KR100308617B1 - process for the production of alkyl cyclohexanecarboxylates using [2+4] Diels-Alder reaction - Google Patents

Abstract

The present invention relates to a method for preparing alkyl cyclohexanecarboxylate using [2 + 4] Diels-Alder reaction, wherein 1,3-butadiene is reacted with alkyl acrylate and [2 + 4] Diels-Alder to give alkyl 3- After preparing the cyclohexene-1-carboxylate, and then hydrogenated to a hydrogen pressure of 10-20psi under palladium or platinum catalyst to a method for producing an alkyl cyclohexanecarboxylate.

According to the present invention, it is possible to provide a method for producing an alkyl cyclohexanecarboxylate having a simple and easy reaction and easy reaction treatment and high yield since no side reaction occurs.

Description

[2 + 4] process for the production of alkyl cyclohexanecarboxylates using [2 + 4] Diels-Alder reaction

The present invention relates to a method for preparing alkyl cyclohexanecarboxylate using the [2 + 4] Diels-Alder reaction. More specifically, 1,3-butadiene is converted into alkyl acrylate and [2 + 4] dills. It relates to a method of producing alkylcyclohexanecarboxylate by producing an alkyl 3-cyclohexene-1-carboxylate by an alder reaction and then hydrogenating it.

Alkyl cyclohexanecarboxylates are widely used as raw materials contained in fragrances, perfumes, fabric cleaners, detergents, air fresheners, cosmetics, soaps, shampoos and the like.

Generally, various conventional methods, such as a method of reducing a benzene ring, are used to prepare alkyl cyclohexanecarboxylate. However, conventional methods used conventionally have a disadvantage in that the reaction conditions are very difficult and the reaction is difficult and the yield is not economical.

[2 + 4] Diels-Alder reaction is a well-known and useful reaction. Patents related to the [2 + 4] Diels-Alder reaction of 1,3-butadiene and various acrylates are described in Japanese Patent No. Hei 5-310885 (1993). Japanese Patent No. 57-028165 (1982), International Patent No. 8460602 (1986), US Patent No. 4,623,473 (1986), and the like. To a method for preparing alkyl 3-cyclohexene-1-carboxylate and applying it to the preparation of other compounds, wherein the alkyl 3-cyclohexene-1-carboxylate of the present invention is hydrogenated to give alkyl cyclohexane There has been no prior study on the preparation of the carboxylates.

In addition, Japanese Patent No. 62-22739 (1987) discloses the preparation of cyclohexanecarboxaldehyde by hydrogenation after a [2 + 4] dils-alder reaction between 1,3-butadiene and acrolein. The contents are disclosed, and US Patent No. 5,698,253 discloses the preparation of 1,4-dimethyl cyclohexane-1-carboxylic esters by hydrogenation. Although disclosed, it is clearly different from the present invention in terms of reaction conditions and reactants.

Therefore, the present invention was devised to improve the difficulty of the conventional method for preparing alkyl cyclohexanecarboxylate, and the reaction is simple using the [2 + 4] Diels-Alder reaction, and the treatment after the reaction is easy, It is an object of the present invention to provide a process for producing alkyl cyclohexanecarboxylate which is high in yield and economically advantageous.

In order to achieve the above object, the present invention prepares alkyl 3-cyclohexene-1-carboxylates by reacting 1,3-butadiene with alkyl acrylates and [2 + 4] Diels-Alder, and then uses palladium or An alkyl cyclohexanecarboxylate is prepared by hydrogenation at a hydrogen pressure of 10-20 psi under a platinum catalyst.

The [2 + 4] Diels-Alder reaction has a reaction mechanism in which a bond is formed and a bond is broken in a cooperative reaction between a diene and a dienophile, and is also referred to as a [2 + 4] cycloaddition reaction. It is a useful compounding means that provides one of the best ways to form an atomic ring.

In the [2 + 4] Diels-Alder reaction, an alkyl acrylate and a solvent were added to a 1L pressure reactor, 1,3-butadiene was injected, and then reacted at a temperature of 80-200 ° C to give an alkyl 3-cyclohexene-1-carboxyl. Prepare the rate.

In the [2 + 4] Diels-Alder reaction, alkyl acrylate acted as a diene body, 1,3-butadiene acted as a diene body, and 1,3-butadiene as a diene was 1-to 1 mole of alkyl acrylate as a diene body. Preference is given to using 1.2 moles.

The solvent used in the [2 + 4] Diels-Alder reaction is preferably selected from toluene or ethyl acetate.

The compound obtained by the [2 + 4] Diels-Alder reaction was removed by distillation under reduced pressure and analyzed by nuclear magnetic resonance to obtain alkyl 3-cyclohexene-1-carboxylate in a yield of 95-100%. The result was obtained. The hydrogenation reaction was carried out in the same reactor as the 1 L pressure reactor used for the [2 + 4] Diels-Alder reaction, or the alkyl 3-cyclohexene-1-carboxylate obtained by separation from the solvent was dissolved again in the solvent. You may advance a reaction by this. In the present invention, in order to quantitatively and qualitatively analyze the alkyl 3-cyclohexene-1-carboxylate, which is an intermediate, a solvent is separated after the [2 + 4] Diels-Alder reaction, and the obtained alkyl 3-cyclohexene-1-car Part of the cyclate was taken to undergo a hydrogenation reaction.

Meanwhile, in the present invention, the [2 + 4] Diels-Alder reaction and the hydrogenation reaction can be performed in the same pressure group, and the two reactions can be performed without separating the intermediate material from the solvent.

After separating the alkyl 3-cyclohexene-1-carboxylate prepared in the [2 + 4] Diels-Alder reaction with a solvent, a part of the alkyl 3-cyclohexene-1-carboxylate is dissolved in a solvent such as toluene or tetrahydrofuran, and a platinum or palladium catalyst. The mixture was put together in a bomb reactor and hydrogenated at a hydrogen pressure of 10-20 psi at room temperature.

The result was analyzed by gas chromatography, and the alkyl cyclohexanecarboxylate was obtained with a conversion rate of 95-100%.

On the other hand, it is preferable that 0.5-5 weight% of the catalyst of the said hydrogenation reaction is used with respect to the alkyl 3-cyclohexene-1-carboxylate.

The hydrogenation reaction was easily carried out at a low hydrogen pressure of about 10-20 psi at room temperature, and the conversion rate of alkyl 3-cyclohexene-1-carboxylate to alkyl carboxylate by hydrogenation was also 95-100%. It is very high.

The amount of the solvent used in the hydrogenation reaction is preferably used in a ratio of 1-50 times relative to the alkyl 3-cyclohexene-1-carboxylate.

The [2 + 4] Diels-Alder reaction and the hydrogenation reaction may proceed in the same pressure reactor. Therefore, the reaction is simple because the hydrogenation reaction can proceed without the need for removing the solvent after the [2 + 4] Diels-Alder reaction or separating the synthesized alkyl 3-cyclohexene-1-carboxylate. It is easy.

Therefore, by using the [2 + 4] Diels-Alder reaction which is useful from 1,3-butadiene according to the present invention, the reaction is simple and easy, no side reactions occur, so that the treatment after the reaction is convenient and the yield is very high. It is possible to provide a method for producing a carboxylate.

The [2 + 4] Diels-Alder reaction of the present invention was reacted in a pressure reactor and the hydrogenation reaction was carried out using a hydrogen reactor or a pressure reactor. The reactions were analyzed by nuclear magnetic resonance (NMR) spectra and gas chromatography-mass spectrometry detector (GC). -MSD), and quantitative analysis using gas chromatography was carried out under the following conditions, and the component ratio was used in terms of area ratio.

Capillary column: ULTRA 1 Crosslinked Methyl Silicone Gum, 50m x 0.22m x 0.33㎛

Carrier: Nitrogen

Upper Pressure: 18psi

Oven: 150 ° C. (2 minutes) to 280 ° C., β = 20 ° C./min

Detector and Temperature: FID (280 ℃)

Split ratio: 50: 1

Manufactured gas outflow: 38 ml

An embodiment of the present invention will be described in detail as follows. However, the present invention is not limited to the examples.

Example 1

* Method for preparing methyl 3-cyclohexene-1-carboxylate

Methyl acrylate (90 ml, 1 mol) and 288 g of toluene were added to a 1 L pressure reactor, 65 g of 1,3-butadiene was injected, the temperature was raised to 120 ° C. for 4 hours, and some of the solutions were taken and the solvent was distilled off under reduced pressure. It removed and obtained methyl 3-cyclohexene-1-carboxylate.

This was confirmed by analysis by nuclear magnetic resonance method, the yield was obtained to be 95%.

Example 2

* Preparation of ethyl 3-cyclohexene-1-carboxylate

Ethyl acrylate (106 mL, 1 mol) was used instead of the methyl acrylate used in Example 1, and the reaction was carried out in the same manner as in Example 1, yielding 98% of ethyl 3-cyclohexene-1-carboxylate. Got it.

Example 3

* Method for preparing t-butyl 3-cyclohexene-1-carboxylate

In Example 1, instead of methyl acrylate, t-butyl acrylate (146 ml, 1 mol) was used to change the reaction solvent, temperature, and time, and the reaction was performed in the same manner as in Example 1, where t-butyl 3-cyclohexene was used. -1-carboxylate was obtained in the yield shown in Table 1.

Table 1. Yield Change with Reaction Solvent and Reaction Temperature

Reaction solvent Reaction temperature (℃) Response time (h) yield(%) toluene 120 7 30 Ethyl acetate 150 7 50 Ethyl acetate 160 7 90

Example 4

* Method for preparing methyl cyclohexanecarboxylate 1

10 g of methyl 3-cyclohexene-1-carboxylate prepared in Example 1 was dissolved in 50 ml of toluene, and 0.5 g of 5% Pd / C catalyst was added to a bomb reactor and hydrogenated at 10 psi. It carried out and obtained methyl cyclohexane carboxylate. Part of the mixture was analyzed by gas chromatography, and the conversion to methyl cyclohexanecarboxylate was 97%.

Example 5

* Method 2 for preparing methyl cyclohexanecarboxylate

Instead of using toluene as a reaction solvent in Example 4, except that the reaction using tetrahydrofuran (tetrahydrofuran) in the same manner as in Example 4 to prepare a methyl cyclohexane carboxylate, the conversion rate is 96 A result of% was obtained.

Example 6

* Method for preparing ethyl cyclohexanecarboxylate

Ethyl cyclohexanecarboxylate was prepared in the same manner as in Example 4 except that ethyl 3-cyclohexene-1-carboxylate was used instead of methyl 3-cyclohexene-1-carboxylate in Example 4. It was. At this time, the conversion to ethyl cyclohexanecarboxylate was 95%.

Example 7

* Method for preparing t-butyl cyclohexanecarboxylate

In Example 4, except that t-butyl 3-cyclohexene-1-carboxylate is used instead of methyl 3-cyclohexene-1-carboxylate and ethanol is used as the solvent, the same as in Example 4. The reaction was carried out to prepare t-butyl cyclohexanecarboxylate, at which time the conversion was 100%.

As a result of the experiment as in the above embodiment, the alkyl cyclohexanecarboxylate production method of the present invention is simple in reaction, and no side reaction occurs, so that the treatment after the reaction is also simple. In addition, the reaction can be carried out at low pressures, and both [2 + 4] Diels-Alder and hydrogenation have a considerably high yield of 95-100%.

Although the present invention has been described with reference to specific embodiments, the scope of the present invention is not limited to the features described in the claims, and modifications can be made without departing from the intended purpose of the present invention.

Claims (7)

Alkyl 3-cyclohexene-1-carboxylate was prepared by reacting 1,3-butadiene with [2 + 4] Diels-Alder with alkyl acrylate, which was then hydrogenated at a hydrogen pressure of 10-20 psi under palladium or platinum catalyst. To prepare an alkyl cyclohexanecarboxylate. The method of claim 1, wherein the alkyl acrylate is one of methyl acrylate, ethyl acrylate and t-butyl acrylate. The method of claim 1, wherein the [2 + 4] Diels-Alder reaction is performed at 80-200 ° C. The method according to claim 1, wherein the palladium or platinum catalyst is used in an amount of 0.5-5 wt% based on alkyl 3-cyclohexene-1-carboxylate. The method of claim 1, wherein the hydrogenation reaction is carried out at room temperature. The method of claim 1, wherein the hydrogenation is selected from ethanol, methanol, toluene, and used as a solvent. 7. The method of claim 6, wherein the solvent is used at a ratio of 1-50 times the alkyl 3-cyclohexene-1-carboxylate.