JP2009007267A - Method for producing trans-1,2-cyclohexane dimethanol - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for commercially advantageous production of trans-1,2-cyclohexane dimethanol useful as a raw material for various industrial base materials, and as a medicine in a high yield. <P>SOLUTION: A dialkyl 1,2-cyclohexanedicarboxylate having a trans isomer content of ≥80% is hydrogenated in the presence of a catalyst. The hydrogenation reaction is efficiently carried out with high pressure hydrogen in the presence of the catalyst, to give trans-1,2-cyclohexane dimethanol in high selectivity. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a process for producing trans-1,2-cyclohexanedimethanol.

  The trans-1,2-cyclohexanedimethanol according to the present invention is useful as a raw material for various industrial substrates such as polyester resins and polyurethane resins, as well as other cyclohexanedimethanols. It is also known to be useful as a pharmaceutical intermediate (see Patent Document 1 and Non-Patent Document 1).

  Conventionally, as a method for producing trans-1,2-cyclohexanedimethanol, a hydrogenated compound such as lithium aluminum hydride or sodium borohydride is used, and 1,2-cyclohexanedicarboxylic acid dialkyl ester is hydrogenated in an organic solvent. There is known a method for converting to the above (Patent Document 2, Non-Patent Document 2). However, since this hydrogenated compound is water-inhibiting and ignitable and requires careful handling, it may not be industrially preferred. In addition, the hydrogenated compound is expensive, and further, the post-treatment of the by-product during the hydrogenation reaction and the product purification process are complicated, and therefore, it is not an industrially advantageous method in terms of cost.

  On the other hand, 1,3-cyclohexanedimethanol or 1,4-cyclohexanedimethanol is produced from a corresponding cyclohexanedicarboxylic acid dialkyl ester in a high yield and industrially in a hydrogenation reaction using high-pressure hydrogen without using a hydrogenated compound. A method of producing it advantageously is known (Patent Documents 3 to 7). However, these known documents do not specifically disclose a method for producing trans-1,2-cyclohexanedimethanol by a hydrogenation reaction using high-pressure hydrogen.

Japanese Patent Laid-Open No. 5-17440 JP 2005-272335 A JP 2000-001447 A JP-A-7-196558 JP-A-7-188079 JP 2005-007595 A International Publication No. WO1998 / 000383 Pamphlet Journal of Organic Chemistry, 58, 7 (1993) Journal of American Chemical Society, 75,4780 (1953)

  An object of the present invention is to provide a method for producing trans-1,2-cyclohexanedimethanol with high purity, high yield, and industrially advantageously.

  As a result of intensive studies to solve such problems, the present inventors have obtained the following knowledge in the course of developing a process for producing trans-1,2-cyclohexanedimethanol.

(1)
It is known that the corresponding cyclohexanedimethanol can be obtained by hydrogenating 1,3-cyclohexanedicarboxylic acid dialkyl ester or 1,4-cyclohexanedicarboxylic acid dialkyl ester using high-pressure hydrogen. However, even when a cis isomer of 1,2-cyclohexanedicarboxylic acid dialkyl ester or a cis / trans isomer mixture having a low trans isomer content is subjected to a hydrogenation reaction under the same conditions as in this known reaction method, the reactivity is high. Since it is bad, it is difficult to obtain the desired 1,2-cyclohexanedimethanol with good yield, and it is difficult to selectively obtain the trans isomer.
(2)
The hydrogenation reaction using high-pressure hydrogen using 1,2-cyclohexanedicarboxylic acid dialkyl ester having a trans isomer content of 80% or more as a hydrogenation raw material proceeds at high conversion and high selectivity, and trans-1, 2-cyclohexanedimethanol can be obtained efficiently.

  That is, the present invention has been completed based on such knowledge and provides the following inventions.

(Claim 1)
A process for producing trans-1,2-cyclohexanedimethanol, wherein a 1,2-cyclohexanedicarboxylic acid dialkyl ester having a trans isomer content of 80% or more is hydrogenated in the presence of a catalyst. -Method for producing cyclohexanedimethanol.

(Section 2)
The production method according to (Item 1), wherein the hydrogenation reaction is performed in the presence of a copper-based catalyst under reaction conditions of a reaction temperature of 180 to 280 ° C. and a reaction pressure of 10 to 30 MPa.

(Section 3)
The production method according to (Item 1) or (Item 2), wherein the 1,2-cyclohexanedicarboxylic acid dialkyl ester is obtained via an isomerization reaction.

  According to the present invention, it is possible to obtain trans-1,2-cyclohexanedimethanol which is useful as a raw material for various industrial base materials or pharmaceutical intermediates with high yield / high selectivity by an industrially advantageous production method. it can.

[Raw material for hydrogenation reaction]
The 1,2-cyclohexanedicarboxylic acid dialkyl ester of the hydrogenation reaction raw material according to the present invention is an ester compound having a trans isomer content of 80% or more.
In the present specification and claims, the 1,2-cyclohexanedicarboxylic acid dialkyl ester and the trans isomer content of 1,2-cyclohexanedimethanol are the 1,2-cyclohexanedicarboxylic acid dialkyl ester and 1,2-cyclohexanedicarboxylic acid dialkyl ester. It represents the ratio of the trans isomer in the cis-trans isomer of 2-cyclohexanedimethanol.
The ratio of the cis-trans isomer can be measured by various instrumental analyses. For example, when using gas chromatography analysis (hereinafter abbreviated as GC analysis; measurement conditions are shown in the examples below), the peak area attributed to the trans isomer of 1,2-cyclohexanedicarboxylic acid dialkyl ester observed is From the area of the peak attributed to the cis isomer, the ratio of the trans isomer in the cis-trans isomer can be determined.

  The 1,2-cyclohexanedicarboxylic acid dialkyl ester is an ester compound in which the alkyl chain in the ester group has 1 to 9, preferably 1 to 3, particularly preferably 1. Specific examples of the 1,2-cyclohexanedicarboxylic acid dialkyl ester include 1,2-cyclohexanedicarboxylic acid dimethyl ester, 1,2-cyclohexanedicarboxylic acid diethyl ester, 1,2-cyclohexanedicarboxylic acid di n-propyl ester, 1, 2-cyclohexanedicarboxylic acid diisopropyl ester, 1,2-cyclohexanedicarboxylic acid di-n-butyl ester, 1,2-cyclohexanedicarboxylic acid diisobutyl ester, 1,2-cyclohexanedicarboxylic acid di-n-hexyl ester, 1,2-cyclohexanedicarboxylic ester Examples include acid di-2-ethylhexyl ester, 1,2-cyclohexanedicarboxylic acid di-n-octyl ester, 1,2-cyclohexanedicarboxylic acid diisononyl ester and the like. Cyclohexanedicarboxylic acid dimethyl ester.

The 1,2-cyclohexanedicarboxylic acid dialkyl ester according to the present invention may be a commercially available product, or can be produced according to a known method.
The 1,2-cyclohexanedicarboxylic acid dialkyl ester is preferably a high-purity product, and the purity is preferably 90% or more, more preferably 95 or more, and particularly preferably 98% or more.
The 1,2-cyclohexanedicarboxylic acid dialkyl ester is preferably one having a small amount of catalyst poison in the hydrogenation reaction, and examples of the catalyst poison include sulfur, phosphorus and halogen compounds. Moreover, when containing a thing with low purity or a catalyst poisonous substance, you may refine | purify and use it by well-known methods, such as distillation, recrystallization, an adsorption process, column separation, solvent extraction, for example.

The preferred trans isomer content of the 1,2-cyclohexanedicarboxylic acid dialkyl ester having a trans isomer content of 80% or more is 84% or more, more preferably 90% or more, particularly preferably 95% or more. By increasing the content, the hydrogenation reaction using this ester as a raw material proceeds at a high conversion rate, and the trans-selectivity of 1,2-cyclohexanedimethanol in the hydrogenation reaction is also high.
Examples of methods for increasing the trans isomer content of 1,2-cyclohexanedicarboxylic acid dialkyl ester include methods such as isomerization, rectification, recrystallization, column separation, and solvent extraction. Depending on the above, it is possible to increase the trans isomer content of the present ester by combining these methods.

  Among the above methods, for example, in the isomerization reaction, isomerization proceeds by heating and stirring in the presence of an isomerization catalyst, and 1,2-cyclohexanedicarboxylic acid dialkyl ester having a trans isomer content of 80% or more is efficiently produced. It is a method that can be obtained well.

A known basic compound can be used as the isomerization reaction catalyst. Basic compounds include alkoxides such as sodium methoxide, sodium ethoxide and potassium t-butoxide; alkali metals such as lithium, potassium, sodium and potassium; sodium hydroxide, potassium hydroxide, magnesium hydroxide and hydroxide Examples thereof include metal hydroxides such as calcium, and amines such as methylamine, ethylamine, trimethylamine, triethylamine, N, N-diisopropylethylamine, and ethylenediamine. These basic compounds can be used individually by 1 type or in combination of 2 or more types as appropriate.
Among the basic compounds, alkoxides are preferable as the isomerization reaction catalyst, and among the alkoxides, sodium methoxide is preferable from the viewpoint of cost and simplicity of the post-treatment process.

  Although the usage-amount of an isomerization reaction catalyst can be selected suitably, 0.001-1 weight part is used with respect to 100 weight part of 1, 2- cyclohexane dicarboxylic acid dialkyl ester.

  The reaction temperature of the isomerization reaction is usually 80 to 280 ° C, preferably 100 to 160 ° C. When the temperature is lower than 80 ° C., the reaction rate is slow, and when the temperature is higher than 280 ° C., by-products of reaction decomposition products may be generated and the yield may be lowered.

The isomerization reaction can be carried out in the presence of a solvent or without a solvent, but it is preferably carried out without a solvent from the viewpoint of reactivity and ease of the purification step after the reaction.
In the case of using a solvent, the solvent is not particularly limited as long as it dissolves 1,2-cyclohexanedicarboxylic acid dialkyl ester which is an isomerization reaction raw material and is inactive to the isomerization reaction.

  Specific examples of the solvent include ether solvents such as tetrahydrofuran, ethyl ether, isopropyl ether, butyl ether, methyl tert-butyl ether, propylene glycol monomethyl ether, diethylene glycol dimethyl ether, and dimethoxyethane; benzene, toluene, xylene, ethylbenzene, butyl Aromatic hydrocarbon solvents such as benzene, cumene, trimethylbenzene, alkyl (C6-C14) benzene, tetrahydronaphthalene, and alicyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, trimethylcyclohexane, etc. And aliphatic hydrocarbon solvents such as n-hexane, n-heptane, n-octane, isooctane, and nonane. These solvent can be used individually by 1 type or in combination of 2 or more types.

  The isomerization reaction time varies depending on the amount of catalyst used and the above reaction conditions, but it is preferable to carry out the reaction until the trans isomer content is 80% or more. The reaction time is usually about 0.5 to 15 hours, preferably about 1 to 10 hours, particularly preferably about 1 to 5 hours. If the time is less than 0.5 hours, a high conversion rate is difficult to obtain. On the other hand, if the time exceeds 15 hours, side reactions may occur and the yield may decrease.

[Hydrogenation reaction conditions]
The catalyst used in the hydrogenation reaction of the present invention is a metal catalyst used in the ester hydrogenation reaction, and a copper catalyst is preferable from the viewpoint of reactivity and cost. Examples of such catalysts include copper-zinc-aluminum oxide catalysts, copper-chromium oxide catalysts, and modified catalysts obtained by adding magnesium, barium, calcium and these oxides to these catalysts. These catalysts can be used in the reaction by appropriately combining one type or two or more types. The manufacturing method of these catalysts is not specifically limited, It can manufacture by a well-known method.

  The amount of the hydrogenation catalyst used is preferably 0.01 to 10% by weight, particularly preferably 0.05 to 5% by weight, based on the diester of the hydrogenation reaction raw material. If it is less than 0.01% by weight, the reaction rate is very slow, and if it exceeds 10% by weight, a reaction rate corresponding to the amount added cannot be obtained, which is not rational.

  The form of the hydrogenation reaction catalyst is not particularly limited, and a powder catalyst or a tablet catalyst can be appropriately selected and used depending on the selected reaction method. For batch or continuous suspension bed reactions, powdered catalysts are preferably used.

  As the hydrogenation reaction catalyst, the size of the powder catalyst is not particularly limited, and those having an arbitrary particle size distribution are used.

Although the hydrogenation reaction of the present invention can be carried out without using a solvent, the raw material 1,2-cyclohexanedicarboxylic acid dialkyl ester has a high melting point and is difficult to handle, or for easy removal of reaction heat. Can also use a solvent.

The solvent is not particularly limited as long as it does not adversely affect the hydrogenation reaction, and a solvent usually used for the hydrogenation reaction can be used. The amount of reaction solvent used is appropriately selected.

  As hydrogenation reaction temperature of this invention, it is 180-280 degreeC normally, Comprising: 200-250 degreeC is more preferable. When the reaction temperature is less than 180 ° C., the conversion rate is low, while when the reaction temperature exceeds 250 ° C., side reactions tend to increase.

  The reaction pressure is preferably 10-30 MPa as gauge pressure, more preferably 15-25 MPa. When the pressure is less than 10 MPa, the conversion rate is low. On the other hand, when the pressure exceeds 30 MPa, the construction cost is expensive and the management is difficult even though the effect is small.

  For the hydrogenation reaction of the present invention, any one of batch reaction and continuous reaction can be used.

  The hydrogenation reaction of the present invention can be carried out using any one of a fixed bed reactor and a suspension bed reactor, but is preferably carried out using a suspension bed reactor. Examples of the suspension bed reactor include a suspension bed bubble column reactor and a suspension bed stirrer reactor. Suspension bed bubble column reactor is a device suitable for mass production because it has no problems such as a shaft seal of the stirrer and maintenance of the container is easy compared with the suspension bed stirrer reactor, and the construction cost is low. is there.

The reaction time is preferably shorter from the viewpoint of productivity, but considering the product quality and the load of the post-treatment process (distillation process), the conversion rate is 90% or more, preferably 95% or more, more preferably 97% or more. It is preferred to carry out the hydrogenation reaction until it is achieved.
When the hydrogenation reaction is a continuous reaction system, the average residence time is preferably about 0.5 to 10 hours, more preferably about 1 to 5 hours. When the average residence time is short, the conversion rate tends to be low.
When the hydrogenation reaction is a palindromic reaction system, the reaction time is usually about 0.5 to 15 hours, preferably about 1 to 10 hours. When the reaction time is short, the conversion tends to be low.

  When the hydrogenation reaction is a continuous reaction system, the hydrogen gas linear velocity is preferably 1 to 20 cm / second, more preferably 3 to 4 cm / second. If it is less than 1 cm / sec, the conversion rate is low, whereas if it exceeds 20 cm / sec, the catalyst tends to be too concentrated.

The selectivity of trans-1,2-cyclohexanedimethanol in the hydrogenation reaction of the present invention is represented by the following calculation formula (1).
Hydrogenation reaction trans-1,2-cyclohexanedimethanol selectivity = (A / hydrogenation reaction raw material conversion) * 100 (%) (1)
[A = trans-1,2-cyclohexanedimethanol of reaction product solution (GC area%)]

When 1,2-cyclohexanedicarboxylic acid dialkyl ester having a trans isomer content of 80% or more is used as a hydrogenation reaction raw material, the trans isomer selectivity in the hydrogenation reaction is usually 65% or more and 70% or more. Preferably, it is 75% or more, more preferably 80% or more.

The trans isomer content of 1,2-cyclohexanedimethanol obtained by the hydrogenation reaction of the present invention is represented by the following formula (2).
Hydrogenation reaction product trans isomer content = (A / (A + B)) * 100 (2)
[A = trans-1,2-cyclohexanedimethanol (GC area%) in the reaction product solution
B = cis-1,2-cyclohexanedimethanol (GC area%) in the reaction product solution]

When 1,2-cyclohexanedicarboxylic acid dialkyl ester having a trans isomer content of 80% or more is used as a raw material for the hydrogenation reaction, the trans isomer content of 1,2-cyclohexanedimethanol obtained is usually 70% or more. 80% or more is preferable, and 85% or more is more preferable.

The trans-1,2-cyclohexanedimethanol obtained by the hydrogenation reaction of the present invention can be obtained by using a known purification method such as rectification, recrystallization, column separation, solvent extraction, as necessary. By-produced alcohol and other by-products are removed, and more pure trans-1,2-cyclohexanedimethanol can be obtained.
Moreover, when performing rectification, it is possible to reduce the content of impurities (trace metal components) in the distillation raw material by performing an adsorption treatment using an adsorbent as necessary. When the distillation raw material subjected to the adsorption treatment is used, generation of side reaction products during the distillation operation is suppressed.

  As a specific reaction system, for example, a process using a suspended bed bubble column reactor as shown in the drawing (FIG. 1) described later is exemplified, but the present invention is not limited to this process. Absent.

  In FIG. 1, a hydrogen introduction pipe 2 and a suspension of catalyst and dimethyl 1,2-cyclohexanedicarboxylate (hereinafter referred to as “raw material suspension”) introduction pipe 3 are provided at the bottom of a cylindrical reactor 1. It is arranged. The structure is such that hydrogen bubbles are ejected from the hydrogen introduction pipe through the filter into the reaction solution. In this apparatus, hydrogen gas, product 1,2-cyclohexanedimethanol and catalyst (hereinafter referred to as “product suspension”) are discharged from the discharge pipe 4 at the top of the reaction tower to the gas-liquid separator 5, Separated into hydrogen gas and product suspension. Further, the product suspension is filtered by a filter 6 into a catalyst and 1,2-cyclohexanedimethanol. As a filter, the usual apparatus normally used in the said field | area, such as a Funder type filter, can be used. Here, the catalyst and the recovered hydrogen gas can be discarded or recycled, and are preferably reused from the viewpoint of cost.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these Examples.

The contents of cis- and trans-isomers of 1,2-cyclohexanedicarboxylic acid dialkyl ester and 1,2-cyclohexanedimethanol, and the raw material conversion in the hydrogenation reaction were measured by gas chromatography analysis under the conditions shown below. . Further, the selectivity of trans-1,2-cyclohexanedimethanol in the hydrogenation reaction is calculated using the calculation formula (1) described in [0037], and the hydrogenation is performed using the calculation formula (2) described in [0039]. The trans isomer content of the reaction product was calculated. The GC analysis results and calculation results are shown in Table 1 described later.

<Gas chromatography (GC) analysis>
GC analysis of 1,2-cyclohexanedicarboxylic acid dialkyl ester and 1,2-cyclohexanedimethanol was performed under the following conditions.
Device: SHIMADZU GC-2010
Column: DB-1701 (GL Science Co., Ltd.) 0.25mm × 30m 0.25μm
Column temperature: 250 ° C (constant temperature)
Flow rate: 1ml / min.
Split: 1/50
Injection temperature: 300 ℃
Detection temperature: 300 ℃

Production Example 1
Production of dimethyl cis-1,2-cyclohexanedicarboxylate (1) 100 parts by weight of 1,2-cyclohexanedicarboxylic anhydride and p-toluenesulfone in a reactor equipped with a dropping funnel, a water separator with a condenser, and a thermometer 3 parts by weight of acid monohydrate was added and stirred.
(2) Methanol (100 parts by weight) is added dropwise while controlling the temperature of the reaction system to be 50 ° C. or lower. After confirming that the exotherm disappeared, the temperature was raised to 110 ° C.
(3) While methanol (100 parts by weight × 10) was added dropwise at 110 ° C., the mixture was stirred under reflux to distill off the generated water.
(4) The acid value (AV) of the reaction solution was measured to confirm the completion of the reaction. After cooling the reaction solution, neutralization with sodium carbonate was performed, and after standing, the separated aqueous layer was extracted. Next, the obtained diester layer was washed with warm water until the pH of the washing water became neutral. After washing, dehydration treatment was performed at 110 ° C./20 mmHg to obtain dimethyl cis-1,2-cyclohexanedicarboxylate (GC analysis: 99% cis isomer).

Production Example 2
Production of dimethyl trans-1,2-cyclohexanedicarboxylate Methanol of sodium methoxide with respect to 100 parts by weight of dimethyl cis-1,2-cyclohexanedicarboxylate (GC analysis: 99% cis isomer) obtained in Production Example 1 0.5 parts by weight of a solution (containing 28% sodium methoxide) was added, heated and stirred at 140 ° C. for 2 hours under nitrogen gas flow, cooled to 60 ° C. after the reaction, and washed twice with 50 parts by weight of warm water. Then, dehydration under reduced pressure gave a crude reaction product (trans isomer / cis isomer = 84/16). Further, the reaction crude was rectified with dimethyl trans-cyclohexanedicarboxylate under conditions of 90 ° C./5 mmHg to obtain dimethyl trans-1,2-cyclohexanedicarboxylate (GC analysis: 99% trans isomer).

  Hydrogenation reaction raw materials having different cis- and trans-isomer contents used in Examples and Comparative Examples were prepared by mixing dimethyl 1,2-cyclohexanedicarboxylate obtained in Production Examples 1 and 2. In Examples and Comparative Examples, dimethyl 1,2-cyclohexanedicarboxylate having a purity of 99.5% (the purity in this case indicates the total value of cis and trans forms in GC analysis) was used. .

Example 1
While maintaining the hydrogen pressure of the cylindrical high-pressure bubble column (inner diameter 4.6 cm, length 3 m) at a pressure of 20 MPa and the reaction temperature of 220 ° C. with an overflow mechanism of 4 L, the hydrogen gas from the bottom of the bubble column reactor is 3 cm / In addition, a suspension of dimethyl 1,2-cyclohexanedicarboxylate (trans content 99%) and a copper-chromium oxide catalyst (manufactured by JGC Chemicals, trade name N-203SD) (catalyst concentration 5%) ) At 1 L / h (average residence time: 4 hours) and continuously operated for 20 hours to obtain 1,2-cyclohexanedimethanol as a hydrogenation reaction product. It was confirmed that a steady state was reached 7 hours after the start of the reaction.
GC analysis of the reaction product solution showed that the conversion rate of dimethyl 1,2-cyclohexanedicarboxylate was 98%. The content of the trans isomer of 1,2-cyclohexanedimethanol in the hydrogenation reaction product was 88% (trans isomer = 84 GC area%, cis isomer = 12% GC area%).
The conversion rate obtained by GC analysis, and the hydrogenation reaction transduct selectivity calculated from the content of the trans isomer and cis isomer of the hydrogenation reaction product was 86%.

The reaction product obtained by the hydrogenation reaction was treated with demethanol, and then rectified in a precision distiller having 20 theoretical plates under the conditions of 148 ° C./0.7 kPa, and high-purity trans-1,2-cyclohexane. Dimethanol (distillation yield 81%, trans isomer content 99%) was obtained.

Example 2
The hydrogenation reaction was carried out under the same reaction conditions as in Example 1 except that dimethyl 1,2-cyclohexanedicarboxylate (trans isomer content 84%, cis isomer content 16%) was used. The reaction product solution was analyzed by gas chromatography. The conversion of dimethyl 1,2-cyclohexanedicarboxylate was 98%, and the content of the trans isomer of 1,2-cyclohexanedimethanol, a hydrogenation reaction product, was trans. The body content was 88% (trans isomer = 77 GC area%, cis isomer = 11% GC area%).
The conversion rate obtained by GC analysis, and the hydrogenation reaction trans-isomer selectivity calculated from the content of the trans-isomer and cis-isomer of the hydrogenation reaction product was 79%.

Example 3
A hydrogenation reaction was carried out under the same reaction conditions as in Example 2 except that a copper-zinc-aluminum catalyst (manufactured by JGC Chemicals, trade name E01-X1) was used. As a result of gas chromatography analysis of the reaction product solution, the conversion of dimethyl 1,2-cyclohexanedicarboxylate was 97%, and the content of the trans isomer of 1,2-cyclohexanedimethanol in the product was 88%. (Trans isomer = 73 GC area%, cis isomer = 10% GC area%).
The conversion rate obtained by GC analysis and the hydrogenation reaction transisomer selectivity calculated from the contents of the trans isomer and cis isomer of the hydrogenation reaction product were 75%.

Comparative Example 1
The hydrogenation reaction was carried out under the same reaction conditions as in Example 1 except that 1,2-cyclohexanedicarboxylic acid dimethyl ester (trans isomer content 75%, cis isomer content 25%) was used. When the reaction product solution was analyzed by gas chromatography, the conversion of dimethyl 1,2-cyclohexanedicarboxylate was 84%, and the content of the trans isomer of 1,2-cyclohexanedimethanol in the product was 69%. (Trans form = 51 GC area%, cis form = 23 GC area%).
The conversion rate obtained by GC analysis, and the hydrogenation reaction transduct selectivity calculated from the content of the trans isomer and cis isomer of the hydrogenation reaction product was 61%.

Comparative Example 2
The hydrogenation reaction was carried out under the same reaction conditions as in Example 2 except that 1,2-cyclohexanedicarboxylic acid dimethyl ester (trans isomer content 53%, cis isomer content 47%) was used. As a result of gas chromatography analysis of the reaction product solution, the conversion of dimethyl 1,2-cyclohexanedicarboxylate was 71%, and the content of trans isomer of 1,2-cyclohexanedimethanol in the product was 68%. (Trans form = 45 GC area%, cis form = 21 GC area%).
The conversion rate obtained by GC analysis and the hydrogenation reaction trans-isomer selectivity calculated from the contents of the trans-isomer and cis-isomer of the hydrogenation reaction product were 63%.

Comparative Example 3
The hydrogenation reaction was carried out under the same reaction conditions as in Example 1 except that 1,2-cyclohexanedicarboxylic acid dimethyl ester (cis content 99%) was used. When the reaction product liquid was analyzed by gas chromatography,
The conversion of dimethyl 1,2-cyclohexanedicarboxylate was 55%, and the content of the trans isomer of 1,2-cyclohexanedimethanol in the product was 52% (trans isomer = 24 GC area%, cis isomer = 22 GC area%). The conversion obtained by GC analysis and the hydrogenation reaction transduct selectivity calculated from the content of the trans isomer and cis isomer of the hydrogenation reaction product were 44%.

As is clear from Table 1 that summarizes the results of the hydrogenation reaction in each Example and Comparative Example, hydrogenation using dimethyl 1,2-cyclohexanedicarboxylate having a trans isomer content of 80% or more of the present invention as a raw material In the reactions (Examples 1 to 3), the hydrogenation reaction proceeded at a high conversion rate and high selectivity, and 1,2-cyclohexanedimethanol having a high trans isomer content was obtained.
On the other hand, the hydrogenation reaction (comparative examples 1 to 3) using dimethyl 1,2-cyclohexanedicarboxylate having a trans isomer content of less than 80% as a raw material was compared with the raw material conversion rate and the trans The body selectivity was low and the trans isomer content of the obtained 1,2-cyclohexanedimethanol was also low.

  Trans-1,2-cyclohexanedimethanol, which is advantageously produced industrially by the production method of the present invention, is a material useful as a raw material for various industrial substrates and an intermediate for pharmaceutical products.

FIG. 1 is a drawing showing a preferred embodiment of a suspended bed bubble reactor according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Suspension bubble column type reactor 2 ... Hydrogen introduction pipe 3 ... Raw material suspension introduction pipe 4 ... Discharge pipe 5 ... High pressure gas Liquid separator 6 ... filter

Claims (3)

  A method for producing trans-1,2-cyclohexanedimethanol, wherein a 1,2-cyclohexanedicarboxylic acid dialkyl ester having a trans isomer content of 80% or more is hydrogenated in the presence of a catalyst. -Method for producing cyclohexanedimethanol.   The process according to claim 1, wherein the hydrogenation reaction is carried out in the presence of a copper catalyst under reaction conditions of a reaction temperature of 180 to 280 ° C and a reaction pressure of 10 to 30 MPa. The production method according to claim 1 or 2, wherein the 1,2-cyclohexanedicarboxylic acid dialkyl ester is obtained through an isomerization reaction.

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