JPH0674221B2 - Alkenyl norbornene isomerization method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for isomerizing alkenylnorbornene, and more specifically, in isomerizing alkenylnorbornene to alkylidenenorbornene, the use of a specific fixed base as a catalyst. The present invention relates to a characteristic isomerization method of alkenylnorbornene.

<Prior arts, problems to be solved by the invention> Alkylidene norbornene obtained by isomerization of alkenyl norbornene is an ethylene / propylene / diene monomer terpolymer which is a synthetic rubber, and is extremely useful as a third component of so-called EPDM. It is a useful compound, and is usually produced by isomerizing alkenylnorbornene obtained by the Diels-Alder reaction of a butadiene derivative and a cyclopentadiene derivative in the presence of a catalyst.

As a catalyst for such an isomerization reaction, a liquid base, for example, a mixture of an alkali metal hydroxide and an aprotic organic solvent, an alkali metal amide and an amine, or an organic alkali metal and an aliphatic amine is known. However, in the method using such a liquid base reagent, the catalytic activity is not sufficient and a large amount of an expensive reagent is required, and it is difficult to separate and collect 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 consumed.

Further, as a solid isomerization catalyst, a catalyst in which an alkali metal is dispersed in a carrier having a large surface area, such as activated carbon, silica gel, or alumina, is known (J. Am. Chem. Soc.
82 887 (1960)). However, such a solid catalyst is one in which the alkali metal itself is simply finely dispersed on the carrier, and when contacted with air, it is ignited and deactivated,
There were major problems in terms of operability and safety. The isomerization ability was also unsatisfactory.

The present inventors have already found a new catalyst using alumina, an alkali metal hydroxide, and an alkali metal as a raw material as an efficient catalyst that does not have the problems of the isomerization catalyst, and this one also ignites in the air. It has been found that it is safer and is industrially excellent as an isomerization catalyst without being accompanied by such a danger (Japanese Patent Publication No. 50-3274). However, the isomerization ability is not always satisfactory.

Also known is a method in which a solid catalyst having an alkali metal hydride supported on a carrier is used in combination with ammonia or hydrazine (JP-A-53-121753 and JP-A-59-134736).
Issue). However, in this method, since ammonia, hydrazine and the like are used as an auxiliary agent, the auxiliary agent must be separated and recovered from the reaction mass, and a device for separation and recovery is required and the operation is complicated. Have a point.

As a result of intensive studies to solve the problems of the above-mentioned known methods, the present inventors have found that a solid base catalyst obtained by heating alumina and alkali metal pretreated with an alkali metal salt of carbonic acid at a specific temperature. Was found to have a remarkably high isomerization ability, and the present invention was completed by further conducting various studies.

<Means for Solving the Problems> That is, in the present invention, in isomerizing alkenylnorbornene to alkylidenenorbornene, alumina and alkali metal pretreated with an alkali metal salt of aluminate in an inert gas atmosphere are used as catalysts. The present invention provides an industrially excellent alkenylnorbornene isomerization method characterized by using a solid base obtained by heating the above.

Examples of the alkali metal which is a raw material of the fixed base in the present invention include alkali metals such as sodium, potassium and lithium of Group I of the periodic table. Two or more kinds of alkali metals can be used.

Examples of alumina pretreated with an alkali metal salt of carbonic acid include alumina pretreated with a carbonate of an alkali metal such as sodium, potassium, lithium or rubidium of the Periodic Table 1.

As the alumina to be treated, various forms of alumina other than α-alumina are used, and in particular, high surface area alumina such as γ-, χ-, and ρ-type is preferably used. A water-containing product can also be used.

Alumina interacts with alkali metal salts of carbonic acid and alkali metals to form a certain kind of new bond and also serves as a carrier. Therefore, in addition to alumina, alumina-containing substances such as kaolin and alumina silicate are also included. Although it can be used, the above-mentioned alumina is preferable.

The pretreatment of alumina is usually carried out by impregnating it with an aqueous solution of an alkali metal salt of carbonic acid and then firing it. The impregnation amount of the alkali metal salt of carbonic acid is usually 5 to 80% by weight, preferably 5 to 20% by weight, based on alumina. The firing temperature is usually 300 to 700 ° C.

The fixed base used in the present invention is prepared by heating alumina and alkali metal pretreated with an alkali metal salt of carbonic acid in an inert gas under a specific temperature, and nitrogen is used as the inert gas. Helium, argon, etc. are exemplified.

The solid base used in the present invention is extremely important in its preparation temperature, in particular, the temperature at which the alumina pretreated with the alkali metal salt of carbonic acid and the alkali metal are allowed to act by heating, and the catalyst activity is significantly affected. Its preparation temperature is 200-350
C., preferably 220 to 340.degree.

By preparing at such a temperature, a solid base catalyst having a remarkably high activity, which has never been obtained, can be obtained, and the target reaction can be efficiently completed with a small amount of the catalyst.

The heating time varies depending on the selected temperature conditions, but usually
10 minutes to 10 hours.

Thus, the fixed base used in the present invention is produced. It is considered that the solid base is such that alumina, an alkali metal salt of carbonic acid and an alkali metal act on each other under heating to generate a new active species, which is remarkably high in activity as compared with known catalysts, and ammonia and hydrazine. The desired reaction can be completed without any auxiliary agents, even in small amounts.

The present invention uses such a solid base to isomerize alkenyl norbornene into alkylidene norbornene. Examples of the alkenyl norbornene include 5-vinyl-2-norbornene, 5-propenyl-2-norbornene and 5-isopropenyl-2-. Norbornene, 5-butenyl-2-norbornene, 5-vinyl-6-methyl-
2-norbornene and the like can be mentioned.

Upon isomerizing, the amount of the solid base used is usually 1 / 3,000 to 1/20 weight, and 1 / 2,000 to 1/100 weight is sufficient with respect to the alkenylnorbornene. Regarding the isomerization temperature, the reaction proceeds sufficiently even at room temperature, so that it is not particularly necessary to heat it, but it may be heated depending on the purpose. It is usually carried out in the temperature range of -30 to 120 ° C, preferably -10 to 100 ° C.

If necessary, the reaction can be carried out by diluting with an inert catalyst, for example, hydrocarbons such as pentane, hexane, heptane, dodecane, etc., but the desired high-quality alkylidene norbornene can be obtained only by separating the catalyst after the reaction. Because
It is preferable to select a non-contact body or the above-mentioned solvent used in the next step.

The method of the present invention can be carried out by either a batch method or a continuous method, and it is also effective to pretreat alkenylnorbornene with a desiccant such as alumina in advance for isomerization. In order to carry out isomerization more safely, it may be carried out under an inert gas atmosphere.

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

<Effects of the Invention> Thus, although the alkylidene norbornene which is the object of the present invention can be obtained, according to the method of the present invention, compared to known methods,
The method of the present invention is extremely advantageous as an industrial isomerization method of alkenylnorbornene because it can complete the isomerization of alkenylnorbornene very efficiently with a small amount of catalyst and without requiring an auxiliary agent such as ammonia or hydrazine. .

In addition, the reaction can be safely proceeded without risk of ignition, and further, the target product is selectively produced with almost no by-products such as a polymerized product, resulting in high yield and high yield. The present invention is also advantageous in that a high quality alkylidene norbornene is obtained.

<Example> The present invention will be described below with reference to specific examples, but the present invention is not limited thereto.

Reference Example 1 In an 800 ml flask, 15.0 g of potassium carbonate was dissolved in 200 ml of water, and 109 g of γ-alumina was added to this, and water was distilled off under reduced pressure while stirring at 60 ° C. to dry, and 123.3 g of solid Got

Reference Example 2 25.0 g of the solid obtained in Reference Example 1 was placed in a 100 ml flask and heated at 450 ° C. for 4 hours while stirring in a nitrogen stream, and then 800
The temperature was lowered to 0 ° C., 1.0 g of sodium was added, and the mixture was stirred at the same temperature for 1 hour and then allowed to cool to obtain 23.4 g of a solid base.

Reference Examples 3 to 6 The solid bases shown in Table 1 were obtained in the same manner as in Reference Example 2 except that shown in Table 1.

Example 1 0.28 g of the solid base prepared in Reference Example 2 was placed in a 150 ml flask under a nitrogen atmosphere, 44.6 g of 5-vinyl-2-norbornene (purity 99.9%) was added thereto, and the mixture was stirred at 15 to 20 ° C. for 4 hours. did. After the reaction, the reaction solution was analyzed by gas chromatography to find that it was 5-vinyl-2-norbornene (VN
B) 0.4% and 5-ethylidene-2-norbornene 99.5%. Apart from the catalyst, 44.1 g of product was obtained.

Examples 2, 3 and Comparative Examples 1, 2 5-vinyl-as in Example 1 except that shown in Table 2.
The isomerization of 2-norbornene was performed. Table of the results
Shown in 2.

Example 4 A glass tube with an outer tube having an inner diameter of 5 mmφ and a length of 100 mm was filled with 0.98 g of the solid base prepared in Reference Example 2 under a nitrogen atmosphere.

Pour cooling water of 15 to 20 ° C into the outer tube, and from the top of the inner tube to 3.4g / h
VNB (purity 99.9%) was introduced at a flow rate of r.

The composition of the reaction liquid flowing out from the lower part of the reactor was as follows.

Time (hr) VNB (%) ENB (%) 15 0.3 99.5 25 0.3 99.5 35 0.3 99.5 45 0.3 99.5 Total discharge 151.5 g, ENB average purity was 99.5%.

Claims (1)

[Claims] 1. To isomerize alkenyl norbornene to alkylidene norbornene, alumina and alkali metal pretreated with an alkali metal salt of carbonic acid in an inert gas atmosphere are heated at 200 to 850 ° C. as a catalyst. A method for isomerizing alkenylnorbornene, which comprises using the obtained solid base.