JPS62155227A - Production of high-quality 5-ethylidene-2-norbornene - Google Patents

Abstract

PURPOSE:To obtain the titled compound, by isomerizing 5-vinyl-2norbornene containing restricted amount of 4-vinylcyclohexene using a solid basic catalyst prepared by heating hydrated alumina and a specific amount of an alkali metal in an inert gas. CONSTITUTION:A high-quality 5-ethylidene-2-norbornene can be produced by isomerizing 5-vinyl-2-norbornene containing 1ppm-0.5wt%, practically 5ppm-0.1 wt% 4-vinylcyclohexene in the presence of a solid basic catalyst prepared by heating hydrated alumina and an alkali metal (e.g. Na, K, etc.) in an inert gas atmosphere (e.g. N2, He, etc.) at 180-500 deg.C, especially 200-330 deg.C. The amount of the alkali metal is >=1 equivalent, preferably 1.01-2 equivalent based on the molar amount of water in the hydrated alumina. USE:A third component of EPDM.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing high-grade 5-ethylidene-2-norbornene, and more specifically, the present invention relates to a method for producing high-grade 5-ethylidene-2-norbornene. The present invention relates to a method for producing 5-ethylidene-2-norbornene (hereinafter abbreviated as ENB), which is characterized by isomerizing 5-vinyl-2-norbornene (hereinafter abbreviated as vNB) which has been suppressed to 5-vinyl-2-norbornene.

ENB is an extremely useful compound as the third component of the synthetic rubber ethylene-propylene-diene monomer terpolymer, so-called EPDM, and is usually obtained by the reaction of 1,8-butadiene and cyclopentadiene.
It is produced by isomerizing B in the presence of a catalyst.

As catalysts for such isomerization reactions, liquid bases such as mixtures of alkali metal hydroxides and aprotic organic solvents, alkali metal amides and amines, or organic alkali metals and aliphatic amines are known. however,
Methods using such liquid base reagents do not have sufficient catalytic activity, require a large number of expensive reagents, and require a complicated separation and recovery process to separate and recover the reagents from the reaction mass. The problem is that separation of unreacted VNB and product ENB is not only necessary, but also difficult and consumes a large amount of energy.

Also, 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, 82887 (1960). However, in such a solid catalyst, the alkali metal itself is merely finely dispersed on a carrier, and when it comes into contact with air, it ignites and becomes deactivated, so there are major drawbacks in terms of operability and safety. Also, the isomerization ability was unsatisfactory.

The present inventors have already developed new catalysts using alumina, alkali metal hydroxides, and alkali metals as raw materials and hydrous alumina and alkali metals as raw materials, as efficient catalysts that do not have to deal with the problems of isomerization catalysts. In addition, we discovered that these solid base catalysts are safer and industrially superior as catalysts for the isomerization of olefins such as VNB without the risk of ignition even in the air. (Special Publication No. 57-21878).

However, when we continued to study the isomerization of VNB using such a solid base catalyst using industrial VNB, it was found that in some cases, ENB of lower quality could be obtained. It has also been found that when such ENB is used as the third component of EPDM, it exhibits undesirable effects such as lowering the catalyst efficiency of polymerization and changing the molecular weight distribution of EPDM.

Therefore, the inventors of the present invention have conducted extensive studies on stabilizing the quality of ENB, and have found that the main cause of the decline in the quality of ENB is the raw material VN.
By discovering that VCH is VCH in B and using VNB with a specific VCH content, the quality of ENB can be improved, and ENB can be directly converted into ENB by simply separating the catalyst after the isomerization reaction.
High-quality ENB that can be used as the third component of PDM
They found that this can be efficiently obtained, and after further various studies, they completed the present invention.

That is, in producing 5-ethylidene-2-norbornene by isomerizing 5-vinyl-2-norbornene, the present invention uses hydrated alumina and an alkali metal in an amount exceeding the equivalent amount to the molar amount of water in the alumina. 5-vinylcyclohexene content is suppressed to 1 ppm to 0.5% by weight in the presence of a solid base catalyst which is heated at a temperature of 180 to 500°C in an inert gas atmosphere.
The present invention provides an efficient method for producing high-grade 5-ethylidene-2-norbornene, which is characterized by isomerizing vinyl-2-norbornene.

The solid base catalyst used in the present invention is prepared by heating hydrated alumina and a specific amount of alkali metal at a specific temperature. is used.

Alumina is usually produced by firing aluminum hydroxide, and it is known that alumina exists in various forms, taking various metastable structures depending on the firing temperature and firing time, and the amount of water contained therein also differs. In the present invention, such alumina is mainly used. Especially γ-
High surface area hydrated alumina such as 2χ-9ρ-type is preferably used. Hydrous materials containing alumina, such as kaolin and alumina silicate, can also be used, but the alumina is particularly preferred. It is also said that as the firing temperature increases, the alumina will eventually turn into α-alumina, and the loss of alumina on heating will disappear. Although it is not so easy to measure the amount of water contained in alumina, it can be expressed as the loss of water on heating until the initial plate-shaped alumina is converted to α-alumina. The moisture content of hydrated alumina is usually 1.3 to 10! The percentage is preferably in the range of 2 to 7% by weight.

Examples of the alkali metal, which is another raw material for the catalyst used in the present invention, include sodium, potassium, rubidium, etc. from Group 1 of the periodic table. It is no problem to use more than 20% of these alkali metal scraps, and these alloys,
For example, an alloy of sodium and potassium may be used.

The amount of the alkali metal used must exceed the molar amount of water in the hydrated alumina, preferably 1.01 to 2 times the molar amount of water.

When alkali metal is made to act on hydrated alumina, a predetermined amount of alkali metal may be added at once, or the remaining amount of alkali metal may be added after adding the amount of water in hydrated alumina to our company's level and allowing a sufficient reaction. . In the latter case, the alkali metal added first and the alkali metal added later may be different.

The catalyst used in the present invention is prepared by reacting the above-mentioned hydrated alkali with an alkali metal at a specific temperature in an inert gas atmosphere, but nitrogen is used as the inert gas. , helium, argon, etc.

The preparation temperature of the catalyst used in the present invention, that is, the temperature at which hydrated alumina and alkali metal are allowed to interact with each other, is extremely important, and is usually 180 to 500°C. Especially 180 to 86011c, more preferably 200 to 8
If the catalyst is prepared at a temperature of 80° C., 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.

Heating time varies depending on the temperature conditions selected, but is usually 15
Minutes to 10 hours is sufficient.

The present invention utilizes the thus obtained solid base catalyst to produce VNB
is isomerized to ENB, and the VNB used has a VCH content of t ppm to 0.5% by weight, more practically 51)1)m to 0.1% by weight. Such VNB can be obtained, for example, by distilling a reaction product of butadiene and cyclopentadiene.

If more than 0.5% by weight of VCH is present in the VNB, ENB with reduced quality is obtained, which cannot be used as the third component of EPDM only by separating the catalyst, which is complicated and inefficient. It is necessary to purify it by distillation etc. Using VNB with suppressed VCH content as a raw material is an important factor for obtaining high-quality F and NB.

Regarding the influence of VCH in VNB on ENB quality, 2-ethylidenenorbornane, ethylbenzene, etc. are detected in the reaction solution after isomerization when vCH is present, so VCH is isomerized and dehydrogenated to ethylbenzene. It is thought that the hydrogen generated at this time causes side reactions such as saturating the double bonds of ENB, etc., and as a result, the purity of the product ENB decreases, making it undesirable as a third component of EPDM.

The present invention isomerizes the above-mentioned specific VNB in the presence of the above-mentioned specific solid base catalyst, but the amount of the solid base catalyst used relative to the VNB is usually 1/2,0.
00 to 115 weight, preferably 1/1,000
The weight is 1/20 to 1/20.

Regarding the isomerization temperature, since the reaction proceeds satisfactorily even at room temperature, there is no particular need for heating, but heating may be used depending on the purpose. Usually -80 to 120℃, preferably -10℃
The temperature range is from 100" to 100"C.

If necessary, the reaction can be carried out by diluting with an inert medium such as a hydrocarbon such as pentane, hexane, heptane, dodecane, etc., but no medium is sufficient. The method of the present invention can be carried out either batchwise or continuously, and for isomerization,
It is also effective to pre-treat VNB with a desiccant such as alumina. In order to carry out isomerization more safely and reliably, it may be carried out under an inert gas atmosphere.

The isomerization reaction product is analyzed by a known method such as gas chromatography and separated from the catalyst by filtration or the like.

The ENB obtained in this way is of high quality as it is,
It can be fully used as a third component of EPDM, etc.

According to the method of the present invention, high-quality ENB can be obtained by simply separating the catalyst after the isomerization reaction without undergoing inefficient purification steps such as rectification, and ENB can be produced on an industrial scale. Extremely advantageous for production.

The present invention will be explained in more detail with reference to Examples below.
The present invention is not limited only to the examples.

Reference Example 1 γ-Alumina go, oy containing 2.0% moisture was placed in a 100 ml flask and heated to 290 to 800°C while stirring in a nitrogen gas stream.

0.9 g of metallic sodium was introduced into this material, and at the same temperature
After stirring for an hour, the mixture was allowed to cool to room temperature. Thus, 80
．． A 7F catalyst was obtained.

Reference Example 2 R-alumina go, oy containing 2.2 fl % of water was placed in a 100 ml flask and heated to 810 to 820°C while stirring in a nitrogen gas stream.

1.2g of metallic sodium was introduced into this material and 1.2g of sodium was introduced at the same temperature.
After stirring for an hour, the mixture was allowed to cool to room temperature. Thus, Bo
, 7 fl of catalyst was obtained.

Reference Example 8 γ-Alumina so, oy containing 2.2% by weight of water was placed in a 100 ml flask and heated to 400 to 410° C. while stirring in a nitrogen gas stream.

1.21% of metallic sodium was introduced into this material, and at the same temperature
After stirring for an hour, the mixture was allowed to cool to room temperature. Thus, 80
．． 61 catalysts were obtained.

Example 1 0.18 f of the catalyst prepared in Reference Example 1 was placed in a 100 ml flask under a nitrogen atmosphere, and 5-vinyl-2-norbornene (purity 99.9%) 87, containing 20 ppm of 47 vinylcyclohexene, was added. Add 71 and 8 at 20℃
Stir for hours.

After the reaction, when the catalyst is filtered off, 87. Of (yield 98
%) of the reaction solution was obtained. When this material was analyzed by gas chromatography, 4-vinylcyclohexene was not detected.
Ethylbenzene 0.002%, 5-vinyl-2-norbornene 0.89%, 5-ethylidene-2-norbornene 99.47%, 2-ethylidenenorbornane 0.002
%, 1-vinylnortricyclene 0.088%.

Example 2 In a 100 ml flask under a nitrogen atmosphere,
0.241% of the W-treated catalyst was added thereto, and 59.01M [99.5%] of 5-vinyl-2-norbornene containing 0.4% of 4-vinylcyclohexene was added thereto, and the mixture was stirred at 15°C for 8 hours.

After the reaction, the catalyst was removed by filtration to obtain a reaction solution with a yield of 58.31% (99%). When this product was analyzed by gas chromatography, 4-vinylcyclohexene was not detected, ethylbenzene was 0.89%, and 5-vinyl-2-norbornene was 0.
．． 49%, 5-ethylidene-2-norbornene 98.5
9%, 2-ethylidenenorbornane 0.82%, and 1-vinylnortricyclene 0.082%.

Example 8 0.20 f of the catalyst prepared in Reference Example 1 was placed in a 100 ml flask under a nitrogen atmosphere, and 40.0 g of 5-vinyl-2-norbornene (purity 99.9%) containing 20 ppm of 4-vinylcyclohexene was added. 6F was added and stirred at 50°C for 5 hours.

After the reaction, the catalyst was cooled to room temperature and the catalyst was filtered off.
A reaction solution of F (yield 98%) was obtained.

When this substance was analyzed by gas chromatography, 4
-No vinylcyclohexene detected, ethylbenzene 0.0
02%, 5-vinyl-2-norbornene 0.15%, 5
-ethylidene-2-norbornene 99.48%, 2-ethylidene norbornane 0.002%, and 1-vinylnortricyclene 0.040%.

Example 4 0.521 of the catalyst prepared in Reference Example 3 was placed in a 100 g flask under a nitrogen atmosphere, and 68.8 flt of 5-vinyl-2-norbornene containing 20 ppm of 4-vinylcyclohexene was added to the flask at a concentration of 99.9%. ) and heat at 20°C.
Stir for hours.

After the reaction, when the catalyst was filtered off, 62.6F (yield 99%)
A reaction solution was obtained. When this material was analyzed by gas chromatography, 4-vinylcyclohexene was not detected.
Ethylbenzene 0.002%, 6-pinylene-2-norbornene 0.28%, 5-ethylidene-2-norbornane 99.56%, 2-ethylidene-norbornane 0.00
2%, and 1-vinylnortricyclene 0.034%.

Comparative Example 0.251 of the catalyst prepared in Reference Example 1 was placed in a 100 ml flask under a nitrogen atmosphere, and 5-vinyl-2-norbornene (purity 9a, g%) containing 1.3% of 4-vinylcyclohexene was added to the flask. ) was added thereto, and the mixture was stirred at 20°C for 8 hours.

After the reaction, the catalyst was removed by filtration to obtain 46.8 f (yield: 99%) of the reaction solution. When ξ was analyzed by gas chromatography, 4-vinylcyclohexene was not detected, ethylbenzene was 1.24%, and 5-vinyl-2-norbornene was 0.
82%, 5-ethylidene-2-norbornene 96.91
%, 2-ethylidene-norbornane 1.20%, and 1-vinylnortricyclene 0.084%.

Claims (1)

[Claims] In producing 5-ethylidene-2-norbornene by isomerizing 5-vinyl-2-norbornene, hydrated alumina and an alkali metal in an amount equivalent to the molar amount of water in the alumina are heated in an inert gas atmosphere. The content of 4-vinylcyclohexene was 1 ppm to 0.5 in the presence of a solid base catalyst prepared at a temperature of 180 to 500°C.
High-grade 5-ethylidene-2 characterized by isomerizing 5-vinyl-2-norbornene in a controlled amount by weight%
-Production method of norbornene.