KR100932223B1 - Method for preparing 5-vinyl-2-norbornene using aprotic polar solvent - Google Patents

Abstract

The present invention relates to a method of preparing 5-vinyl-2-norbornene using an aprotic polar compound, and more particularly, to a Diels-Alder reaction of cyclopentadiene and 1,3-butadiene. By using an aprotic polar compound as both a catalyst and a solvent in the reaction for preparing 5-vinyl-2-norbornene, the conversion of cyclopentadiene and the formation of by-products are suppressed, thereby increasing the yield of 5-vinyl-2-norbornene. It relates to a process for producing nene.

Cyclopentadiene, 1,3-butadiene, aprotic polar compounds, 5-vinyl-2-norbornene

Description

Preparation method of 5-vinyl-2-norbornene using aprotic polar solvent {Preparation method of 5-vinyl-2-norbornene using polar aprotic solvent}

The present invention relates to a process for preparing 5-vinyl-2-norbornene by Diels-Alder reaction of cyclopentadiene with 1,3-butadiene using an aprotic polar compound.

5-vinyl-2-norbornene (hereinafter referred to as 'VNB') is made of ethylene-propylene-diene copolymer (hereinafter referred to as 'EPDM') rubber. It is a raw material of 5-ethylidene-2-norbornene (hereinafter referred to as 'ENB'), which is used as three substances, and cyclopentadiene (hereinafter, referred to as 'CPD') as shown in Scheme 1 below. And 1,3-butadiene (hereinafter referred to as 'BD') can be prepared through the Diels-Alder reaction.

The Diels Alder reaction is a reaction between dienes and dienophiles such as CPD. In general, a reaction occurs easily when an electron-donating group is present in the diene and an electron-withdrawing group is present in the dienophile.

In the case of the VNB reaction, cyclopentadiene acts as a diene and 1,3-butadiene acts as a dienophile. In the case of these compounds, the reaction proceeds at a high temperature due to the absence of substituents that may affect the electron density. Is also low. In particular, in the case of 1,3-butadiene can act as a diene and a dienophile due to the sisoid (cisoid) and the transoid structure (transoid) structure, not only VNB but also CPD as a dienopropyl, 1,3- An excess of 3a, 4, 7, 7a-tetrahydroindene (THI), produced by butadiene acting as a diene (Scheme 2). In addition, 4-vinylcyclohexene, which is produced by the action of two molecules of 1,3-butadiene as dienes and dienopropyl, is also produced as a by-product of the reaction [Scheme 3].

It is also known from the literature that the resulting VNB is converted to THI through an isomerization reaction at high temperature [T. Maeda et al., Journal of Chemical Society of Japan, 1974 (8), 1587-9]

In order to overcome the low yield of VNB, a catalyst such as an alkali metal is used [Korean Patent Publication No. 1999-017713] or a titania-based catalyst is used for the production of VNB [US Pat. No. 4,891,460]. The effect is not great due to the absence of heavy functional groups.

Japanese Patent No. 49-25665 reports a method for producing a VNB using a hydrocarbon compound having 5 to 7 carbon atoms or an ester compound having 2 to 7 carbon atoms as a solvent. In addition, US Patent No. 4,219,688 discloses a method of increasing the yield of VNB and THI by using decayronaphthalene (cis-decahydronaphthalene) or chloronaphthalene (alpha-chloronaphthalene) having a molecular refractive index (RD) of 30 or more as a solvent. Is described.

However, the above-mentioned methods have high solvents, have a large amount of reaction by-products such as THI and polymer compounds, and most of them have a high boiling point of 200 ° C. or higher and a low boiling point of 100 ° C. or lower. There is a drawback that the purification is uneconomical, a new attempt to improve it is required.

The present invention was to prepare a method for producing 5-vinyl-2-norbornene (VNB) more efficiently. That is, the Diels-Alder reaction of cyclopentadiene and 1,3-butadiene can be more effectively performed to convert cyclopentadiene, inhibit the formation of by-products, and yield of 5-vinyl-2-norbornene (VNB). I would like to present a way to improve this.

The present invention is a method for preparing 5-vinyl-2-norbornene by reacting cyclopentadiene and 1,3-butadiene with Diels-Alder, wherein the aprotic polar compound is reacted with the reaction catalyst and solvent. The manufacturing method of 5-vinyl-2-norbornene used has the characteristics.

In the production method according to the present invention, the production of 5-vinyl-2-norbornene with high conversion, selectivity and high yield of cyclopentadiene using aprotic polar compounds having a lower cost as a reaction solvent and a catalyst than in the related art. Is possible. In addition, the separation and recovery of the aprotic polar compound from the target product is easy, and economical production of 5-vinyl-2-norbornene is possible.

In the present invention, 5-vinyl-2-norbornene is prepared by using aprotic polar compound as a catalyst and a reaction solvent when cyclopentadiene (CPD) and 1,3-butadiene (1,3-butadiene, BD) are reacted. Characterized in that the manufacturing method.

Hereinafter, the present invention will be described in more detail.

The cyclopentadiene used in the present invention, which is used as the reactant of the present invention, may be prepared by pyrolysis distillation of dicyclopentadiene (DCPD), which is generally known in the art. Since it is converted, it is preferable to use the cyclopentadiene in the state of purity of 95% or more in actual experiments stored at -20 ℃ immediately.

In the present invention, 5-vinyl-2-norbornene is prepared by performing a Diels-Alder reaction of cyclopentadiene and 1,3-butadiene, wherein 1,3-butadiene is 1 mole of cyclopentadiene. It is preferable to use 1 to 5 molar ratios, preferably 3 to 5 molar ratios. The cyclopentadiene and 1,3-butadiene should be maintained at a molar ratio of at least 1,3-butadiene in a 1: 1 molar ratio, and even if it exceeds 5 molar ratio, it is irrelevant to the reaction yield and is rather economical. Therefore, it is preferable to maintain the above range.

The present invention is characterized by the technical construction of using an aprotic polar compound as a reaction catalyst and a solvent.

The aprotic polar compound has higher solubility in cyclopentadiene and 1,3-butadiene as compared to the conventional nonpolar solvent, resulting in an increase in the concentration of 1,3-butadiene in the reaction solution. In addition, it is assumed that the yield of the reaction is increased by stabilizing the transition state of the Diels-Alder reaction to lower the activation energy of the reaction. As a result, when used in the Diels-Alder reaction of cyclopentadiene and 1,3-butadiene, the conversion of cyclopentadiene and the selectivity of 5-vinyl-2-norbornene are improved.

That is, the aprotic polar compound of the present invention does not affect the Diels-Alder reaction itself, but has a high solubility in the reaction raw material and a difference in boiling point from 5-vinyl-2-norbornene for separation from the reaction product. I like to use things. Specifically, dimethylformamide (DMF), monomethylformamide (MF), monomethylacetamide (MAC), dimethylacetamide (DMAC) and methylpyrrolidinone (NMP) may be used. The compound shows a difference from the boiling point of 141 ℃, which is a boiling point of 5-vinyl-2-norbornene, in the range of 150 to 200 ° C., so that the compound is easily separated, and thus the product can be easily separated from the mixture using a simple distillation method after the reaction. It has industrial utility in that it is possible.

Since the aprotic polar compound is used as a reaction catalyst and a solvent, it may be used in a small amount when used as a catalyst, but when used as a catalyst simultaneously with a solvent, it is preferable to use it in a relatively excessive range. Specifically, it is used in the range of 10 to 1000% by weight, preferably 50 to 500% by weight relative to the cyclopentadiene. When the amount is less than 10% by weight, the effect on the reaction is insignificant and the amount of polymer byproducts is increased. In the case of more than 1000% by weight, the reaction rate is slowed and it is not economical to separate 5-vinyl-2-norbornene produced after the reaction.

The reaction for preparing 5-vinyl-2-norbornene using the aprotic polar compound described above may be performed using a high pressure reactor equipped with a stirrer.

The reaction temperature is preferably carried out at a temperature range of 150 to 280 ° C., preferably 230 to 280 ° C., and particularly at a high temperature of about 280 ° C. However, if the reaction temperature is less than 150 ℃, the reactivity is low, and if it exceeds 280 ℃ product is 5-vinyl-2- norbornene is rapidly isomerized to 3a, 4,7,7a-tetrahydroindene (THI) There is a problem that the amount of by-products generated by the polymerization of the reaction raw material increases rapidly.

The reaction pressure is preferably performed at a pressure range of 200 to 700 psig, preferably 500 to 700 psig, and particularly at a high pressure of about 700 psig. In this case, when the reaction is carried out using an inert gas such as nitrogen and argon in a state of maintaining the pressure in the above range, the reaction yield is significantly increased than when the reaction is performed at normal pressure. However, when the reaction pressure is less than 200 psig, there is a problem in that the yield of the reaction is low because the concentration of 1.3-butadiene in the solution is low, and when it exceeds 700 psig, one problem is generated by the Diels-Alder reaction between 1,3-butadiene. Since the amount of vinyl cyclohexene to be produced increases, it is preferable to maintain the above range.

The reaction time is preferably 10 to 120 minutes, preferably 90 to 120 minutes. The reaction time may vary depending on the amount of reactants, the ratio of reactants, and the reaction temperature, but is usually in the above range. As the reaction time increases, the conversion is increased little by little, but the amount of side reactions is also increased, so that the overall selectivity of 5-vinyl-2-norbornene is reduced.

As described above, when the aprotic polar compound is used as a catalyst and a reaction solvent in the production of 5-vinyl-2-norbornene by the Diels-Alder reaction according to the present invention, the conversion rate and the target product of cyclopentadiene Improved selectivity of phosphorus 5-vinyl-2-norbornene, inhibits the formation of byproducts 3a, 4,7,7a-tetrahydroindene (THI), dicyclopentadiene (DCPD) and oligomers This is significantly shortened.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the following Examples.

Example 1

In a 100 mL high pressure reactor, 30 g of solvent dimethylformamide (DMF), 5.0 g (76 mmol) of cyclopentadiene (CPD) and 8.2 g (152 mmol) of 1,3-butadiene (BD) were added under a nitrogen atmosphere. . After the temperature was raised to 200 ° C. while stirring the reactor, nitrogen gas as an inert gas was injected into the reactor, and the reaction was performed for 60 minutes after fixing the pressure in the reactor to 400 psig.

After completion of the reaction, the temperature was lowered to room temperature, the reaction product was taken, and the organic solvent layer in the reaction product was analyzed using gas chromatography. As a result, the conversion rate of cyclopentadiene (CPD) was 95.3%, and the composition of the product was 42.5% by weight of 5-vinyl-2-novodene (VNB), 3a, 4,7,7a-tetrahydroindene (THI). 5.6 wt%, dicyclopentadiene (DCPD) 51.5 wt% and oligomer 0.4 wt%.

Examples 2 to 6: Kind change of aprotic polar compound

In the same manner as in Example 1, the reaction was carried out by changing the type of aprotic polar compound as shown in Table 1 below, and the results are shown in Table 1 below.

Examples 7-11: Change in content of solvent

In the same manner as in Example 1, using DMF as an aprotic polar compound, the reaction was carried out in the content shown in Table 2, and the results are shown in Table 2 below.

Examples 12-15: Change of reaction temperature

In the same manner as in Example 1, using DMF as an aprotic polar compound, as shown in the following Table 3, the reaction was carried out at a pressure of 400 psig for 1 hour while changing the reaction temperature in the range of 150 ~ 280 ℃ The results are shown in Table 3 below.

Examples 16-19 Change in reaction time

In the same manner as in Example 1, but using DMF as an aprotic polar compound, the reaction time is carried out for 10 to 120 minutes at 200 ℃ reaction temperature, 400 psig reaction time as shown in Table 4, The results are shown in Table 4 below.

Examples 20 to 24: change in reaction pressure

In the same manner as in Example 1, using DMF as an aprotic polar compound, the reaction temperature is 200 ℃, as shown in the following Table 5, the reaction is carried out for 60 minutes while changing the reaction pressure to 200 ~ 700 psig, The results are shown in Table 5 below.

Examples 25-28 Change in the Content of Reactants

In the same manner as in Example 1, the CPD is 5.0 g, the molar ratio of BD / CPD is changed to 1 to 5 as shown in Table 6, the reaction temperature 200 ℃, 400 psig, the reaction pressure is carried out for 60 minutes The results are shown in Table 6 below.

Comparative Example 1

In the same manner as in Example 1, the reaction was performed without using a reaction solvent. After completion of the reaction, the temperature was lowered to room temperature, the reaction product was taken, and the organic solvent layer in the reaction product was analyzed using gas chromatography.

As a result, the conversion of CPD was 90.4%, and the composition of the product was 30.2 wt% of VNB, 13.8 wt% of THI, 48.7 wt% of DCPD, and 7.3 wt% of oligomer.

Comparative Example 2

The reaction was carried out in the same manner as in Example 1, using trimethyl benzene as the reaction solvent. After completion of the reaction, the temperature was lowered to room temperature, the reaction product was taken, and the organic solvent layer in the reaction product was analyzed using gas chromatography.

As a result, the conversion of CPD was 92.8%, and the composition of the product was 32.4 wt% of VNB, 10.5 wt% of THI, 53.4 wt% of DCPD, and 3.7 wt% of oligomer.

Comparative Example 3

The reaction was carried out in the same manner as in Example 1, using chloronaphthalene, which was conventionally used as a reaction solvent. After completion of the reaction, the temperature was lowered to room temperature, the reaction product was taken, and the organic solvent layer in the reaction product was analyzed using gas chromatography.

As a result, the conversion of CPD was 88.4%, and the composition of the product was 30.1 wt% of VNB, 11.3 wt% of THI, 52.1 wt% of DCPD, and 6.5 wt% of oligomer.

Comparative Example 4

In the same manner as in Example 1, the reaction was carried out using ethyl acetate, which was conventionally used as a reaction solvent. After completion of the reaction, the temperature was lowered to room temperature, the reaction product was taken, and the organic solvent layer in the reaction product was analyzed using gas chromatography.

As a result, the conversion of CPD was 92.5%, and the composition of the product was 31.6 wt% of VNB, 12.8 wt% of THI, 50.2 wt% of DCPD, and 5.4 wt% of oligomer.

Table 7 below shows the conversion rate of the CPD and the composition of the product of Comparative Examples 1 to 4 in a brief summary.

As shown in Table 1 to Table 6, the reaction using an aprotic polar compound according to the present invention was confirmed that the conversion of cyclopentadiene and selectivity of 5-vinyl-2-norbornene is excellent.

In addition, as shown in Table 7, in the case of Comparative Examples 1 to 4 using no reaction catalyst and solvent in the conventional method or using trimethylbenzene, chloronaphthalene, ethyl acetate and the like, the conversion rate of cyclopentadiene was low and the side reaction product was used. It was confirmed that the selectivity of the relatively low selectivity of 5-vinyl-2-norbornene for the present invention is high.

Claims (7)

In a method of producing 5-vinyl-2-norbornene by reacting cyclopentadiene and 1,3-butadiene with Diels-Alder, An aprotic consisting of dimethylformamide (DMF), monomethylformamide (MMF), monomethylacetamide (MMAC), dimethylacetamide (DMAC), dimethylsulfoxide (DMSO) and methylpyrrolidone (NMP) A method for producing 5-vinyl-2-norbornene, comprising using a single compound or a mixture of two or more selected from polar compounds as a reaction catalyst and a solvent. delete The method according to claim 1, wherein the aprotic polar compound is used in the range of 10 to 1000% by weight based on cyclopentadiene. The method according to claim 1, wherein the 1,3-butadiene is used in an amount of 1 to 5 moles per 1 mole of cyclopentadiene. The method of claim 1, wherein the reaction is performed at a temperature in the range of 150 to 280 ° C. The method of claim 1, wherein the reaction is performed at a pressure in the range of 200 to 700 psig. The method of claim 1, wherein the reaction is carried out for 10 to 120 minutes.