JP2005330239A - Method for producing 1,4-cyclohexanedicarboxylic acid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for industrially producing high-purity 1,4-cyclohexanedicarboxylic acid suitably utilizable as a raw material for a polyester having excellent weather resistance, transparency, electric characteristics and moldability, and usable for an optical material or an electronic material, and a medicine. <P>SOLUTION: The method for producing the 1,4-cyclohexanedicarboxylic acid involves hydrolyzing a dialkyl 1,4-cyclohexanedicarboxylate in an aqueous solution in the presence of an acidic catalyst. The hydrolysis is carried out while continuously evaporating water and alcohol by-produced in the hydrolysis to the outside of the reaction system and continuously or intermittently adding water to the reaction system. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing 1,4-cyclohexanedicarboxylic acid, and more particularly, to a method for efficiently producing high-purity 1,4-cyclohexanedicarboxylic acid by hydrolyzing dialkyl 1,4-cyclohexanedicarboxylate. .

  1,4-cyclohexanedicarboxylic acid is useful as a raw material for pharmaceuticals, synthetic resins, synthetic fibers, dyes and the like. In particular, in recent years, demand for high-purity 1,4-cyclohexanedicarboxylic acid is increasing as an acid component of polyester resins for use in optical materials and electronic materials because of heat resistance, electrical properties, and optical properties.

  As a method for producing 1,4-CHDA, a disodium salt of terephthalic acid is hydrogenated in an aqueous solution to obtain a disodium salt of 1,4-CHDA, which is obtained by acid precipitation using hydrochloric acid or sulfuric acid. Is common (Patent Document 1). However, since 1,4-cyclohexanedicarboxylic acid produced by this method remains a metal such as sodium derived from the raw material, and an acid component containing Cl, S, etc. used when acidifying out, it is from such a raw material. The obtained polymer has a problem that the degree of polymerization does not increase, the remaining acid component corrodes the device and the like, and the electrical characteristics are affected.

  In addition, as another method, a method of directly nuclear hydrogenating terephthalic acid (Patent Document 2 and Patent Document 3) is also known. In any of these methods, by-products of organic impurities such as cyclohexanecarboxylic acid and 4-methylcyclohexanecarboxylic acid cannot be avoided, and these monocarboxylic acids cannot be separated by ordinary methods such as recrystallization. It was difficult. For this reason, when 1,4-cyclohexanedicarboxylic acid containing these organic impurities is used as the acid component of the polyester resin, the degree of polymerization of the polymer does not increase and heat resistance, weather resistance, physical strength, etc. are not sufficiently obtained. There was a problem.

International Publication No. 93/06076 Pamphlet JP-A-58-198439 US Pat. No. 6,291,706

  An object of the present invention is to provide a method for producing a high-purity 1,4-cyclohexanedicarboxylic acid that can be suitably used for pharmaceuticals, agricultural chemicals, optical materials, and polyester raw materials for electronic materials by an industrially simple method. .

  The present inventors diligently studied to solve the above problems. Nuclear hydrogenation of dialkyl terephthalate (for example, JP-A-2000-1447), followed by alkaline hydrolysis of the obtained 1,4-cyclohexanecarboxylic acid dialkyl, in the resulting 1,4-cyclohexanedicarboxylic acid Contains organic impurities such as metals and monocarboxylic acids such as cyclohexanecarboxylic acid and 4-methylcyclohexanecarboxylic acid, and the content can be reduced to a level that can sufficiently meet the current high demands. It turned out that it was not necessarily sufficient.

  However, as a result of further investigation, when 1,4-cyclohexanedicarboxylic acid is hydrolyzed in the presence of an acidic catalyst in the presence of an acidic catalyst, 1,4-cyclohexanedicarboxylic acid is obtained in the aqueous solution. It was found that water can be efficiently hydrolyzed by continuously or intermittently adding water to the reaction system while continuously evaporating the generated alcohol to the outside of the reaction system. It has been found that organic impurities such as alkyl monocarboxylates can be removed from the reaction system without producing monocarboxylic acids that are difficult to separate from the target product, and the present invention has been completed based on such findings.

  That is, the present invention provides the following method for producing 1,4-cyclohexanedicarboxylic acid.

  Item 1 A method for obtaining 1,4-cyclohexanedicarboxylic acid by hydrolyzing a dialkyl 1,4-cyclohexanedicarboxylate in an aqueous solution in the presence of an acidic catalyst, wherein water and alcohol by-produced during the hydrolysis reaction are obtained. A process for producing 1,4-cyclohexanedicarboxylic acid, wherein water is continuously or intermittently added to the reaction system to cause a hydrolysis reaction while continuously evaporating out of the reaction system.

  Item 2 The method for producing 1,4-cyclohexanedicarboxylic acid according to Item 1, wherein the reaction is performed by adding water such that the liquid space velocity is 0.2 to 0.05 / h based on the reaction solution volume.

  Item 3 The method for producing 1,4-cyclohexanedicarboxylic acid according to Item 1 or 2, wherein the dialkyl 1,4-cyclohexanedicarboxylate is produced by a nuclear hydrogenation reaction of dialkyl terephthalate.

  Item 4 The method for producing 1,4-cyclohexanedicarboxylic acid according to any one of Items 1 to 3, wherein the dialkyl 1,4-cyclohexanedicarboxylate is dimethyl 1,4-cyclohexanedicarboxylate.

  Item 5 The 1,4-cyclohexanedicarboxylic acid content in the 1,4-cyclohexanedicarboxylic acid after hydrolysis is 0.1% by weight or less, A method for producing cyclohexanedicarboxylic acid.

  According to the method of the present invention, 1,4-cyclohexanedicarboxylic acid can be efficiently produced from dialkyl 1,4-cyclohexanedicarboxylate with high purity and high yield under the condition that 1,4-cyclohexanedicarboxylic acid is miscible, and the content of metal and organic impurities can be reduced to pharmaceuticals. In addition to the intermediate for producing agricultural chemicals, it can be said that it has industrially significant significance that a production method significantly reduced to such an extent that it can be used as a raw material for synthesizing polyester for optical materials or electronic materials can be established.

Specific examples of the dialkyl 1,4-cyclohexanedicarboxylate used as a hydrolysis raw material in the present invention include dimethyl 1,4-cyclohexanedicarboxylate, diethyl 1,4-cyclohexanedicarboxylate, and 1,4-cyclohexanedicarboxylic acid dialkyl. Dialkyl (C ₁ -C ₄₎ of 1,4-cyclohexanedicarboxylic acid such as n-propyl, diisopropyl 1,4-cyclohexanedicarboxylate, di-n-butyl 1,4-cyclohexanedicarboxylate, diisobutyl 1,4-cyclohexanedicarboxylate ) Esters, among which dimethyl 1,4-cyclohexanedicarboxylate is particularly preferred. By using the dialkyl ester, lower alcohols such as methyl alcohol and ethyl alcohol are by-produced, and these alcohols have a boiling point lower than that of water and can be very easily distilled out of the reaction system by distillation. These esters are not limited to cis and / or trans isomers, and can be used alone or as a mixture of two or more.

  As these dialkyl esters, dialkyl 1,4-cyclohexanedicarboxylate produced by a nuclear hydrogenation reaction of dialkyl terephthalate is preferable, and dimethyl 1,4-cyclohexanedicarboxylate is particularly preferable.

  These dialkyl 1,4-cyclohexanedicarboxylates can usually be easily produced by nuclear hydrogenation of dialkyl terephthalate in the presence of nickel, ruthenium, palladium, platinum or rhodium catalyst (particularly ruthenium catalyst). Examples of such production methods include the methods described in JP-A Nos. 54-163554, 6-192146, 7-149694, and WO9800383.

  Among them, the production method of dialkyl 1,4-cyclohexanedicarboxylate described in JP-A No. 2000-1447 is capable of obtaining a target product having a purity of 98% or more, and organic impurities such as alkyl monocarboxylate are present. The content is particularly preferable because the content can be easily removed by the inventive method. The organic impurities in the present invention refer to monocarboxylic acid alkyls such as alkyl cyclohexanecarboxylate and alkyl 4-methylcyclohexanecarboxylate (particularly alkyl 4-methylcyclohexanecarboxylate) that are by-produced by the nuclear hydrogenation reaction. .

  As the acid catalyst used in the present invention, any catalyst can be used without limitation. Specifically, mineral acids such as hydrochloric acid and sulfuric acid; organic acids such as methanesulfonic acid and p-toluenesulfonic acid; phosphotungstic acid Heteropolyacids such as solid acids such as sulfonic acid type cation exchange resins.

  Examples of the sulfonic acid type ion exchange resin include, for example, trade names: Dowex HCR-W2, Dowex 650 C-H, Dowex 88, Dowex MWC-1-H, Amberlite-200C, Amberlite XH. -105, Deniolite C-433, Deniolite C-464, Levacit SPC-108, Levacit SPC-118, Diaion RCP-105H, Diaion RCP-145H, Sumikaion KC-470, and the like. Moreover, fluorinated sulfonic acid resins such as Nafian-H can also be used.

  Of these, sulfuric acid and p-toluenesulfonic acid are particularly preferably used.

  The acid catalyst is used in an amount of about 0.5 to 10% by weight, preferably about 1 to 7% by weight, based on the starting dialkyl 1,4-cyclohexanedicarboxylate. When the amount is 0.5% by weight or less, a practical reaction rate cannot be obtained. On the other hand, even if the amount exceeds 10% by weight, an effect corresponding to the amount added cannot be obtained, which is not economical.

  Examples of water used as the reaction solvent include tap water, ion-exchanged water, distilled water, and the like, but purified water such as ion-exchanged water and distilled water is preferable because there is no fear of a trace amount of metal contamination.

  As the amount of the feed water in the hydrolysis reaction, the ratio (weight) of dialkyl 1,4-cyclohexanedicarboxylate: water is usually in the range of about 2:98 to 50:50, preferably about 10:90 to 30:70. It is. If the water ratio is too small, the slurry concentration when crystallization purification of 1,4-cyclohexanedicarboxylic acid becomes high, making it difficult to handle, or conversely, if the water ratio is too large, the production efficiency decreases. A tendency is seen, which is not preferable.

  The reaction conditions in the present invention are appropriately selected depending on the raw material 1,4-cyclohexanedicarboxylate dialkyl and the kind of the catalyst, but the reaction temperature is usually 90 to 100 ° C., preferably 98 to 100 ° C., The reaction time is not particularly limited, but is usually in the range of 5 to 15 hours.

  Although there is no restriction | limiting in particular as reaction pressure, Usually, it implements at a normal pressure.

  In the present invention, since the hydrolysis reaction is an equilibrium reaction, water is preferably the same as the distillate of water and alcohol while water and alcohol by-produced during the reaction are continuously evaporated out of the reaction system. It is preferable to carry out by adding a weight of water continuously or intermittently to the reaction system. This distillate, which is a mixture of water and alcohol, contains a small amount of alkyl monocarboxylate by-produced by the nuclear hydrogenation reaction of dialkyl terephthalate, and further dialkyl dicarboxylate. Alkyl monocarboxylate is easily separated by steam distillation, and the content of organic impurities in 1,4-cyclohexanedicarboxylic acid can be reduced to a level that can sufficiently meet the current high demands.

  The composition of the distillate varies with the reaction time. For example, in the case of dimethyl 1,4-dicarboxylate, the average composition is, by weight, water: methanol: (alkyl monocarboxylate and dialkyl dicarboxylate). = 87: A range of about 1:12.

  The distillate amount may be adjusted by adjusting the heating temperature, but the distillate may be condensed with a condenser, a predetermined amount may be extracted out of the reaction system, and the remainder may be returned to the reaction system. .

  The distilled water and methanol mixture can be reused as long as the methanol content is small enough to shift the equilibrium to the hydrolysis side.

  The water to be added may be added as it is, but it is preferably added by heating to a predetermined temperature in order to prevent the reaction temperature from decreasing. Furthermore, a predetermined amount of water vapor can be directly blown into the reaction solution.

  The amount of water added continuously or intermittently is suitably 0.2 to 0.05 / h, more preferably 0.15 to 0.1 / h, based on the liquid space velocity based on the reaction solution volume. It is. The rate of water addition is an important factor that determines the reaction rate. When the evaporation rate exceeds 0.2 at the liquid space velocity, the amount of heat supplied per unit time becomes large and industrially difficult. When the evaporation rate is less than 0.05, the reaction rate becomes small and is not practical.

  The reaction atmosphere is not particularly limited, but is preferably an inert gas atmosphere. Further, the present invention can be carried out by either a continuous type or a batch type.

  After completion of the hydrolysis reaction, the reaction solution is usually cooled to 30 ° C. or lower, preferably 20 ° C. or lower, more preferably 0 to 15 ° C. to crystallize 1,4-cyclohexanedicarboxylic acid, followed by centrifugation or filtration. A high-purity product that can be used as a product can be obtained simply by performing water washing, then reducing pressure, or drying under normal pressure.

  High purity 1,4-cyclohexanedicarboxylic acid having a content of organic impurities in the 1,4-cyclohexanedicarboxylic acid after the hydrolysis reaction thus obtained is 0.1% by weight or less and having a very low metal content. An acid can be obtained.

Hereinafter, the present invention will be described in detail with reference to Examples, Comparative Examples, and Reference Examples. In addition, the component% in each example was shown by weight% of each component of the gas chromatograph analysis or the high performance liquid chromatograph analysis on the following measurement conditions.
1) Gas chromatograph analyzer: GC-14A (manufactured by Shimadzu Corporation)
Detector: FID 280 ° C (internal standard method)
Column: Advance DS (30cm x 0.25mmφ)
Injection temperature: 280 ° C
Column temperature: 200 ° C

2) Liquid chromatograph analyzer: LC-6A (manufactured by Shimadzu Corporation)
Detector: UV 210nm (internal standard method)
Column: SCR-101H (0.3 m × 7.9 mmφ)
Eluent: 3.9 g of 60% perchloric acid diluted to 3 liters with ion-exchanged water Flow rate: 0.8 ml / min
Oven temperature: 40 ° C

3) S content analyzer: TS-30 (formerly manufactured by Mitsubishi Kasei Co., Ltd.)
A sample for analysis was prepared as a 1 wt% aqueous solution of cyclohexanedicarboxylic acid (when it was difficult to dissolve, sodium hydroxide was added), and the sample was subjected to the microcoulometric titration method of JIS standard K2541.

Example 1
140 g of dimethyl 1,4-cyclohexanedicarboxylate with a purity of 98.5% (methyl monocarboxylate 0.8%), ion-exchanged water in a 1 l glass four-necked flask equipped with a stirrer, thermometer, decanter and condenser 360 g of sulfuric acid and 4.2 g of sulfuric acid were charged, the reaction was conducted for 10 hours while adjusting the distillate so that the reaction temperature was 100 ° C. and the liquid space velocity was 0.13, and the reaction solution was analyzed by high performance liquid chromatography. The diester contained trace amounts, the dicarboxylic acid contained 98.5%, and the monoester carboxylic acid contained 1.5%. The obtained reaction solution was gradually cooled to 10 ° C. over 4 hours, and the precipitated crystals were separated by filtration. The crystals were washed with ion-exchanged water at 10 ° C., followed by 0.65 kPa at 100 ° C. for 3 hours. Drying was performed to obtain 110 g (yield 93%) of the desired 1,4-cyclohexanedicarboxylic acid. When the obtained 1,4-cyclohexanedicarboxylic acid was analyzed by gas chromatography using dimethyl ester, the purity was 99.9% and methyl monocarboxylate was not detected. When metal analysis was performed by ICP emission analysis (trade name “Optima 2000DV”, manufactured by PerkinElmer), Na was detected at 2 ppm and Fe was detected at 0.03 ppm. The S content was 0.7 ppm.

Example 2
Except that the liquid space velocity was 0.05 and the reaction time was 18 hours, the reaction was carried out in the same manner as in Example 1, and the reaction liquid was analyzed by high performance liquid chromatograph. 0% and monoester carboxylic acid were contained in a proportion of 1.9%. After completion of the reaction, post-treatment was carried out in the same manner as in Example 1 to obtain 108 g (yield 91%) of the desired 1,4-cyclohexanedicarboxylic acid. When the obtained 1,4-cyclohexanedicarboxylic acid was analyzed by gas chromatography using dimethyl ester, the purity was 99.8% and methyl monocarboxylate was not detected. When metal analysis was conducted by ICP emission analysis, 3 ppm of Na and 0.03 ppm of Fe were detected. Moreover, S content was 0.5 ppm.

Comparative Example 1
The reaction was conducted in the same manner as in Example 1 except that water and alcohol by-produced during the hydrolysis reaction were continuously evaporated out of the reaction system, and the distillate was continuously returned to the reaction system. The hydrolysis reaction reached equilibrium and the reaction did not proceed any further. When this reaction solution was analyzed by liquid chromatography, it was found that diester: monoestercarboxylic acid: 1,4-cyclohexanedicarboxylic acid was contained in a ratio of 7:50:43.

Reference example 1
In a 1 L glass four-necked flask equipped with a stirrer, a thermometer, and a condenser tube, 140 g of dimethyl 1,4-cyclohexanedicarboxylate having a purity of 98.5% (methyl monocarboxylate 0.8%), 360 g of ion-exchanged water, 30 g of sodium hydroxide was added, the reaction was carried out for 2 hours while refluxing at a reaction temperature of 100 ° C., and the reaction solution was analyzed by high performance liquid chromatography. As a result, diester and monoester carboxylic acid sodium salt were traces. The sodium salt was obtained almost quantitatively. The resulting reaction solution was acid-returned while adding about 67 mL of concentrated hydrochloric acid dropwise at 10 ° C. to precipitate 1,4-cyclohexanedicarboxylic acid. The precipitated crystals were separated by filtration, washed thoroughly with ion exchange water at 10 ° C., and then dried at 0.65 kPa and 100 ° C. for 3 hours to obtain 81 g of desired 1,4-cyclohexanedicarboxylic acid (yield). 68%). When the obtained 1,4-cyclohexanedicarboxylic acid was analyzed by gas chromatography using dimethyl ester, the purity was 99.3% and contained 0.4% methyl monocarboxylate. As a result of metal analysis by ICP emission analysis, 400 ppm of Na and 0.03 ppm of Fe were detected. Further, S component was not detected.

Reference example 2
A 500 ml autoclave equipped with an electric magnetic stirrer was charged with 15 g of terephthalic acid, 7.2 g of sodium hydroxide, 100 g of ion-exchanged water and 0.15 g of 5% ruthenium / alumina catalyst. After replacing the system with hydrogen, the reaction temperature was 180 ° C., The reaction was carried out at a pressure of 3 Mpa for 1.5 hours. After cooling, the catalyst was removed by filtration, and the resulting filtrate was acid-reduced while adding about 16 ml of concentrated hydrochloric acid dropwise at 10 ° C. to precipitate 1,4-cyclohexanedicarboxylic acid. The precipitated crystals were separated by filtration, washed thoroughly with ion exchanged water at 10 ° C., and then dried at 0.65 kPa and 100 ° C. for 3 hours to obtain 11 g of desired 1,4-cyclohexanedicarboxylic acid (yield). 71%) was obtained. When the obtained 1,4-cyclohexanedicarboxylic acid was analyzed by gas chromatography using dimethyl ester, the purity was 99.8% and methyl monocarboxylate was not detected. Further, metal analysis by ICP emission analysis detected Na of 430 ppm and Fe of 0.15 ppm. Further, S component was not detected.

Reference example 3
A 500 ml autoclave equipped with an electric magnetic stirrer was charged with 11 g of terephthalic acid, 99 g of ion-exchanged water and 1.1 g of 5% palladium / carbon catalyst, and after replacing the hydrogen with the system, the reaction temperature was 145 ° C. and the pressure was 4.5 MPa. Reacted for 5 hours. After removing the catalyst from the reaction solution by pressure filtration at 120 ° C., the obtained filtrate was cooled to 5 ° C. to precipitate crystals. The precipitated crystals were separated by filtration, and the crystals were thoroughly washed with ion exchange water at 10 ° C., followed by drying at 0.65 kPa and 100 ° C. for 3 hours to obtain the desired 1,4-cyclohexanedicarboxylic acid 9. 3 g (yield 82%) was obtained. When the obtained 1,4-cyclohexanedicarboxylic acid was analyzed by gas chromatography using dimethyl ester, the purity was 98.7% and it contained 0.3% methyl monocarboxylate. Furthermore, when metal analysis was performed by ICP emission analysis, 0.05 ppm of Na and 210 ppm of Fe were detected.

By carrying out the present invention, by carrying out a hydrolysis reaction from 1,4-cyclohexanedicarboxylic acid dialkyl ester, high-purity 1,4-cyclohexanedicarboxylic acid with significantly reduced contents of metals and organic impurities is industrially produced. It is possible to produce a highly pure 1,4-cyclohexanedicarboxylic acid that can sufficiently meet the current high demands.

Claims (5)

  A method for obtaining 1,4-cyclohexanedicarboxylic acid by hydrolyzing a dialkyl 1,4-cyclohexanedicarboxylate in an aqueous solution in the presence of an acidic catalyst, comprising water and an alcohol by-produced during the hydrolysis reaction. A process for producing 1,4-cyclohexanedicarboxylic acid, wherein water is continuously or intermittently added to the reaction system to cause a hydrolysis reaction while continuously evaporating to the outside.   The method for producing 1,4-cyclohexanedicarboxylic acid according to claim 1, wherein water is added and reacted so that the liquid space velocity is 0.2 to 0.05 / h based on the reaction liquid volume.   The method for producing 1,4-cyclohexanedicarboxylic acid according to claim 1 or 2, wherein the dialkyl 1,4-cyclohexanedicarboxylate is produced by a nuclear hydrogenation reaction of dialkyl terephthalate.   The method for producing 1,4-cyclohexanedicarboxylic acid according to any one of claims 1 to 3, wherein the dialkyl 1,4-cyclohexanedicarboxylate is dimethyl 1,4-cyclohexanedicarboxylate. The 1,4-cyclohexane according to any one of claims 1 to 4, wherein the content of organic impurities in 1,4-cyclohexanedicarboxylic acid after the hydrolysis reaction is 0.1 wt% or less. A method for producing dicarboxylic acid.