A process for the indirect preparation of cyclohexanol from cyclohexene

Abstract

This invention discloses a method for indirectly preparing cyclohexanol from cyclohexene. The method involves etherifying cyclohexene with ethanol under a nitrogen atmosphere in the presence of molecular sieve catalyst I to obtain cyclohexylethyl ether. Then, in the presence of molecular sieve catalyst II, the cyclohexylethyl ether undergoes hydrolysis with water. The oil phase is extracted and distilled to obtain cyclohexanol. This invention, which uses etherification of cyclohexene with ethanol followed by hydrolysis to prepare cyclohexanol, is suitable for continuous industrial production and has advantages such as high safety, environmental friendliness, low production cost, high selectivity for cyclohexanol, and environmentally friendly and recyclable catalysts. It is an effective route for preparing cyclohexanol.

Description

Technical Field

[0001] This invention relates to the field of cyclohexanol preparation technology, and more specifically to a method for indirectly preparing cyclohexanol from cyclohexene. Background Technology

[0002] Cyclohexanol is a crucial raw material for fine chemical products such as nylon, solvents, plastic additives, pharmaceuticals, and fragrances, and its demand is closely related to the development of the global polymer materials industry. Currently, the main industrial processes for producing cyclohexanol include cyclohexane oxidation, phenol hydrogenation, and cyclohexene hydration. Among these, cyclohexene hydration is gradually becoming the mainstream method due to its advantages such as low energy consumption, good operational safety, and fewer byproducts. However, this process still suffers from problems such as low conversion rates (typically less than 15%), high energy consumption, equipment corrosion, and catalyst deactivation, limiting its further application in green and high-efficiency directions.

[0003] In recent years, some technicians have proposed a two-step method for preparing cyclohexanol, which improves the conversion rate of cyclohexene. For example, CN103232325B discloses a method for preparing cyclohexanol by esterifying cyclohexene with carboxylic acid to generate cyclohexyl carboxylate, followed by transesterification with a lower alcohol. This technology improves the conversion rate of cyclohexene and the selectivity of cyclohexanol to some extent, but its reaction process is significantly constrained by equilibrium, usually requiring excess raw materials and high energy consumption. Furthermore, the reaction system is complex, product separation is difficult, and its industrial applicability and economic efficiency are insufficient. Therefore, there is an urgent need to develop a more efficient method for preparing cyclohexanol.

[0004] Etherification and hydrolysis reactions have attracted widespread attention in the field of green organic synthesis due to their high selectivity and flexible reaction control. However, existing research mainly focuses on single-step etherification or single-step hydrolysis processes, lacking systematic studies on the overall coupling rules, condition matching, by-product control, and catalyst stability improvement of the etherification and hydrolysis processes. Furthermore, mature technologies are still lacking in how to effectively integrate the two-step reaction, control the formation of by-products such as ethanol, cyclohexyl acetate, and dietherification products, and how to improve catalyst stability and lifespan. Overall, the cyclohexene etherification-rehydrolysis process route remains a technological gap, urgently requiring breakthroughs in new catalytic systems and process routes. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for indirectly preparing cyclohexanol from cyclohexene. The method involves an etherification reaction of cyclohexene with ethanol, followed by hydrolysis of the resulting ether to synthesize cyclohexanol.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for indirectly preparing cyclohexanol from cyclohexene includes the following steps:

[0008] (1) Cyclohexene and ethanol were etherified in a nitrogen atmosphere in the presence of molecular sieve catalyst I, wherein the molar ratio of cyclohexene to ethanol was 1:(1.5-5), and the reaction temperature was 50-100 °C. o At C, under a pressure of 0.1-1 MPa and a reaction time of 1-12 h, cyclohexylethyl ether is obtained.

[0009] (2) In the presence of molecular sieve catalyst II, cyclohexylethyl ether undergoes a hydrolysis reaction with water, wherein the volume ratio of cyclohexylethyl ether to water is 1:(1-10), and the reaction temperature is 100-150 °C. o C, the reaction pressure is 0.1-1 MPa, the reaction time is 2-10 h, and the oil phase is extracted and distilled to obtain cyclohexanol.

[0010] The method involves a two-step reaction of etherification and hydrolysis, with a cyclohexanol yield of not less than 85%.

[0011] Through extensive experiments, this invention has revealed that the etherification of cyclohexene and the hydrolysis of cyclohexylethyl ether are not simply physical sequences. The two reactions exhibit significant coupling effects in terms of acid strength requirements, temperature sensitivity, and control of side reactions. Specifically: (1) If the etherification reaction temperature is too high (>100°C), o (C) will promote the polymerization of cyclohexene to generate heavy components, leading to the deactivation of the subsequent hydrolysis catalyst; (2) if the hydrolysis reaction temperature is too low (<100) o C) Insufficient conversion of cyclohexyl ethyl ether, but the temperature is too high (>150). o C) This will trigger the dehydration of cyclohexanol to form dicyclohexyl ether. This invention controls the etherification temperature at 50-100°C. o C. Hydrolysis temperature is controlled at 100-150°C. o C, and by matching specific molecular sieve acidity, synergistic optimization of the two-step reaction was achieved.

[0012] Further, the molecular sieve catalyst I mentioned in step (1) is at least one of ZSM-5, Beta, and USY molecular sieves with a silicon-to-aluminum ratio (Si / Al atomic ratio) between 8 and 15, and the amount of molecular sieve catalyst I is 0.5-4% of the total mass of cyclohexene and ethanol. Using a molecular sieve with a low silicon-to-aluminum ratio as a catalyst can provide abundant acidic sites, which is conducive to the etherification reaction of cyclohexene and ethanol to generate cyclohexylethyl ether. In this process, the conversion rate of cyclohexene is not less than 95%, and the selectivity of cyclohexylethyl ether is not less than 98%.

[0013] Furthermore, the oxygen content in the nitrogen atmosphere described in step (1) is less than 50 ppm.

[0014] Further, the molecular sieve catalyst II mentioned in step (2) is at least one of ZSM-5, ZSM-11, and ZSM-5 / ZSM-11 eutectic molecular sieves, and the amount of molecular sieve catalyst II used is 1-5% of the total mass of cyclohexylethyl ether and water.

[0015] Furthermore, the extractant used in step (2) is at least one of n-butanol, isoamyl alcohol, and ethyl acetate.

[0016] Furthermore, the extraction temperature in step (2) is 25-40°C. o C, the volume ratio of extractant to oil phase is (1-3):1.

[0017] Furthermore, in step (2), the selectivity of cyclohexanol is not less than 95%, and the yield of cyclohexanol is not less than 85%.

[0018] The present invention employs the above technical solution to prepare cyclohexanol by etherification of cyclohexene and ethanol followed by hydrolysis. Compared with existing cyclohexanol synthesis methods, it has the following main advantages:

[0019] (1) This invention overcomes the inherent defect of low conversion rate in the direct hydration method of cyclohexene by using a two-step tandem process of etherification and hydrolysis. Data from the examples show that the cyclohexene conversion rate is ≥98% and the cyclohexanol yield is ≥85%, which are significantly higher than the conversion rate (12%) and yield (11%) of the direct hydration method in Comparative Example 1. Crucially, the two reaction conditions are mildly matched. The high conversion rate and high selectivity of the first etherification reaction provide a high-purity intermediate for the subsequent hydrolysis, avoiding the energy consumption and equipment load caused by raw material recycling in traditional processes.

[0020] (2) The present invention uses a molecular sieve catalyst, which has the advantages of adjustable acid strength, significant pore shape selection effect and high thermal stability compared with Amberlyst-15 resin or homogeneous acid catalyst. Furthermore, it can be recovered by simple filtration after reaction, which significantly reduces the cost of catalyst and the burden of solid waste treatment, and meets the requirements of green chemical development.

[0021] (3) The stepwise process of etherification-hydrolysis adopted in this invention is suitable for segmented reactors or microchannel reactors. Compared with the high-pressure direct method, it is easier to achieve continuous production and is suitable for continuous operating systems in process industries. It can achieve steady-state operation under normal pressure and improve the level of automation and safety.

[0022] (4) The main byproduct of this invention is ethanol produced by hydrolysis, which can be recovered by distillation and recycled to the etherification step to achieve the recycling of raw materials. The reaction path has high atom utilization rate, avoiding the disadvantages of generating a large amount of carboxylic acid byproducts in the cyclohexane oxidation method and consuming hydrogen resources in the phenol hydrogenation method. Detailed Implementation

[0023] The present invention will be further illustrated below by means of specific embodiments, but these embodiments do not constitute a limitation of the present invention.

[0024] Example 1

[0025] A method for indirectly preparing cyclohexanol from cyclohexene includes the following steps:

[0026] (1) Add 10.0 g of cyclohexene, 13.5 g of ethanol and 0.1180 g of ZSM-5 molecular sieve catalyst with a silicon-to-aluminum ratio of 8 to a high-pressure reactor, and repeatedly purge with nitrogen three times to replace the air in the reactor. Apply a nitrogen pressure of 0.1 MPa under stirring and raise the temperature to 50°C. o C. After the reaction proceeded for 12 hours, the reaction was stopped. Subsequently, samples were taken and analyzed by gas chromatography. The calculated conversion rate of cyclohexene was 98.8%, the selectivity of cyclohexyl ethyl ether was 98.0%, and the yield of cyclohexyl ethyl ether was 96.8%. At the same time, the mixture after the reaction was filtered and distilled to obtain cyclohexyl ethyl ether.

[0027] (2) Add 17.49 mL of the cyclohexyl ethyl ether obtained above, 17.49 mL of deionized water, and 0.32 g of ZSM-5 molecular sieve catalyst to a high-pressure reactor, and repeatedly purge with nitrogen three times to replace the air in the reactor. Apply a nitrogen pressure of 0.1 MPa under stirring, and raise the temperature to 100°C. o C. Stop the reaction after 10 hours. Mix the oil phase and n-butanol at a volume ratio of 1:1 and heat at 35°C. o Extraction was performed at C, and after distillation, samples were analyzed by gas chromatography. The calculated conversion rate of cyclohexyl ethyl ether was 90.0%, the selectivity of cyclohexanol was 95.0%, and the yield of cyclohexanol was 85.5%.

[0028] Example 2

[0029] A method for indirectly preparing cyclohexanol from cyclohexene includes the following steps:

[0030] (1) 10.0 g of cyclohexene, 16.8 g of ethanol and 0.2680 g of Beta molecular sieve catalyst with a silicon-to-aluminum ratio of 9 were added to a high-pressure reactor, and nitrogen gas was repeatedly introduced three times to replace the air in the reactor. Under stirring, a nitrogen pressure of 0.4 MPa was applied, and the temperature was raised to 65°C. o C. After the reaction proceeded for 9 hours, the reaction was stopped. Subsequently, samples were taken and analyzed by gas chromatography. The calculated conversion rate of cyclohexene was 99.5%, the selectivity of cyclohexyl ethyl ether was 98.6%, and the yield of cyclohexyl ethyl ether was 98.1%. At the same time, the mixture after the reaction was filtered and distilled to obtain cyclohexyl ethyl ether.

[0031] (2) Add 17.72 mL of the cyclohexyl ethyl ether obtained above, 35.44 mL of deionized water, and 0.9820 g of ZSM-11 catalyst to a high-pressure reactor, and repeatedly purge with nitrogen three times to replace the air in the reactor. Apply a nitrogen pressure of 0.4 MPa under stirring, and raise the temperature to 115°C. o C, stop the reaction after 7 hours. Mix the oil phase and isoamyl alcohol at a volume ratio of 1:2 and heat at 35°C. o After extraction and distillation at C, samples were analyzed by gas chromatography. The calculated conversion rate of cyclohexyl ethyl ether was 91.0%, the selectivity of cyclohexanol was 95.4%, and the yield of cyclohexanol was 86.8%.

[0032] Example 3

[0033] A method for indirectly preparing cyclohexanol from cyclohexene includes the following steps:

[0034] (1) 10.0 g of cyclohexene, 22.4 g of ethanol and 0.6480 g of USY molecular sieve catalyst with a silicon-to-aluminum ratio of 8 were added to a high-pressure reactor, and nitrogen gas was repeatedly introduced three times to replace the air in the reactor. Under stirring, a nitrogen pressure of 0.7 MPa was applied, and the temperature was raised to 80°C. o C. After the reaction proceeded for 4 hours, the reaction was stopped. Subsequently, samples were taken and analyzed by gas chromatography. The calculated conversion rate of cyclohexene was 98.2%, the selectivity of cyclohexyl ethyl ether was 98.1%, and the yield of cyclohexyl ethyl ether was 96.3%. At the same time, the mixture after the reaction was filtered and distilled to obtain cyclohexyl ethyl ether.

[0035] (2) 17.35 mL of the cyclohexyl ethyl ether obtained above, 69.4 mL of deionized water, and 2.50 g of ZSM-5 / ZSM-11 eutectic molecular sieve catalyst were added to a high-pressure reactor, and nitrogen gas was repeatedly introduced three times to replace the air in the reactor. A nitrogen pressure of 0.7 MPa was applied under stirring, and the temperature was raised to 125 °C. o C, stop the reaction after 6 hours. Mix the oil phase and ethyl acetate at a volume ratio of 1:3 and heat at 35°C. o Extraction was performed at C, and samples were taken after distillation and analyzed by gas chromatography. The calculated conversion rate of cyclohexyl ethyl ether was 92.8%, the selectivity of cyclohexanol was 96.7%, and the yield of cyclohexanol was 89.7%.

[0036] Example 4

[0037] A method for indirectly preparing cyclohexanol from cyclohexene includes the following steps:

[0038] (1) 10.0 g of cyclohexene, 25.3 g of ethanol and 1.0590 g of ZSM-5 molecular sieve catalyst with a silicon-to-aluminum ratio of 12 were added to a high-pressure reactor, and nitrogen gas was repeatedly introduced three times to replace the air in the reactor. Under stirring, a nitrogen pressure of 0.8 MPa was applied, and the temperature was raised to 90°C. o C. After the reaction proceeded for 3 hours, the reaction was stopped. Subsequently, samples were taken and analyzed by gas chromatography. The calculated conversion rate of cyclohexene was 98.8%, the selectivity of cyclohexyl ethyl ether was 98.0%, and the yield of cyclohexyl ethyl ether was 96.8%. At the same time, the mixture after the reaction was filtered and distilled to obtain cyclohexyl ethyl ether.

[0039] (2) 17.46 mL of the cyclohexyl ethyl ether obtained above, 122.2 mL of deionized water, and 4.730 g of ZSM-5 molecular sieve catalyst were added to a high-pressure reactor, and nitrogen gas was repeatedly introduced three times to replace the air in the reactor. A nitrogen pressure of 0.8 MPa was applied under stirring, and the temperature was raised to 135 °C. o C. Stop the reaction after 4 hours. Mix the oil phase and n-butanol at a volume ratio of 1:1 and heat at 35°C. o Extraction was performed at C, and samples were taken after distillation and analyzed by gas chromatography. The calculated conversion rate of cyclohexyl ethyl ether was 94.7%, the selectivity of cyclohexanol was 95.1%, and the yield of cyclohexanol was 87.1%.

[0040] Example 5

[0041] A method for indirectly preparing cyclohexanol from cyclohexene includes the following steps:

[0042] (1) 10.0 g of cyclohexene, 28.1 g of ethanol, and 1.5240 g of ZSM-5 molecular sieve catalyst with a silicon-to-aluminum ratio of 15 were added to a high-pressure reactor, and nitrogen gas was repeatedly introduced three times to replace the air in the reactor. Under stirring, a nitrogen pressure of 1 MPa was applied, and the temperature was raised to 100°C. o C. After the reaction proceeded for 1 hour, the reaction was stopped. Subsequently, samples were taken and analyzed by gas chromatography. The calculated conversion rate of cyclohexene was 98.4%, the selectivity of cyclohexyl ethyl ether was 98.6%, and the yield of cyclohexyl ethyl ether was 97.0%. At the same time, the mixture after the reaction was filtered and distilled to obtain cyclohexyl ethyl ether.

[0043] (2) Add 17.53 mL of the cyclohexyl ethyl ether obtained above, 175.3 mL of deionized water, and 9.30 g of ZSM-5 molecular sieve catalyst to a high-pressure reactor, and repeatedly purge with nitrogen three times to replace the air in the reactor. Apply a nitrogen pressure of 1 MPa under stirring, and raise the temperature to 150°C. o C, stop the reaction after 2 hours. Mix the oil phase and n-butanol at a volume ratio of 1:1 and heat at 35°C. oExtraction was performed at C, and samples were taken after distillation and analyzed by gas chromatography. The calculated conversion rate of cyclohexyl ethyl ether was 93.6%, the selectivity of cyclohexanol was 95.4%, and the yield of cyclohexanol was 89.3%.

[0044] Comparative Example 1

[0045] Direct hydration of cyclohexene to prepare cyclohexanol

[0046] 8.2 g of cyclohexene was added to a 100 mL stainless steel reactor, along with 50 mL of deionized water and 1.0 g of Amberlyst-15 solid acid catalyst. After three nitrogen purgings, the mixture was reacted at 80 °C. o The reaction was stirred at C for 4 h. After the reaction was complete, the mixture was cooled to room temperature and neutralized with 10 wt% NaOH solution. The mixture was then transferred to a separatory funnel and extracted three times with ethyl chloroform. The organic layers were combined, dried over anhydrous sodium sulfate, and the solvent was removed by vacuum evaporation to obtain the crude product. GC analysis showed a single-pass conversion of cyclohexene of 12.0%, a selectivity of 92.0% for cyclohexanol, and a yield of approximately 1.15 g of cyclohexanol. Byproducts mainly included small amounts of polymers and heavy impurities. This comparative process requires high acidity conditions, has a low conversion rate, and is prone to side reactions, which is not conducive to industrial application.

[0047] Comparative Example 2

[0048] catalytic oxidation of cyclohexane to cyclohexanol

[0049] Add 8.4 g cyclohexane, 20 mL acetic acid, 0.5 mmol cobalt acetate, 0.5 mmol manganese acetate, and a trace amount of NBS (0.01 mmol) to a 100 mL autoclave. After three oxygen purgings, raise the temperature to 150 °C. o At C, oxygen was introduced to 1.0 MPa, and the reaction was stirred for 6 h under these conditions. After the reaction was completed, the mixture was cooled to room temperature and the residual pressure was released. The system was diluted with ethyl acetate, filtered to remove metal precipitates, washed with saturated NaHCO3 solution until neutral, dried, and the solvent was removed to obtain a KA oil mixture. GC analysis showed a cyclohexane conversion of 35.2% and a cyclohexanol selectivity of 60.0%, corresponding to a cyclohexanol yield of approximately 2.10 g. This route has limited selectivity, and the product is a mixture of cyclohexanol / cyclohexanone, requiring further separation or hydrogenation. The process involves significant energy consumption and post-processing burden.

[0050] Comparative Example 3

[0051] Preparation of cyclohexanol by hydrogenation of phenol

[0052] 9.4 g of phenol and 30 mL of ethanol were added to a high-pressure hydrogenation reactor, along with 200 mg of 5 wt% Ru / C catalyst. After purging with nitrogen and then hydrogen, the pressure was increased to 5.0 MPa and the temperature was raised to 80°C.o C reacted under stirring for 4 h. After the reaction, the temperature was lowered and the gas was slowly released. The catalyst was recovered by filtration, and the solvent was removed by rotary evaporation of the filtrate to obtain the crude product. High-purity cyclohexanol was obtained by vacuum distillation or short column purification. GC results showed that the phenol conversion rate was 98.7% and the cyclohexanol selectivity was 93.2%. Although this process can obtain high-purity cyclohexanol, it requires high-pressure hydrogen and a precious metal catalyst, has high equipment requirements, and is costly.

[0053] Compared to the embodiments of the present invention, the direct hydration method of cyclohexene in Comparative Example 1 requires high acidity conditions, has a single-pass conversion rate of only 12.0%, a low cyclohexanol yield (only about 11-12 mmol), and produces byproducts including polymers and heavy impurities. The reaction conditions are harsh and prone to side reactions, hindering industrial application. In contrast, the embodiments of the present invention achieve a cyclohexene conversion rate of up to 98.2% and a cyclohexanol yield of 90.0% under mild conditions through a two-step coupling of cyclohexene etherification and re-hydrolysis, with fewer byproducts. This green and efficient process is more suitable for large-scale production.

[0054] While the cyclohexane oxidation method in Comparative Example 2 utilizes cyclohexane as a feedstock, its conversion rate is limited (cyclohexane conversion is approximately 35%), with cyclohexane accounting for only 60% of the total product, resulting in a low yield (approximately 21 mmol). Furthermore, the product is a mixture of cyclohexane and cyclohexanone, requiring additional separation or hydrogenation, leading to high energy consumption and a heavy post-processing burden. In contrast, the embodiments of this invention employ an etherification-hydrolysis coupled route, achieving a high-selectivity cyclohexane yield (90.0% cyclohexane yield) under atmospheric or low-pressure conditions. This avoids complex separation, reduces energy consumption and process difficulty, demonstrating significant industrial advantages.

[0055] While the phenol hydrogenation route in Comparative Example 3 can yield high-purity cyclohexanol (92% yield), it requires high-pressure hydrogen and a precious metal catalyst (such as Ru / C), placing high demands on equipment, incurring high operating costs, and posing significant safety risks. In contrast, the embodiments of this invention utilize a ZSM-5 molecular sieve-catalyzed etherification-hydrolysis tandem route, eliminating the need for high-pressure hydrogen or precious metal catalysts. This route achieves high yield and high selectivity of cyclohexanol (90.0% yield) under mild conditions. The process is safer and more economical, and the catalyst is easily recyclable, demonstrating significant advantages in terms of greenness and cost-effectiveness.

[0056] This invention utilizes a ZSM-5 molecular sieve-catalyzed cyclohexene etherification-rehydrolysis tandem process to efficiently prepare cyclohexanol. Compared to existing cyclohexene hydration methods, this process is milder, has higher conversion rates, better yields, and fewer byproducts. Compared to cyclohexane oxidation, it is simpler, offers higher product selectivity, and reduces energy consumption and separation difficulty. Compared to phenol hydrogenation, it eliminates the need for high-pressure hydrogen or precious metal catalysts, ensuring safer operation, lower costs, and catalyst recyclability. This process balances high yield, high selectivity, and industrial feasibility, achieving green and efficient cyclohexanol production.

[0057] Table 1. Reaction results of Examples 1-5 and Comparative Examples 1-3

[0058]

[0059] It should be noted that the present invention is not limited to the specific embodiments described above. Any suitable modifications made without contradiction should be considered as part of the content disclosed in the present invention.

Claims

1. A method for indirectly preparing cyclohexanol from cyclohexene, characterized in that, Includes the following steps: (1) In the presence of molecular sieve catalyst I, cyclohexene and ethanol were subjected to an etherification reaction under a nitrogen atmosphere at a reaction temperature of 50-100 °C. o C, at a pressure of 0.1-1 MPa, and a reaction time of 1-12 h, yields cyclohexylethyl ether; The molecular sieve catalyst I is at least one of ZSM-5, Beta, and USY molecular sieves with a silica-alumina ratio between 8 and 15. (2) In the presence of molecular sieve catalyst II, cyclohexylethyl ether undergoes a hydrolysis reaction with water at a reaction temperature of 100-150 °C. o C, the reaction pressure is 0.1-1 MPa, the reaction time is 2-10 h, and the oil phase is extracted and distilled to obtain cyclohexanol; The molecular sieve catalyst II is at least one of ZSM-5, ZSM-11, and ZSM-5 / ZSM-11 eutectic molecular sieves.

2. The method for indirectly preparing cyclohexanol from cyclohexene according to claim 1, characterized in that, The amount of molecular sieve catalyst I used in step (1) is 0.5-4% of the total mass of cyclohexene and ethanol.

3. The method for indirectly preparing cyclohexanol from cyclohexene according to claim 1, characterized in that, The molar ratio of cyclohexene to ethanol in step (1) is 1:1.5-5.

4. The method for indirectly preparing cyclohexanol from cyclohexene according to claim 1, characterized in that, The oxygen content in the nitrogen atmosphere described in step (1) is less than 50 ppm.

5. The method for indirectly preparing cyclohexanol from cyclohexene according to claim 1, characterized in that, The amount of molecular sieve catalyst II used in step (2) is 1-5% of the total mass of cyclohexyl ethyl ether and water.

6. The method for indirectly preparing cyclohexanol from cyclohexene according to claim 1, characterized in that, The volume ratio of cyclohexyl ethyl ether to water in step (2) is 1:1-10.

7. The method for indirectly preparing cyclohexanol from cyclohexene according to claim 1, characterized in that, The extractant used in step (2) is at least one of n-butanol, isoamyl alcohol, and ethyl acetate.

8. A method for indirectly preparing cyclohexanol from cyclohexene according to claim 7, characterized in that, The extraction temperature in step (2) is 25-40°C. o C, the volume ratio of extractant to oil phase is 1-3:1.

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