A METHOD OF PREPARING CYCLOHEXANECARABOXYLIC ACID USING [2+4] DIELS-ALDER REACTION

Abstract: Disclosed herein is a method of preparing cyclohexanecarboxylic acid in which 1,3-butadiene and acrylic acid are subjected to [2+4] Diels-Alder reaction to produce 3-cyclohexene-1-carboxylic acid which is then hydrogenated. The [2+4] Diels-Alder reaction is carried out at a temperature of room temperature to 200 DEG C in an aromatic hydrocarbon solvent, such as toluene or xylene. The hydrogenation is carried out at a temperature of room temperature to 150 DEG C under a hydrogen pressure of 10 psi to 150 psi in the presence of the platinum of palladium catalyst. The disclosed method is featured in that it enables the use of 1,3-butadiene as the raw material for fine chemicals, unlike the prior methods. Moreover, the method disclosed is advantageous in that the reaction can be carried out in a relatively simple and easy manner and also the reaction by-products can be conveniently treated after the reaction.

Description: A METHOD OF PREPARING CYCLOHEXANECARBOXYLIC ACID USING [2+4] DIELS-ALDER REACTION Technical Field The present invention relates to a method of preparing cyclohexanecarboxylic acid in which 1,3- butadiene and acrylic acid are subjected to [2,4] Diels- Alder reaction to produce 3-cyclohexene-l-carboxylic acid which is then hydrogenated with hydrogen in the presence of a platinum or palladium catalyst. Background Art Cyclohexanecarboxylic acid is used as the raw material for synthetic organic materials, pharmaceutical agents, and fine chemicals. Cyclohexanecarboxylic acid derivatives are used as insecticides, tumor inhibitors, allergy inhibitors, and rheumatism inhibitors. For example, cyclohexanecarboxylic acid is known to be prepared by a synthesis process using carboxylation of cyclohexyl magnesium chloride, or by an industrial process using hydrogenation of benzoic acid. Literature regarding [2+4] Diels-Alder reaction of 1, 3-butadiene and acrylic acid includes Japanese Patent Publication Pyoung 5-301885 (1993) , Japanese Patent Publication No. Sho 57-028165 (1982), and WO 86/04602(1986). In these patents, there are described the preparation of 3-cyclohexene-l-carboxylic acid with [2+4] Diels-Alder reaction, and the application of such a compound to other compounds . Although a method of preparing cyclohexanecarboxylic acid by hydrogenation of 3-cyclohexene-l-carboxylic acid is not yet known, the following is known with respect to the preparation of cyclohexanecarboxylic acid derivatives by hydrogenation: For example, in Japanese Patent Publication No. Pyoung 9-40606(1997) and Japanese Patent Publication No. Sho 49-026261(1974), there is disclosed a method of preparing cyclohexanecarboxylic acid substituted at the 4-position by reducing benzoic acid substituted at the 4-position in the presence of an alkali and a hydrogenation catalyst. Moreover, German Patent Publication No. 2349056 A(1975) discloses a method of preparing 4-aminomethylcyclohexane by reducing p- aminomethyl benzoic acid using a ruthenium catalyst and an alkali . Disclosure of the Invention The present invention is a method of preparing cyclohexanecarboxylic acid in which 1, 3-butadiene and acrylic acid are subjected to [2+4] Diels-Alder reaction to obtain 3-cyclohexene-l-carboxylic acid which is then hydrogenated using a Pt or Pd catalyst and hydrogen. The method according to this invention is advantageous in that the reaction for preparing cyclohexanecarboxylic acid is carried out in a relatively simple manner and a side reaction does not substantially occur. In [2+4] Diels-Alder reaction of the method according to this invention, examples of a solvent capable of being used include an aromatic hydrocarbon solvent, such as toluene, benzene, and xylene, and an inexpensive and easily available solvent, such as alcohol, such as ethanol and methanol, and water, and the like. The [2+4] Diels- Alder reaction solvent is used in the amount of 100% to 5000% based on the weight of acrylic acid. Moreover, the temperature for carrying out [2+4] Diels-Alder reaction is in the range of room temperature to 200°C. The [2+4] Diels-Alder reaction of the method according to this invention produces cyclohexanecarboxylic acid in a yield of 95% or more. The higher the reaction temperature, the faster the reaction rate, but some polymers are generally produced. As a way to solve such a drawback, the use of 4-tert- butylcatecol (hereinafter, called "TBC") or hydroquinone as a polymerization inhibitor during the [2+4] Diels-Alder reaction results in the inhibition of the production of polymer . After [2+4] Diels-Alder reaction, the obtained 3- cyclohexene-1-carboxylic acid is hydrogenated in the presence of a Pd or Pt catalyst and hydrogen. This hydrogenation is carried out at a temperature of room temperature to 100°C under a hydrogen pressure of 10 psi to 150 psi, in a solvent selected from the group consisting of ethanol, methanol, water, toluene, and xylene. The hydrogenation solvent is used in the amount of 100% to 5000% based on the volume of 3-cyclohexene-l- carboxylic acid. Consequently, unlike the prior methods for the preparation of cyclohexanecarboxylic acid, the method of this invention is significant in the preparation of fine chemicals using 1, 3-butadiene . In addition, the method of the invention is advantageous in that the reaction for preparing cyclohexanecarboxylic acid is carried out in a relatively simple and easy manner and also the reaction by-products are conveniently treated. Best Mode for Carrying Out the Invention The following examples are for illustration purposes only and in no way limit the scope of this invention. Examples In the following examples, 3-cyclohexene-l-carboxylic was synthesized using acrylic acid as dienophile, and 1,3- butadiene as diene. As a solvent for [2+4] Diels-Alder reaction, an aromatic hydrocarbon compound, such as toluene, benzene, or xylene, alcohol, or water, was used. The molar ratio of 1, 3-butadiene to dienophile is in the range of 1 to 1.4. TBC or hydroquinone, as a polymerization inhibitor, was used in the amount of zero to 10,000 ppm based on the weight of 1, 3-butadiene . After producing 3-cyclohexene-l-carboxylic acid which is a [2+4] Diels-Alder reaction product, hydrogenation of 3- cyclohexene-1-carboxylic acid was carried out using a Pd or Pt catalyst. The use of each of these catalysts showed the conversion of 100%. Meanwhile, [2+4] Diels-Alder reaction was carried out in a pressure reactor, and hydrogenation was carried out in a hydrogen reactor or a pressure reactor. The analysis of the reaction product was performed by the Nuclear Magnetic Resonance (NMR) spectrum and the Gas Chromatography-Mass Spectroscopy Detector (GC-MSD) to confirm the product. When confirming the quantitative analysis value of the reaction product by gas chromatography, the analysis was carried out in accordance with the following conditions: Capillary column: HP-20, 25mm X 0.20mm X 0.2 m. Carrier gas: nitrogen Head pressure: 18 psig Oven: 80°C(0min.) to 190°C, β=10°C/min. Detector and temperature: FID(280°C). Split ratio : 40 : 1 Make up gas flow rate: 38ml. Moreover, the ratio of the components was used in terms of the area ratio of gas chromatography. Example 1 Into a 1 liter pressure reactor were charged acrylic acid (72g, 1 mol) , xylene 288g and TBC 75mg. Then, while stirring the contents of the reactor, 1, 3-butadiene 75g was introduced into the reactor. After that, a temperature of the resultant mixture was elevated to 120 °C and left to react at this temperature for 3 hours. Thereafter, the analysis of the reaction product by NMR spectrometry and gas chromatography confirmed that 3-cyclohexen-l- carboxylic acid was obtained in a yield of 99%. Example 2 The procedure of Example 1 was repeated five times with a reaction temperature and a molar ratio varying for each time as described in Table 1 below. For each time, 3- cyclohexene-1-carboxylic acid was obtained in a yield described in Table 1. Table 1 Effect of the varying reaction temperatures and molar ratios of reactants on a yield of 3-cyclohexene-l- carboxylic acid 1,3- Temperature (°C) Reaction Time Yield (%) BD(g)/AA(g) * (hr) 65/72 90 12 89 65/72 100 9 93 75/72 120 3 99 72/73 140 1.5 99 77/74 200 1 99 *1,3-BD: 1, 3-butadiene, AA: acrylic acid Example 3 Into a 1 liter pressure reactor were charged acrylic acid (72g, 1 mol) and toluene 288g. Then, 1,3- butadiene 75g was introduced into the reactor. After that, a temperature of the resultant mixture was elevated to 120 °C and left to react at this temperature for 6 hours. Thereafter, the analysis of the reaction product by NMR spectrometry and gas chromatography confirmed that 3-cyclohexene-l-carboxylic acid was obtained in a yield of 98%. Example 4 The procedure of Example 3 was repeated four times with a reaction solvent and a reaction temperature varying for each time as described in Table 2 below. For each time, 3-cyclohexene-l-carboxylic acid was obtained in a yield described in Table 2. Table 2 Effect of the varying kinds of solvents and reaction temperatures on a yield of 3-cyclohexene-l-carboxylic acid Solvent Yield (%) Reaction Time Reaction (hr) Temperature (°C) Xylene 99 4.5 120 Toluene 98 6 120 Ethanol 66 8 100 Water 98 8 100 None 99 7 100 Example 5 The procedure was repeated four times with a reaction temperature varying for each time as described in Table 3. For each time, 3-cyclohexene-l-carboxylic acid was obtained in a yield described in Table 3. Table3 Effect of the varying reaction temperatures on a yield of 3-cyclohexene-l-carboxylic acid Reaction Temperature Yield (%) Reaction Time (°C) (hr) 100 85 6 120 98 6 150 100 6 180 100 3 Example 6 The reaction was carried out for 3 hours under the same conditions as those in Example 3 except that anhydrous aluminum trichloride (A1C1 3 ) as a catalyst was further used. 3-Cyclohexene-l-carboxylic acid was obtained in a yield of 94%. Example 7 3-Cyclohexene-l-carboxylic acid 53g prepared in Example 1 was dissolved in xylene 125g. The resultant mixture was hydrogenated at room temperature in the presence of a 5%Pd/C catalyst (3 wt%) under a hydrogen pressure of 85 psi. Cyclohexanecarboxylic acid was obtained in a yield of 95% at one hour after starting hydrogenation and in a yield of 99% at 2 hours after starting hydrogenation. Example 8 The procedure of Example 7 was repeated four times with the amount of catalyst varying for each time as described in Table 4 below. For each time, cyclohexanecarboxylic acid was obtained in a yield described in Table . Table 4 Effect of the varying amounts of catalyst on a yield of cyclohexanecarboxylic acid Amount of Amount of Amount of Reaction Yield reactant * solvent catalyst time(hr) (%) 53 125 1.6(3wt%) 1 95 58 140 1.2(2wt%) 2 95 45 105 0.5(lwt%) 3 92 43 100 0.2(0.5wt%) 6 72 'Reactant : 3-cyclohexene-l-carboxylic acid Example 9 3-Cyclohexene-l-carboxylic acid lOg prepared in Example 3 was dissolved in toluene 0.5 liter. Then, the resultant mixture was hydrogenated in the presence of 0.2 g of a 5%Pd/C catalyst (3 wt%) under a hydrogen pressure of 10 psi. Cyclohexanecarboxylic acid was obtained in a yield of 97%. Example 10 The procedure of Example 9 was repeated three times with a hydrogen pressure varying for each time as described in Table 5 below. For each time, cyclohexanecarboxylic acid was obtained in a yield described in Table 5: Table 5 Ef fect of the varying hydrogen pres sures on a yield of cyclohexanecarboxylic acid Hydrogen pressure (psi ) Yield ( % ) 10 97 20 100 50 100 Example 11 The procedure of Example 9 was repeated three times with the ratio of reactant to solvent varying for each time as described in Table 6 below. For each time, cyclohexanecarboxylic acid was obtained in a yield described in Table 6. Table 6 Effect of the varying ratios of reactant to solvent on a yield of cyclohexanecarboxylic acid Reactant /Solvent Yield ( % ) 1 / 4 100 1 / 9 97 1 /50 97 Example 12 The procedure of Example 9 was repeated three times with the amount of catalyst varying for each time as described in Table 7 below. For each time, cyclohexanecarboxylic acid was obtained in a yield described in Table 7. Table 7 Effect of the varying amounts of catalyst on a yield of cyclohexanecarboxylic acid Amount of catalyst Yield (%) 0.1 80 0.2 97 0.5 100 Example 13 The procedure of Example 9 was repeated except that 3% Pd/C catalyst was used instead of 5% Pd/C catalyst. Cyclohexanecarboxylic acid was obtained in a yield of 100%. Example 14 The procedure of Example 9 was repeated except that ethanol was used instead of toluene. Cyclohexanecarboxylic acid was obtained in a yield of 100%. Industrial Applicability The method of this invention produces cyclohexanecarboxylic acid by subjecting 1, 3-butadiene and acrylic acid to [2+4] Diels-Alder reaction to produce 3- cyclohexene-1-carboxylic acid, and then hydrogenating the obtained 3-cyclohexene-l-carboxylic acid. Thus, the method of this invention is advantageous in that the reaction is carried out in a relatively simple manner, and also a side reaction does not occur. In the method of this invention, [2+4] Diels-Alder reaction of 1, 3-butadiene and acrylic acid is carried out using an aromatic hydrocarbon solvent, such as toluene, benzene, or xylene, at a temperature of room temperature to 200 °C. In addition, hydrogenation of 3-cyclohexene-l- carboxylic acid is carried out using an inexpensive and easily available solvent, such as alcohol, such as ethanol or methanol, or water, and the like, under very low pressure, such as a hydrogen pressure of 10 psi to 150 psi, and the reaction yield is 95% or more. Consequently, this invention is advantageous in that it enables the production of fine chemicals using 1, 3-butadiene, unlike the prior methods for the preparation of cyclohexanecarboxylic acid. Moreover, other advantages of this invention are that the reaction is carried out in a relatively simple and easy manner, and also the reaction by-products are conveniently treated after the reaction. Although the preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims: Claims : 1. A method of preparing cyclohexanecarboxylic acid, comprising : subjecting 1, 3-butadiene and acrylic acid to [2+4] Diels-Alder reaction to synthesize 3- cyclohexene-1-carboxylic acid; and catalytic hydrogenating the 3-cyclohexene-l-carboxylic acid. 2. The method of Claim 1, wherein the [2+4] Diels- Alder reaction is carried out at a temperature of room temperature to 200°C. 3. The method of Claim 1, wherein the [2+4] Diels- Alder reaction is carried out in a solvent selected from the group consisting of water, ethanol, toluene, benzene, and xylene or under the condition using no solvent. 4. The method of Claim 3, wherein the [2+4] Diels- Alder reaction solvent is used in the amount of 100% to 5000% based on the weight of acrylic acid. 5. The method of Claim 1, wherein the [2+4] Diels- Alder reaction is carried out in the presence of 4-tert- butylcatechol or hydroquinone, as a polymerization inhibitor. 6. The method of Claim 1, wherein the catalytic hydrogenation is carried out at a temperature of room temperature to 100°C. 7. The method of Claim 1, wherein the catalytic hydrogenation is carried out in the presence of a Pt or Pd catalyst. 8. The method of Claim 7, wherein the hydrogenation catalyst is used in the amount of 0.5 to 5% based on the weight of 3-cyclohexene-l-carboxylic acid. 9. The method of Claim 1, wherein the catalytic hydrogenation is carried out under a hydrogen pressure of 10 psi to 150 psi. 10. The method of Claim 1, wherein the catalytic hydrogenation is carried out in a solvent selected from the group consisting of ethanol, methanol, water, toluene, and xylene or under the condition using no solvent. 11. The method of Claim 10, wherein the hydrogenation solvent is used in the amount of 100% to 5000% based on the volume of 3-cyclohexene-l-carboxylic acid.

Inventors: JOO HYUN-SANG, JOO YOUNG J, KIM CHANG-MIN, KIM JIN-EOK, WON JEONG-IM, JOO, HYUN-SANG, JOO, YOUNG, J., KIM, CHANG-MIN, KIM, JIN-EOK, WON, JEONG-IM
Applicants: JOO HYUN SANG, JOO YOUNG J, KIM CHANG MIN, KIM JIN EOK, KOREA KUMHO PETROCHEM CO LTD, WON JEONG IM, JOO, HYUN-SANG, JOO, YOUNG, J., KIM, CHANG-MIN, KIM, JIN-EOK, KOREA KUMHO PETROCHEMICAL CO., LTD., WON, JEONG-IM
Application year: 1999
Main classification: C07C61
IPC codes: C07B61, C07C51, C07C61