another object of the present invention to provide a method for producing ENB by isomerizing VNB in the presence of a solid base catalyst having higher catalytic activity than the catalyst described above and exhibiting a catalytic effect in small amounts.

The above and other objects of the present invention are contained in a solid base catalyst prepared by reacting alumina and an alkali metal hydroxide at 200 to 500 ° C. and then reacting the reaction product with an alkali metal at 180 to 350 ° C., and water-containing alumina and alumina. At least one selected from the group consisting of a solid base catalyst prepared by reacting an alkali metal in an amount corresponding to a molar equivalent of water at a melting point of the alkali metal at 500 ° C. and then reacting the resulting reaction product with an alkali metal at 180 ° C. to 350 ° C. It is achieved by the process for producing ENB according to the invention, characterized in that the VNB isomerized in the presence of a catalyst of.

In the method of the invention, in the isomerization of the VNB to ENB, the catalysis of the catalyst is carried out at the production temperature, i.e. This reaction was completed based on the finding that the reaction temperature, in particular the hydrous alumina, was affected by the temperature of the reaction with an excess of alkali metal relative to the molar amount of water contained in the alumina.

Examples of alkali metal hydroxides are lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide and cesium hydroxide and mixtures thereof and can be used in the solid or liquid state.

As the alkali metal, alkali metals of Group 1 of the periodic table are used, for example sodium, potassium and rubidium. These are used as mixtures or alloys. Of these, sodium, potassium and their alloys are preferred.

Alkali metals and alkali metal hydroxides are generally used in combination with alkali metals and their corresponding alkali metal hydroxides, such as sodium and sodium hydroxide, potassium potassium hydroxide, etc., but with alkali metals and other alkali metal hydroxides. For example, a combination of potassium and sodium hydroxide, a combination of sodium and potassium hydroxide, or a combination of sodium and lithium hydroxide can be used. Substantially preferred is a combination of sodium metal and sodium hydroxide. The amounts of alkali metal and alkali metal hydroxide are 2 to 10% by weight and 5 to 40% by weight, respectively, based on the weight of alumina in terms of catalytic activity.

In general, alumina having a large surface area such as γ-, χ-, ρ-, and η-alumina is used. Of these, 50 to 500 mesh alumina, in particular γ-alumina of such a mesh, is preferred from the viewpoint of catalytic activity. Alumina-containing compounds such as kaolin and alumina silicate can be used in place of alumina because alumina not only reacts with alkali metals and alkali metal hydroxides but also acts as a carrier, but is less preferred.

According to the present invention, alumina, alkali metal and alkali metal hydroxides are reacted at the above-mentioned special temperatures to provide a solid base catalyst. In the reaction order, preferably, first, the alumina and the alkali metal hydroxide are reacted, and then the alkali metal is reacted. Although the reaction can be carried out by using an aqueous alkali metal hydroxide solution and heating the reaction mixture to a special temperature, the alkali metal hydroxide, which is stored at a temperature above its melting point, is usually added to the alumina and reacted at a special temperature. Alkali metal can also be added in the form of a solution and heated to a special temperature to effect the reaction, but alkali metal is added at a temperature above its melting point and reacted at a particular temperature. The reaction is preferably carried out in an inert gas such as nitrogen, helium and argon.

In the present invention, the properties of the prepared solid base catalyst are influenced by the reaction temperature. In particular, the catalytic activity of the catalyst is greatly influenced by the temperature at which the alkali metal reacts.

The alumina and the alkali metal hydroxide are reacted at 200 to 500 ° C, preferably 250 to 450 ° C, and the alkali metal is reacted at 180 to 350 ° C, preferably 200 to 300 ° C.

By reacting the compound at this temperature, a catalyst with very high activity is prepared. Therefore, isomerization of VNB to ENB can be effectively performed even with a small amount of catalyst.

The reaction time varies with other reaction conditions such as temperature.

The reaction between alumina and alkali metal hydroxide is completed in 0.5-10 hours, and the reaction of alkali metal is completed in 10-300 minutes.

The solid base catalyst used in the method of the present invention can be produced by reacting hydrous ammonia with an alkali metal in addition to the above method. This is because alkali metal hydroxides are formed from water and alkali metals contained in ammonia. This catalyst preparation will be described below.

Various types of hydrous alumina can be used except for α-alumina.

Generally, alumina is produced by burning aluminum hydroxide. Depending on the firing temperature and time, various aluminas are produced because the alumina has various metastable states and water contents. In the present invention, such alumina can be used. Preferably, alumina having a large area such as γ-, χ-, ρ-, and η-alumina is used.

Although it is difficult to determine the water content of the alumina, the water content can be expressed in terms of the weight lost by heating during the heating step, in which the alumina in its original state no longer contains water to be removed. Typically, the water content of the hydrous alumina is 1.3 to 10% by weight, preferably 2 to 7% by weight, expressed as weight loss by heating.

The alkali metal used in the present production method is as described above. The total amount of alkali metal to be reacted is larger than the amount corresponding to the molar equivalent of water contained in the alumina, preferably 1.01 to 2 times the molar equivalent of the water contained in the alumina.

According to the invention, in an inert gas such as nitrogen, helium and argon, the hydrous alumina is reacted with an alkali metal in an amount corresponding to at least a molar equivalent of water contained in the alumina, and the excess alkali metal is reacted with the alumina. In this method, the alkali metal to be reacted first and the alkali metal to be reacted next may be the same or different.

In the second process for preparing solid base catalysts, the reaction temperature, in particular the reaction temperature of the second stage, has a significant influence on the properties of the catalyst.

In the first reaction of hydrous alumina with an alkali metal in an amount corresponding to the molar equivalent of water contained therein, the reaction temperature is from the melting point of the alkali metal to 500 ° C. In the second reaction of alumina with excess alkali metal, the reaction temperature is 180 to 350 ° C, preferably 200 to 330 ° C. Preferably, the first reaction temperature and the second reaction temperature should be substantially equal. In this case, reaction temperature becomes like this. Preferably it is 180-350 degreeC, More preferably, it is 200-330 degreeC. In this case, alkali metals can be added all at once.

By reacting the compounds at such temperatures, very high activity catalysts are prepared. Therefore, the isomerization reaction of VNB to ENB is effectively performed even with a small amount of catalyst.

The reaction time varies depending on other reaction conditions such as reaction temperature. Usually, reaction time is 15 minutes-10 hours.

Thus, a solid base catalyst of very enhanced activity is obtained as compared to known catalysts.

In the process of the invention, the VNB isomerizes to ENB in the presence of a solid base catalyst prepared as described above. The weight ratio of catalyst to VNB is from 1: 3,000 to 1:50, preferably from 1: 2,000 to 1: 100. Since the isomerization reaction proceeds at room temperature, it is not necessary to heat the reaction system. The reaction temperature may be raised to speed up the isomerization. Usually, reaction temperature is -30-130 degreeC and -10-100 degreeC.

The isomerization reaction can be carried out in an inert liquid medium such as hydrocarbons (eg hexane, heptane and dodecane), but can be carried out without the reaction medium.

The isomerization reaction of the present invention can be carried out batchwise or continuously. The isomerization reaction is preferably carried out in an atmosphere of inert gas. If desired, the VNB is pretreated with a desiccant such as alumina before isomerization.

The isomerization product is analyzed by known methods such as gas chromatography and separated from the catalyst by known separation methods such as filtration.

According to the present invention, ENB can be obtained in high yield by isomerizing VNB in the presence of much less catalyst than known catalysts without substantial formation of byproducts such as polymers. Furthermore, isomerization can be carried out safely without risk of ignition.

Preferred embodiments of the invention are described below.

Reference Example 1

Γ-alumina (31.9 g) was added to a 100 ml flask and heated to 490-500 ° C. for 1 hour with stirring under a nitrogen atmosphere. After cooling to 300 ~ 310 ℃ sodium hydroxide (4.5g) was added, and stirred at the same temperature for 3 hours.

Sodium metal (1.5 g) was added, stirred at the same temperature for 1 hour and then cooled at room temperature to give a solid base (34.9 g).

Example 1

To a 200 ml flask was added VNB (82.5 g) under nitrogen. Solid base (0.25 g) prepared in Reference Example 1 was added and stirred at 15-20 ° C. for 6 hours.

The solid catalyst was filtered off to give a reaction mixture (81.9 g). Gas chromatographic analysis of the mixture showed 99.4% ENB and 0.5% VNB in the mixture.

Reference Example 2

Γ-alumina (31.9 g) was added to a 100 ml flask and heated to 490-500 ° C. for 1 hour with stirring under nitrogen. It cooled to 300-310 degreeC, sodium hydroxide (3.0g) was added, and it stirred at the same temperature for 3 hours.

Sodium metal (1.2 g) and potassium metal (0.3 g) were added, stirred at the same temperature for 30 minutes and then cooled to room temperature to give a solid base (33.8 g).

[Reference Examples 3-11]

A solid base catalyst was prepared in the same manner as in Reference Example 1 except that the reaction was performed under the conditions shown in Table 1.

[Examples 2-9 Comparative Examples 1-2]

The same procedure as in Example 1 was carried out, but VNB was isomerized using the solid base catalysts prepared in Reference Examples 2-9 and Comparative Examples 1-2. The results are shown in Table 2.

TABLE 1

TABLE 2

Reference Example 12

To the 100 ml flask was added γ-alumina (30.0 g) containing 2.2% by weight of water and heated to 300 ° C. for 1 hour with stirring in a nitrogen stream. Metal sodium (1.2 g) was added, stirred at the same temperature for 1 hour and then cooled to room temperature to yield an off-white solid base (30.9 g).

Example 10

The solid base catalyst (0.25 g) and VNB (64.5 g) prepared in Reference Example 12 were sequentially added to a 200 ml flask under a nitrogen atmosphere, and stirred at 15 to 20 ° C. for 8 hours. The catalyst was filtered off to give a reaction mixture (63.9 g). Gas chromatography analysis of the mixture showed that the mixture contained 99.5% ENB and 0.4% VNB.

[Reference Examples 13-21]

A solid base was prepared in the same manner as in Reference Example 12 except that the reaction was performed under the conditions shown in Table 3.

[Examples 11-15 and Comparative Examples 3-6]

In the same manner as in Example 10, VNB was isomerized using the solid bases prepared in Reference Examples 13 to 21 and Comparative Examples 3 to 6 as catalysts. The results are shown in Table 4.

TABLE 3

TABLE 4

Reference Example 22

To a 100 ml flask was added alumina (50 g) containing γ-alumina and 6.0 wt% water, and heated to 200 ° C. under nitrogen injection with stirring. At the same temperature, metal sodium (4.0 g) was added in portions over 20 minutes. After stirring for 1 hour, it was slowly heated to 300 ℃. At this temperature, metal sodium (1.9 g) was further added in portions over 10 minutes, and stirred at the same temperature for 3.5 hours to give a solid base (54.2 g).

Reference Example 23

Alumina (50 g) containing γ-alumina and 6.0% by weight of water was added to a 100 ml flask and heated to 200 ° C. while stirring under a stream of nitrogen. At the same temperature, metal sodium (4.0 g) was added in portions over 20 minutes. After stirring for 1 hour, it was slowly heated to 400 ℃. At this temperature, metal sodium (1.9 g) was added in small portions over 10 minutes and heated at the same temperature for 3.5 hours to give a solid base (54.1 g).

Example 16

To the 200 ml flask was added solid base (0.25 g) and VNB (62.5 g), prepared in Reference Example 22, sequentially under a nitrogen atmosphere and stirred at 15-20 ° C. for 8 hours.

The solid catalyst was filtered off to give a reaction mixture (62.0 g). Gas chromatography analysis of the mixture showed the mixture to contain 99.5% ENB and 0.3 VNB.

Comparative Example 7

The solid base (0.25 g) and VNB (62.5 g) prepared in Reference Example 23 were sequentially added to a 200 ml flask under nitrogen atmosphere and stirred at 15 to 20 ° C. for 8 hours.

The solid catalyst was filtered off to give a reaction mixture (61.9 g). Gas chromatography analysis of the reaction mixture showed that the mixture contained 59.8% ENB and 40.1% VNB.

Claims (16)

A solid base catalyst prepared by reacting alumina with an alkali metal hydroxide at 200 to 500 ° C. and then reacting the reaction product with an alkali metal at 180 to 350 ° C., and an alkali corresponding to a molar equivalent of water contained in the hydrous alumina and alumina. 5-vinyl-2-norbor in the presence of at least one catalyst selected from the group consisting of a solid base catalyst prepared by reacting a metal at a melting point of an alkali metal at 500 ° C. and then reacting the reaction product with an alkali metal at 180 to 350 ° C. A method for producing 5-ethylidene-2-norbornene, characterized in that isomerization of nene. The process for producing 5-ethylidene-2-norbornene according to claim 1, wherein the solid base catalyst is prepared by heating alumina, alkali metal hydroxide and alkali metal. The method for producing 5-ethylidene-2-norbornene according to claim 2, wherein the alumina and the alkali metal hydroxide are reacted at 250 to 450 캜. The method for producing 5-ethylidene-2-norbornene according to claim 2, wherein the alkali metal is reacted at 200 to 330 ° C. The process for producing 5-ethylidene-2-norbornene according to claim 2, wherein the alkali metal hydroxide is selected from the group consisting of lithium hydroxide, sodium hydroxide, potassium hydroxide and cesium hydroxide and mixtures thereof. The method for producing 5-ethylidene-2-norbornene according to claim 2, wherein the alumina is selected from the group consisting of γ-alumina, χ-alumina, ρ-alumina, η-alumina and mixtures thereof. The method for producing 5-ethylidene-2-norbornene according to claim 6, wherein the solid base catalyst is prepared by heating alumina and an alkali metal. 8. The process for producing 5-ethylidene-2-norbornene according to claim 7, wherein the alkali metal is used in an amount corresponding to 1.01 to 2 times the molar equivalent of water contained in the alumina. 8. The 5-ethylidene-2-norbornene according to claim 7, characterized in that an excess amount of alkali metal is reacted at 200 to 330 DEG C in the presence of a catalyst with respect to the molar equivalent of water contained in the hydrous alumina and the alumina. Manufacturing method. 8. The 5-ethylidene-2-norbornene according to claim 7, wherein the alumina and the molar equivalent of the alkali metal and the alumina and the molar equivalent of the alkali metal are reacted at 200 to 330 DEG C in the presence of a catalyst. Manufacturing method. 8. The 5-ethylidene-2-norbornene according to claim 7, characterized in that the hydrous alumina is selected from the group consisting of γ-alumina, χ-alumina, ρ-alumina, preferably prepared by burning ammonium hydroxide. Manufacturing method. 8. The process for producing 5-ethylidene-2-norbornene according to claim 7, wherein the water content of alumina is 1.3 to 10% by weight. 8. The process for producing 5-ethylidene-2-norbornene according to claim 7, wherein the water content of alumina is 2-7 wt%. 8. A process according to claim 7, wherein the alkali metal is at least one selected from the group consisting of sodium, potassium and rubidium and mixtures and alloys thereof. The process for preparing 5-ethylidene-2-norbornene according to claim 1, wherein the weight ratio of solid base catalyst to 5-vinyl-2-norbornene is from 1: 2,000 to 1: 100. The method for producing 5-ethylidene-2-norbornene according to claim 1, wherein the temperature of the isomerization reaction is -10 to 100 ° C.