JPH0443890B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for isomerizing at least a part of the endo isomer in dicyclopentadiene containing the endo isomer to the exo isomer. The objective is to lower the freezing point of dicyclopentadiene and provide high purity dicyclopentadiene that is liquid at normal room temperature. [Prior Art] Dicyclopentadiene is a useful compound that is widely used as a raw material for producing agricultural chemicals, medicines, synthetic resins, and the like. Dicyclopentadiene is generally manufactured industrially by dimerizing cyclopentadiene, which is contained in large amounts in the so-called _C5 fraction of the thermal decomposition products of naphtha, and is available in various purity. supplied to the market. Therefore, this dicyclopentadiene is required to have a high purity depending on its use.For example, when it is used as a monomer for optical lenses to which an acrylate monomer is added, a purity of 97% or more is required. 99% as a raw material monomer for crosslinking polymerization using a polymerization catalyst
or higher purity is required. Dicyclopentadiene, which has traditionally been industrially produced and supplied to the market, is a mixture of stereoisomers consisting of endo and exo isomers, but in general, the endo isomer accounts for 95-99% of dicyclopentadiene. ing. However, while the exo isomer is liquid at room temperature, the melting point of the endo isomer is as high as 33.6°C. Therefore, the above-mentioned high-purity product of dicyclopentadiene whose main component is the endo isomer can be produced at the average environmental temperature in a normal factory. It is a solid substance with a freezing point exceeding . However, it is very complicated to industrially transport or store solid dicyclopentadiene, so it is usually handled after being liquefied by heating. However, this requires heat insulation treatment for transfer pipes, storage equipment, etc.
It costs a lot of money to maintain the temperature, making it uneconomical. In addition, since dicyclopentadiene is a highly reactive compound, sealing with an inert gas is used to prevent deterioration due to contact with oxygen. must be carried out more strictly,
The problem was that it was time consuming. On the other hand, as a method for lowering the freezing point of dicyclopentadiene, for example, dicyclopentadiene is added to 5-alkylidenebicyclo[2,2,1]hept-2-ene or 5-alkenylbicyclo[2,2,1]hept-2-ene. A method of mixing 2-ene is known (Japanese Unexamined Patent Publication No. 63-3017, No. 63-
12612). However, this method has drawbacks such as, for example, when used as a raw material for synthetic resin, the additives inhibit the synthetic resin production reaction or have an adverse effect on the resulting synthetic resin. Another possible method for lowering the freezing point of dicyclopentadiene is to isomerize the endo isomer, which has a high freezing point, into the exo isomer, which has a low freezing point. The method for isomerizing the endo-dicyclopentadiene to the exo-isomer is to treat the endo-dicyclopentadiene with hydrogen bromide at 75°C to convert it into a hydrogen bromide adduct of the exo-isomer, which is then converted into an alcoholic A method of obtaining dicyclopentadiene mainly composed of exo isomers by treating with potassium hydroxide and further heating to 170 to 190°C to decompose and remove the remaining endo isomer into cyclopentadiene [Synthesis, 105 (1975)], and a method for isomerizing the endo isomer to the exo isomer by heating dicyclopentadiene to 180-200°C in the presence of a solvent [Angewandte Chemie, 72 , 865 (1960) and
Angewandte Chemie, 73 , 241 (1961)] is known. However, this method requires various chemicals and is complicated to operate.Also, the method produces a large amount of polymer, resulting in a low yield of the target exo-isomer, and it requires a large amount of solvent. None of these methods are satisfactory, as they have the disadvantage that separation is complicated. Furthermore, regarding the isomerization of the endo isomer to the exo isomer, endo-dicyclopentadiene or endo-tetrahydrodicyclopentadiene, which is a hydride of endo-dimethyldicyclopentadiene, or endo-tetrahydrodimethyldicyclopentadiene A known method is to isomerize into each exo isomer using a catalyst such as a Friedel-Crafts catalyst, Ni-silica alumina, activated alumina, or a super strong acid. However, even if such a catalyst is used to isomerize the endo isomer of dicyclopentadiene, the polymerization reaction takes precedence over the isomerization reaction, and the desired exo isomer is hardly obtained. As described above, no method has been proposed so far to efficiently lower the freezing point of dicyclopentadiene whose main component is the endo isomer using a simple operation. There is also no easy way to do so. [Problems to be Solved by the Invention] Therefore, an object of the present invention is to provide a method for efficiently isomerizing the endo isomer of dicyclopentadiene into the exo isomer by a simple operation. Another object of the present invention is to provide a method for efficiently lowering the freezing point of high-purity dicyclopentadiene containing endo-isomer as a main component by a simple operation. Yet another object is to provide highly purified dicyclopentadiene that is liquid at room temperature. [Means for Solving the Problems] Under these circumstances, the present inventors conducted intensive research to achieve the above object, and found that if a specific catalyst is used, a polymerization reaction can be achieved without causing a polymerization reaction.
The endo isomer of dicyclopentadiene can be efficiently isomerized to the exo isomer, and the isomerized dicyclopentadiene containing a certain amount or more of the exo isomer is
The present invention was completed based on the discovery that the isomer has a freezing point of 20°C or less and is liquid under normal environmental conditions, and that the reactivity of this isomer is no different from that of dicyclopentadiene, which has an endo isomer as its main component. . That is, in the present invention, raw material dicyclopentadiene containing an endo isomer is converted into activated clay, acid clay,
At least a portion of the endo-body is brought into contact with one or more catalysts selected from horujasite, X-type zeolite, Y-type zeolite, offretite/erionite, mordenite, ferrierite, silica alumina and strongly acidic ion exchange resin. The present invention provides a method for isomerizing dicyclopentadiene, which is characterized by isomerizing dicyclopentadiene into an exo isomer. As the raw material dicyclopentadiene of the present invention,
If it contains an endo-isomer, its manufacturing method;
Various materials can be used regardless of composition, for example,
Both low-purity dicyclopentadiene containing an inert low-boiling fraction or solvent and high-purity dicyclopentadiene with a purity of 99.8% or more can be used as the raw material in the present invention. Among these, when the present invention is applied to industrially produced high-purity dicyclopentadiene that contains 95 to 99% by weight of the endo isomer and is solid at room temperature, at least a part of the endo isomer is isomerized to the exo isomer. This is particularly preferable because an isomerized product that is liquid at room temperature can be obtained. As the catalyst, one or more selected from the above-mentioned activated clay, acid clay, horujasite, X-type zeolite, Y-type zeolite, offretite/erionite, mordenite, ferrierite, silica alumina, and strongly acidic ion exchange resin. is used. Examples of strong acidic ion exchange resins include Amberlyte 15, 16, 18 and 30, Amberlyte 120 and 200 (Rohm & Haas), Diaion SK-, PK-, HPK- and
RCP-series (Mitsubishi Kasei), Dowex
Examples include 50W-series, HCR-W, MSC-1 (Dow Chemical Company), etc. The isomerization reaction of the present invention can be carried out by any method such as a distribution method or a batch method. In the batch method, the amount of catalyst used is preferably 0.1 to 20% by weight, particularly 1 to 10% by weight, based on the dicyclopentadiene starting material. In addition, in the case of flow method, liquid hourly space velocity (LHSV)
is preferably 0.1 to 3 hr ^-1 , particularly 0.5 to 1 hr ^-1 . The reaction temperature is preferably 40 to 160°C and the reaction time is preferably 0.5 to 4 hours. The pressure may be normal pressure or increased pressure. The isomerized product obtained by isomerization in this manner is optionally subjected to vacuum distillation to remove a low boiling point fraction to obtain a highly purified isomerized dicyclopentadiene. A small amount of polymer produced by the isomerization reaction is also removed by the distillation operation. This isomerized product can be further purified to a high purity depending on the use. According to the present invention, a dicyclopentadiene isomer can be obtained from the raw material dicyclopentadiene in a yield of about 90% or more. In the dicyclopentadiene isomerate, if the content of the exo isomer is 3 parts by weight or more per 100 parts by weight of the endo isomer.
Even when purified to dicyclopentadiene with a high purity of 99% or more, it remains liquid at room temperature, but it is preferable that the exo isomer is contained in an amount of 5.5 parts by weight or more based on 100 parts by weight of the endo isomer. [Effects of the Invention] According to the present invention, endo-dicyclopentadiene can be efficiently converted to exo-dicyclopentadiene using an inexpensive catalyst and with a simple operation, without substantially causing side reactions such as polymerization. Can be isomerized to pentadiene. Furthermore, if the present invention is applied to high-purity dicyclopentadiene, which has an endo isomer as a main component and has a high freezing point, the freezing point of this high-purity dicyclopentadiene can be easily lowered without impairing its reactivity, etc. It can be made into a liquid that is convenient to handle. [Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited by these. Example 1 In a 200 ml Erlenmeyer flask, 100 g of dicyclopentadiene with the composition shown in Table 1 and acid clay (350 g in air) were added.
Bake at ℃ for 5 hours, add 10g of Mizusawa Chemical Co., Ltd.),
The mixture was heated and stirred at 80°C for 4 hours.

【table】

[Table] This was cooled to room temperature, filtered, and then distilled under reduced pressure to obtain 91.2 g of a colorless and transparent liquid. The composition is 66.8% by weight of endo-dicyclopentadiene and 33.2% by weight of exo-dicyclopentadiene.
The freezing point was -44.0°C. Examples 2 to 9 Reactions were carried out in the same manner as in Example 1, except that the type of catalyst and reaction temperature were changed as shown in Table 2. The results are shown in Table 2.

【table】

【table】

[Table] Examples 10 to 12 The reaction was carried out in the same manner as in Example 1, except that the reaction temperature was changed to 110°C, 65°C, and 50°C. The results are shown in Table 3. Comparative Example 1 Using 2 g of anhydrous aluminum chloride as a catalyst,
The reaction was carried out in the same manner as in Example 12 except that the reaction time was 1 hour. The results are shown in Table 3. Comparative Example 2 A reaction was carried out in the same manner as in Comparative Example 1 except that 2 g of boron trifluoride was used as a catalyst. 3rd result
Shown in the table.

[Table] Reference Example An example of use of the dicyclopentadiene isomerized product purified in Example 1 in crosslinking polymerization using a metathesis catalyst will be described. Preparation of catalyst component solution A: 20 g of tungsten hexachloride and 70 ml of dry toluene.
A 0.5 M tungsten-containing catalyst solution was prepared by adding a solution of 21 g of nonylphenol and 16 ml of toluene to the solution in a nitrogen stream, and nitrogen gas was passed through the solution overnight to remove the generated hydrogen chloride gas. This was used as a polymerization catalyst. 10 ml of the catalyst solution, 1.0 ml of acetylacetone,
A solution A having a tungsten content of 0.001M was prepared by mixing 500ml of purified dicyclopentadiene isomerate. Solution A did not solidify when stored at 5°C. Preparation of activator component solution B 0.18 g of diethylaluminum chloride, 0.375 ml of isopropyl ether, and 500 ml of purified dicyclopentadiene isomerate were mixed to prepare solution B with an aluminum content of 0.003 M.
Solution B also did not solidify when stored at 5°C. Crosslinking Polymerization Polymerization was carried out by mixing 1 ml of solution A and 1 ml of solution B in a test tube. The temperature during mixing is
It was 25℃. When the test tube was shaken vigorously, a rapid exotherm was observed after a short induction period, and a solid insoluble polymer was formed. The time required to start polymerization and the maximum temperature of the sample were as shown in Table 4, and there was almost no difference between them and the case of dicyclopentadiene whose main component was endo isomer.

【table】

Claims (1)

[Scope of Claims] 1. Raw material dicyclopentadiene containing an endo isomer is prepared from activated clay, acid clay, hojiasite, X
type zeolite, Y type zeolite, offretite/
erionite, mordenite, fuerierite,
A method for isomerizing dicyclopentadiene, which comprises contacting with one or more catalysts selected from silica alumina and strongly acidic ion exchange resins to isomerize at least a portion of the endo isomer into the exo isomer. 2 The raw material dicyclopentadiene is dicyclopentadiene containing 95% by weight or more of endo isomer,
2. The isomerization method according to claim 1, wherein the isomerized product is dicyclopentadiene containing 3 parts by weight or more of the exo isomer per 100 parts by weight of the endo isomer.