Trans-1,4-cyclohexyl organic compound and synthesis method thereof

Abstract

The present application relates to a trans-1,4-cyclohexyl organic compound and a synthesis method thereof, the synthesis method comprising: providing a cyclohexanol compound; adding the cyclohexanol compound to a solvent and silicotungstic acid or its hydrate and mixing them uniformly, generating a mixed system containing cyclohexene compounds under the catalytic action of silicotungstic acid or its hydrate; providing hydrogen and a hydrogenation catalyst to the mixed system so that the cyclohexene compounds undergo a hydrogenation reaction to generate trans-1,4-cyclohexyl organic compounds. The synthesis process of the present application is simple, and the yield of the synthesized trans-1,4-cyclohexyl organic compound is high.

Description

Technical Field

[0001] The present application relates to the field of material production technology, and more specifically, to trans-1,4-cyclohexyl organic compounds and synthesis methods thereof. Background Art

[0002] Trans-1,4-cyclohexyl organic compounds are often used in materials such as liquid crystals due to their advantages such as low viscosity coefficient. However, the yield of trans-1,4-cyclohexyl organic compounds is currently low and needs to be further improved. Summary of the Invention

[0003] The present application provides a trans-1,4-cyclohexyl organic compound and a synthesis method thereof. The synthesis method has a simple synthesis process and a high yield of the synthesized trans-1,4-cyclohexyl organic compound.

[0004] In the first aspect, the present application proposes a method for synthesizing trans-1,4-cyclohexyl organic matter, which comprises: providing a cyclohexanol compound; adding the cyclohexanol compound to a solvent and silicotungstic acid or a hydrate thereof and mixing them evenly, and generating a mixed system containing cyclohexene compounds under the catalytic action of silicotungstic acid or a hydrate thereof; providing hydrogen and a hydrogenation catalyst to the mixed system so that the cyclohexene compound undergoes a hydrogenation reaction to generate a trans-1,4-cyclohexyl organic matter.

[0005] In any embodiment, the cyclohexanol compound includes a compound represented by formula (I):

[0006]

[0007] In formula (I),

[0008] R1 and R2 are each independently selected from a substituted or unsubstituted linear alkyl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted aromatic group; when substituted, the substituent includes a halogen atom; further optionally, the substituent includes a fluorine atom.

[0009] In any embodiment, R1 and R2 are each independently selected from a substituted or unsubstituted C1 to C10 chain alkyl group, a substituted or unsubstituted C3 to C10 cycloalkyl group, or a substituted or unsubstituted C6 to C10 aromatic group; alternatively, R1 and R2 are each independently selected from a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a phenyl group, a naphthyl group or a fluorophenyl group.

[0010] In any embodiment, the cyclohexanol compound comprises a cis-cyclohexanol compound, a trans-cyclohexanol compound, or a mixture of both.

[0011] In any embodiment, based on the total mass of the cyclohexanol compound, the mass content of silicotungstic acid or its hydrate is C%, and 0.1≤C≤2.0.

[0012] In any embodiment, based on the total mass of the cyclohexanol compound, the mass content of the hydrogenation catalyst is D%, 0.2≤D≤2.0; and / or the hydrogenation catalyst includes a palladium-based catalyst and / or a platinum-based catalyst supported on the surface of an adsorbent such as activated carbon, alumina, or diatomaceous earth.

[0013] In any embodiment, the hydrogenation reaction includes a first reaction stage and a second reaction stage; the hydrogenation reaction satisfies condition (1) and / or condition (2):

[0014] (1) The reaction temperature in the first reaction stage is 60°C to 120°C;

[0015] (2) The reaction temperature of the second reaction stage is -20°C to 20°C; and / or the reaction time is 5h to 20h.

[0016] In any embodiment, the solvent includes an aliphatic hydrocarbon solvent and / or an aromatic hydrocarbon solvent; optionally, the solvent includes one or more of petroleum ether, cyclohexane, methylcyclohexane, benzene, toluene or xylene.

[0017] In a second aspect, the present application provides a trans-1,4-cyclohexyl organic compound prepared by the method described in any embodiment of the first aspect of the present application.

[0018] According to the synthesis method of the present invention, silicotungstic acid or its hydrate is added during the synthesis process as a catalyst for the dehydration of cyclohexanol compounds and then added to the hydrogenation reaction of substituted cyclohexene compounds. This results in a final product containing far more trans-1,4-substituted cyclohexyl compounds than cis-1,4-substituted cyclohexyl compounds. Specifically, silicotungstic acid or its hydrate reacts with substituted cyclohexene compounds to form carbocations, which can cause the substituted cyclohexyl compounds to undergo a configurational transformation. Because the trans-1,4-cyclohexyl group has a more stable configuration, the final result of the configurational transformation reaction is a far greater proportion of trans-1,4-substituted cyclohexyl compounds than cis-1,4-substituted cyclohexyl compounds. This increases the proportion of the trans-1,4-cyclohexyl isomer in the final product from 40-60% under typical hydrogenation conditions to over 85%. DETAILED DESCRIPTION

[0019] The embodiments of the present application will be described in detail below. The embodiments of the present application should not be interpreted as limiting the present application.

[0020] In addition, amounts, ratios, and other numerical values ​​are sometimes presented herein in a range format. It should be understood that such a range format is used for convenience and brevity and should be interpreted flexibly to include not only the values ​​explicitly specified as limits of the range, but also all individual values ​​or sub-ranges encompassed within the range, as if each value and sub-range were explicitly specified.

[0021] In the detailed description and claims, a list of items connected by the terms "one or more of," "one or more of," "one or more of," or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0022] The term "chain alkyl" encompasses both straight-chain and branched alkyl groups. For example, the chain alkyl group may be a C1-C50 alkyl group, a C1-C40 alkyl group, a C1-C30 alkyl group, a C1-C20 alkyl group, a C1-C12 alkyl group, a C1-C10 alkyl group, a C1-C6 alkyl group, or a C1-C4 alkyl group. In some embodiments, the alkyl group includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, or the like. In addition, the chain alkyl group may be optionally substituted.

[0023] The term "cyclic alkyl" refers to a ring structure having more than or equal to three carbon atoms. For example, the cyclic alkyl can be a C3 to C50 cycloalkyl, a C3 to C40 cycloalkyl, a C3 to C30 cycloalkyl, a C3 to C20 cycloalkyl, a C3 to C12 cycloalkyl, a C3 to C10 cycloalkyl, a C3 to C6 cycloalkyl, or a C3 to C4 cycloalkyl. In certain embodiments, the cyclic alkyl includes a cyclopropyl, a cycloisopropyl, a cyclobutyl, a cycloisobutyl, a cyclotert-butyl group, a cyclopentyl, a cyclohexyl, a cycloheptyl, a cyclooctyl group, or the like. In addition, the cyclic alkyl can be optionally substituted.

[0024] The term "aromatic group" refers to a closed aromatic ring or ring system. For example, the aromatic group can be a C6 to C50 aromatic group, a C6 to C40 aromatic group, a C6 to C30 aromatic group, a C6 to C20 aromatic group, or a C6 to C10 aromatic group. Wherein a C6 to C30 aromatic group refers to a group containing 6 to 30 carbon atoms and including an aromatic ring structure. In certain embodiments, the aromatic group includes phenyl, naphthyl, phenanthrenyl, anthracenyl, biphenyl, triphenylene, pyrenyl, spirobifluorenyl, phenanthrenyl, peryl, indenyl, and azulenyl. In addition, the aryl group can be optionally substituted.

[0025] The term "halogen atom" refers to a fluorine atom, a chlorine atom, a bromine atom or the like.

[0026] The term "heteroatom" refers to a nitrogen atom, a sulfur atom, a phosphate atom, and the like.

[0027] The term "hydrogen" refers to 1H (protium, H), 2H (deuterium, D), or 3H (tritium, T). In various embodiments, "hydrogen" may be 1H (protium, H).

[0028] In various places of this specification, the substituent of compound is disclosed with group or scope.It is clearly expected that this description comprises each individual subcombination of the member of these groups and scope.For example, it is clearly expected that term " C1 to C8 alkyl" discloses C1, C2, C3, C4, C5, C6, C7, C8, C1 to C8, C1 to C7, C1 to C6, C1 to C5, C1 to C4, C1 to C3, C1 to C2, C2 to C8, C2 to C7, C2 to C6, C2 to C5, C2 to C4, C2 to C3, C3 to C8, C3 to C7, C3 to C6, C3 to C5, C3 to C4, C4 to C8, C4 to C7, C4 to C6, C4 to C5, C5 to C8, C5 to C7, C5 to C6, C6 to C8, C6 to C7 and C7 to C8 alkyl individually.

[0029] As further examples, the integers in the range of 5 to 40 are specifically contemplated as individually disclosing 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, and 40; the integers in the range of 1 to 20 are specifically contemplated as individually disclosing 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20. Additional groups or ranges are expressly contemplated accordingly.

[0030] When the above groups are substituted, the substituent group may be a halogen atom or a heteroatom. The halogen atom may be a fluorine atom.

[0031] When the inventors conducted research on the synthesis of trans-1,4-cyclohexyl organic compounds, they found that there are multiple synthesis methods in the relevant technology. For example, the raw materials can be dehydrated under the catalysis of p-toluenesulfonic acid or the like to generate olefin compounds (generally a mixture of multiple isomers of olefins); the olefin compounds are then hydrogenated to obtain a mixture of cis- and trans-1,4-substituted cyclohexyl compounds (which are isomers of each other). However, the proportion of trans-1,4-cyclohexyl organic compounds in the mixture is low, approximately 40% to 60%; the yield after purification can only reach 20% to 40%, which is low and the cost is high.

[0032] In view of this, the inventors considered improving the yield of trans-1,4-cyclohexyl organic compounds by starting from the reaction process.

[0033] Method for synthesizing trans-cyclohexyl organic compounds

[0034] In a first aspect, the present application proposes a method for synthesizing trans-1,4-cyclohexyl organic compounds.

[0035] The method comprises S100 providing raw materials, S200 catalytic dehydration process, and S300 catalytic hydrogenation process.

[0036] In step S200, the present invention uses silicotungstic acid or its hydrate as a catalyst, effectively catalyzing the dehydration of cyclohexanol compounds in the raw material. Furthermore, in step S300, silicotungstic acid or its hydrate remains in the system. During the hydrogenation reaction, the silicotungstic acid or its hydrate facilitates the transposition reaction of the cyclohexyl group, effectively increasing the yield of trans-1,4-cyclohexyl organic compounds in the final product. Furthermore, the present invention's method simplifies the post-processing process of steps S200 and S300, and has a low overall cost.

[0037] In step S100, the raw material may be a cyclohexanol compound. Further, the cyclohexanol compound includes a compound represented by formula (I):

[0038]

[0039] In formula (I),

[0040] R1 and R2 are each independently selected from a substituted or unsubstituted chain alkyl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted aromatic group;

[0041] Alternatively, R1 and R2 are each independently selected from a substituted or unsubstituted C1 to C10 chain alkyl group, a substituted or unsubstituted C3 to C10 cycloalkyl group, or a substituted or unsubstituted C6 to C10 aromatic group;

[0042] When the above groups are substituted, the substituents may include a halogen atom, and further, the substituents may include a fluorine atom.

[0043] Illustratively, R1 and R2 are each independently selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, cyclopropyl, cyclopentyl, cyclohexyl, phenyl, naphthyl or fluorophenyl.

[0044] In some embodiments, the cyclohexanol compound includes a cis-cyclohexanol compound, a trans-cyclohexanol compound, or a mixture thereof in any proportion. Mixing the above substances in any proportion can ensure a high yield of the product.

[0045] In some embodiments, the compound represented by formula (I) includes one or more of formula (I-1) to formula (I-6):

[0046]

[0047] Step S200 specifically involves adding a cyclohexanol compound to a solvent and silicotungstic acid or its hydrate and mixing them evenly, generating a mixed system containing cyclohexene compounds under the catalytic action of the silicotungstic acid or its hydrate. The cyclohexanol compound is evenly mixed in the solvent, which is more conducive to the catalysis of the silicotungstic acid or its hydrate. Specifically, a solvent, a cyclohexanol compound, and silicotungstic acid or its hydrate can be added to a reactor equipped with a reflux water separation device, and heated under stirring until reflux occurs; a water separator is used to separate the water produced by the reaction and carried out by the solvent azeotropically, and the reaction is stopped until no more water is separated. The product mixed system obtained by the step S200 reaction includes not only the cyclohexene compounds obtained by the catalytic action, but also substances such as silicotungstic acid or its hydrate. In the mixed system of the raw materials (cyclohexanol compounds) and the solvent in step S200, silicotungstic acid or silicotungstic acid hydrate has good solubility; however, in the mixed system of the product (cyclohexene compounds) and the solvent in step S200, silicotungstic acid or silicotungstic acid hydrate has poor solubility. Therefore, as the reaction conversion rate of step S200 increases, a portion (or even most) of the silicotungstic acid or silicotungstic acid hydrate will precipitate from the reaction mixture.

[0048] In some embodiments, the solvent includes an aliphatic hydrocarbon solvent and / or an aromatic hydrocarbon solvent. Further, the solvent may include one or more of petroleum ether, cyclohexane, methylcyclohexane, benzene, toluene or xylene. The above solvent not only has good solubility for the raw material, but also has good solubility for the product of the present application. The amount of the solvent is not strictly required, and the product generated in step S200 (generally a mixture of multiple isomers of olefins) can be completely dissolved at the temperature at which the solvent refluxes.

[0049] In some embodiments, based on the total mass of the cyclohexanol compound, the mass content of silicotungstic acid or its hydrate is C%, 0.1≤C≤2.0. When the mass content of silicotungstic acid or its hydrate is within the above range, the catalytic effect in step S200 can be ensured, and it is beneficial to ensure the cyclohexyl metathesis reaction in step S300. For example, the mass content of silicotungstic acid or its hydrate can be 0.1%, 0.2%, 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, 1.8% or 2%. It should be noted that silicotungstic acid or its hydrate refers to silicotungstic acid, silicotungstic acid hydrate or a mixture of the two.

[0050] In some embodiments, the catalytic process in step S200 requires heating. The heating temperature (i.e., the reaction temperature) can be selected to be a temperature at which the solvent refluxes. The reaction time is not strictly required and is determined when the refluxed solvent no longer azeotropes water (produced by the reaction).

[0051] In step S300, hydrogen and a hydrogenation catalyst are provided to the mixed system to cause the cyclohexene compound to undergo a hydrogenation reaction to produce a trans-1,4-cyclohexyl organic compound. Specifically, after the reaction liquid in step S200 cools to near room temperature, the mixed system obtained in step S200 (including the precipitated silicotungstic acid or its hydrate) can be transferred to a hydrogenation reactor; then the hydrogenation catalyst is added. The hydrogenation reactor is replaced with nitrogen and hydrogen, stirred, heated to 60 to 120°C, and hydrogen is continuously introduced. After the reaction stops absorbing hydrogen, the temperature is lowered to -20 to 20°C and the reaction is continued for 5 to 20 hours, after which the reaction is stopped. The hydrogen pressure during the continuous introduction of hydrogen is between 0.1 and 0.5 MPa. The silicotungstic acid or its hydrate can further participate in the reaction in step S300, and a cyclohexyl transposition reaction can be achieved simultaneously with the hydrogenation reaction. The reaction product in step S300 contains cis-1,4-cyclohexyl organic compounds, but the yield of trans-1,4-cyclohexyl organic compounds is higher than 85%.

[0052] In some embodiments, the hydrogenation catalyst includes a palladium-based catalyst and / or a platinum-based catalyst. Specifically, the hydrogenation catalyst can be palladium-carbon, platinum-carbon, or a palladium-based, platinum-based hydrogenation catalyst supported on other carriers.

[0053] In some embodiments, the mass content of the hydrogenation catalyst is D%, based on the total mass of the cyclohexanol compound, and 0.2≤D≤2.0. The above mass content of the hydrogenation catalyst is conducive to the full progress of the hydrogenation reaction.

[0054] In some embodiments, after step S300, step S400 may be further included to concentrate the reaction product of step S400.

[0055] Specifically, after the reaction in step S300 is completed, the hydrogenation reactor is replaced with nitrogen, and then the reaction mixture is taken out and filtered. After the filtrate obtained by filtration is concentrated to remove the solvent, the concentrated residue is a mixture of compounds containing cis and trans-1,4-substituted cyclohexyl groups (isomers of each other), wherein the content of the compound containing trans-1,4-substituted cyclohexyl group (target product) is ≥85%. The solvent obtained by concentration can be reused. The filter cake obtained by filtration can be further washed with methanol (or ethanol, water) and filtered again. The filter cake obtained after the second filtration is a hydrogenation catalyst, which can be recycled; the filtrate obtained is further concentrated to remove methanol (or ethanol, water), and the residue is silicotungstic acid or its hydrate, which can also be recycled.

[0056] In some embodiments, after step S400, step S500 may be further included to purify the trans-1,4-cyclohexyl organic compound in the concentrated product of step S400. The purification can be performed using equipment and instruments known in the art, which will not be described in detail here.

[0057] The synthesis process of this application is as follows:

[0058]

[0059] In the present application, silicotungstic acid or its hydrate is added during the synthesis process as a catalyst for catalyzing the dehydration of cyclohexanol compounds, and is added to the hydrogenation reaction of cyclohexene compounds containing substituents; as a result, the final product contains far more compounds containing trans-1,4-substituted cyclohexyl groups than compounds containing cis-1,4-substituted cyclohexyl groups. It should be noted that the mechanism by which silicotungstic acid or its hydrate exerts the above-mentioned effect is that silicotungstic acid or its hydrate can also be adsorbed on the carrier of the hydrogenation catalyst and then form a carbon cation with the substituted cyclohexene compound; this carbon cation can cause the compound containing the substituted cyclohexyl group to undergo a configurational transformation. Because the configuration of the trans-1,4-cyclohexyl group is more stable, the final result of the configurational transformation reaction is that the compound containing the trans-1,4-substituted cyclohexyl group is far more than the compound containing the cis-1,4-substituted cyclohexyl group; as shown below:

[0060]

[0061] This application uses silicotungstic acid as the key catalyst and cleverly designs the experimental scheme to allow the three reactions of substituted cyclohexene to generate substituted cyclohexyl carbon cations, substituted cyclohexene to hydrogenate to generate 1,4-substituted cyclohexyl, and substituted cyclohexyl carbon cations to cause configurational transformation of the substituted cyclohexyl to proceed simultaneously, thereby increasing the proportion of trans-1,4-cyclohexyl isomers in the final product from 40-60% under general hydrogenation reaction conditions to more than 85%.

[0062] In addition, the advantage of selecting silicotungstic acid as the key catalyst in this application is that although there are many catalysts that can react with substituted cyclohexene compounds and generate carbocations, such as aluminum chloride, boron trifluoride etherate, trifluoromethanesulfonic acid, trifluoroacetic acid, sulfuric acid, and various solid superacids, aluminum chloride, boron trifluoride etherate, and sulfuric acid are too active, causing the cyclohexyl carbocation to rearrange, generating a large amount or even 100% of byproducts such as five-membered rings and open rings. Boron trifluoride etherate, trifluoromethanesulfonic acid, and trifluoroacetic acid produce hydrofluoric acid during the hydrogenation reaction, which not only severely corrodes the hydrogenation reactor but also deactivates the hydrogenation catalyst. Other solid superacids, except silicotungstic acid, are mostly insoluble in water and organic solvents, making them difficult to separate from hydrogenation catalysts such as palladium-carbon and platinum-carbon.

[0063] During the implementation of this application, the amount of carbocation rearrangement byproducts caused by silicotungstic acid is less than 0.1%, which has little impact on the purification difficulty and yield of the product. Furthermore, silicotungstic acid does not corrode or poison the hydrogenation reactor or hydrogenation catalyst. Furthermore, silicotungstic acid is readily soluble in water and alcohols, while the hydrogenation catalyst is insoluble in water and organic solvents. Therefore, the two can be easily separated and then recovered for reuse.

[0064] In addition, the advantage of the present application is that silicotungstic acid can also be used to catalyze the previous step of preparing substituted cyclohexene compounds from substituted cyclohexanol compounds; after the reaction is completed, the reaction liquid can be put into the subsequent hydrogenation reaction without treatment, which simplifies the post-processing operation between the two steps of the reaction and further reduces the process cost.

[0065] trans-cyclohexyl organic compounds

[0066] In a second aspect, the present application proposes a trans-1,4-cyclohexyl organic compound, which can be synthesized by the method described in any embodiment of the first aspect of the present application.

[0067] Example

[0068] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are intended only to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be purchased commercially.

[0069] Example 1: Preparation of (trans, trans) 4-ethyl-4'-propylbicyclohexane.

[0070]

[0071] 1.1. To a 1000 ml reaction flask equipped with a reflux water separator, add 500 ml of methylcyclohexane, 126.0 g (0.5 mol) of a mixture of (cis, trans)-4-ethyl-4'-propylbicyclohexyl-4-ol and (trans, trans)-4-ethyl-4'-propylbicyclohexyl-4-ol, and 0.126 g of silicotungstic acid. Heat to reflux with stirring, separating the water produced by the reaction and azeotropically removed by the solvent using a water separator. When no more water is released, stop heating.

[0072] 1.2. After the reaction solution obtained in 1.1 has cooled to near room temperature, transfer the entire reaction mixture obtained in 1.1 (including the precipitated silicotungstic acid) to a 2000ml autoclave; then add 0.252g of platinum-on-carbon. Replace the autoclave with nitrogen and then hydrogen, stirring, heating to 110-120°C while continuously introducing hydrogen to 0.5MPa. After the reaction stops absorbing hydrogen, cool to -20--10°C and allow to react for 20 hours, then stop the reaction.

[0073] 1.3. Replace the hydrogenation reactor with nitrogen, then remove the reaction mixture from 1.2 and filter. The filtrate is filtered and concentrated to remove the methylcyclohexane. The residue is a mixture of (trans, trans)-4-ethyl-4'-propylbicyclohexane and (cis, trans)-4-ethyl-4'-propylbicyclohexane, weighing approximately 117 g (wet weight, yield ≥ 100%). Gas chromatography reveals that the content of (trans, trans)-4-ethyl-4'-propylbicyclohexane is 85.7%, and the content of (cis, trans)-4-ethyl-4'-propylbicyclohexane is 14.1%. The methylcyclohexane obtained by concentration is recovered and reused.

[0074] 1.4. Wash the filter cake obtained in 1.3 with methanol and filter again. The resulting filter cake is platinum carbon and can be recycled. Concentrate the filtrate to remove the methanol, leaving a residue of silicotungstic acid, which can also be recycled.

[0075] Comparative Example 1: Preparation of (trans, trans) 4-ethyl-4'-propylbicyclohexane.

[0076] 2.1. To a 1000 ml reaction flask equipped with a reflux water separator, add 500 ml of methylcyclohexane; 126.0 g (0.5 mol) of a mixture of (cis, trans)-4-ethyl-4'-propylbicyclohexyl-4-ol and (trans, trans)-4-ethyl-4'-propylbicyclohexyl-4-ol; and 1.26 g of p-toluenesulfonic acid. Heat to reflux with stirring, separating the water produced by the reaction and azeotropically removed by the solvent using a water separator. When no more water is released, stop heating.

[0077] 2.2. After the reaction mixture obtained in 2.1 is cooled to near room temperature, wash the reaction mixture obtained in 2.1 with 100 ml of 5% sodium bicarbonate and separate the liquids; then wash and separate the liquids twice with 100 ml of water to remove p-toluenesulfonic acid.

[0078] 2.3. Transfer the entire reaction solution from 2.2 to a 2000ml autoclave; then add 0.252g of platinum-on-carbon. Replace the autoclave with nitrogen and then hydrogen, stirring, heating to 110-120°C while continuously introducing hydrogen to 0.5MPa. After the reaction stops absorbing hydrogen, cool to -20-10°C and allow to react for 20 hours, then stop the reaction.

[0079] 2.4. Replace the hydrogenation reactor with nitrogen, then remove the reaction mixture from 2.3 and filter. The filtrate is filtered and concentrated to remove the methylcyclohexane. The residue is a mixture of (trans, trans)-4-ethyl-4'-propylbicyclohexane and (cis, trans)-4-ethyl-4'-propylbicyclohexane, weighing approximately 118 g (wet weight, yield ≥ 100%). The content of (trans, trans)-4-ethyl-4'-propylbicyclohexane is 47.2%, and the content of (cis, trans)-4-ethyl-4'-propylbicyclohexane is 52.7%.

[0080] In Comparative Example 1, p-toluenesulfonic acid was used for the catalytic reaction, and the yield of (trans, trans)-4-ethyl-4'-propyl-bicyclohexane was low. Compared with Comparative Example 1, silicotungstic acid was added to the system for reaction, which significantly improved the yield of (trans, trans)-4-ethyl-4'-propyl-bicyclohexane.

[0081] Example 2: Preparation of (trans, trans)-4-ethyl-4′-(3″,4″,5″-trifluoro)phenylbicyclohexane.

[0082]

[0083] 3.1. To a 1000 ml reaction flask equipped with a reflux water separator, add 600 ml of toluene, 102.0 g (0.3 mol) of a mixture of (cis, trans)-4-ethyl-4'-(3",4",5"-trifluoro)phenyl-bicyclohexyl-4'-ol and (trans, trans)-4-ethyl-4'-(3",4",5"-trifluoro)phenyl-bicyclohexyl-4'-ol, and 2.04 g of silicotungstic acid hydrate. Heat to reflux with stirring, separating the water produced by the reaction and carried away by the solvent azeotropy using a water separator. When no more water is released, stop heating.

[0084] 3.2. After the reaction solution obtained in 3.1 has cooled to near room temperature, transfer the entire reaction mixture obtained in 3.1 (including the precipitated silicotungstic acid) to a 2000ml autoclave; then add 2.04g of palladium on carbon. Replace the autoclave with nitrogen and then hydrogen, stirring, heating to 60-70°C while continuously introducing hydrogen to 0.1MPa. After the reaction stops absorbing hydrogen, cool to 10-20°C and allow to react for 5 hours, then stop the reaction.

[0085] 3.3. Replace the hydrogenation reactor with nitrogen, then remove the reaction mixture from 3.2 and filter. The filtrate is concentrated to remove toluene. The residue is a mixture of (trans, trans)-4-ethyl-4'-(3",4",5"-trifluoro)phenyl-bicyclohexane and (cis, trans)-4-ethyl-4'-(3",4",5"-trifluoro)phenyl-bicyclohexane, weighing approximately 105 g (wet weight, yield ≥ 100%). Gas chromatography reveals a 92.5% (trans, trans)-4-ethyl-4'-(3",4",5"-trifluoro)phenyl-bicyclohexane content and a 7.3% (cis, trans)-4-ethyl-4'-(3",4",5"-trifluoro)phenyl-bicyclohexane content. The toluene obtained from the concentration is recovered for reuse.

[0086] 3.4. Wash the filter cake obtained in 3.3 with ethanol and filter again. The resulting filter cake is palladium on carbon and can be recycled. Concentrate the filtrate to remove the ethanol, leaving a residue of silicotungstic acid, which can also be recycled.

[0087] Comparative Example 2: Preparation of (trans, trans)-4-ethyl-4′-(3″,4″,5″-trifluoro)phenylbicyclohexane.

[0088] 4.1. To a 1000 ml reaction flask equipped with a reflux water separator, add 600 ml of toluene, 102.0 g (0.3 mol) of a mixture of (cis, trans)-4-ethyl-4'-(3",4",5"-trifluoro)phenyl-bicyclohexyl-4'-ol and (trans, trans)-4-ethyl-4'-(3",4",5"-trifluoro)phenyl-bicyclohexyl-4'-ol, and 2.04 g of p-toluenesulfonic acid. Heat to reflux with stirring, separating the water produced by the reaction and carried away by the solvent azeotropy using a water separator. When no more water is released, stop heating.

[0089] 4.2. After the reaction mixture obtained in 4.1 is cooled to near room temperature, wash the reaction mixture obtained in 4.1 with 100 ml of 5% sodium bicarbonate and separate the liquids; then wash and separate the liquids twice with 100 ml of water to remove p-toluenesulfonic acid.

[0090] 4.3. Transfer the entire reaction solution from 4.2 to a 2000ml autoclave; then add 2.04g of palladium on carbon. Replace the autoclave with nitrogen and then hydrogen, stirring, heating to 60-70°C while continuously introducing hydrogen to 0.1MPa. After the reaction stops absorbing hydrogen, cool to 10-20°C and allow to react for 5 hours, then stop the reaction.

[0091] 4.4. Replace the hydrogenation reactor with nitrogen, then remove the reaction mixture from 4.3 and filter. After the filtrate is filtered and concentrated to remove toluene, the residue is a mixture of (trans, trans)-4-ethyl-4'-(3",4",5"-trifluoro)phenyl-bicyclohexane and (cis, trans)-4-ethyl-4'-(3",4",5"-trifluoro)phenyl-bicyclohexane, with a total weight of approximately 104 g (wet weight, yield ≥100%). The content of (trans, trans)-4-ethyl-4'-(3",4",5"-trifluoro)phenyl-bicyclohexane is 56.8%, and the content of (cis, trans)-4-ethyl-4'-(3",4",5"-trifluoro)phenyl-bicyclohexane is 43.1%.

[0092] In Comparative Example 2, p-toluenesulfonic acid was used to catalyze the reaction, and the yield of (trans, trans)-4-ethyl-4'-(3",4",5"-trifluoro)phenyl-bicyclohexane was low. Compared with Comparative Example 2, Example 2 used silicotungstic acid to add to the system for reaction, which can significantly improve the yield of (trans, trans)-4-ethyl-4'-(3",4",5"-trifluoro)phenyl-bicyclohexane.

[0093] Although illustrative embodiments have been shown and described, those skilled in the art should understand that the above embodiments should not be construed as limitations on the present application, and that changes, substitutions, and modifications may be made to the embodiments without departing from the spirit, principles, and scope of the present application.

Claims

1. A method for synthesizing a trans-1,4-cyclohexyl organic compound, comprising: Providing cyclohexanol compounds; adding a cyclohexanol compound to a solvent and silicotungstic acid or a hydrate thereof and mixing them uniformly, thereby generating a mixed system containing a cyclohexene compound under the catalytic action of the silicotungstic acid or a hydrate thereof; Providing hydrogen and a hydrogenation catalyst to the mixed system to cause the cyclohexene compound to undergo a hydrogenation reaction to generate a trans-1,4-cyclohexyl organic compound, The cyclohexanol compound is a compound represented by formula (I): In formula (I), R1 and R2 are each independently selected from a substituted or unsubstituted chain alkyl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted aromatic group; when substituted, the substituent is a halogen atom; The hydrogenation catalyst is a palladium carbon catalyst and / or a platinum carbon catalyst.

2. The method according to claim 1, wherein The substituent is a fluorine atom.

3. The method according to claim 1 or 2, wherein: R1 and R2 are each independently selected from a substituted or unsubstituted C1 to C10 chain alkyl group, a substituted or unsubstituted C3 to C10 cycloalkyl group, or a substituted or unsubstituted C6 to C10 aromatic group.

4. The method according to claim 3, wherein: R1 and R2 are each independently selected from methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, cyclopropyl, cyclopentyl, cyclohexyl, phenyl, naphthyl or fluorophenyl.

5. The method according to claim 1, wherein The cyclohexanol compound is a mixture of one or both of cis-cyclohexanol compounds and trans-cyclohexanol compounds.

6. The method according to claim 1, wherein Based on the total mass of the cyclohexanol compound, the mass content of the silicotungstic acid or its hydrate is C%, and 0.1≤C≤2.

0.

7. The method according to claim 1, wherein Based on the total mass of the cyclohexanol compounds, the mass content of the hydrogenation catalyst is D%, and 0.2≤D≤2.

0.

8. The method according to claim 1, wherein The hydrogenation reaction includes a first reaction stage and a second reaction stage; the hydrogenation reaction satisfies condition (1) and / or condition (2): (1) The reaction temperature of the first reaction stage is 60°C to 120°C; (2) The reaction temperature of the second reaction stage is -20°C to 20°C; and / or the reaction time is 5h to 20h.

9. The method according to claim 1, wherein The solvent is an aliphatic hydrocarbon solvent and / or an aromatic hydrocarbon solvent.

10. The method according to claim 9, wherein: The solvent is one or more of petroleum ether, cyclohexane, methylcyclohexane, benzene, toluene or xylene.

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