A process for the isomerization-directed synthesis of methyl decenol

Abstract

This application relates to the field of organic chemical synthesis and discloses a directional isomerization synthesis process for methyldecenol, comprising the following steps: Stage 1, preparation of the intermediate 2-methyl-2-pentenal; Stage 2, preparation of Grignard reagent; Stage 3, synthesis of the target product 4-methyl-3-decen-5-ol; and Stage 4, product purification. In the aldol condensation reaction of Stage 1, this invention effectively suppresses side reactions such as the self-condensation of propanal by using an ice-salt bath to strictly control the reaction system at a low temperature of 0-5°C, combined with subsequent sufficient low-temperature ripening steps. This ensures a high yield and high purity of the intermediate 2-methyl-2-pentenal, improving the final yield of the entire process. Furthermore, in the key Grignard addition step of Stage 3, this invention achieves efficient directional synthesis of the target product by precisely controlling the reaction temperature at 10-15°C and using an ice-cold saturated ammonium chloride solution for gentle quenching.

Description

Technical Field

[0001] This invention relates to the field of organic chemical synthesis technology, specifically to a directional synthesis process for the isomerization of methyldecenol. Background Technology

[0002] Methyldecenol, as an important chemical, has wide applications in the fine chemical industry, including fragrances and flavorings. Its synthesis typically employs the classic route of addition reaction between Grignard reagents and α,β-unsaturated aldehydes. However, existing synthetic processes still face numerous technical challenges in practical applications. These challenges are interconnected and collectively restrict product yield and production efficiency. In the raw material preparation stage, the synthetic reaction conditions of α,β-unsaturated aldehydes (such as 2-methyl-2-pentenal in this invention), which are key intermediates, are often difficult to control, leading to increased side reactions and low intermediate purity. This directly affects the reaction efficiency of subsequent steps and the quality of the final product.

[0003] A more critical challenge lies in the core Grignard addition step. Due to the presence of two electrophilic sites in α,β-unsaturated aldehydes, the attack of Grignard reagents lacks sufficient directional selectivity, often resulting in the coexistence of the desired 1,2-addition product and the undesirable 1,4-conjugated addition byproduct. This not only significantly reduces the yield of the target product but also poses great difficulties for subsequent separation and purification. Furthermore, the post-reaction processing is equally crucial. The hydrolysis of the magnesium alkoxide and the quenching of the remaining Grignard reagent require mild conditions. Improper handling, such as using strongly acidic conditions, can easily cause side reactions such as dehydration of the structurally sensitive target product (allyl alcohol), further impairing the yield. Finally, in the product purification stage, traditional extraction, washing, batch drying, and filtration processes are cumbersome, time-consuming, and labor-intensive. Material loss is inevitable during multiple transfers, thus lowering the overall yield of the process and hindering efficient and economical large-scale production. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a directional isomerization synthesis process for methyldecenol, which solves the problems of low overall yield caused by poor reaction selectivity, numerous side reactions, and cumbersome post-processing.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a directional synthesis process for the isomerization of methyldecenol, comprising the following steps: Stage 1, Preparation of intermediate 2-methyl-2-pentenal: Propanal was subjected to aldol condensation and dehydration reaction under low temperature and alkaline conditions to prepare and purify the core intermediate 2-methyl-2-pentenal required for the subsequent Grignard addition reaction. Phase 2, Preparation of Grignard reagent: Magnesium pentyl chloride Grignard reagent, another key reactant for nucleophilic addition, is prepared by reacting magnesium powder with 1-chloro-n-pentane in anhydrous tetrahydrofuran solvent. Phase 3, Synthesis of the target product 4-methyl-3-decen-5-ol: The 2-methyl-2-pentenal prepared in Phase 1 and the n-pentyl magnesium chloride Grignard reagent prepared in Phase 2 were subjected to a Grignard addition reaction at a controlled low temperature. After quenching and extraction, a crude solution of the target product was obtained. Phase 4, Product Purification: The crude product solution obtained in Phase 3 is efficiently dehydrated and filtered using online zone drying technology, and then purified by solvent removal and vacuum distillation to finally obtain the high-purity target product 4-methyl-3-decen-5-ol.

[0006] Preferred, one stage includes: S1. Preparation and cooling of alkali solution: Prepare 400ml of 10% sodium hydroxide aqueous solution in a 1000ml three-necked flask, start stirring, and cool the alkali solution at 0~5℃ using an external cooling device. S2, Aldol Condensation Reaction: In the alkaline solution prepared in step S1 and cooled to 0~5℃, while keeping the mixture stirred, slowly add 232g of n-propanal. During the addition process, adjust the addition rate to ensure that the reaction temperature does not exceed 5℃. S3. Reaction ripening and separation: After all the propanal in step S2 has been added, continue stirring at 0~5℃ to ripen the reaction for 2 hours. After the reaction is completed, stop stirring and transfer the reaction solution to a separatory funnel to stand. S4. Washing and purification of intermediate: Take the upper organic phase obtained in step S3, discard the lower aqueous phase, and wash the organic phase with 200 ml of water in sequence. After washing, transfer the organic phase to a distillation apparatus and perform atmospheric distillation. Collect the target fraction to obtain the pure intermediate 2-methyl-2-pentenal.

[0007] Preferably, Phase Two includes: S5. Equipment preparation and feeding: Take another 1000ml three-necked flask, cool it to room temperature under nitrogen or argon protection, and quickly add 48.6g of dry magnesium powder and 500ml of dried anhydrous tetrahydrofuran solvent to the dry flask. S6. Reaction initiation: Start stirring and add a small grain of iodine as an initiator to the magnesium-THF suspension prepared in step S5. After the reaction starts, immediately prepare for the next step of dropwise addition. S7. Grignard reagent generation: After the reaction in step S6 is successfully initiated, 178.4 g of 1-chloro-n-pentane is slowly added dropwise through a constant pressure dropping funnel. After the addition is complete, the reaction is stirred for another hour to obtain a gray-black or brown granitic magnesium chloride Grignard reagent solution.

[0008] Preferably, Phase 3 includes: S8. Grignard addition reaction: The Grignard reagent solution obtained in step S7 is cooled to 10°C by external cooling. At the same time, 164.3g of 2-methyl-2-pentenal obtained in step S4 is diluted with an appropriate amount of anhydrous THF and placed in a constant pressure dropping funnel. The diluted aldehyde solution is then slowly added dropwise to the Grignard reagent. S9. Reaction ripening: After all the aldehyde solution in step S8 has been added dropwise, keep the cooling water circulating and continue to stir the reaction at 10-15℃ for 5 hours. S10. Reaction quenching: Take another large-capacity beaker, add 200ml of saturated ammonium chloride aqueous solution and enough crushed ice in advance, and place it in an ice bath and stir. Slowly and in batches, pour the reaction solution that has been matured in step S9 into the chilled quenching solution while stirring. S11. Product extraction and washing: Transfer all the mixture after quenching in step S10 to a separatory funnel, let it stand to separate the layers, separate the organic layer, and the aqueous layer can be back-extracted once with a small amount of THF or ether. Combine all the organic layers, and then wash them twice with 200ml of saturated saline solution.

[0009] Preferably, Phase Four includes: S12. Online Zone Drying: Based on the organic phase washed in step S11, online zone drying technology is used for efficient dehydration, including: Preparation of drying column: Prepare a glass column with a glass frit plate at the bottom in advance, lay a layer of filter aid about 1 cm thick at the bottom, and then tightly fill it with anhydrous sodium sulfate particles to a height of 5 to 10 cm to construct the drying zone; Online filtration and drying: The organic phase obtained in step S11, which still contains trace amounts of moisture, is poured directly from the top of the drying column; Collection: The organic phase is allowed to flow through the drying zone by gravity. At the column outlet, the clear filtrate that has been dried and filtered simultaneously is collected directly in a pre-weighed round-bottom flask. S13. Solvent Removal and Vacuum Distillation Purification: The round-bottom flask containing the dried filtrate collected in step S12 is directly connected to a rotary evaporator. The solvent tetrahydrofuran is efficiently removed by atmospheric distillation or vacuum distillation using a water pump. After the solvent is basically evaporated and the remaining oily crude product is left in the flask, the apparatus is changed to vacuum distillation configuration. The remaining crude product is then distilled, with careful control of the vacuum degree and heating temperature. The fraction with the specified boiling range is collected, which is the high-purity target product 4-methyl-3-decen-5-ol.

[0010] This invention provides a directional isomerization synthesis process for methyldecenol. It offers the following advantages: 1. This invention effectively suppresses side reactions such as the self-condensation of n-propanal by using an ice-salt bath to strictly control the reaction system at a low temperature of 0~5℃ in the aldol condensation reaction of stage one, and by combining it with a sufficient low-temperature ripening step thereafter. This ensures the high yield and high purity of the intermediate 2-methyl-2-pentenal, providing a high-quality raw material basis for the subsequent highly selective Grignard addition reaction, thereby improving the final yield of the entire process route.

[0011] 2. In the key Grignard addition step of stage three, this invention achieves efficient and targeted synthesis of the target product by precisely controlling the reaction temperature at 10-15℃ and using an ice-cold saturated ammonium chloride solution for gentle quenching.

[0012] 3. In the product purification process of stage four, this invention innovatively employs online zone drying technology, directly passing the organic phase containing trace amounts of water through a pre-fabricated anhydrous sodium sulfate drying column. This method combines the traditional stirring drying and filtration steps into one, significantly simplifying the post-processing procedures and shortening the processing time. It also avoids product loss caused by multiple material transfers, making the entire purification process more efficient and convenient, and conducive to industrial-scale production. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the chemical structure of the present invention; Figure 5 This is a flowchart of the first stage of the present invention; Figure 2 This is a flowchart of the second stage of the present invention; Figure 3 This is a flowchart illustrating the three stages of the present invention; Figure 4 This is a flowchart of the four stages of the present invention. Detailed Implementation

[0014] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] Please see the appendix Figure 1 —Appendix Figure 5 This invention provides a process for the isomerization-directed synthesis of methyldecenol, comprising the following steps: Stage 1: Preparation of intermediate 2-methyl-2-pentenal: S1. Preparation and cooling of alkali solution: Prepare 400ml of 10% sodium hydroxide (NaOH) aqueous solution in a 1000ml three-necked flask, start stirring, and cool the alkali solution at 0~5℃ using an external cooling device to prepare for the subsequent low-temperature condensation reaction. The external cooling device includes: an ice-salt bath; S2, Aldol Condensation Reaction: In the alkaline solution prepared in step S1 and cooled to 0~5℃, while maintaining stirring, slowly add 232g of n-propanal. During the addition process, the temperature inside the reactor must be strictly monitored, and the addition rate must be adjusted to ensure that the reaction temperature does not exceed 5℃ to suppress the occurrence of side reactions. S3. Reaction ripening and separation: After all the propanal in step S2 has been added, continue stirring at 0~5℃ to ripen the reaction for 2 hours to ensure that the condensation reaction is fully carried out. After the reaction is completed, stop stirring, transfer the reaction solution to a separatory funnel and let it stand until it is fully separated. S4. Washing and purification of intermediate: Take the upper organic phase obtained in step S3, discard the lower aqueous phase, and wash the organic phase with 200 ml of water twice in total to remove residual alkali and water-soluble impurities. After washing, transfer the organic phase to a distillation apparatus and perform atmospheric distillation. Collect the target fraction to obtain the pure intermediate 2-methyl-2-pentenal, and seal it for later use. Phase Two: Preparation of Grignard Reagents S5. Equipment preparation and feeding: Take another 1000ml three-necked flask, and ensure that it and all the matching glassware have undergone strict flame drying or oven drying treatment, and cool to room temperature under nitrogen or argon protection. Quickly add 48.6g of dried magnesium powder and 500ml of dried anhydrous tetrahydrofuran solvent to the dried flask. S6. Reaction initiation: Start stirring and add a small particle of iodine (I2) as an initiator to the magnesium-THF suspension prepared in step S5. Closely observe the system and prepare for the next dropwise addition immediately after the reaction starts. The initiation of the reaction typically manifests as the decolorization of iodine, a slight discoloration of the solution, or a mild exothermic reaction in the system. S7. Grignard reagent generation: After the reaction initiation in step S6 is successful, 178.4 g of 1-chloro-n-pentane is slowly added dropwise through a constant pressure dropping funnel. The dropping rate is precisely controlled so that the temperature of the reaction solution is kept under slight reflux due to the exothermic reaction. After the addition is complete, the reaction is stirred for 1 hour to ensure that the magnesium powder is completely consumed, resulting in a gray-black or brown n-pentyl magnesium chloride Grignard reagent solution. This reagent is used directly for subsequent Grignard addition reactions without separation and purification. Phase 3: Synthesis of the target product, 4-methyl-3-decen-5-ol: S8. Grignard addition reaction: The Grignard reagent solution obtained in step S7 is cooled to 10°C by external cooling. Simultaneously, 164.3 g of 2-methyl-2-pentenal purified in step S4 is diluted with an appropriate amount of anhydrous THF and placed in a constant-pressure dropping funnel. The diluted aldehyde solution is then slowly added dropwise to the Grignard reagent. During the addition process, the temperature of the reaction system is strictly controlled within the range of 10-15°C, and the addition process is completed within 2 hours. The external cooling method includes: an ice-water bath; S9. Reaction ripening: After all the aldehyde solution in step S8 has been added dropwise, keep the cooling water circulating and continue to stir the reaction at 10-15℃ for 5 hours to ensure that the Grignard addition reaction proceeds fully and to generate the magnesium alkoxide of the target product to the maximum extent. S10. Reaction quenching: Take another large-capacity beaker, add 200ml of saturated ammonium chloride (NH4Cl) aqueous solution and sufficient crushed ice in advance, and place it in an ice bath and stir. Slowly and in batches, pour the reaction solution that has been matured in step S9 into the chilled quenching solution while stirring, so as to gently decompose the remaining Grignard reagent and hydrolyze the magnesium alkoxide into the target product alcohol. S11. Product extraction and washing: Transfer all the mixture after quenching in step S10 to a separatory funnel, let it stand to separate the layers, separate the organic layer, and the aqueous layer can be back-extracted once with a small amount of THF or ether. Combine all the organic layers, and then wash them twice with 200ml of saturated saline solution to remove most of the residual water and inorganic salts. Phase 4: Product Purification S12. Online Zone Drying: Based on the organic phase washed in step S11, online zone drying technology is used for efficient dehydration, including: Preparation of drying column: Prepare a glass column with a glass frit plate at the bottom in advance, lay a layer of filter aid about 1 cm thick at the bottom, and then tightly fill it with anhydrous sodium sulfate (Na2SO4) particles with a height of 5 to 10 cm to construct the drying zone; The filter aid includes: diatomaceous earth; Online filtration and drying: The organic phase obtained in step S11, which still contains trace amounts of moisture, is poured directly from the top of the drying column; Collection: The organic phase is allowed to flow through the drying zone by gravity. At the column outlet, the clear filtrate that has been dried and filtered simultaneously is collected directly in a pre-weighed round-bottom flask. S13. Solvent Removal and Vacuum Distillation Purification: The round-bottom flask containing the dried filtrate collected in step S12 is directly connected to a rotary evaporator. The solvent tetrahydrofuran is efficiently removed by atmospheric distillation or vacuum distillation using a water pump. After the solvent is basically evaporated and the remaining oily crude product is left in the flask, the apparatus is changed to vacuum distillation configuration. The remaining crude product is then distilled, with careful control of the vacuum degree and heating temperature. The fraction with the specified boiling range is collected, which is the high-purity target product 4-methyl-3-decen-5-ol. Comparative experiment: To verify the beneficial effects of the present invention, the embodiments provided by the present invention are used as Example 1, and a parallel experiment is conducted using a comparative example 1 that simulates existing conventional technology. Both experiments use the same batch and specifications of raw materials, and the amount of materials added is kept consistent to ensure the fairness of the comparison.

[0016] Example 1 (Process of the Invention) The steps S1 to S13 described in the invention were strictly followed. Key parameters and results are recorded below: Stage 1: The aldol condensation reaction temperature was strictly controlled between 0 and 5℃. After the reaction, 215.0 g of the intermediate 2-methyl-2-pentenal was obtained after purification. Gas chromatography (GC) analysis showed that its purity was 98.5%.

[0017] Stage 3: The Grignard addition reaction temperature is strictly controlled at 10~15℃. The reaction is quenched using an ice-cold saturated ammonium chloride aqueous solution.

[0018] Phase 4: Product purification employs online zone drying technology. The organic phase is directly passed through an anhydrous sodium sulfate drying column followed by rotary evaporation and vacuum distillation.

[0019] Final result: 248.1 g of the target product 4-methyl-3-decen-5-ol was finally obtained, with an overall yield (based on n-propionaldehyde) of approximately 75.1%. GC analysis showed that the product purity was 99.2%, and no obvious 1,4-addition byproducts were detected.

[0020] Comparative Example 1 (Conventional Technology and Process) This comparative example simulates a common but not precisely controlled synthesis method found in the literature.

[0021] Stage 1: Preparation of intermediate 2-methyl-2-pentenal: Step 1: Prepare 400ml of 10% sodium hydroxide (NaOH) aqueous solution in a 1000ml three-necked flask, start stirring, and cool the alkaline solution to 0~10℃ using an ice-water bath.

[0022] Step 2: Slowly add 232g of n-propanal to an alkaline solution at 0~10℃, and try to keep the reaction temperature below 10℃ by adjusting the dropping rate.

[0023] Steps 3 and 4: The subsequent aging, separation, washing and distillation steps are the same as in Example 1.

[0024] Results: After the reaction was completed, 188.5 g of the intermediate 2-methyl-2-pentenal was obtained after purification. GC analysis showed that its purity was 92.0%, and it contained a significant amount of other condensation byproducts.

[0025] Phase Two: Preparation of Grignard Reagents The steps are exactly the same as in stage two of Example 1, and equal amounts of n-pentyl magnesium chloride Grignard reagent solution are obtained.

[0026] Phase 3: Synthesis of the target product, 4-methyl-3-decen-5-ol: Step 8: Cool the Grignard reagent solution to approximately 0°C using an ice-water bath. Begin slowly adding 164.3 g of 2-methyl-2-pentenal prepared in Comparative Stage 1. After the addition is complete, remove the ice bath and continue stirring at room temperature (approximately 25°C).

[0027] Step 9: Continue stirring the reaction for 5 hours at room temperature.

[0028] Step 10: While stirring, slowly pour the reaction solution into a 10% dilute hydrochloric acid solution that has been pre-cooled with ice water for quenching and hydrolysis.

[0029] Step 11: Subsequent extraction and washing steps are the same as in Example 1.

[0030] Phase 4: Product Purification Step 12: Use the conventional batch drying method. Transfer the organic phase obtained in Step 11 to a 1000ml Erlenmeyer flask, add approximately 50g of anhydrous sodium sulfate powder, and stir to dry for 30 minutes. Then, remove the desiccant by filtration, and collect the filtrate in a clean round-bottom flask.

[0031] Step 13: Perform rotary evaporation and vacuum distillation on the collected filtrate.

[0032] Final result: 195.5 g of the target product 4-methyl-3-decen-5-ol was finally obtained, with a total yield (based on n-propanal) of approximately 59.2%. GC analysis showed that the product purity was 95.5%, containing approximately 2.8% 1,4-addition byproducts and a small amount of impurities generated by acid-catalyzed dehydration.

[0033] Comparison and Analysis of Experimental Results Conclusion: Comparative experiments clearly demonstrate that the isomerization-oriented synthesis process of methyldecenol provided by this invention, through precise control of reaction conditions and innovative post-processing steps, exhibits significant advantages over existing conventional technologies in terms of reaction selectivity, operational efficiency, final product yield, and purity.

[0034] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for the isomerization directed synthesis of methyl decenol, characterized in that, Includes the following steps: Stage 1, Preparation of intermediate 2-methyl-2-pentenal: Propanal was subjected to aldol condensation and dehydration reaction under low temperature and alkaline conditions to prepare and purify the core intermediate 2-methyl-2-pentenal required for the subsequent Grignard addition reaction. Phase 2, Preparation of Grignard reagent: Magnesium pentyl chloride Grignard reagent, another key reactant for nucleophilic addition, is prepared by reacting magnesium powder with 1-chloro-n-pentane in anhydrous tetrahydrofuran solvent. Phase 3, Synthesis of the target product 4-methyl-3-decen-5-ol: The 2-methyl-2-pentenal prepared in Phase 1 and the n-pentyl magnesium chloride Grignard reagent prepared in Phase 2 were subjected to a Grignard addition reaction at a controlled low temperature. After quenching and extraction, a crude solution of the target product was obtained. Phase 4, Product Purification: The crude product solution obtained in Phase 3 is efficiently dehydrated and filtered using online zone drying technology, and then purified by solvent removal and vacuum distillation to finally obtain the high-purity target product 4-methyl-3-decen-5-ol.

2. A process for the isomerization-directed synthesis of methyl decenoyl alcohol according to claim 1, characterized in that, One stage includes: S1. Preparation and cooling of alkali solution: Prepare 400ml of 10% sodium hydroxide aqueous solution in a 1000ml three-necked flask, start stirring, and cool the alkali solution at 0~5℃ using an external cooling device. S2, Aldol Condensation Reaction: In the alkaline solution prepared in step S1 and cooled to 0~5℃, while keeping the mixture stirred, slowly add 232g of n-propanal. During the addition process, adjust the addition rate to ensure that the reaction temperature does not exceed 5℃. S3. Reaction ripening and separation: After all the propanal in step S2 has been added, continue stirring at 0~5℃ to ripen the reaction for 2 hours. After the reaction is completed, stop stirring and transfer the reaction solution to a separatory funnel to stand. S4. Washing and purification of intermediate: Take the upper organic phase obtained in step S3, discard the lower aqueous phase, and wash the organic phase with 200 ml of water in sequence. After washing, transfer the organic phase to a distillation apparatus and perform atmospheric distillation. Collect the target fraction to obtain the pure intermediate 2-methyl-2-pentenal.

3. A process for the isomerization directed synthesis of methyl decenol according to claim 1, characterized in that, Phase Two includes: S5. Equipment preparation and feeding: Take another 1000ml three-necked flask, cool it to room temperature under nitrogen or argon protection, and quickly add 48.6g of dry magnesium powder and 500ml of dried anhydrous tetrahydrofuran solvent to the dry flask. S6. Reaction initiation: Start stirring and add a small grain of iodine as an initiator to the magnesium-THF suspension prepared in step S5. After the reaction starts, immediately prepare for the next step of dropwise addition. S7. Grignard reagent generation: After the reaction in step S6 is successfully initiated, 178.4 g of 1-chloro-n-pentane is slowly added dropwise through a constant pressure dropping funnel. After the addition is complete, the reaction is stirred for another hour to obtain a gray-black or brown granitic magnesium chloride Grignard reagent solution.

4. A process for the isomerization directed synthesis of methyl decenoyl alcohol as claimed in claim 1, wherein, Phase Three includes: S8. Grignard addition reaction: The Grignard reagent solution obtained in step S7 is cooled to 10°C by external cooling. At the same time, 164.3g of 2-methyl-2-pentenal obtained in step S4 is diluted with an appropriate amount of anhydrous THF and placed in a constant pressure dropping funnel. The diluted aldehyde solution is then slowly added dropwise to the Grignard reagent. S9. Reaction ripening: After all the aldehyde solution in step S8 has been added dropwise, keep the cooling water circulating and continue to stir the reaction at 10-15℃ for 5 hours. S10. Reaction quenching: Take another large-capacity beaker, add 200ml of saturated ammonium chloride aqueous solution and enough crushed ice in advance, and place it in an ice bath and stir. Slowly and in batches, pour the reaction solution that has been matured in step S9 into the chilled quenching solution while stirring. S11. Product extraction and washing: Transfer all the mixture after quenching in step S10 to a separatory funnel, let it stand to separate the layers, separate the organic layer, and the aqueous layer can be back-extracted once with a small amount of THF or ether. Combine all the organic layers, and then wash them twice with 200ml of saturated saline solution.

5. A process for the isomerization directed synthesis of methyl decenoyl alcohol as claimed in claim 1, wherein, Phase four includes: S12. Online Zone Drying: Based on the organic phase washed in step S11, online zone drying technology is used for efficient dehydration, including: Preparation of drying column: Prepare a glass column with a glass frit plate at the bottom in advance, lay a layer of filter aid about 1 cm thick at the bottom, and then tightly fill it with anhydrous sodium sulfate particles to a height of 5 to 10 cm to construct the drying zone; Online filtration and drying: The organic phase obtained in step S11, which still contains trace amounts of moisture, is poured directly from the top of the drying column; Collection: The organic phase is allowed to flow through the drying zone by gravity. At the column outlet, the clear filtrate that has been dried and filtered simultaneously is collected directly in a pre-weighed round-bottom flask. S13. Solvent Removal and Vacuum Distillation Purification: The round-bottom flask containing the dried filtrate collected in step S12 is directly connected to a rotary evaporator. The solvent tetrahydrofuran is efficiently removed by atmospheric distillation or vacuum distillation using a water pump. After the solvent is basically evaporated and the remaining oily crude product is left in the flask, the apparatus is changed to vacuum distillation configuration. The remaining crude product is then distilled, with careful control of the vacuum degree and heating temperature. The fraction with the specified boiling range is collected, which is the high-purity target product 4-methyl-3-decen-5-ol.

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