A method for synthesizing 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol

Abstract

This invention provides a method for synthesizing 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol. The raw materials used in this method are inexpensive and readily available, and the raw materials and excipients used do not involve hazardous reagents. The reaction is highly safe, and the post-processing is simple, resulting in low production costs. This method is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis and relates to a method for synthesizing 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol. Background Technology

[0002] In the liquid crystal industry, there is a need to prepare liquid crystal mixtures with high resistivity, low power consumption, low driving threshold voltage and low viscosity. For example, 2-(trans-4-n-propylcyclohexyl)-1,3-propanediol is an organic material that has been proven to be suitable as an intermediate for preparing liquid crystal mixtures.

[0003] There are currently three main methods for synthesis.

[0004] Method 1:

[0005]

[0006] This method uses propylcyclohexanone and dimethyl malonate as starting materials, and through coupling, hydrogenation, and reduction reactions, yields trans-2-(trans-4-n-propylcyclohexyl)-1,3-propanediol. In the coupling reaction, titanium tetrachloride is used as a catalyst. Titanium tetrachloride undergoes an exothermic decomposition reaction upon heating or contact with water, releasing toxic and corrosive fumes.

[0007] Method 2:

[0008]

[0009] This method uses propylcyclohexanol as a starting material, and proceeds through bromination, substitution, and reduction reactions to obtain trans-2-(trans-4-n-propylcyclohexyl)-1,3-propanediol. The bromination reaction involves phosphorus tribromide, which is highly fuming, toxic, and hazardous, while the substitution reaction utilizes lithium methoxide, which is extremely dangerous.

[0010] Method 3:

[0011]

[0012] This method uses 2-(4-propylcyclohexyl)propenal as the starting material, and through dehydration and hydrogenation reactions, yields trans-2-(trans-4-n-propylcyclohexyl)-1,3-propanediol. However, the starting material 2-(4-propylcyclohexyl)propenal is not a conventional reagent and is not readily available. Summary of the Invention

[0013] To address the aforementioned technical problems, this application provides a method for synthesizing 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol. This method uses inexpensive and readily available raw materials, and the raw materials and excipients used do not involve hazardous reagents. The reaction is highly safe, and the post-processing is simple, resulting in low production costs, making it suitable for industrial production.

[0014] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution:

[0015] This invention provides a method for synthesizing 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol, as shown in the following formula:

[0016]

[0017] R1 and R2 are independently C1-6 alkyl or C3-6 cycloalkyl groups, respectively.

[0018] As a preferred embodiment of the present invention, the method for synthesizing 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol includes:

[0019] 4-Propylcyclohexyl ketone, cyanoacetate, condensing agent and first organic solvent are mixed and reacted to give compound A;

[0020] Under a protective atmosphere, compound A and a second organic solvent are mixed, and a first reducing agent is added to react and give compound B.

[0021] Compound B, a base, a third organic solvent, and water were mixed and hydrolyzed to obtain compound C.

[0022] Compound C, a fourth organic solvent, and an acid were mixed and reacted to give compound D.

[0023] Under a protective atmosphere, compound D, Lewis acid, and fifth organic solvent are mixed, and a second reducing agent is added to react and give compound E.

[0024] The compound E was purified to obtain 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol.

[0025] As a preferred technical solution of the present invention, cyanoacetate includes any one or a combination of at least two of methyl cyanoacetate, ethyl cyanoacetate, n-propyl cyanoacetate, isopropyl cyanoacetate, n-butyl cyanoacetate, n-pentyl cyanoacetate, n-hexyl cyanoacetate, or cyclopentyl cyanoacetate.

[0026] And / or, the first organic solvent includes any one or a combination of at least two of toluene, xylene, n-heptane, n-hexane, dichloroethane, or dichloromethane.

[0027] And / or, the condensing agent includes any one or a combination of at least two of ammonium formate, ammonium acetate, p-toluenesulfonic acid, or titanium tetrachloride.

[0028] As a preferred technical solution of the present invention, the temperature of the reaction for synthesizing compound A is 40-120°C and the time is 2-12 hours.

[0029] As a preferred embodiment of the present invention, the first reducing agent includes any one or a combination of at least two of potassium borohydride, sodium borohydride, lithium borohydride, lithium aluminum hydride, or red aluminum.

[0030] And / or, the temperature for synthesizing compound B is -10 to 50°C, and the time is 0.5 to 5 h.

[0031] As a preferred embodiment of the present invention, the alkali includes any one or a combination of at least two of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, or lithium hydroxide.

[0032] And / or, the temperature for synthesizing compound C is 50–100°C, and the time is 8–24 h.

[0033] As a preferred embodiment of the present invention, the fourth organic solvent includes C1-C6 alkyl alcohols and / or C3-C6 cycloalkyl alcohols.

[0034] And / or, the acid includes sulfuric acid.

[0035] And / or, the temperature for synthesizing compound D is 50–100 °C, and the time is 8–24 h.

[0036] As a preferred technical solution of the present invention, Lewis acids include any one or a combination of at least two of lithium chloride, zinc chloride, aluminum chloride, ferric chloride, or boron trifluoride ether.

[0037] And / or, the second reducing agent includes any one or a combination of at least two of potassium borohydride, sodium borohydride, lithium borohydride, lithium aluminum hydride, or red aluminum.

[0038] As a preferred technical solution of the present invention, the temperature for the synthesis of compound E is -10 to 50°C and the time is 2 to 12 hours.

[0039] As a preferred technical solution of the present invention, the purification process is recrystallization.

[0040] As a preferred technical solution of the present invention, the recrystallization method includes: dissolving the compound E in n-heptane, heating to completely dissolve the compound E, cooling and stirring to precipitate a solid, and separating the solid and liquid to obtain 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol.

[0041] Compared with the prior art, the present invention has at least the following beneficial effects:

[0042] This invention provides a method for synthesizing 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol. The raw materials used in this method are inexpensive and readily available, and the raw materials and excipients used do not involve hazardous reagents. The reaction is highly safe, and the post-processing is simple, resulting in low production costs. This method is suitable for industrial production. Detailed Implementation

[0043] The technical solution of this application will be further described below through specific implementation methods.

[0044] This invention provides a method for synthesizing 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol, as shown in the following formula:

[0045]

[0046] R1 and R2 are independently C1-6 alkyl or C3-6 cycloalkyl groups, respectively.

[0047] In one specific embodiment of the present invention, R1 and R2 can be methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, or n-hexyl, etc.

[0048] In one specific embodiment of the present invention, R1 and R2 can be cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl, etc., respectively.

[0049] In one specific embodiment of the present invention, the method for synthesizing 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol includes:

[0050] 4-Propylcyclohexyl ketone, cyanoacetate, condensing agent and first organic solvent are mixed and reacted to give compound A;

[0051] Under a protective atmosphere, compound A and a second organic solvent are mixed, and a first reducing agent is added to react and give compound B.

[0052] Compound B, a base, a third organic solvent, and water were mixed and hydrolyzed to obtain compound C.

[0053] Compound C, a fourth organic solvent, and an acid were mixed and reacted to give compound D.

[0054] Under a protective atmosphere, compound D, Lewis acid, and fifth organic solvent are mixed, and a second reducing agent is added to react and give compound E.

[0055] The compound E was purified to obtain 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol.

[0056] In one specific embodiment of the present invention, the cyanoacetate includes any one or a combination of at least two of methyl cyanoacetate, ethyl cyanoacetate, n-propyl cyanoacetate, isopropyl cyanoacetate, n-butyl cyanoacetate, n-pentyl cyanoacetate, n-hexyl cyanoacetate, or cyclopentyl cyanoacetate. Preferably, it is methyl cyanoacetate and ethyl cyanoacetate.

[0057] In one specific embodiment of the present invention, the first organic solvent includes any one or a combination of at least two of toluene, xylene, n-heptane, n-hexane, dichloroethane, or dichloromethane. Preferably, it is toluene, n-heptane, and dichloromethane.

[0058] In one specific embodiment of the present invention, the condensation reagent includes any one or a combination of at least two of ammonium formate, ammonium acetate, p-toluenesulfonic acid, or titanium tetrachloride. Preferably, it comprises ammonium formate and ammonium acetate.

[0059] In one specific embodiment of the present invention, the reaction temperature for synthesizing compound A is 40–120°C, and the reaction time is 2–12 h. The reaction temperature can be 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, or 120°C, etc., and the reaction time can be 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, or 12 h, etc., but is not limited to the listed values; other unlisted values ​​within the above ranges are also applicable.

[0060] In one specific embodiment of the present invention, 4-propylcyclohexyl ketone and cyanoacetate can be added according to the stoichiometric ratio of the chemical reaction equation, or adjusted according to the stoichiometric ratio based on the reaction conditions, without specific limitations.

[0061] In one specific embodiment of the present invention, the amount of condensing reagent added in the reaction for synthesizing compound A can be adjusted according to the reaction conditions, and is not specifically limited here.

[0062] In one specific embodiment of the present invention, in the reaction for synthesizing compound A, the amount of the first organic solvent added can be adjusted according to the reaction situation when a homogeneous reaction phase is formed, and no specific limitation is made here.

[0063] In one specific embodiment of the present invention, the first reducing agent includes any one or a combination of at least two of potassium borohydride, sodium borohydride, lithium borohydride, lithium aluminum hydride, or red aluminum.

[0064] In one specific embodiment of the present invention, the reaction temperature for synthesizing compound B is -10 to 50°C, and the time is 0.5 to 5 hours. The temperature can be -10°C, 0°C, 10°C, 20°C, 30°C, 40°C, or 50°C, etc., and the time can be 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, or 5 hours, etc., but is not limited to the listed values; other unlisted values ​​within the above ranges are also applicable.

[0065] In one specific embodiment of the present invention, in the reaction for synthesizing compound B, compound A and the first reducing agent can be added according to the stoichiometric ratio of the chemical reaction equation, or adjusted according to the stoichiometric ratio based on the reaction conditions, without specific limitations.

[0066] In one specific embodiment of the present invention, in the reaction for synthesizing compound B, the amount of the second organic solvent added can be adjusted according to the reaction situation when a homogeneous reaction phase is formed, and no specific limitation is made here.

[0067] In one specific embodiment of the present invention, the alkali includes any one or a combination of at least two of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, or lithium hydroxide. Preferably, it includes sodium hydroxide, potassium hydroxide, and lithium hydroxide.

[0068] In one specific embodiment of the present invention, the reaction temperature for synthesizing compound C is 50–100°C, and the reaction time is 8–24 h. The reaction temperature can be 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C, etc., and the reaction time can be 8 h, 10 h, 12 h, 15 h, 18 h, 20 h, or 24 h, etc., but is not limited to the listed values; other unlisted values ​​within the above ranges are also applicable.

[0069] In one specific embodiment of the present invention, in the reaction for synthesizing compound C, compound B and water can be added according to the stoichiometric ratio of the chemical reaction equation, or adjusted according to the stoichiometric ratio based on the reaction conditions, without specific limitations.

[0070] In one specific embodiment of the present invention, in the reaction for synthesizing compound C, the amount of alkali added can be adjusted according to the reaction conditions while maintaining the alkaline environment of the reaction, and no specific limitation is made here.

[0071] In one specific embodiment of the present invention, in the reaction for synthesizing compound C, the amount of the third organic solvent added can be adjusted according to the reaction situation, provided that a homogeneous reaction phase is formed; no specific limitation is made here.

[0072] In one specific embodiment of the present invention, the fourth organic solvent includes C1-C6 alkyl alcohols and / or C3-C6 cycloalkyl alcohols.

[0073] In one specific embodiment of the present invention, the fourth organic solvent may be methanol, ethanol, n-propanol, isopropanol, n-butanol, n-pentanol, n-hexanol, cyclopentanol, or cyclohexanol, etc.

[0074] In one specific embodiment of the present invention, the acid includes sulfuric acid. The amount and concentration of sulfuric acid added can be selected according to the pH of the desired reaction, and are not specifically limited herein.

[0075] In one specific embodiment of the present invention, in the reaction for synthesizing compound D, the amount of acid added can be adjusted according to the reaction conditions while maintaining an acidic environment for the reaction; no specific limitation is made here.

[0076] In one specific embodiment of the present invention, in the reaction for synthesizing compound D, the amount of the fourth organic solvent added can be adjusted according to the reaction situation, provided that a homogeneous reaction phase is formed and the stoichiometric ratio for substitution reaction with compound C is satisfied. No specific limitation is made here.

[0077] In one specific embodiment of the present invention, the reaction temperature for synthesizing compound D is 50–100°C, and the reaction time is 8–24 h. The reaction temperature can be 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C, etc., and the reaction time can be 8 h, 10 h, 12 h, 15 h, 18 h, 20 h, or 24 h, etc., but is not limited to the listed values; other unlisted values ​​within the above ranges are also applicable.

[0078] In one specific embodiment of the present invention, the Lewis acid includes any one or a combination of at least two of lithium chloride, zinc chloride, aluminum chloride, ferric chloride, or boron trifluoride ether. Preferably, it is lithium chloride, aluminum chloride, or boron trifluoride ether.

[0079] In one specific embodiment of the present invention, the second reducing agent includes any one or a combination of at least two of potassium borohydride, sodium borohydride, lithium borohydride, lithium aluminum hydride, or red aluminum. Preferably, it is potassium borohydride, sodium borohydride, or lithium borohydride.

[0080] In one specific embodiment of the present invention, the amount of Lewis acid added in the reaction for synthesizing compound E can be adjusted according to the reaction conditions, and is not specifically limited here.

[0081] In one specific embodiment of the present invention, in the reaction for synthesizing compound E, the amount of the second reducing agent added can be adjusted according to the reaction conditions, and is not specifically limited here.

[0082] In one specific embodiment of the present invention, in the reaction for synthesizing compound E, the amount of the fifth organic solvent added can be adjusted according to the reaction situation when a homogeneous reaction phase is formed, and no specific limitation is made here.

[0083] In one specific embodiment of the present invention, the reaction temperature for synthesizing compound E is -10 to 50°C, and the time is 2 to 12 hours. The temperature can be -10°C, 0°C, 10°C, 20°C, 30°C, 40°C, or 50°C, etc., and the time can be 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 12 hours, etc., but is not limited to the listed values; other unlisted values ​​within the above ranges are also applicable.

[0084] In one specific embodiment of the present invention, the second organic solvent, the third organic solvent, and the fourth organic solvent can each independently be any one or a combination of at least two of methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, tetrahydrofuran, 2-methyltetrahydrofuran, or water.

[0085] In one specific embodiment of the present invention, the purification process is recrystallization.

[0086] In one specific embodiment of the present invention, the recrystallization method includes: dissolving compound E in n-heptane, heating to completely dissolve compound E, cooling and stirring to precipitate a solid, and separating the solid and liquid to obtain 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol.

[0087] In one specific embodiment of the present invention, during recrystallization, the temperature is cooled to -10 to -30°C, preferably -20°C.

[0088] In one specific embodiment of the present invention, the stirring time during recrystallization is 3 to 4 hours.

[0089] In one specific embodiment of the present invention, the protective atmosphere includes nitrogen, helium, or argon, preferably nitrogen. Specifically, before adding the reaction raw materials, nitrogen is introduced into the reaction apparatus to replace the air therein.

[0090] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0091] Example 1

[0092] This embodiment provides a method for synthesizing 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol, wherein the preparation method of compound A includes:

[0093]

[0094] In a 1L three-necked flask, 100g (0.713mol) of propylcyclohexanone, 88.73g (0.784mol) of ethyl cyanoacetate, 110g (1.43mol) of ammonium acetate, and 500mL of dichloromethane were added sequentially. The mixture was heated to 65℃ and refluxed for 8 hours. After the reaction was complete, the reaction solution was extracted with 600mL of water, and the organic phase was concentrated to give 159g of a yellow oily liquid (compound A), with a GC purity of 81.74% and a yield of 96%.

[0095] m / z: 235.16 (100.0%), 236.16 (15.5%), 237.16 (1.5%).

[0096] Example 2

[0097] This embodiment provides a method for synthesizing 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol, wherein the preparation method of compound B includes:

[0098]

[0099] Compound A (83 g, 0.35 mol) and 450 mL of methanol were added sequentially to a 1 L three-necked flask. The mixture was cooled to 0 °C under nitrogen protection. Sodium borohydride (8.01 g, 0.21 mol) was added in portions. After the addition was complete, the mixture was kept at 0 °C for 2 h. After the reaction was complete, the reaction solution was poured into water and quenched with 10% dilute hydrochloric acid. The solution was extracted with 500 mL of ethyl acetate, and the organic phase was concentrated to give 76 g of a yellow oily liquid (compound B), with a GC purity of 73.45% and a yield of 92%.

[0100] m / z: 237.17 (100.0%), 238.18 (15.5%), 239.18 (1.5%).

[0101] Example 3

[0102] This embodiment provides a method for synthesizing 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol, wherein the preparation method of compound C includes:

[0103]

[0104] In a 500 mL three-necked flask, compound B (76 g, 0.32 mol), potassium hydroxide (72 g, 1.28 mol), 250 mL of ethanol, and 50 mL of water were added sequentially, and the mixture was heated to 80 °C and reacted for 18 h. After the reaction was complete, the ethanol was concentrated and evaporated, and the mixture was extracted with 150 mL of water and 150 mL of ethyl acetate. The pH of the aqueous phase was adjusted to 1–2 with 600 mL of dilute hydrochloric acid, and a solid precipitated. The solid was filtered, dried, and 53 g of a yellow solid (compound C) was obtained, with a GC purity of 90.23% and a yield of 73%.

[0105] m / z: 228.14 (100.0%), 229.14 (13.4%), 230.14 (1.6%).

[0106] Example 4

[0107] This embodiment provides a method for synthesizing 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol, wherein the preparation method of compound D includes:

[0108]

[0109] Compound C (50 g, 0.13 mol), concentrated sulfuric acid (25.8 g, 0.26 mol), and 150 mL were added sequentially to a 250 mL three-necked flask, and the mixture was heated to 80 °C and reacted for 18 h. After the reaction was complete, the mixture was extracted with 200 mL of saturated sodium bicarbonate solution, followed by extraction with 100 mL of ethyl acetate. The organic phase was concentrated to give 37 g of a yellow oily liquid (compound D), with a GC purity of 75.26% and a yield of 99%.

[0110] m / z: 284.20 (100.0%), 285.20 (17.5%), 286.21 (1.5%).

[0111] Example 5

[0112] This embodiment provides a method for synthesizing 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol, wherein the preparation method of compound E includes:

[0113]

[0114] In a 500 mL three-necked flask, compound C (50 g, 0.18 mol), lithium chloride (1.49 g, 0.035 mol), 125 mL tetrahydrofuran, and 125 mL ethanol were added sequentially. Under nitrogen protection, the mixture was cooled to 0 °C, and sodium borohydride (26.6 g, 0.72 mol) was added in portions. After the addition was complete, the mixture was slowly brought to room temperature and reacted for 6 h. After the reaction was complete, the mixture was quenched in 500 mL of water, extracted with 300 mL of ethyl acetate, and the organic phase was concentrated to give 33 g of a white solid (compound E) with a GC purity of 91.57% and a yield of 94%.

[0115] m / z: 200.18 (100.0%), 201.18 (13.3%), 202.18 (1.2%).

[0116] Example 6

[0117] This embodiment provides a method for synthesizing 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol, wherein the method for isolating 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol from compound E includes:

[0118]

[0119] Compound E (33 g, 0.16 mol) and 150 mL of n-heptane were added sequentially to a 250 mL single-necked flask. The mixture was heated under nitrogen protection until the solid was completely dissolved. The mixture was then slowly cooled to -20 °C and stirred for 3–4 h. After filtration, 26 g of white solid was obtained with a GC purity of 99.5% and a yield of 81%.

[0120] m / z: 200.18 (100.0%), 201.18 (13.3%), 202.18 (1.2%).

[0121] The applicant declares that the detailed process equipment and process flow of the present invention are illustrated through the above embodiments, but the present invention is not limited to the above detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for synthesizing 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol, characterized in that, The synthesis method is shown in the following formula: R1 and R2 are independently C1-6 alkyl or C3-6 cycloalkyl groups, respectively.

2. The synthesis method according to claim 1, characterized in that, The synthesis method includes: 4-propylcyclohexyl ketone, cyanoacetate, condensing agent and first organic solvent are mixed and reacted to give compound A; Under a protective atmosphere, compound A and a second organic solvent are mixed, and a first reducing agent is added to react and yield compound B. Compound B, a base, a third organic solvent, and water were mixed and hydrolyzed to obtain compound C. Compound C, a fourth organic solvent, and an acid were mixed and reacted to give compound D. Under a protective atmosphere, compound D, Lewis acid, and fifth organic solvent are mixed, and a second reducing agent is added to react and give compound E. The compound E was purified to obtain 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol.

3. The synthesis method according to claim 2, characterized in that, The cyanoacetate includes any one or a combination of at least two of the following: methyl cyanoacetate, ethyl cyanoacetate, n-propyl cyanoacetate, isopropyl cyanoacetate, n-butyl cyanoacetate, n-pentyl cyanoacetate, n-hexyl cyanoacetate, or cyclopentyl cyanoacetate. And / or, the first organic solvent includes any one or a combination of at least two of toluene, xylene, n-heptane, n-hexane, dichloroethane, or dichloromethane; And / or, the condensing agent includes any one or a combination of at least two of ammonium formate, ammonium acetate, p-toluenesulfonic acid, or titanium tetrachloride.

4. The synthesis method according to claim 2, characterized in that, The reaction for synthesizing compound A is carried out at a temperature of 40–120 °C for 2–12 h.

5. The synthesis method according to claim 2, characterized in that, The first reducing agent includes any one or a combination of at least two of potassium borohydride, sodium borohydride, lithium borohydride, lithium aluminum hydride, or red aluminum; And / or, the temperature for synthesizing compound B is -10 to 50°C, and the time is 0.5 to 5 h.

6. The synthesis method according to claim 2, characterized in that, The alkali includes any one or a combination of at least two of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, or lithium hydroxide; And / or, the temperature for synthesizing compound C is 50–100°C, and the time is 8–24 h.

7. The synthesis method according to claim 2, characterized in that, The fourth organic solvent includes C1-C6 alkyl alcohols and / or C3-C6 cycloalkyl alcohols; And / or, the acid includes sulfuric acid; And / or, the temperature for synthesizing compound D is 50–100 °C, and the time is 8–24 h.

8. The synthesis method according to claim 2, characterized in that, The Lewis acid includes any one or a combination of at least two of lithium chloride, zinc chloride, aluminum chloride, ferric chloride, or boron trifluoride ether. And / or, the second reducing agent includes any one or a combination of at least two of potassium borohydride, sodium borohydride, lithium borohydride, lithium aluminum hydride, or red aluminum.

9. The synthesis method according to claim 2, characterized in that, The reaction temperature for synthesizing compound E is -10 to 50°C, and the reaction time is 2 to 12 hours.

10. The synthesis method according to claim 2, characterized in that, The purification process is recrystallization; And / or, the recrystallization method comprises: dissolving the compound E in n-heptane, heating to completely dissolve the compound E, cooling and stirring to precipitate a solid, and separating the solid and liquid to obtain 2-(trans-4-n-propylcyclohexyl)propane-1,3-diol.

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