KR100225379B1 - Process for the preparation of 5-ethylidene-2-norbornene - Google Patents

Abstract

The present invention is a 2-norbornenyl-5-carboxyaldehyde or 5-acetyl-2-norbornene by [2 + 4] dils-aldehyde reaction using cyclopentadiene as a diene and acrolein or methylvinyl ketone as a dienophile. The resulting 2-norborneneyl-5-carboxyaldehyde was reacted with Grignard, and 5-acetyl-2-norbornene was reduced to give 5- (1'-hydroxyethyl) -2-norbornene. After the preparation, it relates to a method for producing 5-ethylidene-2-norbornene by dehydration reaction.

In the production method of the present invention, the reaction can proceed without the by-products to increase the conversion and selectivity, and can easily prepare the target material 5-ethylidene-2-norbornene by a simple dehydration reaction using a dehydrating agent. .

Description

Method for preparing 5-ethylidene-2-norbornene

In the present invention, 2-pent is reacted by cyclopentadiene as a diene and acrolein or methylvinylketone as a dienophile as a dienophile. Obtained 2-norbornenyl-5-carboxylaldehyde (hereinafter referred to as 2-NBC) or 5-acetyl-2-norbornene, and produced 2-norbornenyl-5-carboxyaldehyde 5- (1'-hydroxyethyl) -2-norbodene (5-) by Grignard reaction or reduction of 5-acetyl-2-norbornene (5-acetyl-2-norbornene). (1'-hydroxyethyl) -2-norbornene (hereinafter referred to as 5-HNB) and then dehydrated to 5-ethylidene-2-norbornene (hereinafter referred to as 5-ENB). It relates to a method of manufacturing).

ENB is a tertiary copolymer used as a third component of ethylene, propylene, and diene monomer, which are raw materials of ethlene-propylene-diene-monomer (EPDM), and are very important fine chemicals. Product.

In general, ENB is prepared by isomerization using sodium in 5-VNB obtained by [2 + 4] dils-alder reaction of 1,3-butadiene and cyclopentadiene. As such, since 5-VNB is an important intermediate for the manufacture of ENB, the manufacture of ENB is mostly related to the reporting method of 5-VNB.

Most of the patent documents related to the production method of 5-VNB are [2 + 4] dils-Alder reaction of cyclopentadiene and butadiene. The conversion rate is about 20 to 80% and the selectivity is about 30 to 70%. . Thus, the yield of 5-VNB, the product of the [2 + 4] dils-alder reaction of cyclopentadiene and 1,3-butadiene, is lower than that of the general [2 + 4] dils-alder reaction. This is because all of the cyclopentadienes are dienes and also act as dienophiles to produce various kinds of products. 4-vinylcyclohexene, cyclooctadiene, 3a, 4,7,7a-tetrahydroindene (3a, 4,7,7a-tetrahydroindene) ), Dicyclopentadiene, trimers, and the like are generated as side reactions, thereby lowering the selectivity of 5-VNB. Therefore, in recent years, reducing the by-products in the production of 5-VNB has become the mainstream of the patent literature.

In addition, as a method of isomerizing 5-VNB to ENB, an alkali metal, which is not easy to handle in the process, must be used.

Patent documents related to this include Japanese Patent Laid-Open Nos. 69-134736 (1984), 69-170021, 70-94925 (1985), 72-81334 (1987), 72-148432 No. 73-215645 (1988), No. 73-215646, No. 1-332 (1989), No. 2-48042 (1990), No. 6-40956 (1994), etc. . European Patent No. 157222 (1985), 279397 (1988), International Publication No. 9220639, and US Patent No. 5292985 (1994).

In the present invention, by selecting the primary dienophiles studied to solve the by-product generation problem in the 5-VNB manufacturing, it was possible to reduce by-products and increase the conversion rate, and also to simplify the process by simply dehydrating the precursor of ENB. Could.

Accordingly, it is an object of the present invention to react 2-norbornenyl-5-carboxyaldehyde or 5-acetyl-2- by reacting cyclopentadiene with [2 + 4] dils-aldehyde using acrolein or methylvinyl ketone as a dienophile. Norbornene was obtained and 5- (1'-hydroxyethyl) -2-norbornene was subjected to Grignard reaction of the resulting 2-norborneneyl-5-carboxyaldehyde or reduced 5-acetyl-2-norbornene. After the preparation, it is to provide a method for producing 5-ethylidene-2-norbornene by dehydration reaction.

In the preparation method of 5-ENB according to the present invention, 2-norborneenyl-5-carboxyaldehyde or 5-acetyl-2-norne is obtained by reacting cyclopentadiene with acrolein or methyl vinyl ketone [2 + 4] dils-aldehyde. Obtained bonene, the resulting 2-norborneneyl-5-carboxyaldehyde is Grignard reaction or reduced 5-acetyl-2-norbodene to give 5- (1'-hydroxyethyl) -2-norbornene After preparation, it is dehydrated.

In the present invention, 2-NBC is prepared by reacting cyclopentadiene with [2 + 4] dils-Alder using acrolein as a dienophile, and 5-HNB is prepared by Grignard reaction using methylmagnesium bromide. As described above, the [2 + 4] dils-Alder reaction obtained a typical reaction with a high yield of 90% or more without byproducts at room temperature using ethyl ether as a reaction solvent. The resulting 2-NBC was cooled to −78 ° C. with ethyl ether as a solvent, and then subjected to Grignard reaction to prepare 5-HNB without byproducts. The reaction yield was not high during the Greenid reaction, but the by-products were so small that the target product could be synthesized without difficulty of separation.

Another route for preparing 5-HNB in the present invention is to prepare 5-ANB by reacting cyclopentadiene with [2 + 4] dils-Alder using methylvinyl ketone as a dienophile, and then reducing the same. . This was carried out at room temperature reaction of methyl vinyl ketone in an ethyl ether solvent to synthesize 5-ANB in a yield of 85% or more without by-products. Sodium borohydride (NaBH ₄ ) was used as a reducing agent to reduce the prepared 5-ANB.

In the present invention, cyclopentadiene was distilled after pyrolysis of dicyclopentadiene at 170 ° C., and the reaction was performed at room temperature using ethyl ether as a [2 + 4] dils-Alder reaction solvent.

In the Grignard reaction, methyl magnesium fluoride (CH ₃ MgF), methyl magnesium chloride (CH ₃ MgCl), methyl magnesium bromide (CH ₃ MgBr), and methyl magnesium iodide (CH ₃ MgI) are used. Of these, methylmagnesium bromide is suitable.

5-HNB prepared by the above method was subjected to dehydration using a dehydrating agent such as p-toluenesul-fonylchloride to prepare 5-ENB.

Other dehydration reactions are dehydrating agents such as phosphorus trichloride (POCl ₃ ), boron trifluoride (BF ₃ ), oxalic acid, phosphoric acid, sulfuric acid, hydrogen bromide, phosphorus pentoxide (P ₂ O ₅ ), and p-toluenesulfonic acid (p-TsOH), sodium sulphate (NaHSO ₄ ), potassium sulphate (KHSO ₄ ), copper sulfate (CuSO ₄ ), alumina (Al ₂ O ₃ ) and the like to dehydrate by gas phase reaction.

Among these reaction conditions, in the present invention, 5-VNB was prepared by carrying out dehydration reaction of 5-HNB by liquid phase reaction using p-toluenesulfonyl chloride as a dehydrating agent. In the dehydration reaction of 5-HNB, in addition to 5-ENB, there is also the possibility of generating 5-VNB, but in the present invention, 5-VNB is not produced and only 5-ENB is produced, which is more stable than 5-VNB in terms of thermodynamics. It was possible because of the form.

In the present invention, 5-ENB was prepared by dehydration using pyridine or p-dimethylaminopyridine (DMAP) as a dehydration catalyst. The 5-ENB thus prepared was confirmed by gas chromatography to obtain a good result with a yield of 77%.

The present invention used a batch reactor capable of homogeneous solution reaction. Analysis of the reactants was confirmed using nuclear magnetic resonance (NMR) spectra and gas chromatography-mass spectrometry detector (GC-MSD). Analytical conditions of gas chromatography for quantitative analysis are as follows, and the component ratio was used in terms of area ratio.

Capillary column: ULTRA 1 (Crosslinked Methyl Silicone Gum)

50cm2 x 0.22m x 1.33㎛

Carrier gas: nitrogen

Head pressure: 18psig

Oven: 80 ℃ (2min) to 280 ℃, β = 3 ℃ / min

Injection Temp. : 280 ℃

Detector & Temp. FID (280 ℃)

Spilit ratio: 50: 1

Makeup gas flowrate: 38ml

Hereinafter, the present invention will be described in detail with reference to Examples. However, the present invention is not limited by this embodiment.

(Manufacture of 2-NBC)

20.7 ml (0.3 mol) of cyclopentadiene was added to the flask, 20.1 ml (0.3 mol) of acrolein and ethyl ether were added to the dropwise funnel, and the flask was slowly added while cooling, stirred at room temperature for 2 hours, and then reacted by gas chromatography. As a result of confirming the degree of the product, 2-NBC was obtained in a yield of 90%.

Example 1

After dissolving 27.3 ml (0.082 mol) of methylmagnesium bromide in ethyl ether in the flask, 10 g (0.082 mol) of 2-NBC synthesized by the above method was added to the dropwise funnel, and the flask was slowly added dropwise while cooling at -78 ° C. After dropwise addition, the mixture is slowly stirred to room temperature. After completion of the reaction, dilute hydrochloric acid solution was added dropwise to decrease the reactivity, and excess water was added to separate the ethyl ether layer. After extraction, the ethyl ether layer was collected to remove the solvent, and then confirmed by nuclear magnetic resonance spectrum to confirm that 5-HNB was produced.

Example 2

150 ml (2.16 mol) of cyclopentadiene was added to the flask, ethyl ether was added as a solvent, and the reactor was cooled with water and ice. 183 mL (2.16 mol) of methyl vinyl ketone was added to the dropwise funnel, and then slowly added dropwise to the reactor, followed by stirring at room temperature for 3 hours. When the reaction product was confirmed by gas chromatography, 5-ANB was produced in a yield of 85%.

Example 3

100 g (0.73 mol) of 5-ANB synthesized in Example 2, 2 g of potassium hydroxide, and 100 ml of methanol were put into a flask and maintained at 40 ° C. 40 g of sodium borohydride, 320 ml of methanol, 200 ml of water, and 2 g of carboxy hydroxide are added to the dropping funnel and slowly added dropwise to the flask. It is exothermic during the dropping and the temperature in the flask is maintained at 40 ℃. After stirring for 3 hours, 5-HNB was produced in 80% yield in accordance with 5-HNB obtained in Example 2, which was confirmed by gas chromatography and nuclear magnetic resonance spectra.

Example 4

58 g (0.42 mol) of 5-HNB, a compound synthesized in Examples 1 and 3, was added to a flask and dissolved in methylene chloride. Then, 140 g (0.72 mol) of p-toluenesulfonyl chloride and 61 ml (0.73 mol) of pyridine were added thereto. The mixture was stirred at room temperature for 2 hours, and then reacted with gas chromatography and nuclear magnetic resonance spectrum to obtain 5-ENB in a yield of 77%.

Example 5

As in Example 4, 10.1 g (0.0652 mol) of p-toluenesulfonyl chloride was added to 4 g (0.026 mol) of 5-HNB in a flask, followed by reaction of methylene chloride with a solvent using p-dimethylaminopyridine at room temperature for 2 hours. As a result of stirring, 5-ENB was synthesized in 42% yield.

The present invention is to solve the conventional method in which a by-product is generated in a large amount during the [2 + 4] dils-alder reaction of cyclopentadiene and 1,3-butadiene to cause pollution. Using acrolein or methylvirine ketone as the activating dienophile, the reaction can proceed without the formation of byproducts, thereby increasing the conversion and selectivity. In addition, in order to prepare 5-ENB with precursor 5-VNB, an isomerization reaction using an alkali metal that is difficult to handle was required, but in the present invention, 5-ENB was prepared by a simple dehydration reaction without using an alkali metal. .

Claims (5)

In the process for producing 5-ethylidene-2-norbornene, cyclopentadiene is reacted with acrolein or methylvinyl ketone [2 + 4] dils-aldehyde to give 2-norborneneyl-5-carboxyaldehyde or 5- Acetyl-2-norbornene was obtained, and the resulting 2-norborneneyl-5-carboxyaldehyde was subjected to Grignard reaction or 5-acetyl-2-norbornene was reduced to give 5- (1'-hydroxyethyl)- A method for producing 5-ethylidene-2-norbornene consisting of preparing 2-norbornene and then dehydrating it. The method for producing 5-ethylidene-2-norbornene according to claim 1, wherein the reaction temperature of acrolein and methyl vinyl ketone in cyclopentadiene and [2 + 4] dils-Alder is room temperature. The method for preparing 5-ethylidene-2-norbornene according to claim 1, wherein methylmagnesium bromide is used in the reaction of 2-norborneneyl-5-carboxyaldehyde with greenidation. The method for preparing 5-ethylidene-2-norbornene according to claim 1, wherein sodium borohydride is used as a reducing agent when reducing 5-acetyl-2-norbornene. The method of claim 1, wherein 5- (1'-hydroxyethyl) -2-norbornene is dehydrated to prepare 5-ethylidene-2-norbornene, and P-toluenesulfonyl chloride is used as a dehydrating agent. A pyridine or p-dimethylaminopyridine is used as a catalyst for producing 5-ethylidene-2-norbornene.